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Title: Effect of supersonic molecular-beam injection on edge fluctuation and particle transport in Heliotron J

Edge fluctuation in a supersonic molecular-beam injection (SMBI) fueled plasma has been measured using an electrostatic probe array. After SMBI, the plasma stored energy (W{sub p}) temporarily decreased then started to increase. The local plasma fluctuation and fluctuation induced particle transport before and after SMBI have been analyzed. In a short duration (∼4 ms) just after SMBI, the density fluctuation of broad-band low frequency increased, and the probability density function (PDF) changed from a nearly Gaussian to a positively skewed non-Gaussian one. This suggests that intermittent structures were produced due to SMBI. Also the fluctuation induced particle transport was greatly enhanced during this short duration. About 4 ms after SMBI, the low frequency broad-band density fluctuation decreased, and the PDF returned to a nearly Gaussian shape. Also the fluctuation induced particle transport was reduced. Compared with conventional gas puff, W{sub p} degradation window is very short due to the short injection period of SMBI. After this short degradation window, fluctuation induced particle transport was reduced and W{sub p} started the climbing phase. Therefore, the short period of the influence to the edge fluctuation might be an advantage of this novel fueling technique. On the other hand, although their roles are not identifiedmore » at present, coherent MHD modes are also suppressed as well by the application of SMBI. These MHD modes are thought to be de-exited due to a sudden change of the edge density and/or excitation conditions.« less
Authors:
; ; ;  [1] ; ; ; ; ; ; ; ; ; ; ; ; ;  [2] ;  [3] ;  [4] ;  [5] more »; « less
  1. Graduate School of Energy Science, Kyoto University, Uji 611-0011 (Japan)
  2. Institute of Advanced Energy, Kyoto University, Gokasho, Uji 611-0011 (Japan)
  3. Graduate School of Engineering, Hiroshima University, Higashihiroshima 739-8527 (Japan)
  4. Naka Fusion Institute, Japan Atomic Energy Agency, Naka 311-0193 (Japan)
  5. National Institute for Fusion Science, Toki 509-5292 (Japan)
Publication Date:
OSTI Identifier:
22253068
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ELECTROSTATIC PROBES; EXCITATION; FLUCTUATIONS; HELIOTRON; MAGNETOHYDRODYNAMICS; MOLECULAR BEAMS; PLASMA; PROBABILITY DENSITY FUNCTIONS; STORED ENERGY