[Table of Contents]

Plasma and Fusion Research

Volume 4, 015 (2009)

Rapid Communications

Phase Alignments between MHD Modes Followed by Minor Collapses on TST-2
Hiroshi TOJO, Akira EJIRI, Yuichi TAKASE, Yoshihiko NAGASHIMA, Osamu WATANABE, Yuuki ADACHI, Takuya OOSAKO, Takashi YAMAGUCHI, Byung Il AN1), Hiroaki KOBAYASHI, Hiroki KURASHINA, Haduki MATSUZAWA, Kotaro YAMADA, Makoto SASAKI1) and Tetsuya MASUDA
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
1)
Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
(Received 21 January 2009 / Accepted 10 February 2009 / Published 7 May 2009)

Abstract

MHD instabilities followed by minor collapses in the TST-2 plasma are studied. Precursors with toroidal mode numbers n = 1 and n = 2 localized in the plasma's core become phase aligned so that their mode amplitudes strengthen each other at a certain spatial point. During phase alignment, the total mode amplitude on the soft X-ray radiation profile does not show significant change, and a minor collapse occurs but does not terminate the discharge. This behaviour is similar to the results during a non-linear growth phase in three-dimensional MHD simulations [N. Mizuguchi et al., Phys. Plasmas 7, 940 (2000)]. However, predicted pressure-driven modes are not confirmed in these experiments.

Keywords

IRE (Internal Reconnection Event), mode coupling, spherical tokamak, soft X-ray

DOI: 10.1585/pfr.4.015

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This paper may be cited as follows:

Hiroshi TOJO, Akira EJIRI, Yuichi TAKASE, Yoshihiko NAGASHIMA, Osamu WATANABE, Yuuki ADACHI, Takuya OOSAKO, Takashi YAMAGUCHI, Byung Il AN, Hiroaki KOBAYASHI, Hiroki KURASHINA, Haduki MATSUZAWA, Kotaro YAMADA, Makoto SASAKI and Tetsuya MASUDA, Plasma Fusion Res. 4, 015 (2009).