Density fluctuation phenomena in the scrape-off layer and edge plasma of the Wendelstein 7-AS stellaratorFunded under: EAEC-FUSION 12C
The fluctuation of electron density in the scrape-off layer and edge plasma regions of the Wendelstein 7-AS stellerator is investigated by the beam emission spectroscopy technique, observing fluctuations in the electron density fluctuations from correlation's of beam light fluctuations. Depending on the plasma electron density, the radial range of the measurement is either limited to r/a>0/9 or can extend to about r/a 0.3 at the lowest densities. As the techniques is nonperturbing to the plasma, several hundred shots were analyzed and a catalogue of the observed phenomena was established. The result always show a change in the properties of the fluctuations at approximately the last closed flux surface. This observation might indicate differences in the turbulence drive in the SOL and the edge plasma. However, one cannot exclude that the same turbulence phenomenon results in different density fluctuations in the two regions due to the different magnetic topologies. The relevance of the observed phenomena to anomalous transport is discussed.
Bibliographic Reference: Article: Physics of Plasmas, 6 (1999)11, 4239-4247
Record Number: 199911711 / Last updated on: 1999-12-24
Original language: en
Available languages: en