Exploring refinement criteria for adaptive meshes used in kinetic plasma modelling

• Promoter: Prof. Sven Van Loo
• Mentors: Ce Wang, Sebastian Konewko
• Study programs: Master of Science in Engineering Physics, Master of Science in Physics and Astronomy, Master of Science in Teaching in Science and Technology (Physics and Astronomy), European Master of Science in Nuclear Fusion and Engineering Physics
• Location: Technicum, at home

In order to achieve enough energy output viable for commercial exploitation of fusion reactors, fusion plasmas need to be ridden from global instabilities in the magnetic structure of the plasma. To understand the dynamics and arising instabilities, theoretical modelling needs to be tightly integrated with the experiments. While a fluid approach has been successfully applied to many problems in fusion devices, it is restricted because it is based on the assumption that collisions between plasma particles cause the velocity distribution function to be Maxwellian. However, in tokamak plasmas, the electrons also often exhibit markedly non-Maxwellian distributions. Thus, in many cases the details of the kinetics cannot be neglected and the plasma needs to be described using the Vlasov equation which follows the evolution of the particle distribution function in phase-space. In the nuclear fusion group we have developed a Vlasov code to model such kinetic plasmas. Vlasov codes need very fine grids to reduce truncation errors resulting from the discretisation of the Vlasov equation. This results in very computationally expensive simulations, but we can reduce the computational cost of our Vlasov codes through the use of adaptive-mesh refinement (AMR) techniques.

In this project you will study the practical application of AMR in kobra. Currently we are using a refinement criterium based on truncation errors, but the numerical results depend on other parameters of the AMR algorithm. Using a set of benchmark problems for plasma physics you will explore the optimal settings of the AMR in kobra, but also investigate other refinement criteria that are more physics based.