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Time Evolution of the Magnetic Structure of a Field-Reversed Configuration in a Super-Alfvénic Translation Process

Tomohiko ASAI, Shunsuke AKAGAWA, Kazuhiro AKIMOTO, Naoki TADA, Tsutomu TAKAHASHI and Hiroyasu TAZAWA

Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308, Japan

(Received 7 December 2010 / Accepted 9 May 2011 / Published 2 December 2011)

Abstract

The effects of the conducting wall on the FRC translation process have been investigated by using a confinement coil with a toroidal cut on the coil spool. Using the simple ring current model, the induced current on the conducting coil spool and chamber wall, and the separatrix shape, were estimated. A deceleration force produced by the induced currents equals to approximately 10% of the acceleration one generated by the gradient of the magnetic guide field. To investigate these effects experimentally, FRC translation was performed with a toroidal cut on the coil spool. In this case, typical translation velocity was increased from 100 to 150 km/s. However, a shift type (toroidal mode number n = 1) motion was triggered, likely by the asymmetry of the wall boundary.

Copyright (c) 2011 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

field-reversed configuration (FRC), super-Alfvenic translation, separatrix shape, rotational mode instability, shift motion

DOI: 10.1585/pfr.6.2402151

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This paper may be cited as follows:

Tomohiko ASAI, Shunsuke AKAGAWA, Kazuhiro AKIMOTO, Naoki TADA, Tsutomu TAKAHASHI and Hiroyasu TAZAWA, Plasma Fusion Res. 6, 2402151 (2011).