Upgrading LHDGauss Code by Including Obliquely Propagating Wave Absorption Effect for ECH

Ryoma Yanai,Toru Tsujimura,Shin Kubo,Ryota Yoneda,Yasuo Yoshimura,Masaki Nishiura,Hiroe Igami,Hiromi Takahashi,Takashi Shimozuma

Plasma and Fusion Research（2021）

Natl Inst Nat Sci

Cited 3|Views40

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. (C) 2021 The Japan Society of Plasma Science and Nuclear Fusion Research

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Key words

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

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