ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
High-frequency density fluctuations with m=1/n=1 have been observed in a currentless high-β plasma. The line density was measured with a 5-ch FIR laser interferometer. A high-β plasma with 〈β〉∼2% was obtained with about 2-MW neutral beam injection into a currentless target plasma produced by second-harmonic ECRH. With weak gas puffing [β(0)(approximately-greater-than)1%], sawteeth-like oscillations accompanied by high-frequency fluctuations of about 2–5 kHz were observed on the line density. These fluctuations coincide with the soft x-ray fluctuations. From both signals the mode number of this instability is estimated to be m=1 and n=1. During the fluctuations, rapid enhancement (10%–20%) in the edge ion saturation current was also measured, which indicates that this instability causes particle loss from the bulk to the edge. The instability is quenched by a change in density profile from peaked to broad with intense gas puffing. This behavior is consistent with a theoretical analysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1138042
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