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Title: Understanding the bursty electron cyclotron emission during a sawtooth crash in the HT-7 tokamak

Bursts in electron cyclotron emission (ECE) were observed during sawtooth crashes in HT-7 in discharges with ion cyclotron resonance heating injected near the q = 1 rational surface (q is the safety factor). The local ECE measurement indicated that the bursty radiation is only observed on channels near but a little away outward from the q = 1 magnetic surface. In conjunction with the soft x-ray tomography analysis, it was determined that, for the first time, only a compression process survives in the later stage of fast magnetic reconnection but before prompt heat transport. The compression enhanced the electron radiation temperature, the increased amplitude of which agreed well with the estimation according to a kinetic compression theory model [R. J. Hastie and T. C. Hender, Nucl. Fusion 28, 585 (1988)]. This paper presents the experimental evidence that there indeed exists a transient compression phase which results in the bursty ECE radiation during a sawtooth crash.
Authors:
; ;  [1]
  1. Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China)
Publication Date:
OSTI Identifier:
22252187
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 1; 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; AMPLITUDES; COMPRESSION; CYCLOTRON RESONANCE; CYCLOTRONS; EMISSION; HEAT TRANSFER; HT-7 TOKAMAK; MAGNETIC RECONNECTION; MODE RATIONAL SURFACES; PLASMA INSTABILITY; SAWTOOTH OSCILLATIONS; SOFT X RADIATION; TOMOGRAPHY