Fast ion temperature measurements in the SOL using the ExB analyzer
Project ID:*WP12-FRF-IPP.CR/Komm
Provider:Euratom under European Fusion Development Agreement
Period:Apr 01, 2012 - Apr 30, 2014
Principal Investigator:Mgr. Michael Komm, Ph.D.
Co-investigatorsJ. Stöckel

Aims of the project: Convective transport of particles and energy across the scrape-off layer (SOL) by Edge Localized Modes (ELMs) and turbulence can impact the performance of burning plasma tokamaks. Both, turbulence and ELMs, produce field-aligned plasma filaments (appearing as blobs in the plane perpendicular to the magnetic field B) that evolve in the SOL in a similar manner: they propagate outwards due to interchange motions while losing particles and energy parallel to open field lines. Despite the parallel dissipation, filaments can convey hot and dense plasma over large radial distances. In ITER, the radial filament transport can cause unwanted plasma interactions with the walls of the main chamber. In order to amend extrapolations towards ITER, many filament properties are more or less routinely diagnosed in the present tokamaks. Among the parameters that are measured extremely rarely for both, ELM and turbulence filaments, is the ion temperature. Although several diagnostics have been developed to measure Ti in the SOL of tokamaks, such as Katsumata probe, Segmented tunnel probe (STP)] or Retarding Field Analyzer (RFA), in general they suffer either from poor temporal resolution (methods based on sweeping) or insufficient sensitivity (STP). Fast Ti measurements at ~μs scale would be a novelty which would allow to temporally resolve the filaments and contribute to he understanding of their impact on the PFCs. The measurements will also focus on filaments in mitigated ELMs in order to evaluate their effectivity and predict their performance on ITER.