[Table of Contents]

Plasma and Fusion Research

Volume 8, 1402139 (2013)

Regular Articles

Development of a Quasi-Steady Equilibrium Field System for Plasma Merging ST Startup Experiments on the UTST Device
Hirotomo ITAGAKI, Michiaki INOMOTO, Shuji KAMIO, Qinghong CAO, Koichiro TAKEMURA, Kotaro YAMASAKI, Takenori G WATANABE and Takuma YAMADA
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
(Received 18 February 2013 / Accepted 25 August 2013 / Published 15 November 2013)

Abstract

A novel equilibrium field (EF) system has been developed for use in the merging start-up of spherical tokamak (ST) plasma in the University of Tokyo Spherical Tokamak (UTST) device. Since the UTST device utilizes external poloidal field (PF) coils to form two STs on the top and bottom of the device by huge induction voltages, it is necessary to decouple the slow EF coil system from the fast-swing PF coils. A new EF system using electric double-layer capacitors was constructed and evaluated through the merging start-up experiment in the UTST. Using a very long duration of the EF current waveform and a thick magnetic shield successfully reduced the induction voltages from the PF coils and prolonged the equilibrium time constant.

Keywords

pulsed power supply, spherical tokamak, equilibrium field, plasma merging, high-beta tokamak

DOI: 10.1585/pfr.8.1402139

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This paper may be cited as follows:

Hirotomo ITAGAKI, Michiaki INOMOTO, Shuji KAMIO, Qinghong CAO, Koichiro TAKEMURA, Kotaro YAMASAKI, Takenori G WATANABE and Takuma YAMADA, Plasma Fusion Res. 8, 1402139 (2013).