Research team

Plasma Lab for Applications in Sustainability and Medicine - Antwerp (PLASMANT)

Expertise

Combination of experimental and computational research on plasmas and plasma-surface interactions for various applications: 1) Plasma-based gas conversion and plasma catalysis for CO2 conversion into value-added chemicals and fuels, N2 fixation from the air to produce building blocks for our life (e.g. fertilizers), CH4 conversion into higher hydrocarbons and oxygenates,... This includes experiments in various plasma reactors to improve the conversion, selectivity and energy efficiency, as well as modeling the plasma chemistry, plasma reactor design and plasma-surface interactions. 2) Plasma treatment of cancer cells: pancreatic cancer, melanoma, glioblastoma, lung cancer, breast cancer. Study of the mechanisms of selective cancer treatment by comparison with normal cells. 3) Plasma-liquid interaction, for medical applications: Study of the behavior of plasma species in liquid. 4) Plasmas for analytical chemistry, materials science and micro-electronics applications: modeling the plasma chemistry for various gas mixtures and in various types of plasma reactors.

Towards the accurate modelling of the "building blocks" of plasma catalysis. 01/08/2021 - 31/07/2023

Abstract

Plasma catalysis is a potential technology to convert sustainable energy into value-added chemicals. However, little is known about how plasma catalysis works. Therefore, fundamental "building blocks" of plasma catalysis will be investigated here, i.e., the effect of vibrational excitation, electric fields, and charged surfaces, as induced by plasma . To do so, several different methods will be developed and combined with neural network potentials (NNPs). Furthermore, with these tools, accurate dynamical studies will be performed for the first time, for molecule-metal surface reactions under plasma conditions for the first time. By performing dynamical atomistic studies, insight into plasma reaction mechanisms can be gained. Such dynamical insights will then subsequently be implemented into a newly developed microkinetic model, which goes beyond microkinetic models that traditionally operate from a static point of view. Specifically, the reaction of vibrationally excited methane on Pt(111) will be investigated and tested against experiments in order to validate the employed approach. Furthermore, the dissociation of CO2 on Cu(111) upon influence of an electric field and a charged surface will be investigated with the newly developed methods and a state-of-the-art NNP. Finally, a microkinetic model for the hydrogenation of CO2 towards methanol on Cu(111) will be developed, which will include the aforementioned dynamical effects .

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CO2 utilization for the circular economy (D-CRBN). 01/04/2021 - 30/03/2022

Abstract

This postdoc project consists of two phases. The aim of phase 1 is to design innovative plasma reactors based on fundamental principles, and the knowledge present at PLASMANT. In the meantime, D-CRBN, the spin-off company of UAntwerp, targets a proof-of-principle of an improved atmospheric plasma reactor. In phase 2, the best reactor design will be constructed based on all collected information, and a complete prototype will be developed to be used by D-CRBN.

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Catalysis for CCU: Valorization of CO and CO2 by carbon capture and utilization 01/01/2021 - 31/12/2025

Abstract

This Scientific Research Network is composed of researchers with diverse but complementary backgrounds in the CCU field. This critical pool of scientific expertise can accelerate the development of catalytic CCU technologies and provide advice to government, industrial and public sectors. Our goal is to build a CCU network relevant to the Flemish/European industrial landscape, focused on sharing best practices and knowledge; stimulating collaboration; exposing young researchers; creating a community; being a go-to place for expertise; and sharing resources that individual researchers and knowledge institutes lack. We believe the conditions are perfect to make Flanders the leading region for the development and implementation of CCU technologies in Europe.

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Power-to-olefins: Electrified steam cracking and plasma booster. 01/01/2021 - 31/12/2024

Abstract

The aim of this product is to drastically reduce CO2 emissions of olefin production by replacing the combustion furnaces, responsible for 90% of the CO2 emissions of this process, by a combination of two new electrified reactor concepts, i.e., an electrified rotor stator steam cracker, and a plasma-based ethylene booster. Our contribution is the latter concept, for which we will develop a kinetic model and a reactor model for process optimization.

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Proof-of-concept for novel combination strategies with immunotherapy to treat solid tumors. 01/12/2020 - 30/11/2022

Abstract

Cancer immunotherapy strategies leave room for improvement. Given that a 'one-size-fits-all' approach is not the solution due to tumor heterogeneity, personalized therapy is the way forward. It is my mission to overcome hard-to-treat solid tumors and to push boundaries in achieving effective personalized immunotherapies. To accomplish this, the immunosuppressive nature of the tumor microenvironment needs to be overcome, allowing to significantly reduce its hampering effect on the activation and the infiltration of immune cells in tumors. My team recently demonstrated the power of certain activated immune cells to kill both cancer cells and cells of the tumor microenvironment that contribute to immunosuppression. With a view to further enhance antitumor effects, me and my team will unravel different inhibitory mechanisms that hamper antitumor immune cell responses and use these new insights to develop effective and personalized therapies that combine direct activation of immune cells with inhibition of immunosuppression. In the current 2-year project, we will gather novel tumor immunology data on 1) characterization of the tumor microenvironment, 2) interactions between tumor cells and immune cells, 3) relevant targeted treatment strategies and 4) biomarker identification; as important proofs-of-concept to further strengthen my European and consortium project applications in the near future.

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Fertiliser from air by plasma treatment (Sustainable Manure). 01/12/2020 - 30/11/2022

Abstract

This project's main objective is the commercialisation of a breakthrough technology for upgrading livestock manure to an improved fertiliser. The overall aim of the project is to fundamentally improve global food production, by increasing productivity and reducing emissions. The technology enables farmers to produce environmentally friendly fertiliser on the farm using slurry or biogas digestate, air and electricity. The technology is a manure processing unit that consists of a plasma reactor, an absorption system and a plasma generator with power supply. The consortium consists of three organisations, ScanArc Plasma Technologies AS, University of Antwerp and N2 Applied. The plasma technology for treating livestock manure, is an innovative technology with the following benefits: • providing a cost-effective alternative to chemical fertiliser, and thus improving farm economics • ensuring compliance with stricter environmental regulations, which in turn mitigates risk for farmers and ensures business continuity • reducing emissions in the farm-cycle and thus contributing to reducing greenhouse gases and air pollution • removing odour, giving the farmer flexibility in spreading, optimising the fertilising effect of manure, which reduces nutrient loss and pollution.

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Plasma-catalytic hydrogenation of CO2 to CH3OH: Study of the underlying mechanisms by integrated microkinetic modeling of plasma chemistry and surface reactions. 01/11/2020 - 31/10/2022

Abstract

There is a growing interest into strategies to convert CO2 into high-value chemicals. An interesting route is hydrogenation to CH3OH, which is a valuable fuel and chemical intermediate. However, by heterogeneous catalysis, the CO2 conversion and the corresponding CH3OH selectivity are limited by thermodynamics. A possible solution is combining catalysis with non-thermal plasma, which offers a unique way to enable kinetically limited processes, while maintaining thermodynamically favourable temperatures. In my project, I will computationally study the plasma-catalytic conversion of CO2 to CH3OH to gain a better understanding of the underlying mechanisms. Indeed, the knowledge of the mechanisms governing plasma catalysis is quite limited. I will start by developing a 0D chemical kinetics model for a CO2/H2 plasma. Subsequently, I will develop a microkinetic surface model to simulate the reactions occurring at the catalyst surface. In the following step I will couple these models to gain insight in how the catalyst reactions affect the gas phase composition and vice versa. I will also investigate the effect of different catalyst materials and of ZnO promotion. These models will be validated with experiments and improved when they do not produce adequate results. The ultimate goal is to optimize the plasma and catalyst conditions for the plasma-catalytic hydrogenation of CO2 to CH3OH.

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Nitrogen fixation through plasma-liquid interaction: Computational and experimental studies. 01/11/2020 - 31/10/2022

Abstract

The NH3 produced in the Haber-Bosch (H-B) process today sustains over 40% of the global population in the form of fertilizer. However, the H-B process is an extremely energy-intensive and CO2 emitting process that does not have much room left for optimization. In light of the pressing issue of climate change, the world thus calls for an environmentally friendly alternative for nitrogen fixation. My project will explore plasma-liquid interaction as a possible alternative. Plasma-based NH3 synthesis in general has the advantage of working at ambient conditions and can be coupled to renewable energy. Plasma-liquid interaction provides an additional advantage of eliminating the CO2-emitting methane steam reforming step, as it uses H2O as the hydrogen source instead of H2. To be able to optimize NH3 synthesis through plasma-liquid interaction, an in-depth knowledge of the underlying mechanisms is needed, which I aim to obtain through a combined 0D-2D modeling approach. I will use two different plasma sources, i.e. jet and DBD, and investigate their advantages and how to optimize their NH3 production. A research stay is planned at MIPSE for the development of the DBD model. Finally, I will perform experiments for validation of the models, as well as to gain a more complete understanding of the plasma-liquid systems and their capabilities.

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Model-based reactor design improvement in a gliding arc plasmatron for CO2 conversion with and without catalyst 01/11/2020 - 31/10/2022

Abstract

Global warming is a complex problem and the pressure for change is high. One pressing aspect is the greenhouse gas CO2. By converting the CO2 into value added chemicals and fuels, a sustainable cycle can be established. Plasma technology has the potential to fulfill this role, especially with the gliding arc plasmatron (GAP) reactor. However, its current performance is not sufficient. My project will focus on the conversion of CO2 and CO2/CH4 mixtures into value added chemicals in this reactor. Indeed, despite the promising results of the GAP, the current GAP design also faces limitations. Therefore, to optimize the conversion and energy efficiency, innovative designs are crucial. Moreover, the implementation of a catalyst for increased conversion and selectivity has not been tested. In order to achieve an optimal design and catalyst implementation, a thorough knowledge of the underlying mechanisms is needed, which I will gain by modeling and experiments. I plan to develop new designs by combining 0D chemical kinetics modeling and 3D fluid dynamics modeling, both with and without a catalytic bed. I will then validate these models experimentally. For dedicated plasma diagnostics, I will perform two research stays of two months each, i.e. at the Eindhoven University of Technology and Bochum University. In the end, this combined study will result in a fundamental understanding of this plasma reactor for an optimized performance.

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Investigation of non-thermal plasma therapy with first-line treatments of recurrent and metastatic head and neck squamous cell carcinoma: a novel combination with platinum-based chemotherapy and immunotherapy. 01/11/2020 - 31/10/2022

Abstract

Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cancer worldwide, and advanced HNSCC patients often experience relapse or metastasis (R/M HNSCC) resulting in dismal prognoses. These patients receive immunotherapy (ICI) alone or in combination with platinum-based chemotherapeutics (PLAT) as first-line treatment. While these combination treatments have some clinical benefit, they are limited by low response rates and severe side effects in already weakened patients. To address this, I will investigate a novel combination strategy with non-thermal plasma (NTP). NTP, an ionised gas, is a localised therapy that induces immunogenic cancer cell death (ICD), which can activate the patient's anti-cancer immunity. To date, no adverse side effects have been reported with the clinical use of NTP. Therefore, we hypothesize that combining NTP with PLAT/ICI will be well-tolerated and improve clinical efficacy in R/M HNSCC. In this project, I will perform 3D in vitro experiments on cell lines and primary patient material, and two mouse models will be used to validate the safety and clinical efficacy of this combination strategy. The successful completion of my project will help integrate NTP into current first-line therapies of R/M HNSCC as a new combination strategy to improve treatment efficacy and quality of life for those patients. This study will also be a stepping stone towards a broader implementation of NTP technology in other cancer types.

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InSusChem - Consortium for Integrated Sustainable Chemistry Antwerp. 15/10/2020 - 31/12/2026

Abstract

This IOF consortium connects chemists, engineers, economic and environmental oriented researchers in an integrated team to maximize impact in key enabling sustainable chemical technologies, materials and reactors that are able to play a crucial role in a sustainable chemistry and economic transition to a circular, resource efficient and carbon neutral economy (part of the 2030 and 2050 goals in which Europe aims to lead). Innovative materials, renewable chemical feedstocks, new/alternative reactors, technologies and production methods are essential and central elements to achieve this goal. Due to their mutual interplay, a multidisciplinary, concerted effort is crucial to be successful. Furthermore, early on prediction and identification of strengths, opportunities, weaknesses and threats in life cycles, techno-economics and sustainability are key to allow sustainability by design and create effective knowledge-based decision-making and focus. The consortium focuses on sustainable chemical production through efficient and alternative energy use connected to circularity, new chemical pathways, technologies, reactors and materials, that allow the use of alternative feedstock and energy supply. These core technical aspects are supported by expertise in simulation, techno-economic and environmental impact assessment and uncertainty identification to accelerate technological development via knowledge-based design and early stage identified key research, needed for accelerated growth and maximum impact on sustainability. To achieve these goals, the consortium members are grouped in 4 interconnected valorisation programs focusing on key performance elements that thrive the chemical industry and technology: 1) renewable building blocks; 2) sustainable materials and materials for sustainable processes; 3) sustainable processes, efficiently using alternative renewable energy sources and/or circular chemical building blocks; 4) innovative reactors for sustainable processes. In addition, cross-cutting integrated enablers are present, providing expertise and essential support to the 4 valorisation programs through simulation, techno-economic and environmental impact assessment and uncertainty analysis.

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From physical plasma to cellular pathway: a multi-disciplinary approach to unravel the response pathways induced by nonthermal plasma for cancer therapy. 01/10/2020 - 30/09/2023

Abstract

Cancer therapy has been rapidly transforming in part due to progress in seemingly unrelated fields. This has led to the development of profound tools for studying cancer pathways and innovative therapies. Non-thermal plasma (NTP) is a novel treatment that has been emerging for cancer immunotherapy. Bioinformatics is another field experiencing rapid growth, as the ability to collect and process large amounts of 'omics' data has become increasingly accessible. In the context of oncology, this has led to success in elucidating therapy-induced pathways and therapy target discovery. Therefore, in my project, I will use a combination of experimental and bioinformatics approaches to study fundamental effects of NTP on cancerous cells: 1) mechanisms driving cell sensitivity and 2) immunological changes to be exploited for combination therapy. In vitro experiments will be performed to categorize cells into sensitivity groups based on NTP-induced cell death; cellular redox and death modalities will also be studied. Transcriptome analysis and bioinformatics techniques will be used to uncover the activated pathways. Signature gene sets from transcriptome data will be studied to obtain a more comprehensive picture of the immunologic changes in NTP-treated cells. All in silico results will be validated experimentally. Success of this project will benefit multiple science fields and open new lines of research while providing insight into underlying mechanisms of NTP-induced cancer response.

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Research in plasma chemistry 01/02/2020 - 31/01/2026

Abstract

This research includes experiments and modeling on plasma used for environmental, green chemistry, and medical applications, more specifically: plasma-based gas conversion (CO2, N2, CH4) into value added compounds, as well as plasma for cancer treatment.

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Plasma-liquid interaction: Combined 0D-2D modeling and experimental validation. 01/01/2020 - 31/12/2023

Abstract

Plasma-liquid interaction is an important subfield of plasma science, with several promising applications, including water treatment, chemical synthesis, and especially in plasma medicine, e.g., cancer treatment, where plasma-treated liquids seem to have similar anti-cancer properties as the plasma itself, and can be more readily applied, e.g., to tumors inside the body. However, in spite of the growing interest in plasma-liquid interaction, there is still a poor understanding of the fundamental physical and chemical processes at the plasma-liquid interface and inside the liquid. The aim of this project is to obtain detailed insight in these mechanisms, by means of combined 0D-2D modeling, for two major plasma types, i.e., a plasma jet and a dielectric barrier discharge (DBD). The combination of 0D and 2D models is very interesting, because it allows us to combine their advantages, while avoiding their drawbacks. Indeed, a 0D model will describe the full plasma-liquid chemistry (i.e. gas phase, interface and liquid phase) with limited calculation time, but without spatial information, while the 2D fluid dynamics models will include limited chemistry, as they are time-consuming, but they will focus on the physical mechanisms of the interaction, including gas and liquid flow dynamics and transport of species, and DBD streamer interaction with the liquid. Finally, experiments will be performed to measure the important species in the liquid, in order to validate the models.

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Investigating fundamental plasma effects on tumor microenvironment through development of a controlled plasma treatment system for clinical cancer therapy. 01/01/2020 - 31/12/2023

Abstract

Non-thermal plasma technology is gaining attention as a novel cancer therapeutic. In the clinic, plasma has been applied to patients with head and neck squamous cell carcinoma, the 6th most common cancer worldwide with long-term survival below 50%. While initial studies are promising (e.g. partial remission, decreased levels of pain, no reported side-effects), a critical issue became apparent when translating plasma technology from the laboratory to the clinic: low reproducibility of treatment. Current plasma devices are handheld and require the operator (clinician) to make a judgement as to how long to treat the patient. This leads to large variability, which becomes even more pronounced when the clinician must move the plasma applicator over a large area of treatment. We aim to develop a robotic plasma treatment system that will enable us to investigate fundamental plasma effects on the tumor for clinical cancer therapy. We will use multiple sensors to detect the patient environment, artificial intelligence to 'learn and predict' patient disturbance patterns (e.g. breathing), and a robotic arm to deliver plasma. We will test our developed system in 3D and mouse cancer models and study the consequence of plasma treatment in the tumor, and to the survival of the animal. Altogether, our project will progress plasma technology for clinical translation by elucidating previously unknown biological responses to plasma and addressing issues in the clinic.

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CO2-conversion in a microwave plasma in the presence of H2O: Study of the underlying mechanisms by computational and experimental methods. 01/11/2019 - 31/10/2023

Abstract

Climate change is a pressing issue; therefore, action must be taken now. An important part of the fight against climate change is mitigation and prevention of CO2 from entering the atmosphere. However, this is not enough. By combining the prevention of more CO2 emission with the conversion of the CO2 already present in the atmosphere into value added (industrial) products and fuels, a more sustainable cycle can be created. My project will focus on conversion of CO2 in presence of H2O (a hydrogen source, often found in exhausts and the atmosphere) into value added chemicals by means of microwave (MW) plasma. Indeed, in spite of the abundance of H2O, there exist no models yet for CO2/H2O mixtures in MW plasma. To optimize the conversion, a thorough knowledge of the underlying mechanisms is needed, which I will obtain by combined modelling and experiments. I will develop a 0D chemical kinetics model and a 2D fluid dynamics model. For the experimental part, I will perform two times two research stays: at UMONS and DIFFER. I will evaluate the effect of various plasma and reactor parameters by both modelling and experiments, to obtain a more global understanding for optimized conversion and energy efficiency.

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Atmospheric plasma as green solution for enhanced adhesion and functionalization (PlasmaSol). 01/11/2019 - 31/10/2022

Abstract

The general purpose of the project is to use non-thermal atmospheric plasma technology as an eco-friendly surface modification method to replace the currently used non-ecofriendly processes and/or to achieve surface properties which are not within reach with other conventional processes. Within the PlasmaSol project, this technology will be researched to (i) assure a good adhesion between various substrates and foils or coatings, (ii) provide wood plastic composites and textiles with an antimicrobial functionality, and (iii) increase the flame retardant properties of textiles. By obtaining fundamental knowledge on the plasma chemistry and physics, thanks to a comprehensive toolset of advanced characterization techniques, a valuable dataset of suitable precursors compatible with the treated substrates will be obtained, finding applications in fields that might even fall outside of the scope of this project. To get more fundamental insight of the plasma process, the experimental work will be complemented by theoretical modeling of both the plasma reactor and nozzle design, by means of fluid dynamics modeling of the gas flow and the plasma process. The simulations will be performed for the extreme range of conditions of the equipment in order to determine an operational window of the plasma deposition process. To summarize, this fundamental work will assist and simplify the optimization and future implementation (i.e. industrialization) of the plasma deposition process.

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Surface-COnfined fast-modulated Plasma for process and Energy intensification in small molecules conversion (SCOPE). 01/04/2019 - 31/03/2025

Abstract

This ERC Synergy project will introduce a ground-breaking approach to use renewable energy in three major industrial reactions: 1) N2 fixation, 2) CH4 valorization and 3) CO2 conversion to liquid solar fuels. We will use non-thermal plasma, which has large potential to convert these small (low reactive) molecules under near ambient temperature and pressure, particularly for distributed processes based on renewable energy. The new processes have drastically lower carbon footprint (up to over 90% with respect to current ones). Furthermore, CO2 conversion is crucial for a worldbased distribution of renewable energy. However, the selectivity and energy efficiency of plasma technologies for these reactions are too low, making radically new approaches necessary. The Project idea is to realize a highly innovative approach for non-thermal plasma symbiosis with catalysis. By inducing excited states in solid catalysts to work in synergy with the excited short-lived plasma species, we introduce a brand new idea for catalyst-plasma symbiosis. In addition, we introduce a fully new concept of nano-/micro-plasma array through a novel electrode design, to generate the plasma at the catalyst surface, thereby overcoming long distance transport. By embedding ferro-magnetic nano-domains in the catalyst support and inducing radiofrequency heating, we create fast temperature modulations directly at the catalyst active sites. Combining these elements, the project will overcome the actual limits and enhance the selectivity and energy efficiency to levels suitable for exploitation. This requires a synergy over different scale elements: nano at catalyst, micro at the level of modelling plasma generated species, milli at the reactor scale and mega at the plant level for sustainability-driven opportunity guidance and impact assessment by Life-Cycle-Assessment. The synergy value derives from the integration of the PI competencies over this entire dimensional-scale level.

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Plasma catalysis for CO2 recycling and green chemistry (PIONEER). 01/01/2019 - 31/12/2022

Abstract

The main objective of this project is the formation of a new generation of experts in the subject of CO2 valorization using plasma-catalytic coupled processes.Plasma intensification of CO2 valorization processes, such as CO2 hydrogenation and dry reforming of methane, can greatly contribute to the stabilization of CO2 concentration in our atmosphere through the production of synthetic fuels that will be involved in overall zero or near zero emission cycles. This alternative utilization of yet C-based fuels will play an important role in our transition to a 100% renewable future. Chemical and thermochemical CO2 valorization processes are hindered by very slow reaction kinetics. Catalysts are often used but, most of the time, they either are not enough, or their utilization is not feasible under real operation conditions. The use of plasmas in combination with a well-designed catalyst can turn this sluggish CO2 valorization processes feasible. There is however a complete lack of knowledge about almost every aspect of this plasma-catalysis coupling. Research efforts are directed towards the understanding of CO2 plasmas, their interaction with solid catalytic surfaces, the formation of excited species and the fundamentals of the reaction mechanisms involved. Different plasmas and different catalysts are needed. Novel reactor concepts need to be found. The PhD topics cover many different scientific disciplines: from the physics of plasmas to the physicochemical characterization of solid surfaces and catalysis. The students will be instructed in several fields, not only considering science but also other important skills, such as soft skills training, as well as specific formation on managing, marketing and business skills along the duration of this project.

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Designing the packing materials and catalysts for selective and energy efficient plasma-driven conversion (PLASMACATDESIGN). 01/01/2019 - 31/12/2022

Abstract

PlasMaCatDESIGN aims to develop design rules for (catalytically activated) packing materials to enhance plasma-activated gas phase conversion reactions to basic chemicals. By understanding the material - properties – activity correlation we target enhanced conversion, selectivity and energy efficiency of plasma driven chemical production for two selected industrially and environmentally relevant model reactions in which plasma catalysis can have specific advantages: selective CO2 conversion towards C1-C5 (oxygenated) hydrocarbons and inorganic amine synthesis (nitrogen fixation).

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Plasma for environmental, medical, analytical chemistry and materials applications. 01/05/2018 - 31/12/2024

Abstract

Plasma is an ionized gas. It is the fourth state of matter, next to solid, liquid and gaseous state. It exists in nature, but it can also be generated in laboratories by applying electric fields or heat to a gas. It consists of gas molecules, but also many reactive species, like electrons, various types of ions, radicals and excited species. This highly reactive chemical cocktail makes plasma interesting for many applications. We are studying the underlying mechanisms in plasma, including the plasma chemistry, plasma reactor design and plasma‐surface interactions, by means of computer simulations and experiments, to improve the following applications: (1) in materials science (for nanotechnology and microchip fabrication), (2) for analytical chemistry, (3) in environmental/energy applications (i.e., conversion of greenhouse gases and nitrogen fixation), and (4) for medicine (mainly cancer research).

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CO2PERATE: all renewable CCU based on formic acid integrated in an industrial microgrid. 01/03/2018 - 28/02/2023

Abstract

The main objective of the project is the development of technologies for the conversion of CO2 to value-added chemicals using catalysis and renewable energy. To benchmark, compare and develop the various technologies, the formation of formic acid is selected as the initial target.

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Experimental and theoretical study of the fundamental mechanisms of nitrogen fixation by plasma and plasma-catalysis: towards the development of novel, environmentally friendly and efficient processes (NITROPLASM). 01/01/2018 - 31/12/2021

Abstract

Nitrogen is a crucial element for living organisms on earth. Transforming atmospheric N2 into molecules that can be incorporated by most organisms (N2 fixation) is either done by microorganisms or through energetically costly chemical processes (lightning strikes, Haber- Bosch (H-B) process). As the theoretical limit for the energy consumption of N2 fixation via non-thermal plasma (NTP) is more than 2.5 times lower than the energy consumption of the H-B process, this project aims to exploit NTP processes to fix N2 by reduction and by oxidation. The objective is to acquire an in depth understanding of the N2 fixation mechanisms in N2/O2 and N2/CH4 plasmas by combining experimental and numerical investigations of a wide range of gas and plasma-liquid discharges. To increase the N2 fixation rate and the yield, plasma catalysis will also be studied in the same gas mixtures. Catalysts will be prepared traditionally but also by plasma-based calcination and plasma-based modification of supports and synthesized catalysts. By successfully completing this project, we will gain fundamental understanding of the mechanisms and master plasma assisted N2 fixation in the gas phase, liquid phase and on catalyst surfaces.

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Dioxide to monoxide (D2M): innovative catalysis for CO2 to CO conversion (D2M). 01/01/2020 - 30/09/2021

Abstract

The aim of this project is to study, explore and develop various (catalytic) technologies for the production of CO as platform chemical via conversion of CO2. A technology assessment will subsequently be carried out to evaluate the potential of each technology, pinpointing promising strategies for further development and upscaling. Concrete objectives and criteria The efficiency/productivity of existing homogeneous catalytic systems for CO2 reduction to CO will be mapped out and evaluated to identify the most promising systems to achieve this reduction and to explore ways to improve its larger scale viability through detailed catalyst modification studies. The focus will be on cobalt and nickel systems containing N-heterocyclic carbene (NHC) species as ligands. The goal of the heterogeneous catalytic conversion of CO2 to CO is to assess the potential of the oxidative propane dehydrogenation (OPD) reaction with CO2 as a soft oxidant. The main purpose here is to focus on and maximize CO2 reduction and CO formation via novel catalyst synthesis, surface engineering and investigation of catalyst support. In the field of electrocatalytic conversion of CO2 to CO we aim to (1) develop metal-based electrodes (electrocatalysts integrated in gas diffusion electrodes) exhibiting enhanced stability, (2) to investigate a novel type of metal-free electrocatalyst that can tackle the current challenges witnessed in N-doped carbons and (3) to demonstrate the continuous production of CO from CO2 by the development of a prototype lab scale reactor including the best-performing electrocatalysts developed in this project Another goal of this project is providing a proof-of-concept for plasmonic enhanced CO2 conversion into CO in an energy-lean process involving only solar light at ambient pressure as energy input i.e. without external heating. The objective of the plasma catalytic route for CO production is to enhance the conversion and energy efficiency of CO2 conversion in different plasma reactor types, with major focus on Gliding Arc plasma and Nanosecond pulsed discharges (NPD) plasma reactors. The project also takes up the challenge to activate CO2 and bio-CH4 and turn them into CO by combining chemical looping processes, into which catalysis is integrated, mediated by multifunctional materials (combine different functionalities into one smartly engineered material) and/or spatial organization of materials in dynamically operated packed-bed reactors.

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Power to chemicals (P2C). 01/01/2020 - 30/06/2021

Abstract

The aim of this project is to demonstrate CO2-neutral ammonia production by renewable electricity-driven processes via novel (photo-)electrocatalytic and plasma-based routes. Five scientific objectives have been defined. Objective 1. To reveal the mechanism of N2 activation in candidate electrocatalysts. The first step of the nitrogen reduction reaction (NRR), N2 activation that relies on the choice of electron donor-acceptor pairs, will be studied by means of density functional theory (DFT) calculations and mechanistic study of known transition metal compounds. Objective 2. To screen and rationally develop highly efficient electrocatalysts for NRR. Catalysts with the theoretically electron donor-acceptor pairs will be prepared, tested and further optimized to achieve efficient NRR. The aim is to develop low-cost and environmental-friendly electrocatalysts with a Faradaic efficiency over 10% at a current density of at least 0.1 mA/cm2. Objective 3. Investigation and optimization of extrinsic parameters for durable NRR performance. Mass transport limitations will be studied via electrocatalyst integration in tailor-made gas diffusion electrodes. The influence of process parameters will be investigated and optimized, aiming at electrode stability for continuous and stable NH3 production. Objective 4. Investigation and development of plasma reactors for NH3 production. Three different plasma setups will be investigated for NH3 production, i.e., dielectric barrier discharge (DBD) and gliding arc (GA), as well as a plasma jet interacting with liquid H2O. The first two setups will also be tested with the electrocatalysts. The experiments will be supported by modeling, and conditions with maximum NH3 yield and minimum energy cost will be explored. The target is to achieve an NH3 yield above 1% and energy cost below 30 MJ/mol. Objective 5. Develop stand-alone electro- and plasma reactor driven by a photovoltaic solar cell. Integration of both reactor concepts (based on electrocatalytic and plasma (catalytic) ammonia production) to a stand-alone device powered with sunlight and usage of atmospheric air as feedstock. In a so-called ammonia panel concept, the electrolyser and plasma gas-flow reactors will be integrated with a photovoltaic solar cell. The N2 and H2O in air are used as reactant for ammonia production. The aim for this prototype is to realize an ammonia production rate of 6.2 mol h-1 m-2.

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Plasma efficient nitrogen fixation (Penfix). 01/10/2019 - 30/09/2021

Abstract

Industrial scale nitrogen fixation (NF) via the Haber-Bosch process dominates artificial fertilizer production and at present, enables yield enhancements which nourish over 40 % of the world population. Owing to the exceptional stability of molecular nitrogen's triple bond the Haber-Bosch process is an energy intensive chemical process which accounts for 1-2 % of the world's energy production, consumes 2-3 % of the global natural gas output and emits more than 300 million tonnes of CO2. In light of an increasing population (and fertilizer demand) coupled with an urgency to reduce CO2 emissions, efforts to find alternative technologies for NF that offer the potential of reduced energy usage while minimizing greenhouse gas emissions have accelerated. Electrically powered plasma processes are considered as a promising alternative for delocalized fertilizer production, based on renewable energy, and more specifically for NO production. To-date, however, plasma designs for NF have not exceeded Haber-Bosch efficiencies. Pulsed powered microwave (MW) generated plasma technology offers some promise in this regard. Pulsing of the discharge power enables strategies which direct energy to primarily heat electrons ('non-thermal' conditions) providing a far more efficient pathway to molecular bond breakage (and resulting NO production) than thermal effects. Indeed, reports on pulsed powered MW discharges have indicated an opportunity to tune electron energies to maximize molecular vibrational excitation, identified as an optimal route for energy efficiency in NO production. In a novel advance, plasma efficient nitrogen fixation 'PENFIX', proposes to interrogate 'pulsed' powered atmospheric microwave (MW) plasma for nitric oxide (NO) production using air. Novel reactor designs informed by validated modelling will be of particular focus. Diagnostic and modelling activities will elucidate the fundamental physics while addressing the challenges of future industrial scale deployment.

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Atomic scale modeling for plasma-enhanced cancer immunotherapy: targeting the signal inhibitory proteins. 01/10/2019 - 30/09/2020

Abstract

Biomedical applications of cold atmospheric plasma (CAP) are gaining increasing interest. In particular, CAP seems very promising for cancer immunotherapy. However, the underlying mechanisms need to be better understood. CAP generates a rich mixture of reactive oxygen and nitrogen species (RONS), which interact with living cells, inducing molecular level modifications to their components (e.g., proteins) upon oxidation. This will influence the intra- and/or intercellular signaling pathways, leading to various alterations in the cellular metabolism, which are stated to cause immunogenic cancer cell death. To better understand the effect of plasma on the process of cancer cell elimination by the immune system, a fundamental insight in the protein-protein interactions of cancer and immune cells, and in the effect of plasma-induced oxidation, is crucial. Complementary to experiments, computer simulations allow us to study the underlying processes with nanoscale precision. Thus, in this project, I aim to elucidate the mechanisms of immunogenic cell death induced by plasma-generated RONS, which leads to unmasking the cancer cells and to effectively eliminating them by immune cells. Specifically, I will perform a combination of different atomic scale simulations to study the interaction between proteins of immune cells and cancer cells, and the subsequent effect of plasma-induced oxidation on their binding affinity.

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Plasma-based cancer treatment: Atomic level simulations. 01/10/2018 - 30/09/2021

Abstract

Cold atmospheric plasmas (CAPs) have attracted significant interest for their promising applications, particularly in cancer therapy. Understanding the anticancer activity of CAP treatment, however, still remains a key challenge. It is largely accepted that the biological effects of CAP are attributed to reactive oxygen and nitrogen species (RONS). It is suggested that CAP-generated RONS regulate key biochemical pathways within intra- and intercellular environments, inducing chemical and physical changes in cells. Yet, the underlying mechanisms are not fully understood. In this project, we aim to gain a better insight into the mechanisms of the effect of CAP on cancer cells, using atomistic simulations to investigate the interaction mechanisms of RONS with 6 different proteins, which play a vital role in cancer (treatment). We use reactive and non-reactive molecular dynamics simulations to study the CAP-induced structural and functional changes in antioxidant, transmembrane and cell-surface proteins, as well as the subsequent effects on their protecting, transporting and binding properties, which will eventually result in cancer cell death.

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Plasma-treated liquids for cancer treatment: elucidating the selectivity against cancer cells by a combined experimental and computational study. 01/10/2018 - 31/01/2019

Abstract

Cold atmospheric plasma (CAP) is gaining interest for cancer treatment, although the application is still in its early stages. Besides direct CAP treatment of cancer cells, plasma can also be used to treat liquids, which appear to have similar anti-cancer effects as the plasma itself. These plasmatreated liquids (PTL) are very promising for cancer treatment, as they can be more generally used, e.g. they might be directly injected into tissue of patients. However, the selectivity of PTL treatment towards cancer cells, leaving normal cells undamaged, is only scarcely explored. This is exactly the focus of this project. We will try to define which cancer cell types are more (or less) sensitive towards PTL treatment and how selectivity towards cancer cells can be promoted. For this purpose, we will link the chemical composition of the PTL (reactive oxygen, nitrogen and chlorine species) with the selectivity in cancer vs. normal cell cytotoxicity, to know which species promote this selectivity (WP1). In parallel, we will develop a 0D and 2D computational model to simulate the plasma-liquid interactions (WP2+3). With the knowledge obtained in WP1, we can use the models to elucidate which plasma treatment conditions enhance the selectivity. Then, we will apply these conditions in the patient cell experiments to optimize the selectivity (WP4). Finally, we will also strive to unravel the underlying mechanisms of this selectivity in the cell experiments (WP4).

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Understanding the material structure-activity correlation in plasma catalytic CO2 conversion (PLASMACAT). 01/05/2018 - 31/03/2019

Abstract

Till now, plasma catalysis has been studied in different reactors, under divergent conditions and in a fragmented way, making it difficult to obtain systematic information on the different aspects of plasma catalysis. Therefore, the aim of this project is to study the impact of materials, controlled in particular properties (properties of the support such as shape, metal dispersion and metal-support interaction), that have not been studied in a systematic way before, to elucidate some of the underlying mechanisms and properties not yet identified. Specifically, this project aims at unravelling the impact of catalyst dispersion to better understand the impact of the properties of the deposited catalyst with respect to activity, selectivity and its stability in dry reforming of CO2 and methane

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Plasma catalysis at the nanoscale: A generic Monte Carlo model for the investigation of the diffusion and the chemical reactions of plasma species at porous catalysts. 01/10/2017 - 30/09/2020

Abstract

In this project we will develop a generic model to simulate the diffusion of plasma species in and out of the pores of a catalyst and the catalytic reactions at the pore surface. In this way we will try to gather insight in the underlying processes in plasma catalysis in general and in the plasma catalytic conversion of CO2 and H2 to methanol specifically. In this project, we will focus on the conversion on a Cu-catalyst. Using quantum chemical calculations we will determine the properties of adsorption of the most important plasma species and the different reaction mechanisms and reaction rates at the surface. In parallel we will develop a Monte Carlo model to examine the diffusion of plasma species inside catalyst pores, as well as their surface reactions, for which we will make use of the results provided by the quantum chemical calculations. This model will allow us to investigate the role of plasma species in the methanol synthesis, the influence of the pore size and the pore shape on the total yield, which reaction products and side products are formed and whether these products can diffuse out of the pores to make room for new reactants. The results of this study will provide the necessary information for understanding plasma catalytic processes at a fundamental level and are essential to further optimise these promising processes.

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Modelling and experimental validation of a flowing atmospheric pressure afterglow source used for ambient ionization mass spectrometry. 01/10/2017 - 30/09/2020

Abstract

Ambient desorption/ionization mass spectrometry is a new field of mass spectrometry, which is becoming increasingly popular in analytical chemistry. An ion source that is gaining increasing interest for this purpose is the flowing atmospheric pressure afterglow (FAPA). It has two separated regions: the plasma ignition zone and the afterglow, which is generated outside the chamber and where the analytes are introduced. Hence, it allows the analysis of samples in the open, ambient environment. The ions and metastables from the plasma react with air constituents, resulting in the formation of reagent ions, which are then capable of ionizing the analyte of interest. The ions of the analyte material are finally detected by a mass spectrometer. The aim of my project is to identify the main ionization mechanisms in the reagent ion formation. First I will develop a zero-dimensional (0D) chemical kinetics model to describe the plasma chemistry of a helium plasma with air impurities, flowing into humid air, and the formation of reagent and analyte ions. Subsequently I will insert the obtained (and reduced) chemistry set into a 2D fluid model to describe the gas flow dynamics as well as the chemistry of the active plasma region and flowing afterglow, and I will study in detail the ionization pathways for a wide range of conditions. I will validate the model with experiments performed during two research visits at Rensselaer Polytechnic Institute (US).

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Elucidating mechanisms of plasma-induced immunogenic cancer cell death and determining efficacy to elicit anti-tumor immunity: An experimental and computational study 01/10/2017 - 30/09/2020

Abstract

Cancer is still a major healthcare issue and many conventional therapies overlook the role of the immune system in the resolution of this disease. Non-equilibrium plasma is emerging as a novel cancer treatment. Promising results showed that plasma can kill cancerous cells and stimulate immune cells, but experiments have largely been in vitro. To address this, we will perform in vivo mouse experiments to validate therapeutic efficacy of plasma and assess immune responses required to eliminate cancer. While treatment may be efficacious, the underlying mechanisms of plasma cancer therapy are not fully understood. When plasma is generated, a complex environment of electric fields, ultraviolet light, charged particles and neutral species is produced. To date, it is unclear which plasma components and reactive species play the major role in cancer therapy. Therefore, we will also delineate the components of plasma that elicit anti-cancer responses. In addition, we will develop a computational model that will predict the behavior of plasma-generated species in liquid, as cells and tissue are treated in the presence of liquid. This will be compared to chemical analysis of plasma-treated liquid for validation and establishment of crucial species for cancer therapy. Altogether, this project will support development of plasma technology for cancer immunotherapy and provide insight into the underlying mechanisms.

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Modelling a gliding arc plasma reactor by means of COMSOL Multiphysics 01/10/2017 - 30/09/2019

Abstract

The beginning of the 21st century is marked by the rising awareness of global warming. The greenhouse gases CO2 and CH4 emitted in the atmosphere by industrial processes and the transportation sector are of major concern. Several efforts are being reported for greenhouse gas reduction by means of process optimization and application of new technologies. A new, promising method is the conversion of these greenhouse gases into value-added chemicals by means of atmospheric pressure plasmas, because of their reliability, efficiency, and ease of use. One of the most promising types is the Gliding Arc discharge (GA). GA plasma sources are favored for their high conversion efficiency and simplicity. They are non-thermal plasma sources, able to produce a high plasma density at a relatively low gas temperature (<3000K). Recently, a new type of GA plasma source, based on the innovative reverse-vortex gas flow stabilization, has been developed, allowing for even higher conversion efficiency and lower electrode degradation. However, this type of GA has not yet been studied in detail. The aim of this project is to gain fundamental knowledge on the physical processes inside the reverse-vortex stabilized GA by means of extensive computer modeling based on the COMSOL Multiphysics Software. Initially, 1D and 2D fluid plasma models will be developed, with later extension into a 3D model. The complete 3D model will involve the plasma physics and chemistry, fluid dynamics and heat transfer.

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Atomic scale simulations for a better understanding of cancer treatment by plasmas. 01/10/2017 - 30/09/2019

Abstract

Atmospheric pressure plasmas are gaining increasing interest for biomedical applications, like sterilization, wound treatment, dental treatment, blood coagulation, and especially cancer treatment. In the latter case, plasmas have demonstrated to give very promising results, both in vitro and in vivo, and are able to attack a wide range of cancer cell lines without damaging healthy cells. However, the underlying mechanisms are not yet fully understood. I will therefore perform atomic scale simulations to study the interaction mechanisms of reactive oxygen and nitrogen species (ROS, RNS) formed in the plasma with biomolecules, present in eukaryotic cells, which play a role in cancer (treatment). More specifically, I will apply classical molecular dynamics and density functional based tight binding simulations, and I will study three types of biomolecules, which play a crucial role in cancer (treatment): (1) a phospholipid bilayer (PLB) as model system for the cell membrane, (2) a part of a DNA string and (3) peptides, as a model system for proteins. I will investigate how the ROS and RNS interact with these biomolecules, which reaction products are formed, and how this can lead to apoptosis (cell death). This research will contribute to a better understanding of the role of plasmas in cancer treatment.

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Towards a fundamental understanding of electrical discharges in and in contact with water. 01/10/2017 - 30/09/2018

Abstract

Electrical discharges in contact with water are under intensive investigation for many possible and established implementations in environmental, chemical and biomedical applications. The fundamental mechanisms of plasma-water interaction are, however, still poorly understood. For instance, the initiation mechanism of electrical discharges directly into the water phase is a topic under debate. Next to that, there is no generally accepted theory on the self-sustainment mechanism of a dielectric barrier discharge (DBD) in contact with a water cathode. For that reason, this project is intended to obtain more fundamental insight in the underlying mechanisms of both plasma initiation in water and DBD in contact with water, by means of extensive modeling, validated by experiments. First, I will study the plasma-induced gas phase and water phase chemistry of both systems by means of 0D kinetics models. Next, I will include the 0D models into 1D and 2D COMSOL models for a more comprehensive simulation of the temporal and spatial plasma evolution. I will experimentally validate these models by means of various plasma diagnostic methods. Additionally, I aim to reveal new information on the investigated mechanisms with the experiments alone, by investigating the effect of the liquid content and voltage characteristics.

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Anticancer activity of plasma activated medium and its underlying mechanisms: Combined experimental and computational study (Anticancer-PAM). 01/09/2017 - 31/08/2019

Abstract

Cold atmospheric plasma (CAP) is gaining increasing interest for cancer treatment, although the application is still in its early stages. Besides direct CAP treatment of cancer cells, plasma can also be used to activate a liquid medium, which seems to have similar anti-cancer effects as the plasma itself. This so-called plasma activated medium (PAM) is very promising for cancer treatment, as it can be more generally used, e.g., it might be directly injected into tissue of patients. However, the anticancer potential of PAM is not yet fully understood. This is exactly the focus of this project. We will measure the reactive oxygen and nitrogen species (RONS) concentrations in PAM, and also calculate them with a model for plasma-liquid interaction. In addition, we will study the effect of PAM on a catalase model protein by experiments, and perform atomic scale simulations for the interaction of RONS with this protein, to better understand the effect of PAM on cancer cells, because catalase aids cancer cells in overcoming oxidative stress created by PAM.

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Low Temperature Plasma for applications in Medicine (LTPAM). 01/05/2017 - 30/04/2019

Abstract

Atmospheric pressure low temperature plasma (LTP) is a burgeoning field due to its vast potential in biomedical applications. Reacting with ambient air, these plasmas generate a variety of molecular, ionic and radical species, responsible for the anti-bacterial, anti-viral and anti-cancer properties ofLTP. It is especially important when more traditional therapies fail, such as antibiotic-resistant bacteria. Recently, a large number of studies of the biological effects ofLTP emerged, as well as diagnostics of the gas phase LTP, and various models. However, the chemical and physical processes in biologically relevant media still lack detailed understanding. Water is an essential part of the bio-milieu, and both initial and secondary LTP-induced chemistries in liquids require deeper studies. This project will aim at several goals, which will aid the progression ofLTP towards wide and diverse clinical use. 1) It will utilise the RF COST plasma jet (created to standardise the LTP research in Europe and the world). The sources of the reactive species induced by the jet will be studied by employing isotopically labelled molecules. 2) The plasma-induced chemistry will be studied in conditions mimicking those in vivo: (i) generation of secondary species from Cl-, one of the most abundant chemicals in bio-media, and assessment of their cytotoxicity; and (ii) quantitative identification of short-lived reactive species (radicals) created by LTP in gels, structures resembling tissue (this is especially important in the case of direct plasma exposure where radical chemistry greatly influences processes in liquids). 3) The enhancement of LTP effects will be studied via generation of ONOO- from its precursors in plasmas with aerosols. The work will be focussed on liquids' analysis by electron paramagnetic resonance and nuclear magnetic resonance spectroscopy, mass spectrometry, ion chromatography, etc.

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Towards plasma for cancer treatment: investigation of alterations in the DNA damage response due to plasma treatment in glioblastoma multiforme as tumour model. 01/01/2017 - 17/09/2017

Abstract

Recently, a new approach based on non-thermal plasma (NTP) to treat cancer cells is gaining interest in the medical field. Plasma is an ionized gas. It is a highly reactive mixture, containing electrons, ions, radicals and energetic neutrals, while still operating at room temperature. Precisely this combination of reactive species and low gas temperature makes it suitable for treating biological samples. It is suggested that the killing capacity of plasma is related to the formation of reactive oxygen and nitrogen species (RONS). Moreover, previous research showed that plasma can selectively kill cancer cells over healthy cells, which is an advantage over traditional treatment methods, such as radio- and chemotherapy. Unfortunately, little is known about the actual working mechanism, or selectivity, making it difficult to convince pharmaceutical collaborators to invest in this technique and develop it into a valuable treatment option for cancer. During this research, I will investigate the anti-cancer capacity of NTP, which RONS are responsible, and how NTP alters the DNA damage response (DDR) of cancer cells. The latter is a collection of mechanisms that are activated whenever DNA damage is detected in order to repair it. This is interesting because (a) plasma is shown to induce DNA damage, and (b) it is known that the DDR of cancer cells is already partially compromised, making it a valuable oncological target. I will use a brain tumour, glioblastoma multiforme, as model.

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Towards a fundamental understanding of plasma for cancer treatment: A combined experimental and computational study. 01/10/2016 - 30/09/2019

Abstract

Non-thermal plasma is gaining interest in recent years for cancer treatment. The underlying mechanisms are, however, not fully understood. Therefore, in this project we will study the interaction of plasma with cancer cells in vitro, and also perform computer simulations. The experiments will be carried out with a plasma jet, operating in helium with some oxygen and/or nitrogen, at different conditions. The plasma is created between two electrodes, but due to the gas flow, it is blown out of the discharge region and can reach the cancer cells to be treated, located at a distance of several mm. After plasma treatment, we will analyze the cell viability, cell morphology and change in cellular membrane integrity, as well as the expression levels of apoptosis related genes. In parallel we will perform computer simulations at two different levels. First, we will study the plasma chemistry at the different conditions used experimentally, by zero-dimensional reaction kinetics modeling, to reveal the most important (biochemically active) plasma species formed in each case. Second, we will apply united-atom non-reactive molecular dynamics simulations to study the important mechanism of phosphatidylserine flipflop in the cell membrane, known as signal for apoptosis (i.e., programmed cell death) of cancer cells. These simulations will give a better insight in the underlying mechanisms of plasma for cancer treatment, and will thus support the experimental work.

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Plasma catalysis at the nanoscale: Model development for diffusion of plasma particles in pores and study of the catalytic behaviour at the pore surface. 01/10/2016 - 30/09/2017

Abstract

In this project we will develop a generic model to simulate the diffusion of plasma species in and out of catalyst pores and the catalytic reactions at the pore surface. We will try to gather insight in the underlying processes of plasma catalysis in general and of the plasma catalytic conversion of CO2 and H2 to methanol specifically. We will focus on the conversion on a Cu-catalyst. Using quantum chemical calculations we will determine the properties of adsorption of the most important plasma species and the different reaction mechanisms and reaction rates. In parallel we will develop a Monte Carlo model to examine the diffusion of plasma species inside catalyst pores, as well as their surface reactions, for which I will apply the results arising from the quantum chemical calculations. We will determine the minimum pore diameter needed for the plasma species to be able to penetrate the catalyst pores and undergo chemical reactions, which reaction products and side products are formed and whether these products can diffuse out of the pores to make room for new reactants. The results of this study will provide the necessary information to understand plasma catalytic processes at a fundamental level and are essential to further optimize these promising processes.

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Modeling of a microwave plasma reactor for energy-efficient CO2 conversion. 15/07/2016 - 14/07/2017

Abstract

In recent years, there is growing interest for plasma-based CO2 conversion, because it can proceed at mild reaction conditions, with limited energy consumption. The most promising plasma reactor, which has demonstrated the highest energy efficiencies up to now, is a microwave plasma reactor. The highest energy efficiencies reported up to now, however, are obtained at specific conditions, i.e., reduced gas pressure and supersonic gas flow, or special vortex gas flow. In this project, we want to investigate the underlying mechanisms of energy-efficient CO2 conversion in a plasma reactor, and to elucidate under which conditions the optimum conversion and energy efficiency can be obtained. This is preferably at atmospheric pressure, which is most convenient for later industrial implementation. For this purpose, we develop a model for a microwave plasma reactor, and the model results will be validated by comparison with experiments performed at collaborating research groups. The model development is done step-by-step, starting with a 0D chemical kinetics model to describe the CO2 plasma chemistry. The detailed plasma chemistry model needs to be reduced in order to be compatible with 2D and 3D models. In parallel, a 2D model for a microwave plasma in argon in a simple geometry is developed, and the reduced CO2 chemistry set will be incorporated in this 2D model. Subsequently, the 2D model will be extended to 3D, to allow studying microwave plasma reactors with supersonic gas flow and vortex gas flow. These models, after validation with experiments, will allow to investigate the most suitable conditions (gas pressure, applied power, frequency, reactor geometry, gas flow pattern and gas flow rate) for optimum CO2 conversion and energy efficiency.

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Computer modelling and experimental validation of plasmas and plasma- surface interactions, for a deep insight in cryogenic etching (Cryoetch). 08/06/2016 - 07/06/2018

Abstract

Microchips have caused a revolution in electronics over the last few decades. Following Moore's law, much effort has been put into continuously shrinking electronic feature dimensions. Indeed, typical feature sizes of semi-conductors decreased from 10 μm in 1971 to 14 nm in 2014. With the shrinkage of feature sizes, plasma etching plays a more and more important role due to its anisotropy during surface processing. However, to go beyond 14 nm features, current state-of-the-art plasma processing faces significant challenges, such as plasma induced damage. Recently, one such novel process with limited plasma damage is cryogenic etching of low-k material with SF6/O2/SiF4 and CxFy plasmas. In this project, the fundamental mechanisms of the plasma, and its interaction with the surface, for these gas mixtures, will be studied to improve cryogenic plasma etching. For this purpose, numerical models (a hybrid Monte Carlo - fluid model and molecular dynamics model) will be employed to describe (i) the plasma behavior for SF6/O2/SiF4 and CxFy gas mixtures applied for cryogenic etching, and (ii) the surface interactions of the plasma species with the substrate during etching. Furthermore, cryogenic etch experiments will also be conducted to validate the modeling results.

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Multi-scale modeling of plasma catalysis/ 01/01/2016 - 31/12/2019

Abstract

This project aims to obtain more insight in the fundamental processes of plasma catalysis by multi-scale modeling. The plasma chemistry in a CH4/CO2 mixture will be described by a 0D model, and inserted in a 3D macro-scale model of a packed bed reactor. The plasma behavior near/in catalyst pores will be modelled on a micro-scale. Finally, the plasma-catalyst interactions on the atomic scale will be modeled by classical MD and DFT simulations.

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Modeling and experimental validation of a gliding arc discharge: Comparison of a classical and a plasmatron gliding arc. 01/01/2016 - 31/12/2019

Abstract

The conversion of greenhouse gases (mainly CO2 and CH4) into value-added chemicals or renewable fuels is gaining increasing interest, to reduce the greenhouse gas concentrations and thus to solve the problem of global warming. A gliding arc plasma is very promising in this respect, as it can activate inert gas molecules at atmospheric pressure and moderate temperature with limited energy cost. However, the underlying mechanisms of a gliding arc are far from understood. In this project, we will try to obtain a better insight in the basic mechanisms of two types of gliding arc plasmas, i.e., a classical gliding arc, and a new type of reverse vortex flow gliding arc (plasmatron), which might be even more promising for greenhouse gas conversion. We will do this by means of extensive modeling, validated by experiments. First, we will study the plasma chemistry of a CH4/CO2 mixture. This plasma chemistry will be inserted in a coupled magnetohydrodynamics (MHD) - kinetics model to study the spatial and temporal plasma properties. The model will be validated by experiments, performed in Antwerp and in Liverpool. We will investigate the effects of CH4/CO2 ratio, discharge power and gas flow rates in both types of gliding arcs, on the gas conversion, the yields and selectivities of the formed products and on the energy efficiency, both theoretically and experimentally. This will allow us to predict which are the optimum conditions and plasma setup for the greenhouse gas conversion.

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The impact of the electrocatalytic properties of Cu/Ag core-shell nanoparticles for the reduction of CO2 in an electrochemical flow microreactor. 01/10/2015 - 30/09/2019

Abstract

In the last decades, the amount of CO2 in the earth's atmosphere has increased enormously. Due to the goals set by Europe, CO2 mitigation is of major importance for industry as well as society. In this project we will focus on the electrochemical reduction of CO2. However, this reaction pathway can only become cost-effective by reducing the large overpotential for the electrochemical CO2 reduction and thus, directs the problem towards the world of electrocatalysis. More specific, the catalytic properties of bimetallic Cu/Ag core-shell nanoparticles on the reduction of CO2 into valuable C1-C3 hydrocarbons will be investigated. Electrochemical measurements will provide an insight in the reaction pathway and this information will be used to adjust the electrodeposition of the NP's and optimizing the core-shell NP morphology of the catalysts. In addition, this project will combine the design and synthesis of these electrocatalysts with the engineering of an electrochemical membrane flow microreactor (including the electrode structure and cell construction). In our opinion, it is this combination that provides the next step in the improvement of CO2 reduction to fuels and chemical building blocks.

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Atomic scale modeling for plasma cancer treatment. 01/10/2015 - 30/09/2018

Abstract

The application of cold atmospheric plasmas (CAPs) in medicine is increasingly gaining attention in recent years and is becoming one of the main topical areas of plasma research. The effective use of CAPs, however, is strongly dependent on the understanding of the underlying processes, both in the plasma and more importantly in the contact region of plasma with the living cells. In order to accurately control the processes occurring at the surface of the bio-organisms, there is a strong need to deeply investigate the exact interaction mechanisms of the plasma-generated species with biochemically relevant structures. This still remains a big challenge. Computer simulations may provide fundamental atomic level insight into the processes occurring at the surface of living cells, which is difficult or even impossible to obtain through experiments. Thus, in this project, I envisage to use atomistic simulations to investigate the interaction mechanisms of reactive plasma species with biomolecules, which play a crucial role in cancer (treatment), to better understand the underlying mechanisms of plasma oncology. For this purpose I will use reactive molecular dynamics as well as density functional based tight binding simulations. Specifically, I aim to determine whether plasma-induced reactive species can react and modify the biomolecular structure (or conformation) and change its function, which can eventually lead to cancer cell death (i.e., apoptosis).

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Computer modeling of plasmas and their surface processes, with experimental validation, for a better understanding of cryogenic etching. 01/10/2015 - 31/08/2018

Abstract

Plasmas are widely used in the microelectronics industry for the fabrication of computer chips, during plasma etching and deposition of materials. Following Moore's law, much effort is put into continuously decreasing electronic feature dimensions. Indeed, typical feature sizes decreased from 10 μm in 1971 to 14 nm in 2014. The gradual shrinking of features thus entails a continuous improvement of the plasma processes. To go beyond 14 nm features, it is crucial to limit plasma induced damage during processing. Recently, one such novel process to limit plasma damage is cryogenic etching of low-k material with SF6/O2/SiF4 and CxFy plasmas. In this project, I wish to obtain a fundamental understanding of the plasma behavior and its interaction with the surface, for these gas mixtures, to improve cryogenic plasma etching. For this purpose, I will apply numerical models to describe (i) the plasma behavior for SF6/O2/SiF4 and CxFy gas mixtures, and (ii) the surface interactions of the plasma species with the substrate. The plasma behavior will be simulated by a hybrid Monte Carlo - fluid model for addressing the various plasma species (electrons, ions, neutrals and excited species). The interaction of the plasma species with the substrate surface will be described by additional Monte Carlo and molecular dynamics (MD) simulations, allowing a detailed insight in the microscopic trench etching process. Furthermore, I plan to validate the models by means of cryogenic etch experiments.

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Project website

Modelling a gliding arc plasma reactor by means of COMSOL Multiphysics. 01/10/2015 - 30/09/2017

Abstract

The beginning of the 21st century is marked by the rising awareness of global warming. The greenhouse gases CO2 and CH4 emitted in the atmosphere by industrial processes and the transportation sector are of major concern. Several efforts are being reported for greenhouse gas reduction by means of process optimization and application of new technologies. A new, promising method is the conversion of these greenhouse gases into value-added chemicals by means of atmospheric pressure plasmas, because of their reliability, efficiency, and ease of use. One of the most promising types is the Gliding Arc discharge (GA). GA plasma sources are favored for their high conversion efficiency and simplicity. They are non-thermal plasma sources, able to produce a high plasma density at a relatively low gas temperature (<3000K). Recently, a new type of GA plasma source, based on the innovative reverse-vortex gas flow stabilization, has been developed, allowing for even higher conversion efficiency and lower electrode degradation. However, this type of GA has not yet been studied in detail. The aim of this project is to gain fundamental knowledge on the physical processes inside the reverse-vortex stabilized GA by means of extensive computer modeling based on the COMSOL Multiphysics Software. Initially, 1D and 2D fluid plasma models will be developed, with later extension into a 3D model. The complete 3D model will involve the plasma physics and chemistry, fluid dynamics and heat transfer.

Researcher(s)

Research team(s)

Project website

Atomic scale simulations for a better understanding of cancer treatment by plasmas. 01/10/2015 - 30/09/2017

Abstract

Atmospheric pressure plasmas are gaining increasing interest for biomedical applications, like sterilization, wound treatment, dental treatment, blood coagulation, and especially cancer treatment. In the latter case, plasmas have demonstrated to give very promising results, both in vitro and in vivo, and are able to attack a wide range of cancer cell lines without damaging healthy cells. However, the underlying mechanisms are not yet fully understood. I will therefore perform atomic scale simulations to study the interaction mechanisms of reactive oxygen and nitrogen species (ROS, RNS) formed in the plasma with biomolecules, present in eukaryotic cells, which play a role in cancer (treatment). More specifically, I will apply classical molecular dynamics and density functional based tight binding simulations, and I will study three types of biomolecules, which play a crucial role in cancer (treatment): (1) a phospholipid bilayer (PLB) as model system for the cell membrane, (2) a part of a DNA string and (3) peptides, as a model system for proteins. I will investigate how the ROS and RNS interact with these biomolecules, which reaction products are formed, and how this can lead to apoptosis (cell death). This research will contribute to a better understanding of the role of plasmas in cancer treatment.

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Project website

EnOp: CO2 for energy storage 30/06/2015 - 30/06/2020

Abstract

The project of the Interreg V EU programme EnOp (in Dutch: CO2 voor Energieopslag - CO2 for Energy Storage) develops technologies for storage of renewable energy into chemical energy by conversion of CO2 into fuels and chemical building blocks. In particular, the project focuses on the application of sun light energy and sustainable electricity to use CO2 as a platform for energy storage. It consists of three technologies that convert CO2 via sunlight and four technologies that convert CO2 with renewable electrical energy into chemicals among other plasma catalysis. This project is established by a contribution of the European Interreg V Flanders-The Netherlands program that stimulates innovation, sustainable energy, a healthy environment and the labor market by means of cross-border projects. Each trajectory within EnOp is executed by international partners. A business team invests in cross-border collaboration. The team consists of Flemish and Dutch entrepreneurs. This way, next to scientific knowledge also Flemish and Dutch market aspects are included in a pragmatic manner.

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Research team(s)

Project website

Towards a fundamental understanding of a gliding arc discharge for the purpose of greenhouse gas conversion into value-added chemicals (GlidArc). 22/06/2015 - 21/06/2017

Abstract

Global climate change due to anthropogenic greenhouse gas emissions is a growing concern. The conversion of greenhouse gases (mainly CO2, CH4) to value-added chemicals or renewable fuels is an effective strategy to reduce these emissions and an interesting process both from economic and ecological point of view. A gliding arc (GlidArc) plasma offers unique perspectives for activating inert molecules at mild conditions and allows the greenhouse gas conversion with limited energy cost. A GlidArc is, however, very complex and poorly understood. Therefore, this project intends to obtain more fundamental insight in the plasma-mechanisms of the GlidArc for greenhouse gas conversion, by means of extensive modeling, validated by experimental diagnostics.

Researcher(s)

Research team(s)

SusChemA. 01/01/2015 - 31/12/2020

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

Researcher(s)

Research team(s)

Nano consortium of excellence. 01/01/2015 - 31/12/2019

Abstract

The NANO consortium of excellence represents the internationally renowned expertise in nanoscience at the University of Anwerp. It consists of three participating groups that are international leaders in their subfield: EMAT, CMT and PLASMANT. The consortium joins forces towards a uniform communication and collaboration in order to further strengthen the international position of the nanosciences at the University of Antwerp.

Researcher(s)

Research team(s)

Systematic research for the impact and opportunities of catalysts in CO2 and methane conversion through plasma. 01/01/2015 - 31/12/2018

Abstract

This research aims at the optimisation of the conversion of CO2 and methane (two greenhouse gasses) through dry reforming. In this process, syngas is formed, which is further transformed to methanol. This will be achieved through the synergy of plasma and catalysis, either in two steps, but preferentially in one step. The synergy will be studied in a packed bed DBD reactor, where a support will be coated onto the packing, and a catalyst will be coated onto the support. Preforming a stepwise process can teach us a lot about the synergy between a plasma and a catalyst.

Researcher(s)

Research team(s)

Sample introduction in inductively coupled plasmas: A better insight through computer modeling. 01/10/2014 - 30/09/2017

Abstract

Inductively coupled plasma mass spectrometry (ICP-MS) is a method to chemically analyze several kinds of (environmental, biological and inorganic) samples. This is achieved by ionizing the sample with an inductively coupled plasma and using a mass spectrometer to separate and quantify the ions. Because of its high sensitivity and ability to measure about 80% of the periodic table, the ICP has become one of the most popular ion sources in analytical chemistry. To improve the analytical performance, fundamental studies are indispensable. They have been carried out for several years both experimentally and computationally. However, there is a strong need for a complete model which can provide details on the sample behavior inside the plasma. This kind of detailed information is barely accessible from experiments, and computational modeling will therefore be very helpful. Thus, in this project, for the first time worldwide, I will develop a comprehensive model for ICPMS, including the behavior of the sample, and I will validate my model with experiments, in collaboration with other groups. First, I will develop a model for elemental droplets and subsequently, I will extend the model to describe samples dissolved in water (i.e., multicomponent droplets) including chemical reactions. Finally, I will apply the model to different geometries, like a dual concentric injector, to propose geometrical optimizations as well as predict the optimal operating conditions for ICP-MS.

Researcher(s)

Research team(s)

Computer simulations of gold-catalyzed growth of carbon nanotubes at the atomic scale. 01/10/2014 - 30/09/2017

Abstract

Recently, Au-catalyzed plasma enhanced chemical-vapor deposition (PECVD) has been shown to significantly narrow the chirality distribution. However, actual control still remains unachieved and moreover, very little is known about the underpinning fundamental mechanisms of chirality formation. In this project, I therefore envisage to use atomistic simulations to investigate these mechanisms and how these mechanisms may be controlled through the PECVD process conditions in order to obtain a definable and predictable CNT structure and chirality. I will therefore investigate the role of several plasma effects, including the electric field, plasma-generated radicals, ion bombardment and etching. By comparing Au-catalyzed CNT growth to Ni-catalyzed growth, the specific role of the catalyst in PECVD will be investigated as well.

Researcher(s)

Research team(s)

Towards a fundamental understanding of plasma-TiO2 catalyst interaction for greenhouse conversion. 01/10/2014 - 30/09/2016

Abstract

In this PhD project, we will build more insight in these fundamental processes on an anatase TiO2 catalyst surface, by means of state-of-the-art computer simulations. The plasma-catalyst interactions will be studied on the atomic scale by a combination of various simulations techniques. These techniques are based on an interatomic potential ("force field") that governs all atomic interactions. First, force field parameters for the Ti/O/C/H system will be developed, in collaboration with various other research groups in Flanders. Subsequently, reaction mechanisms and corresponding reaction rate coefficients for all relevant plasma species interacting with the TiO2 catalyst surface will be studied by nudged elastic band (NEB) and force biased Monte Carlo (MC) simulations. Finally, also the actual plasma catalysis process itself will be simulated by molecular dynamics (MD) and hybrid MD/MC simulations. These results will provide the necessary knowledge of the plasma/catalyst interaction, required for controlling and steering the conversion process of greenhouse gases into value-added chemicals.

Researcher(s)

Research team(s)

Multi-timescale atomistic modeling of plasma catalysis and plasma-based growth of carbon nanostructures. 01/10/2014 - 30/09/2016

Abstract

In this project I will develop a novel atomic scale simulation tool to unravel the fundamental mechanisms underpinning complex plasma-based processes. Specifically, I will concentrate on plasma catalysis, which is envisaged to provide an energy efficient route for greenhouse gas conversion into value-added chemicals, and plasma-based growth of carbon nanostructures, which holds promise to offer control on structure and composition, unattainable by thermal methods.

Researcher(s)

Research team(s)

CO2 conversion to renewable chemical power by synergy between plasma and photocatalysts (SynCO2Chem). 01/04/2014 - 31/08/2019

Abstract

Due to the goals set by Europe, CO2 mitigation is of major importance for industry as well as society. With this project we aim at establishing an experimental proof of principle of using photocatalysts in plasma catalytic CO2 conversion as a new high potential key enabling technology that fills the gap and fits in the requirements and opportunities needed for CO2 conversion technologies. Indeed, we aim at providing experimental evidence for energy efficient CO2 conversion to renewable basic chemicals and/or fuels (chemical energy) directly from low concentrated, water and impurity containing CO2 streams via implementation of photocatalysts in plasma conversion.

Researcher(s)

Research team(s)

Computer modeling for a better insight in the underlying mechanisms of plasma catalysis. 01/01/2014 - 31/12/2017

Abstract

Plasma catalysis is gaining increasing interest in environmental applications, e.g. for the conversion of greenhouse gases into value-added chemicals or new fuels. However, the fundamental mechanisms of plasma-catalyst interaction are virtually unknown. In this project, we hope to obtain more insight in these fundamental processes, by computer modeling and experimental validation.

Researcher(s)

Research team(s)

CO2 conversion by plasma catalysis: unraveling the influence of the plasma and the nanocatalyst properties on the conversion efficiency. 01/01/2014 - 31/12/2017

Abstract

The high CO2 concentration in the earth's atmosphere causes major concern because of its impact on climate change (global warming). In this project, we study the CO2 conversion into renewable fuels and value-added chemicals, such as CO (in case of pure CO2 splitting), syngas (CO/H2) and hydrocarbons (e.g. methanol, formic acid,…) in the case of CO2/CH4 conversion, by means of plasma catalysis. In this way, we can solve two problems in one step, as "waste" can be converted into value-added chemicals.

Researcher(s)

Research team(s)

Comprehensive simulations of microdischarges with a Particle-In-Cell/Monte Carlo/Direct Simulation Monte Carlo model (postdoc. fellowship Ya ZHANG, China). 01/01/2014 - 30/06/2015

Abstract

During this research fellowship, we will try to obtain a better insight by computer simulations. The latter will be compared with experimental data, obtained from literature. More specifically, a comprehensive model based on the Particle-In-Cell/Monte Carlo/Direct Simulation Monte Carlo (PIC/MC/DSMC) method will be developed and applied to simulate the behavior of a MD operating in Ar, He and ambient air, under different conditions and parameters. We will try to elucidate the fundamental physical and chemical process involved, and find the optimum parameters of a MD.

Researcher(s)

Research team(s)

Modeling of the plasma chemistry in CHxFy based gas mixtures for microelectronics applications. 05/10/2013 - 07/04/2014

Abstract

This project represents a formal research agreement between UA and on the other hand Erasmus Mundus. UA provides Erasmus Mundus research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Reactive Atmospheric Plasma processIng - eDucation network (RAPID). 01/10/2013 - 30/09/2017

Abstract

The goal of the Multi-Partner ITN-RAPID (Reactive Atmospheric Plasma processIng - eDucation network) is the realization of an interdisciplinary training involving the disciplines physics, chemistry and engineering. As a result, RAPID will create the platform for a truly European PhD in plasma technology. The scientific goal is the development of non-equilibrium reactive processes in atmospheric pressure plasmas.

Researcher(s)

Research team(s)

Towards a fundamental understanding of "warm plasmas"– Conversion of greenhouse gasses to value added chemicals by gliding arc and microwave discharges. 01/10/2013 - 30/09/2014

Abstract

The main objective of this PhD project is to unravel the fundamental processes and mechanisms that occur in warm plasmas (i.e., gliding arc and microwave discharges) and which give rise to unprecedented energy-efficient reaction chemistry. I will focus on the chemical reactions of various plasma species (including neutral, charged and excited species), originating from the greenhouse gases CH4 and CO2, and on their conversion into new fuels or value-added chemicals, such as syngas (CO and H2), methanol (CH3OH), formaldehyde (CH2O) and higher hydrocarbons.

Researcher(s)

Research team(s)

Francqui research professor "PLASMA" 01/09/2013 - 31/08/2016

Abstract

This project represents a formal research agreement between UA and on the other hand a private institution. UA provides the private institution research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Plasma chemistry modeling in a capacitively coupled plasma used for microelectronics applications. 01/04/2013 - 31/12/2013

Abstract

Plasmas are widely used in the microelectronics industry for the fabrication of computer chips, i.e., in plasma etching and deposition of different materials. Nowadays there is increased interest for the use of very complex gas mixtures, such as based on CHxFy, sometimes even in combination with HBr, Cl2 and O2. In this project, we wish to obtain a better understanding of the plasma chemistry in several CHxFy plasmas, i.e., CHF3, CH2F2 , CH3F and CF4, by means of a computer model. For this purpose, we will make use of the hybrid plasma equipment model (HPEM). A reaction set will be created, based on a large number of plasma species, including various molecules, radicals, ions, excited species, as well as the electrons. These species react with each other in a large number of collisions, namely electron-neutral, electron-ion, ion-ion, ion-neutral and neutral-neutral reactions. A list of all possible reactions will be constructed, along with the corresponding cross sections and reaction rate coefficients. Subsequently, for every plasma species the various production and loss processes need to be specified, for solving the continuity equations. The transport of the species will be described based on diffusion, migration and advection. The electric field distribution inside the plasma will be calculated self-consistently from the charged species densities by solving Poisson's equation. Typical results of this model include the species densities, fluxes and energies, the electromagnetic field distribution, and information on the importance of various reactions in the plasma.

Researcher(s)

Research team(s)

Modeling of plasma and plasma-cell interaction for a better understanding of plasma medicine applications. 01/01/2013 - 31/12/2016

Abstract

The aim of this project is to obtain a better insight in plasma-cell interactions on the atomic scale, and specifically on plasma-bacteria interactions. For this purpose, hybrid MD / Monte Carlo (MC) simulations will be performed, for the plasma species bombarding the "substrate" (i.e., bacteria) to be treated. The plasma species and their fluxes will be determined from plasma modeling. Therefore, this project is a combination of plasma modeling and modeling of plasma-bacteria interactions.

Researcher(s)

Research team(s)

Modeling and experimental validation of a packed bed DBD reactor for CO2 splitting. 01/01/2013 - 31/12/2016

Abstract

Global warming, for 70 % caused by CO2, is becoming a bigger problem. As a possible solution, the use of plasmas for CO2 splitting and conversion to value-added chemicals gains interest every year. In this research, the use of a packed bed DBD plasma reactor will be investigated by means of computer simulations and experimental validation. By changing the properties of the packing as well as operational conditions of the reactor, the process will be optimized, with a strong emphasis on the energy efficiency.

Researcher(s)

Research team(s)

IWT Post-graduate Grant. 01/01/2013 - 31/12/2014

Abstract

This project represents a research agreement between the UA and on the onther hand IWT. UA provides IWT research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Physical chemistry of plasma-surface interaction (PSI). 01/10/2012 - 31/12/2017

Abstract

The project aims at federating Belgian groups involved in research activities on reactive plasmas in order to improve our fundamental understanding of these systems and to develop predictive models. The output of this project, which combines experimental and theoretical activities, is expected to drive technological developments in the area of new materials, new surfaces or new coating processes, and therefore to sustain the economic development of our country. We are developing a multidisciplinary and integrated approach, merging together the expertise of research units specialized in plasma diagnostics (optical, electrical probe, laser induced fluorescence and mass spectrometry techniques), in the fundamental study of the ionized gas phase and its hydrodynamics, in bulk plasma and plasma-surface interaction modeling (molecular dynamics, Monte Carlo) and in (organic and inorganic) material synthesis, functionalization and characterization using state-of-the-art tools.

Researcher(s)

Research team(s)

Project website

Numerical simulations of plasmas and their surface processes, used for microelectronics applications. 01/10/2012 - 30/09/2015

Abstract

The objectives for this project are to achieve a better insight in: 1. the fundamental plasma behavior of novel STI gas mixtures, more specifically, Cl2/O2 in combination with CF4, CHF3, CH2F2 and HBr; 2. the surface processes on the Si substrate and the reactor walls during plasma treatment, including trench profile evolution; 3. the plasma uniformity in next generation 450 mm wafer reactors.

Researcher(s)

Research team(s)

Towards a fundamental understanding of plasma - TiO2 catalyst interaction for greenhouse gas conversion. 01/10/2012 - 30/09/2014

Abstract

In this PhD project, we will build more insight in these fundamental processes on an anatase TiO2 catalyst surface, by means of state-of-the-art computer simulations. The plasma-catalyst interactions will be studied on the atomic scale by a combination of various simulations techniques. These techniques are based on an interatomic potential ("force field") that governs all atomic interactions. First, force field parameters for the Ti/O/C/H system will be developed, in collaboration with various other research groups in Flanders. Subsequently, reaction mechanisms and corresponding reaction rate coefficients for all relevant plasma species interacting with the TiO2 catalyst surface will be studied by nudged elastic band (NEB) and force biased Monte Carlo (MC) simulations. Finally, also the actual plasma catalysis process itself will be simulated by molecular dynamics (MD) and hybrid MD/MC simulations. These results will provide the necessary knowledge of the plasma/catalyst interaction, required for controlling and steering the conversion process of greenhouse gases into value-added chemicals.

Researcher(s)

Research team(s)

Plasma intensifaction in DBD plasma devices by the use of a packed bed of ceramic particles with specific dielectric properties, obtained by a core-shell design and by specific tuning of the particle size distribution (i-PLASMA). 01/01/2012 - 31/12/2013

Abstract

Study of the use of core-shell and particle size distribution designed dielectric ceramic particles as packed bed material in the intensification of plasma based chemical processes. Experience in the field of industrial plasma generation will be combined with the modelling expertise of PLASMANT, in order to check on the valorisation potential of plasma induced chemistry. A dedicated experimental/empirical dataset will be set up and a related CIT process analysis. Valorisation is situated in emission control and synthesis of alternative raw material starting from waste streams.

Researcher(s)

Research team(s)

Computer modelling of plasmas used for etching applications in the microelectronics industry (postdoc.beurs S. ZHAO, China). 15/10/2011 - 14/12/2012

Abstract

Because of the important use of gas discharge plasmas in the microelectronics industry, a good insight in the plasma behavior is desirable. During the research fellowship we will try to obtain this insight by computer simulations. The latter will be compared with experimental data, obtained at her home institution, i.e., Dalian University of Technology.

Researcher(s)

Research team(s)

Computer modelling of an atmospheric pressure glow discharge with flowing afterglow. 01/10/2011 - 30/09/2012

Abstract

A glow discharge (GD) is a partially ionized gas. It consists of neutral atoms or molecules, electrons, ions, radicals, excited species and photons. In its most simple form it is created by applying a potential difference between two electrodes, placed in a reactor, which is filled by a gas. Most of the GDs operate at reduced pressure, however, atmospheric pressure glow discharges (APGDs) are gaining increasing interest due to their wide range of technological applications. In the current research project, we envisage the application in analytical mass spectrometry, for the analysis of solids or gaseous samples. Operating the GD at atmospheric pressure makes it possible to open the design and to mix the discharge species with ambient air. Applying a gas flow helps to draw the metastables and ions out of the discharge and to prevent the entering of impurities. The ions and metastables react with air constituents and reagent ions are formed, which are then capable of ionizing the analytes. The ions of the analytes are detected by a mass spectrometer. The aim of this project is to reveal the main mechanisms of reagent ion formation and to improve the analytical capabilities of this sort of ionization sources.

Researcher(s)

Research team(s)

Project website

Computer modeling for the destruction of volatile organic compounds by means of (catalytic packed bed) DBD plasma reactors. 01/04/2011 - 31/03/2015

Abstract

In this project we wish to obtain a better insight in the destruction of volatile organic compounds (VOC's) in (catalytic packed bed) plasma reactors. By means of computer simulations and experimental validation, we will try to understand and optimize the different steps in the entire project with respect to the influence of the general reactor design, as well as a packing and a catalyst.

Researcher(s)

Research team(s)

Numerical simulations of plasma jets used for biomedical applications. 01/01/2011 - 31/12/2014

Abstract

Plasma Jets are gasdischarges which can be used for various biomedical and therapeutic applications such as sterilization, dermatology, blood coagulation, wound care and dentistry, which resulted in the last decade in a rapidly growing international interest. However, before such technologies may be brought on the market the efficiency, safety, selectivity and reproducibility has to be ensured. A good knowledge of the role of biomedically active elementsin the plasma , e.g. radicals, ions, radiation etc., is extremely important. The objective of this work is to study the mechanisms of various plasma jet configuration and the plasma-tissue interactions, specifically for application optimization. Trough numerical simulations, we will make the advantages and disadvantages of different configurations and discharge conditions clear. The calculations will be performed with the fluid model "nonPDPSIM" developed by the research group of Prof. M. Kushner (University of Michigan). Moreover, we will cooperate with two experimental research groups: Rupt (Universiteit Gent, Prof. C. Leys) and EPG (TU Eindhoven, Prof. P. Bruggeman) to verify our modeling work.

Researcher(s)

Research team(s)

Computer modeling and experimental validation for plasmas used for etching in the microelectronics industry. 01/10/2010 - 30/09/2012

Abstract

Computer simulations will be performed for describing the plasma chemistry and physics in two reactors used for etching in the microelectronics industry, i.e., inductively coupled plasmas (ICP) and dual frequency capacitively coupled plasmas (CCP). Several fluorocarbon-based gas mixtures will be considered. The effect of different operating conditions (pressure, gas ratio, power, frequency,. . .) will be investigated to predict under which conditions both discharges have optimum performance. Experimental validation of the calculations will be carried out in both types of reactors. Finally, the effect of these operating conditions on the trench formation, the etch rate, uniformity, selectivity and anisotropy will be investigated.

Researcher(s)

Research team(s)

Numerical simulations on the atomic scale of nanotechnological C- and Si-materials. 01/10/2010 - 30/11/2011

Abstract

In this project, we wish to investigate the fundamental formation processes that give rise to specific carbon and silicon nanomaterials: (ultra)nanocrystalline diamond, carbon nanotubes, amorphous hydrogenated carbon, and nanocrystalline silicon. The objective is gaining control over their structure in order to tune their properties making them suitable for real life applications. This requires insight into the relevant mechanisms on the atomic scale. Therefore, we will perform atomistic simulations of the growth process under realistic growth conditions, in strong collaboration with experimental groups for validation and further model improvements.

Researcher(s)

Research team(s)

Computer modeling of the plasma chemistry in gas discharges for environmental or biomedical applications. 10/08/2010 - 09/06/2011

Abstract

The goal of the research project is to apply fluid modeling for describing the plasma chemistry in an atmospheric pressure plasma, used for environmental and biomedical applications, in order to improve these applications.

Researcher(s)

Research team(s)

Laser ablation solid sampling station for high-resolution inductively coupled mass spectrometer (LA-HR-ICP-MS). 22/07/2010 - 31/12/2014

Abstract

This project represents a formal research agreement between UA and on the other hand the Flemish Public Service. UA provides the Flemish Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

    Numerical simulations of inductive coupled plasma' s uses for etch processes. 01/01/2010 - 31/12/2011

    Abstract

    In this project we try to obtain a better insight in an inductively coupled plasma (ICP) operating in a Cl2/Ar/O2 gas mixture, as well as in the etch process of this plasma on a Si and Si/Si3N4 surface, to optimize the applications of plasma etching in the semiconductor industry. To realize this aim, we wish to describe the plasma and the etch process by numerical simulations. We make use of an hybrid plasma model in combination with a model for surface reactions.

    Researcher(s)

    Research team(s)

    Atomic simulations for chirality-controlled increase of carbon nanotubes. 01/01/2010 - 30/06/2011

    Abstract

    In this project we try to obtain a better insight in the growth mechanisms of the catalyzed growth of single-wall carbon nanotubes (SWNTs), by means of numerical simulations. The simulations are based on classical molecular dynamics (MD) and Monte Carlo (MC) simulations, complemented by quantum mechanical density functional theory (DFT). We try to elucidate the relationschip between specific growth parameters (such as temperature, composition and growth of the catalyst) and the chirality of the SWNTs. In this way, we hope to enable the chirality-controlled growth of the CNTs, which is of great importance for industrial applications (e.g., in the micro-electronics industry).

    Researcher(s)

    Research team(s)

    Hybrid macroscopic and microscopic simulation of laser ablation. 01/07/2009 - 30/06/2013

    Abstract

    An accurate simulation of laser ablation requires a good description of the solid state, melt, Knudsen layer, plasma and interaction with the laser beam. We propose a hybrid model for these simulations that combines particle-based simulations with partial differential equations. The project will develop and analyze the numerical methods and apply them to realistic systems. The new approach may have a large impact on the field.

    Researcher(s)

    Research team(s)

    Study of plasma-surface interactions, by molecular dynamics simulations, for applications of plasma-etching and plasma-deposition. (FWO Vis.Fel., Fujun GOU, China) 01/02/2009 - 31/01/2010

    Abstract

    In this project plasma-surface interactions will be studied by molecular dynamics simulations, for applications of plasma-etching (of Si/SiO2 surfaces in the micro-electronics industry) and for plasma-deposition of thin films.

    Researcher(s)

    Research team(s)

    Computational modeling of materials. 01/01/2009 - 31/12/2013

    Abstract

    In this "Scientific Research Community" we try to calculate the properties of materials by computer simulations. More specifically we study the growth of thin films and of carbon nanotubes by molecular dynamics simulations. By contact with the other research groups we hope to share and exchange our expertise.

    Researcher(s)

    Research team(s)

    Reactive magnetron sputter deposition : a hybrid model and its experimental verification. 01/01/2009 - 31/12/2012

    Abstract

    Basic aspects of the project "Reactive magnetron sputter deposition : a hybrid model and its experimental verification": This project aims at the development of a hybrid model for the description of the reactive sputter process. This goal shall be reached by a combination of simulations and experiments.

    Researcher(s)

    Research team(s)

    Atomistic multi-time scale simulations of catalyzed carbon nanotube growth 01/01/2009 - 31/12/2012

    Abstract

    This research project aims at bringing atomistic simulations closer to experimental conditions by developing realistic interatomic M-C-H interaction potentials and implementing long-time scale algorithms.

    Researcher(s)

    Research team(s)

    Combined Molecular Dynamics (MD) and Monte Carlo (MC) simulations for the plasma-enhanced deposition of (ultra)nanocrystalline diamond ((U)NCD) films. 01/01/2009 - 31/12/2010

    Abstract

    We wish to study the deposition process of (ultra)nanocrystalline diamond films, formed by microwave plasmas, by means of molecular dynamics simulations. We will use the Brenner interaction potential for hydrocarbons. To simulate the deposition process in a realistic way, we wish to develop also Monte Carlo simulations, to describe the relaxation of the system to a thermodynamically more favorable configuration. These Monte Carlo simulations will be coupled to the molecular dynamics simulations. We wish to investigate, among others, the influence of substrate temperature, applied bias to the substrate and gas mixture.

    Researcher(s)

    Research team(s)

    Plasma-assisted conversion of greenhouse gases to value-added chemicals 01/02/2008 - 31/01/2012

    Abstract

    The aim of this project is to convert greenhouse gases, such as CH4, CO2 en N2O, into value-added chemicals, such as methanol, by means of plasmas, either or not in combination with catalysis. This proces is very difficult to realize under normal conditions, because these greenhouse gases are very inert molecules. In plasmas energetic electrons are formed, which can induce these conversions. New plasma reactors will be developed and tested for a wide range of parameters. Our specific role in the project are the numerical simulations of the plasma chemistry, to support the experimental studies and to predict the optimal process conditions.

    Researcher(s)

    Research team(s)

    Center of excellence NANO. 01/01/2008 - 31/12/2014

    Abstract

    This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

    Researcher(s)

    Research team(s)

    Hybrid macroscopic and microscopic modelling of laser ablation and expansion. 01/01/2008 - 31/12/2011

    Abstract

    The aim of the project is to develop hybrid methods that divide the spatial domain into subdomains where an appropriate microscopic or macroscopic model is used. The domains are connected in a physical and mathematically correct way. This makes it possible to limit the use of the expensive particle based methods to the regions of space where they are strictly necessary. We will apply this method to decribe the transport of particles in laser ablation from the surface. More specifically, the Knudsen layer, which is formed between the surface and the bulk, will be described at the particle level.

    Researcher(s)

    Research team(s)

    Numerical simulations of inductive coupled plasma' s uses for etch processes. 01/01/2008 - 31/12/2009

    Abstract

    In this project we try to obtain a better insight in an inductively coupled plasma (ICP) operating in a Cl2/Ar/O2 gas mixture, as well as in the etch process of this plasma on a Si and Si/Si3N4 surface, to optimize the applications of plasma etching in the semiconductor industry. To realize this aim, we wish to describe the plasma and the etch process by numerical simulations. We make use of an hybrid plasma model in combination with a model for surface reactions.

    Researcher(s)

    Research team(s)

    Atomic simulations for chirality-controlled increase of carbon nanotubes. 01/01/2008 - 31/12/2009

    Abstract

    In this project we try to obtain a better insight in the growth mechanisms of the catalyzed growth of single-wall carbon nanotubes (SWNTs), by means of numerical simulations. The simulations are based on classical molecular dynamics (MD) and Monte Carlo (MC) simulations, complemented by quantum mechanical density functional theory (DFT). We try to elucidate the relationschip between specific growth parameters (such as temperature, composition and growth of the catalyst) and the chirality of the SWNTs. In this way, we hope to enable the chirality-controlled growth of the CNTs, which is of great importance for industrial applications (e.g., in the micro-electronics industry).

    Researcher(s)

    Research team(s)

    Combined numerical simulations of the growth of nanoparticles in reactive plasmas and the deposition of nanomaterials. 01/10/2007 - 30/09/2010

    Abstract

    The aim of this project is to obtain a better insight, by means of numerical simulations, in the behavior of reactive carbon-based plasmas, used for the formation and deposition of nanostructured carbon films and nanomaterials (such as (U)NCD and CNT), as well as about the formation process of the nanomaterials itself. We wish to describe in a fully integrated way the formation, growth and behavior of the nanoparticles in the plasma, the interaction of these particles with the substrate and the walls, and the formation of the nanomaterials.

    Researcher(s)

    Research team(s)

    Growth of Complex Oxides. 01/06/2007 - 31/05/2012

    Abstract

    The project targets to understand the growth of complex oxide thin films by a detailed characterisation and modelling of the process. The relaxation between a number of layer properties and intrinsic properties of the layers will be evaluated.

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    Research team(s)

    GLADNET - Analytical glow discharge network. 01/02/2007 - 31/01/2011

    Abstract

    The GLADNET Consortium aims at integrating teams working on particular aspects in groups in Physics, Chemistry or Material Science departments, concentrating on the discharge physics and spectroscopy, the analytical chemistry or the structure of materials and teams working in industry on particular applications and instrument development and to provide open training facilities for the next generation of researchers in the field. The specific role of the research group PLASMANT is to develop numerical models for the glow discharge plasma, especially to describe the effect of hydrogen, nitrogen or oxygen gas impurities on the argon plasma.

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    Project website

    Quantum effects in clusters and nanowires. 01/01/2007 - 31/12/2011

    Abstract

    In this project the physical properties of individual nanoparticles and nanowires will be investigated. The main activities will be concentrated on nanowires, quantum dots, clusters and nanostructured thin films. The nanosystems will be composed of either semiconductors, metals (e.g. superconductors or ferromagnets), carbon, oxides, organic materials and combinations of these materials. The latter are also called hybrid systems, and give extra flexibility to the properties of the nanosystems.

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    Research team(s)

    Growth, characterisation an simulation of nanocrystalline and ultrananocrystalline PE-CVD diamond films. 01/01/2007 - 31/12/2010

    Abstract

    The aim of the project is the experimental and theoretical study of the growth of nanocrystalline and ultrananocrystalline PE-CVD diamond films, as well as the structural, morphological and (opto)electronic characterisation of these films. The project can be divided in three main parts, which are strongly correlated: A. deposition of NCD and UNCD films B. structural, morphological and (opto-)electronic characterisation C. simulation of the deposition of NCD and UNCD films

    Researcher(s)

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    Combined Molecular Dynamics (MD) and Monte Carlo (MC) simulations for the plasma-enhanced deposition of (ultra)nanocrystalline diamond ((U)NCD) films. 01/01/2007 - 31/12/2008

    Abstract

    We wish to study the deposition process of (ultra)nanocrystalline diamond films, formed by microwave plasmas, by means of molecular dynamics simulations. We will use the Brenner interaction potential for hydrocarbons. To simulate the deposition process in a realistic way, we wish to develop also Monte Carlo simulations, to describe the relaxation of the system to a thermodynamically more favorable configuration. These Monte Carlo simulations will be coupled to the molecular dynamics simulations. We wish to investigate, among others, the influence of substrate temperature, applied bias to the substrate and gas mixture.

    Researcher(s)

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    Numerical simulations of dielectric barrier discharges equipped with a gas flow and a flowing afterglow which are used for the deposition of thin SiO2-layers. 01/01/2007 - 30/09/2007

    Abstract

    A fluid model will be developed for a dielectric barrier discharge, used for the deposition of SiO2 thin films. This discharge operates in a mixture of argon + oxygen, in which HMDSO is introduced as a precursor for the SiO2 layers. The chemistry in the plasma will be described in detail with the model. Moreover, the effect of a gas flow, to stabilize the discharge, will be investigated.

    Researcher(s)

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    Numerical simulations of an inductively coupled plasma used for etching practices. 01/10/2006 - 30/09/2010

    Abstract

    The aim of this project is to obtain a better insight in an inductively coupled plasma (ICP) operating in a Cl2/Ar/N2 gas mixture, as well as in the etch process of this plasma on a Si and Si/Si3N4 surface, to optimize the applications of plasma etching in the semiconductor industry. To realize this aim, we wish to describe the plasma and the etch process by numerical simulations.

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    Development of a "particle-in-cell Monte Carlo" model for pulsed magnetron discharges, used for the reactive sputter-deposition of nitride- and oxide-layers. 01/07/2006 - 31/12/2010

    Abstract

    The aim of the project is the modeling of pulsed magnetron discharges, in a mixture of argon with nitrogen or oxygen, used for the reactive sputter-deposition of nitride- or oxide-layers, respectively. The magnetron plasma will be modeled with a particle-in-cell ¿ Monte Carlo model. The influence of, among others, the gas ratio (i.e., reactive gas to argon) will be studied.

    Researcher(s)

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    Understanding materials at the (sub)nano level scale. 01/01/2006 - 31/12/2007

    Abstract

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    BOF/IWT-fellowship for the project "Fluid modeling of a dielectric barrier discharge, used for the deposition of SiO2 layers". 01/01/2006 - 31/12/2006

    Abstract

    In this project we try to develop a fluid model for a dielectric barrier discharge in a mixture of argon + oxygen, with the precursors HMDSO (hexamethyldisiloxane) or TEOS (tetraethoxysilane), used for the plasma deposition of siliciumdioxide (SiO2) layers. The plasma chemistry of both precursors will be extensively studied. Next, the influence of an external gas flow on the discharge behavior will be investigated, by coupling of the fluid model to a commercial "computational fluid dynamics" (CFD) program "FLUENT". Finally, the formation and behavior of a so-called flowing afterglow, as a result of a high gas flow, will be simulated.

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    Nucleation and durability of very thin CVD oxide films on steel and metallic coated steel. 01/10/2005 - 30/03/2008

    Abstract

    The deposition mechanism of very thin oxide films, deposited by chemical vapor deposition (CVD) on steel and metallic coated steel, is being studied by experiments and computer simulations. Our task within the project is focused on the computer simulations. We are developing a molecular dynamics (MD) model, that gives a detailed description of the deposition process. This model iwill be coupled to a Monte Carlo model, for description of the relaxation of the surface during deposition. We also wish to study the mechanism of nucleation.

    Researcher(s)

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    Particle-in-Cell/Monte Carlo Collision model for a pulsed magnetron discharge, used for the reactive sputter-deposition of nitride- and oxide-layers. 01/10/2005 - 30/09/2007

    Abstract

    We are developing a particle-in-cell/Monte Carlo collision model for a pulsed magnetron discharge, in a mixture of argon+nitrogen, or argon+oxygen, for the description of the reactive sputter-deposition of nitride or oxide layers, respectively. In first instance, the model will be developed for a direct current (dc) magnetron discharge, and the chemical reactions between the various plasma species will be described. Subsequently, the model will be extended to a pulsed discharge. We wish to compare the model results with experiments, carried out by other research groups.

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    Modeling of micrometer-sized particle formation in laser ablation of solid materials. (FWO Vis. Fel., D. BLEINER) 01/09/2005 - 31/08/2006

    Abstract

    A model will be developed to describe the processes occurring during laser ablation (LA) of solids, to improve the application of LA for ICP-analysis. Specifically the mechanisms for micrometer-sized particle formation will be simulated, based on the formation of a "melt pool" by heating of the solid. Liquid splashing of the melt pool will result in the formation of jets, which will break up in micrometer-particles. This will be described with a fluid dynamics model.

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    Numerical simulations of processes occurring and after laser-solid interaction. 01/01/2005 - 31/12/2008

    Abstract

    Laser ablation (LA) is used in several application fields, among others, materials technology (i.e., deposition of layers and production of nanoparticles) and analytical chemistry (e.g., in LIBS, MALDI or as sample introduction method for the ICP). The aim of our research is to obtain a better insight in the processes occurring during and after laser-solid interaction, which might help to improve the applications. In the frame of this project, we will focus mainly on the application of LA as sample introduction method for the ICP, either used for ICP-MS or ICP-OES. For this purpose, we try to develop a numerical model, to describe the processes that occur during and after laser-solid interaction. This model incorporates: * laser-solid interaction (heating, melting, vaporization) * expansion of evaporated material (plume) in a background gas * formation of a plasma in this expanding material plume * interaction between laser and plasma * formation of nanoparticles through condensation in the expanding material plume * formationg of micrometer-sized particles through laser-solid interaction : splashing of droplets of molten material, explosive boiling.

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    Numerical modeling of the interactions of femtosecond and nanosecond laser pulses with a solid and with plasma. 01/01/2005 - 31/12/2006

    Abstract

    We try to model the interaction of laser pulses with solid or plasma. The model includes: * laser-solid interaction: heating, melting, vaporization * expansion of the metal vapor in a background gas * formation of a plasma in the material plume * interaction between laser and plasma

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    Modelling of the formation and behavior of dust in a radio-frequent silane discharge. 01/01/2005 - 30/09/2006

    Abstract

    1. FORMULATION OF THE PROBLEM Low pressure radio-frequency discharges are widely used for dry etching of semiconductor components and for thin layer deposition. Most processing gases used in industrial applications (eg. SiH4) are reactive gases and contain dust particles. Knowledge of the plasma species densities (electrons, positive and negative ions, various molecules and radicals, dust particles) together with a good understanding of their behavior in the discharge is essential from the point of view of optimization of surface processes. Initially dust grains were solely considered harmful, because they contaminated the substrate. In the microelectronics industry, particles with diameter as small as tens of nanometers may cause killer defects. Therefore, initially the research aimed at avoiding the particle formation and/or contamination. Since then this field has been rapidly expanding. It appears that film deposition in solar cells application now even benefits from the presence of nanoparticles. It was found that if particles were deposited in the films, while their size was still small, the films show improved properties. The so-called polymorphous silicon thin films have superior electric properties ' thus making this material a good candidate for use in high-efficiency solar cells. 2. METHODOLOGY In this thesis a one-dimensional numerical model will be developed to investigate the formation and behavior of dust particles in a radio-frequent silane (SiH4) plasma. A number of modelling studies of dusty plasmas have been published recently. Attempts have been made to understand the charging of dust, the forces acting on the dust particles and dust-plasma interactions. None of these, however, fully explain the mechanism behind the dust formation and its influence on plasma parameters. Theoretical and numerical studies up to now have basically followed single dust particles in the electric field and particle fluxes of an undisturbed discharge. An important aspect not covered is the influence of the dust on the discharge. For this a fully self-consistent model is needed. In this thesis a 1-dimensional fluid model will be developed for a radio frequency discharge in silane containing dust. In this model the particle balances, the electron energy balance, and the Poisson equation will be solved, including the transport of the dust fluid. The problem can be divided in different steps and contains the following procedures: - a detailed chemistry model will indicate particle growth: reactions leading to the formation of bigger anions and eventually to nanometer sized clusters will be included. In a SiH4 discharge small clusters are formed in situ: macromolecules and small crystallites are produced as a result of plasma polymerization. - a detailed description of the charge distribution of the dust particles. Dust particles generally charge up negatively to several hundreds to thousands of e (elementary charge) to balance electron and ion currents to the particles. The electrons are more mobile, which requires the particles to acquire negative potentials so that the sum of the currents remains equal. Because the dust particles are charged negatively, they respond to electric fields. - an insertion of transport equations which describe the movement of dust particles in the discharge. The particles in the plasma are subject to several forces that act either to confine them in the plasma i.e., the electrostatic force, or to drag them to the walls i.e., gravity, ion and neutral drag and the thermophoretic force. The aim of our work is to obtain a better understanding of particle behavior, to find ways to control particle contamination or increase incorporation into films, when desirable.

    Researcher(s)

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    Prize "Robert Oppenheimer" 2004. 01/12/2004 - 31/12/2006

    Abstract

    This scientific prize was given for my general scientific activities.

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    Mathematical simulation of the deposition of diamond-like carbon (DLC) films. 01/01/2004 - 31/12/2005

    Abstract

    In this project, computer simulations are performed to investigate the deposition of thin diamond-like carbon (DLC) films. In a first step, molecular dynamics (MD) simulations are used to study chemisorption reactions taking place during DLC-deposition. Molecular dynamics are based on the use of a suitable interatomic potential, from which the forces on all atoms in a system of atoms are calculated in a self-consistent way. The atom's spatial trajectory, as governed by Newtons laws, is integrated explicitly in time. Therefore, using this type of simulations, detailed information regarding film growth, growth mechanisms and film structure on the atomic level can be obtained. In a second step, physisorption is included by changing the interatomic potential, such that it is suited both for chemisorption and physisorption. Finally, diffusion of particles at the substrate will also be included. This can be done by so-called time-dependent Monte Carlo (TDMC) calculations. A TDMC model will be developed, and coupled to the MD model. Ultimately, this will lead to a model which is capable of simulating DLC film.

    Researcher(s)

    Research team(s)

    Simulation of the deposition of diamond-like carbon layers, using combined molecular dynamics and Monte Carlo simulations. 01/08/2003 - 31/07/2004

    Abstract

    In this research project, we try to simulate the plasma deposition of diamond-like carbon layers, by combined molecular dynamics (MD) en Monte Carlo (MC) simulations. MD simulations describe the behavior of individual atoms in a system. The trajectory of the atoms, under the influence of the forces resulting from the other atoms, is calculated as a function of time. The forces are obtained from the interatomic potentials. The deposition process is simulated by following a large number of particles (radicals, ions,') bombarding the surface, and by calculating the interaction with the surface atoms. This MD method is very reliable, but its major disadvantage is the long calculation time. Indeed, a typical timestep in MD simulations is in the order of 10-15 s, whereas certain processes in the deposition mechanism, e.g., diffusion of the atoms over the surface, occur on a timescale of ca. 10-6 s. Therefore, we wish to extend the MD code with a MC model, to take diffusion into account. The diffusion process will be simulated based on 'jumps', calculated in the MC model, using input data (interaction potential) from the MD model.

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    Chemical characterisation of nanostructured materials. 01/01/2002 - 31/12/2006

    Abstract

    The project aims at the development and application of advanced methods for the local chemical analysis of tailored surfaces. To obtain molecular information on the surface components, high mass resolution laser microprobe mass spectrometry (MS) and static secondary ion MS are used. Plasma modelling is applied to elucidate the fundamental processes in the plasma deposition of thin films and during plasma polymerisation.

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      Mathematical simulation of a radiofrequent capacitively coupled CH4/H2-plasma and the deposition of diamond-like-carbon (DLC) films. 01/01/2002 - 31/12/2003

      Abstract

      A low-pressure CH4/H2 plasma will be simulated using a combined fluid / Monte Carlo model. This model yields data like the flux and energy of particles impinging on a substrate. These impinging particles lead to diamand-like carbon film growth. This film growth will be simulated using a Molecular Dynamics model. Also, we will combine the plasma model and the film growth model. The goal is to gain insight into the underlying mechanisms of film growth, and to obtain information about the resulting film, as its structure and composition.

      Researcher(s)

      Research team(s)

      Simulation of a cc rf discharge in a mixture of SiH4/O2/N2/He. 01/12/2001 - 01/06/2002

      Abstract

      A fluid model will be developed for a cc rf discharge in a mixture of SiH4/O2/N2/He, operating at atmospheric pressure, in order to determine the oxygen fraction contained in the deposited silicon thin film. A large number of different plasma species will be taken into account in the model, including electrons, He atoms, ions and excited atoms, various silane species, hydrogen species, oxygen species, nitrogen species, silane-oxygen and silane-nitrogen species. For every type of species, a balance equation will be constructed with different production and loss processes. Based on the calculated fluxes of species bombarding the substrate, an estimate of the deposited layer composition will be made.

      Researcher(s)

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        Modelling of a dielectric barrier discharge for reactive surface treatment. 01/11/2001 - 31/10/2005

        Abstract

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        Physicochemical study of plasma processes in metal vapour ion lasers via numerical simulations. 01/01/2001 - 31/12/2004

        Abstract

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        Development of technology and software for diamond-like carbon deposition in large scale plasma reactors. 01/12/2000 - 30/11/2003

        Abstract

        DLC (diamond-like carbon) films are considered as promising protective low-friction surface coatings with remarkable industrial impact. PE-CVD (plasma enhanced chemical vapor deposition) is a very promising technique for the deposition of DLC films. For industrial applications, it is necessary to develop PE-CVD reactors that allow the deposition of films with the required properties, with a high productivity and high growth rates on flat and non-flat substrates. At present, there are no large-scale reactors that meet all industrial requirements. Moreover, the understanding of plasma-chemical processes, the film growth mechanisms, the correlation between both, and how they change with up-scaling of the installations is far from complete for large scale (LS) PE-CVD reactors. Therefore, the main goal of the project is to develop a scientific method for the up-scaling of plasma reactors. The objectives are: 1) Experimental study of the plasma parameters and their influence on the deposition process in different PE-CVD reactors. 2) Modeling of the deposition process, (i) to simulate the effects of up-scaling of the reactors, and (ii) to predict the uniformity of coatings on samples of complex geometry. 3) Based on the theoretical and experimental studies, the development of the most appropriate LS reactor and the technology of carbon deposition on industrial samples.

        Researcher(s)

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        Numerical simulations of glow discharges used in analytical chemistry and for laser applications. 01/10/2000 - 30/09/2004

        Abstract

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        Computer modeling of gas discharge plasmas used in analytical chemistry and for laser applications. 01/01/2000 - 31/12/2001

        Abstract

        Gas discharges in noble gases are, among others, being used in analytical chemistry (for the analysis of solid samples which play the role of cathode in the discharge) and also as metal vapor lasers. In order to improve the understanding and the results in these application fields, we try to develop comprehensive computer models for the description of the various plasma species in a concrete case : an argon (or neon or helium) discharge with a copper cathode (i.e. argon atoms and ions, excited atoms, electrons, copper atoms and ions, etc.).

        Researcher(s)

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          High beam quality UV lasers for microelectronica. 01/01/1999 - 31/12/2003

          Abstract

          In microlithographic processes, narrow bandwidth excimer lasers are needed to bring down the scale of the structure into or below the 100 nm range. For this purpose, further narrowing of the bandwidth of the excimer lasers would be needed. The aim of this project is to develop laser systems where hollow cathode laser pulses (of CW gas laser beam quality) are used to control the bandwidth of the excimer lasers. The laser development will be supported by modeling calculations and experimental (plasmadiagnostic) measurements.

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          Research around plasma science, gas discharges, and especially glow discharges. 01/10/1998 - 31/12/1999

          Abstract

          A comprehensive modeling netwerk, existing of different submodels for different plasma species (e.g. atoms, ions, excited atoms of the plasmagas and the sputtered material, as welf as electrons), has been developed for a direct current glow discharge in argon. Typical results are the densities, fluxes and energies of the plasma species, information about collision processes in the plasma, the electric field distribution, etc.

          Researcher(s)

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            Mathematical simulations of direct current, radiofrequency, pulsed, and magnetron discharges, used in analytical chemistry and for technological applications. 01/10/1998 - 31/12/1999

            Abstract

            A comprehensive modeling network, existing of different submodels for the different plasma species, has recently been developed for a direct current glow discharge in argon. These models are now being extended and applied on radiofrequency, pulsed and magnetron discharges, e.g. by including a time-dependency and/or magnetic field.

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              Mathematical simulations of direct-current, radio-frequency, pulsed and magnetron assisted discharges, used in analytical chemistry and for technological purposes, and comparison with experiment. 01/10/1997 - 30/09/2000

              Abstract

              Glow discharges are gas plasmas, used in analytical chemistry (as spectroscopic sources or the elemental analysis of solid materials), in the micro-electronics industry (for plasma deposition of thin layers and plasma etching of surfaces), in the laser and light industry, for TV-screens' etc. To optimize the results in these application fields, we have developed a set of mathematical models which try to describe the behavior of the various species present in the glow discharge plasma. In the past few years, we have developed already such models for direct current discharges, and in the current project, we want to extend these models to other types of discharges (i.e. radio-frequency, pulsed and magnetron discharges), which are finding increasing applications.

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                Theoretical and experimental research of the kinetica of non-equilibrium low pressure discharges. 01/09/1997 - 31/08/1999

                Abstract

                The project will initiate a wide cooperation for the investigation of kinetica in low pressure plasmas. The main directions of the research are : (1) theoretical study of plasma physics, (2) development of effective software for numerical simulations of the plasma and surface processes, and (3) experimental studies to validate the developed models.

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                  Experimental study and computer simulation of technological and analytical discharges. 01/06/1997 - 31/12/1998

                  Abstract

                  Gas discharges used for technological and analytical purposes are being studied with the use of computer simulation and experimental plasma diagnostics. Comparison between the results of both methode will give us a better insight in the complexity of these discharges, what will lead to better results in the various application fields.

                  Researcher(s)

                  Research team(s)

                    Mathematical simulations of direct-current, radio-frequency, pulsed and magnetron assisted discharges, used in analytical chemistry and for technological purposes, and comparison with experiment. 01/01/1997 - 31/12/1998

                    Abstract

                    Glow discharges are gas plasmas, used in analytical chemistry (as spectros-copic sources for the elemental analysis of solid materials), in the micro-electronics indus-try (for plasma deposition of thin layers and plasma etching of surfaces), in the laser and light industry, for TV-screens, etc. To optimize the results in these application fields, we have developed a set of mathematical models which try to describe the behavior of the various species present in the glow discharge plasma. In the past few years, we have developed already such models for direct current discharges, and in the current project, we want to extend these models to other types of discharges (i.e., radio-frequency, pulsed and magnetron discharges), which are finding increasing applications.

                    Researcher(s)

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                      Theoretical and experimental study of the relative importance of several fundamental processes in an analytical glow discharge. 01/10/1995 - 30/09/1997

                      Abstract

                      This research is aimed at acquiring a general knowledge on the analytical processes of a glow discharge through the development of theoretical models for the description of the transportbehaviour of electrons, ions and neutrals in the glow discharge plasma. These models will be experimentally tested via several plasma diagnostic techniques, like Langmuir probe measurements, optical emission spectrometry and mass spectrometry.

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                        Theoretical and experimental study of the relative importance of several fundamental processes in an analytical glow discharge. 01/10/1993 - 30/09/1995

                        Abstract

                        This research is aimed at acquiring a general knowledge on the analytical processes of a glow discharge through the development of theoretical models for the description of the transportbehaviour of electrons, ions and neutrals in the glow discharge plasma. These models will be experimentally tested via several plasma diagnostic techniques, like Langmuir probe measurements, optical emission spectrometry and mass spectrometry.

                        Researcher(s)

                        Research team(s)