München 2019 – scientific programme

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P: Fachverband Plasmaphysik

P 18: Postersitzung

P 18.99: Poster

Thursday, March 21, 2019, 16:30–18:30, Foyer Audimax

First Results from a High Time-Resolution Thomson Scattering System at Wendelstein 7-X — •Hannes Damm and Ekkehard Pasch for the The Wendelstein 7-X Team collaboration — Max Planck Institute for Plasma Physics, Greifswald, Germany

Studies of short transient plasma events may reveal fast relaxation mechanisms of the plasma or MHD events.
The poster describes a Thomson Scattering (TS) System, simultaneously providing electron temperature and density profiles, combining high temporal resolution and adjustable measuring times. This "burst" TS mode has a typical 10kHz time resolution spread over a time window of typically 1.2ms, compared to the 30Hz standard mode. Three lasers are employed each emitting up to four laser pulses per burst, providing twelve consecutive measurement points. A burst can be either triggered at pre-defined times or by plasma events, for which a fast trigger logic circuit was developed.
Burst measurements of the following events have been successfully conducted: i) injection of cryogenic hydrogen pellets for plasma fuelling, ii) impurity injection via Tracer-Encapsulated Solid Pellets (TESPEL) and Laser Blow-Off, iii) heat waves driven by Electron-Cyclotron-Current-Drive (ECCD) crashes and iv) modulation of the Neutral Beam Injection and Electron Cyclotron Resonance Heating. Significant effects on the density and temperature profile shapes are shown for different plasma events.