By examining the distribution and dynamics of the visible radiation of the magnetically confined plasma, we can learn a lot about the processes taking place within it.  This PhD topic investigates this issue on the Wendelstein-7X stellarator, the world's largest superconducting stellarator, operating at the MPG Institute for Plasma Physics (Greifswald, Germany).  The workhorse of these investigations is the stellarator video diagnostics system, which, with its numerous views (13+) and various intelligent, fast and ultrafast cameras, covers a large part of the torus interior and, with its good time resolution, is capable of examining processes down to the microsecond time scale.

These investigations are organized around two major areas. One is the investigation of the toroidal-poloidal symmetry/asymmetry of visible radiation, including the issue of turbulent edge plasma filaments. The experimentally obtained radiation distributions should be compared with edge plasma simulations (e.g. EMC3-EIRENE) as well.

The other major area deals with the issue of cryogenic fueling pellets and plasma interaction which on one hand focuses on the more coherent state after the injection of cryogenic pellets, in which a radiation zone appears in the center of the plasma. On the other hand, it explores the pellet trajectories, its acceleration in the plasma and the drift of cloud formed around the ablating pellet which can strongly influence the particle deposition.  It would be useful to compare these results with a pellet ablation code like HPI2.

The student's task is to perform such experiments on the Wendelstein-7X stellarator as a member of the video diagnostics team and to interpret the obtained results comparing them with modelling.