[Table of Contents]

Plasma and Fusion Research

Volume 6, 1302136 (2011)

Letters

Study of Plasma Current Decay in the Initial Phase of High Poloidal Beta Disruptions in JT-60U
Yoshihide SHIBATA, Kiyomasa WATANABE1), Noriyasu OHNO, Masaaki OKAMOTO2), Akihiko ISAYAMA3), Kenichi KURIHARA3), Naoyuki OYAMA3), Tomohide NAKANO3), Yasunori KAWANO3), Go MATSUNAGA3), Yutaka KAMADA3) and Masayoshi SUGIHARA4)
Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
Ishikawa National College of Technology, Ishikawa 929-0392, Japan
3)
Japan Atomic Energy Agency, Naka 311-0193, Japan
4)
ITER Organization, Cadarache 13076 France
(Received 31 May 2011 / Accepted 27 August 2011 / Published 21 October 2011)

Abstract

In order to validate some current decay models during the current quench, the plasma current decay time was studied using the experimental plasma resistance and inductance in high poloidal beta, βp, disruptions in JT-60U. The plasma resistance and inductance were evaluated from an equilibrium calculation code and the measurement value of a magnetic sensor, the electron temperature evaluated by using ECE measurement and the electron density measured by FIR interferometer. In high βp disruptions, it was found that the electron temperature at the plasma center just after current quench starts was approximately 1-4 keV under almost the same current decay time observed during the initial phase of current quench. This result indicates that the electron temperature itself plays no major role in the determination of the current decay time in the initial phase of current quench. Moreover, the current decay time predicted by a modified L/R model [Y. Shibata et al., Nucl. Fusion 50, 025015 (2010)], in which the time derivative of plasma inductance was considered, was in good agreement with the experimental current decay time, while the values obtained from the conventional L/R model were two orders of magnitude larger than the experimental results.

Keywords

current decay model, disruption, high βp plasma discharge, plasma inductance, poloidal beta

DOI: 10.1585/pfr.6.1302136

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This paper may be cited as follows:

Yoshihide SHIBATA, Kiyomasa WATANABE, Noriyasu OHNO, Masaaki OKAMOTO, Akihiko ISAYAMA, Kenichi KURIHARA, Naoyuki OYAMA, Tomohide NAKANO, Yasunori KAWANO, Go MATSUNAGA, Yutaka KAMADA and Masayoshi SUGIHARA, Plasma Fusion Res. 6, 1302136 (2011).