München 2019 – scientific programme
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P: Fachverband Plasmaphysik
P 17: Helmholtz Graduate School VI
P 17.4: Talk
Thursday, March 21, 2019, 15:25–15:50, HS 17
Langmuir probe measurements of plasma fluctuations in the Wendelstein 7-X divertor — •Lukas Rudischhauser1, Michael Endler1, Kenneth Charles Hammond1, and Boyd Douglas Blackwell2 for the The Wendelstein 7-X Team collaboration — 1Max-Planck-Insitute for Plasma Physics, Greifswald, Germany — 2Australian National University, Canberra, Australia
Simultaneous, non-invasive and continous measurement of plasma density, temperature and potential is a unique capability of langmuir probes. During the operation phase 1.2b of the stellerator Wendelstein 7-X two newly installed fast swept Langmuir systems were operated, sampling these quantities with typically 50 kHz.
The first system is a Mirror Langmuir Probe, a time domain triple probe with automatic bias adjustement based on the work of LaBombard (RSI 78, 2007). The second is a new development we call Bridge Probe, removing transmission line influences with a compensation cable.
The two systems are described and evaluation methods explained. Fluctuation results are related to local and global plasma parameter averages, and their spectra discussed in detail. This analysis will guide futher development of diagnostics for the steady state high heatflux divertor operation phase of Wendelstein 7-X.