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Title: Magnetic turbulence and pressure gradient feedback effect of the 1/2 mode soft-hard magnetohydrodynamic limit in large helical device

Abstract

The aim of this study was to analyze the feedback process between the magnetic turbulence and the pressure gradients in Large Helical Device (LHD) inward-shifted configurations as well as its role in the transition between the soft-hard magnetohydrodynamic (MHD) regimes for instabilities driven by the mode 1/2 in the middle plasma. In the present paper, we summarize the results of two simulations with different Lundquist numbers, S=2.5×10{sup 5} and 10{sup 6}, assuming a plasma in the slow reconnection regime. The results for the high Lundquist number simulation show that the magnetic turbulence and the pressure gradient in the middle plasma region of LHD are below the critical value to drive the transition to the hard MHD regime, therefore only relaxations in the soft MHD limit are triggered (1/2 sawtooth-like events) [Phys. Plasmas 19, 082512 (2012)]. In the case of the simulation with low Lundquist number, the system reaches the hard MHD limit and a plasma collapse is observed.

Authors:
 [1]; ; ;  [2]
  1. LESIA, Observatoire de Paris, CNRS, UPMC, Universite Paris-Diderot, 5 place Jules Janssen, 92195 Meudon (France)
  2. National Institute for Fusion Science, Oroshi-cho 322-6, Toki 509-5292 (Japan)
Publication Date:
OSTI Identifier:
22303636
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 21; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CONFIGURATION; LHD DEVICE; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA INSTABILITY; PRESSURE GRADIENTS; SAWTOOTH OSCILLATIONS; SIMULATION

Citation Formats

Varela, J., E-mail: jacobo.varela@obspm.fr, Watanabe, K. Y., Ohdachi, S., and Narushima, Y. Magnetic turbulence and pressure gradient feedback effect of the 1/2 mode soft-hard magnetohydrodynamic limit in large helical device. United States: N. p., 2014. Web. doi:10.1063/1.4895499.
Varela, J., E-mail: jacobo.varela@obspm.fr, Watanabe, K. Y., Ohdachi, S., & Narushima, Y. Magnetic turbulence and pressure gradient feedback effect of the 1/2 mode soft-hard magnetohydrodynamic limit in large helical device. United States. doi:10.1063/1.4895499.
Varela, J., E-mail: jacobo.varela@obspm.fr, Watanabe, K. Y., Ohdachi, S., and Narushima, Y. Mon . "Magnetic turbulence and pressure gradient feedback effect of the 1/2 mode soft-hard magnetohydrodynamic limit in large helical device". United States. doi:10.1063/1.4895499.
@article{osti_22303636,
title = {Magnetic turbulence and pressure gradient feedback effect of the 1/2 mode soft-hard magnetohydrodynamic limit in large helical device},
author = {Varela, J., E-mail: jacobo.varela@obspm.fr and Watanabe, K. Y. and Ohdachi, S. and Narushima, Y.},
abstractNote = {The aim of this study was to analyze the feedback process between the magnetic turbulence and the pressure gradients in Large Helical Device (LHD) inward-shifted configurations as well as its role in the transition between the soft-hard magnetohydrodynamic (MHD) regimes for instabilities driven by the mode 1/2 in the middle plasma. In the present paper, we summarize the results of two simulations with different Lundquist numbers, S=2.5×10{sup 5} and 10{sup 6}, assuming a plasma in the slow reconnection regime. The results for the high Lundquist number simulation show that the magnetic turbulence and the pressure gradient in the middle plasma region of LHD are below the critical value to drive the transition to the hard MHD regime, therefore only relaxations in the soft MHD limit are triggered (1/2 sawtooth-like events) [Phys. Plasmas 19, 082512 (2012)]. In the case of the simulation with low Lundquist number, the system reaches the hard MHD limit and a plasma collapse is observed.},
doi = {10.1063/1.4895499},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 9,
volume = 21,
place = {United States},
year = {2014},
month = {9}
}