Postdoctoral positions in the ASDEX Upgrade Project

Spectroscopy

In ITER, the ramp-up has to be performed at relatively low densities in order to minimize the flux consumption of the central solenoid. However, this features also a hot plasma at the plasma wall contact possibly eroding W at a large rate leading to unacceptable high W concentrations in the plasma. This is facilitated by the effect that a thin, hot plasma in the scrape-off layer (SOL) and in the divertor implies an easy penetration of the eroded W into the main plasma. The latter could be cooling the plasma, counteracting the goal of minimizing flux consumption, but also the reduction of edge heat fluxes may lead to the inaccessibility of H-mode. Thus, for a successful accomplishment of the ramp-up in ITER, it is crucial to understand the relation of W sources at the plasma edge to the core W content during the L mode phase. For such a study, as well as others, reliable measurements of the W concentration profile in the plasma, both edge and core, is crucial.  We are searching for a post doc interested in spectroscopy and impurity transport to improve AUG’s suite of W diagnostics (EUV, soft x-ray) and to explore the impact of the W source in a variety of plasma scenarios including ramp-up, ramp-down, L-mode, and the L-H transition.