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Title: Conversion of the dominantly ideal perturbations into a tearing mode after a sawtooth crash

Forced magnetic reconnection is a topic of common interest in astrophysics, space science, and magnetic fusion research. The tearing mode formation process after sawtooth crashes implies the existence of this type of magnetic reconnection and is investigated in great detail in the ASDEX Upgrade tokamak. The sawtooth crash provides a fast relaxation of the core plasma temperature and can trigger a tearing mode at a neighbouring resonant surface. It is demonstrated for the first time that the sawtooth crash leads to a dominantly ideal kink mode formation at the resonant surface immediately after the sawtooth crash. Local measurements show that this kink mode transforms into a tearing mode on a much longer timescale (10{sup −3}s−10{sup −2}s) than the sawtooth crash itself (10{sup −4}s). The ideal kink mode formed after the sawtooth crash provides the driving force for magnetic reconnection and its amplitude is one of the critical parameters for the length of the transition phase from a ideal into an resistive mode. Nonlinear two fluid MHD simulations confirm these observations.
Authors:
; ; ; ; ; ;  [1] ; ;  [2] ;  [3]
  1. Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany)
  2. FOM-Institute DIFFER, Dutch Institute for Fundamental Energy Research, 3430 BE Nieuwegein (Netherlands)
  3. University of California at Davis, Davis, California 95616 (United States)
Publication Date:
OSTI Identifier:
22403242
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 11; 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; ASDEX TOKAMAK; ASTROPHYSICS; CONVERSION; DISTURBANCES; ELECTRON TEMPERATURE; ION TEMPERATURE; MAGNETIC RECONNECTION; MAGNETOHYDRODYNAMICS; PERTURBATION THEORY; PHASE TRANSFORMATIONS; SAWTOOTH OSCILLATIONS; TEARING INSTABILITY