Numerical simulations of stellarator plasmas
Numerical simulations are essential for the design and layout of machine critical components. Equally important, they allow to predict and validate experimental results. The occurence of critical situations can be checked for plasma scenarios before they are realized experimentally.
The strike point of the plasma on the divertor is an essential parameter for reliable operation of the machine. It also is one of the main factors that influence the quality of the plasma confinement. The strike point is determined by the magnetic field inside the plasma vessel.
The main part of this field is produced by the coil system of Wendelstein 7-X, which allows for great flexibility in shaping the magnetic field. Plasma currents however superpose additional fields, thus changing the magnetic field during a plasma discharge. This presents a considerable challenge for the choice of the field configuration and its control during a discharge.
Numerical methods allow to investigate alternative strategies to meet these challenges, such as dynamical changes of the external fields, or the introduction of additional divertor components. Moreover, numerical methods allow to identify configurations that are meaningul for the operation of Wendelstein 7-X under reactor relevant conditions already in the first operation phase.