Plasma and Fusion Research

Volume 16, 2402084 (2021)

Regular Articles

Upgrading LHDGauss Code by Including Obliquely Propagating Wave Absorption Effect for ECH
Ryoma YANAI1), Toru TSUJIMURA1), Shin KUBO1,2), Ryota YONEDA3), Yasuo YOSHIMURA1), Masaki NISHIURA1), Hiroe IGAMI1), Hiromi TAKAHASHI1) and Takashi SHIMOZUMA1)
1)
National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-Cho, Toki, Gifu 509-5292, Japan
2)
Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya 464-8601, Japan
3)
University of California Los Angeles, Los Angeles, CA, 90095, USA
(Received 7 December 2020 / Accepted 22 April 2021 / Published 18 June 2021)

Abstract

LHDGauss is a multi-ray tracing code to calculate microwave beam propagation and power deposition of electron cyclotron heating (ECH) using the electron density and electron temperature profiles in the Large Helical Device (LHD) plasma. LHDGauss also takes into account the injected wave polarization purity. LHDGauss uses the cold plasma dispersion to calculate ray propagation and derives the power absorption profile of ECH by using the absorption coefficient based on weakly relativistic plasmas and the wave propagating perpendicularly to the magnetic field. However, the ECH beam propagation is mainly oblique to the magnetic field in the LHD and it is necessary to take into account the angular dependence of the absorption coefficient in order to derive more accurate ECH power deposition profiles. We upgraded LHDGauss and were able to calculate the absorption coefficient using the weakly relativistic dielectric tensor which considers the influence of the angle between the magnetic field and the wave vector. We compared the power deposition profiles calculated by previous and upgraded LHDGauss with the changes of the electron temperature profile of the LHD plasma in the oblique and the perpendicular O1-mode ECH injection cases. We have obtained more reasonable power deposition profiles by using the upgraded LHDGauss in both the perpendicular and the oblique injection cases.

Keywords

ECH, ray tracing, plasma heating, magnetically confined plasma, LHD

DOI: 10.1585/pfr.16.2402084

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