Plasma and Fusion Research

Volume 11, 2402100 (2016)

Regular Articles

Generation of Energetic Electrons during Spherical Tokamak Merging in UTST
Tomohiko USHIKI, Michiaki INOMOTO, Kotaro YAMASAKI, Xuehan GUO, Takumichi SUGAWARA, Keita MATSUYAMA, Haruhisa KOGUCHI1) and Takuma YAMADA2)
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8656, Japan
1)
National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8586, Japan
2)
Facility of Arts and Science, Kyushu University, Fukuoka 819-0395, Japan
(Received 30 November 2015 / Accepted 2 June 2016 / Published 15 July 2016)

Abstract

Bursts of bremsstrahlung soft X-ray (SXR) emission (> 200 eV) were observed during spherical tokamak merging in the University of Tokyo Spherical Tokamak (UTST) experiment. SXR signal waveforms coincided well with the time evolution of a reconnection electric field, and their intensity shows a clear dependence on the strength of a toroidal magnetic field. This result suggests that electrons near the X-point are effectively accelerated in the toroidal direction by a parallel electric field during plasma merging in the presence of a strong toroidal magnetic field.

Keywords

spherical tokamak, plasma merging, energetic electron, magnetic reconnection

DOI: 10.1585/pfr.11.2402100

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