Plasma and Fusion Research

Volume 18, 1402089 (2023)

Regular Articles

Anomalous Ion Heating in Lower Hybrid Wave Sustained Plasmas on the TST-2 Spherical Tokamak Device
Kotaro IWASAKI, Akira EJIRI, Naoto TSUJII, Kouji SHINOHARA, Osamu WATANABE, Seowon JANG, Yi PENG, Yuting LIN, Fumiya ADACHI and Tian YIMING
The University of Tokyo, Kashiwa 277-8561, Japan
(Received 10 May 2023 / Accepted 27 October 2023 / Published 8 December 2023)

Abstract

Power flow is important to understand the lower hybrid wave (LHW) sustained plasmas in the TST-2 spherical tokamak device. During LHW power modulation experiments responses of ion temperature were found. The ion temperature increased at the edge region during ON phases of LHW power, while the ion temperature was kept constant at the central region. A 0-dimensional power balance at a steady state was investigated, and it was found that the collisional ion heating by bulk electrons is about two orders of magnitude smaller than the charge exchange loss and the neoclassical transport loss. The results indicate anomalous ion heating by additional unidentified heating mechanism. The estimated additional heating power itself is much smaller than the LHW power, but there are several ambiguities in the estimation, and a further study is necessary.

Keywords

spherical tokamak, lower hybrid wave, ion heating

DOI: 10.1585/pfr.18.1402089

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