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

Journal Article · Tue Apr 15 00:00:00 EDT 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4872001· OSTI ID:22253068

Kasajima, K.; Hashimoto, K.; Kenmochi, N. ^[1]; Ohshima, S.; Mizuuchi, T.; Yamamoto, S.; Sha, M.; Nagasaki, K.; Kado, S.; Okada, H.; Minami, T.; Kobayashi, S.; Shi, N.; Konoshima, S.; Nakamura, Y.; Sano, F. ^[2]; Nishino, N. ^[3]; Takeuchi, M. ^[4]; Mukai, K. ^[5]; others, and

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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)

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 identified 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.

• OSTI ID: 22253068
• Journal Information: Physics of Plasmas, Vol. 21, Issue 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ELECTROSTATIC PROBES
EXCITATION
FLUCTUATIONS
HELIOTRON
MAGNETOHYDRODYNAMICS
MOLECULAR BEAMS
PLASMA
PROBABILITY DENSITY FUNCTIONS
STORED ENERGY