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Advertising division: IEK-4 - Plasma Physics
Reference number: D065/2018, Physics, Mathematics

Master thesis: Modelling of 3D effects of hydrogen outgassing from ion-irradiated materials

Interactions of ionized particles and plasma with solid state materials underlie many technological processes in very different fields of application, in particular when intentional modifications of material morphology and properties are desired. Plasma-material interactions become very intense in a fusion reactor where extremely hot plasma comes into contact with surrounding material walls. Implantation of ions of hydrogen isotopes (deuterium-tritium fuel) into plasma-facing walls causes degradation of material properties, and accumulation of radioactive tritium in the reactor has to be limited and controlled. Therefore it is very important to understand fundamental processes of hydrogen interactions with materials.

The Institute of Energy and Climate Research – Plasma Physics (IEK-4) of the Forschungszentrum Jülich has a unique expertise in the field of plasma-material interactions in fusion research. A number of state-of-the-art facilities and laboratory experiments are operated by IEK-4. Fundamental and reactor-relevant plasma-material interactions are studied, and modelling represents an important tool for interpretation of experimental results. At IEK-4 we perform simulations of hydrogen transport, retention and release in reactor-relevant materials. Evolution of mobile and trapped hydrogen concentrations is described by a system of coupled partial differential equations (PDE) that is implemented and solved numerically in the Wolfram Mathematica technical computing system.

Hydrogen retention and release from ion-irradiated materials is often modelled in 1D. This approach neglects some aspects of the experimental setup, e.g. non-uniform distributions of the ion flux and temperature over the material sample. Modelling of non-uniform materials appears to be even more challenging. The finite element method (FEM) of spatial discretization used for non-uniform computational domains in Mathematica is currently not capable of handling non-linear equations and cannot be directly applied to the problem of interest.

The task for the master studen is to program an iterative non-linear PDE solver using the intrinsic low level FEM functionality in Mathematica and to apply it to modelling of hydrogen outgassing from plasma exposed materials accounting for 3D effects. Ultimately, a better understanding of the involved processes should be achieved by comparing modelling results with experimental data on deuterium outgassing from tungsten and beryllium measured in IEK-4 facilities. The candidate should have good basic knowledge in / passion for physics (thermodynamics, material science, atomic and molecular physics) and mathematics (PDE, numerical methods, FEM). Basic knowledge of Mathematica would be beneficial but is not required if compensated by good programming skills.

Contact:
Dr. Dmitry Matveev
Institute of Energy and Climate Research – Plasma Physics (IEK-4)
Forschungszentrum Jülich
Telefon: + 49-2461-61-96625
E-Mail: d.matveev@fz-juelich.de
Internet: http://www.fz-juelich.de/fusion