# Forschung

#### High temperature plasma physics research area:

Nonlinear dynamics in high temperature plasmas: physics understanding through high performance computing.

The research interest of the chair is nonlinear dynamics in high temperature plasmas. The latter include laboratory as well as astrophysical plasmas. The main (but not the only) research tool is high performance computing, i.e. numerical simulations that require a massive parallel computing approach (> 1000 CPUs).

The main interest in the area of laboratory plasmas is the research on magnetic confinement nuclear fusion, which is a candidate solution for the energy demands of our society. Nuclear fusion is promising due to the unlimited amount of fuel, the fact that it is CO2 neutral, the limited amount of long-lived radioactive waste, and the inherent safety of the approach. As a minor drawback, one could mention that a working concept for this approach still needs to be demonstrated.

The construction of a working fusion reactor is hindered by several, in itself rather interesting, physics phenomena. One of the main problems is that of energy confinement. The large temperature and density gradients in a fusion reactor drive turbulence, which largely enhances the flow of energy from the centre to the wall, and makes it difficult to maintain the high temperatures that are needed for the fusion reactions to occur.

The turbulence in fusion reactors, in which the magnetic field plays an important role, is extensively studied in the group.

The study of astrophysical plasmas also concentrates on nonlinear dynamics and furthermore deals with basic plasma physics problems. The main interests are kinetic effects during magnetic reconnection and the dynamo. Magnetic reconnection is a frequently occurring phenomenon in astrophysical plasmas with solar flares and the tail of the magnetosphere as prominent examples. One of the fundamental problems is the understanding of the reconnection rate. The dynamics at small scales, where kinetic effects are of importance, are crucial for the solution of this problem.

The dynamo, on the other hand, deals with the generation of magnetic fields through the motion of a conducting fluid. Of main interest here is the nonlinear saturation of the magnetic field strength.