Astro-, geo- and plasmaphysics: 4 X 25' invited

 

Elisa Costantini (Netherlands Institute for Space Research (SRON), Utrecht)

 

Astrophysics: The X-ray view of black holes near and far

The matter surrounding black holes is a powerful X-ray emitter. The X-ray observations of the last ten years allowed a significant step forward in understanding these objects. In this talk I will review some of the most significant results on both black holes in our Galaxy and supermassive black holes at the center of the so-called active-galactic nuclei, located at cosmological distance.

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Harro A. J. Meijer (Centre for Isotope Research, Energy and Sustainability Research Institute Groningen, University of Groningen)

Geophysics: Isotopes write climate history - the art of reading

The only way to validate climate models is to let them "hindcast" the past climate. For this reason, and in fact to learn to understand the climate system in the first place, knowledge of earth's climate history is highly valuable. Fortunately, nature has left us a variety of so-called natural archives of climate. The ice caps of Greenland and Antarctica, with their storage of hundreds of thousands of years of precipitation, are amongst the most valuable ones.

The concentration of the rare, heavy isotopes of hydrogen and oxygen in precipitation is dependent on the temperature at the time of precipitation. Thus, by analysing these isotope abundances in cores drilled through the ice caps, a high-resolution "proxy" temperature record can be reconstructed. I will show the development of measurement systems for the routine, but necessarily highly accurate analysis for hydrogen and oxygen isotopes in water of large numbers of samples. Furthermore, I will show the "proxy" character of the relation isotope abundance - temperature, and the various efforts to elucidate this relation and, thus, improve our quantitative knowledge of the paleo-temperature.

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Annemie Bogaerts (Research group PLASMANT, Department of Chemistry, University of Antwerp)

 

Plasmaphysics: Modeling approaches for a better insight in various low temperature plasma applications

In this talk, an overview will be given of different modeling activities going on in our research group, for improving the applications of gas discharge plasmas in different fields. The examples given are all based on collaborations with other (experimental) plasma research groups in Belgium. Indeed, the model calculations are performed to assist in the experimental developments.  The following topics will be presented:

·                     Fluid modeling for describing dielectric barrier discharges (DBDs), used for environmental applications, more specifically for the conversion of greenhouse gases (CO₂, CH₄) into value-added chemicals (like CH₃OH and syngas). This work is in collaboration with VITO and KULeuven.

·                     PIC-MC modeling for describing magnetron discharges, for sputter-deposition applications of thin films. This work is in collaboration with UGent.

·                     Hybrid MC-fluid modeling for describing inductively coupled plasmas, used for etching applications in the microelectronics industry. This will not only include the modeling of the plasma behavior, but also the interaction of the plasma species with the wafer, resulting in etching and etch profile formation. This work is in collaboration with IMEC.

In each case, both the model and the type of discharge will be briefly outlined, and typical calculation results will be presented. Furthermore, it will be demonstrated why this particular modeling approach is most suitable for this application.

Beside these computer models for the plasma itself, it is also of great interest to simulate the interaction between the plasma and the walls of the plasma reactor, because (i) this defines the boundary conditions of the plasma simulations, and (ii) it is essential for important applications such as thin film deposition and surface etching. For this purpose, we apply molecular dynamics (MD) simulations. The capabilities and limitations of MD simulations will be illustrated for the case of plasma deposition of nanocrystalline diamond thin films. This work is in collaboration with UHasselt.

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Jef Ongena (Plasma Physics Laboratory, Ecole Royale Militaire/Koninklijke Militaire School, Brussels)

 

Plasmaphysics: Recent contributions from JET in preparation for ITER

 

JET is the largest fusion device in the world and is the only tokamak device that can operate with deuterium-tritium plasmas, can confine the 3.5MeV fusion alpha's and can operate with Beryllium, one of the wall materials for the next step fusion device ITER. JET has largely contributed to progress in fusion research over the past 20 years. Highlights of fusion research at JET include the first large scale generation of fusion power (16MW) from D-T reactions, equivalent to a record fusion gain of 0.7, i.e, very close to break-even, important contributions to the international confinement database, and plasma-wall interaction studies : divertor physics, study of edge instabilities causing large fluxes of heat and particles (so-called 'ELMs'), and characterization of the plasma boundary.

JET is now also largely contributing to preparing ITER. Main projects are the development of ITER operational scenarios, testing a new type of antenna for ion cyclotron heating of the plasma at high power density (8MW/m²) and resilient to fast changes in the edge plasma parameters and operation with an ITER like wall consisting of Be and W instead of C. These and future projects will provide important information to accelerate a similar implementation on ITER. The few examples discussed in the talk should demonstrate that JET, with its unique properties, has contributed and is still contributing in a profound way to the development of fusion science and technology.