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Low frequency sawto...
Low frequency sawtooth precursor in ASDEX Upgrade
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- Papp, Gergely, 1985 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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Pokol, Gergö, 1979 (författare)
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Por, G (författare)
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visa fler...
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Magyarkuti, A (författare)
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Lazányi, N (författare)
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Horváth, L (författare)
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Igochine, V (författare)
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Maraschek, M (författare)
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ASDEX Upgrade Team, (författare)
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visa färre...
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(creator_code:org_t)
- 2011
- 2011
- Engelska.
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Ingår i: Proceedings of 5th IAEA Technical Meeting on the Theory of Plasma Instabilities. ; , s. B4.1-
- Relaterad länk:
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https://research.cha...
Abstract
Ämnesord
Stäng
- The present paper describes the precursor activity observed in the ASDEX Upgrade tokamakbefore pronounced sawtooth crashes in various neutral beam heated plasmas, utilizing the soft X-raydiagnostic. Besides the well-known (m, n) = (1, 1) internal kink mode and its harmonics, a Low FrequencySawtooth Precursor (LFSP) mode is studied in detail. Indications of a second, lower frequency sawtoothprecursor have been reported on JET and HT-7 as well. Throughout the studied sawtooth crashes, thepower of the lower frequency mode rose by several orders of magnitude just before the crash with a growthrate of 400 1/s, which is shown to be consistent with the growth rate of a resistive core mode. Besidesits temporal behaviour, its spatial structure was estimated with a wavelet based method used on SXRmeasurements, and the most likely value was found to be (m, n) = (1, 1). Power modulation of this modeis found to correlate with the power modulation of the (1,1) kink mode in the quasi-stationary intervals,and significant bicoherence was measured, both indicating non-linear interaction. The frequency ratio ofthe two modes was calculated with an instantaneous frequency following algorithm and was found to bein the 0.5-0.7 range. The LFSP is expected to play a role in the partial magnetic reconnection process,hence every sawtooth crash model involving such reconnection may be affected by the existence of theLFSP.
Ämnesord
- NATURVETENSKAP -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)
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Papp, Gergely, 1 ...
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Pokol, Gergö, 19 ...
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Por, G
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Magyarkuti, A
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Lazányi, N
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Horváth, L
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visa fler...
-
Igochine, V
-
Maraschek, M
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ASDEX Upgrade Te ...
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visa färre...
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