Plasma and Fusion Research

Volume 14, 1401158 (2019)

Regular Articles

Finite Larmor Radius Effect on Ion-Temperature-Gradient Instability in Cylindrical Plasmas
Naohiro KASUYA1,2), Tomotsugu OHNO2), Makoto SASAKI1,2) and Masatoshi YAGI3)
1)
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan
2)
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan
3)
National Institutes for Quantum and Radiological Science and Technology, 2-166 Omotedate, Obuchi, Rokkasho-mura, Aomori 039-3212, Japan
(Received 6 June 2019 / Accepted 19 August 2019 / Published 9 October 2019)

Abstract

Numerical analyses using a gyro-fluid model have been performed to investigate the finite-Larmor-radius (FLR) effect on ion-temperature-gradient (ITG) instability in cylindrical plasmas. A spectrum code with Fourier-Bessel expansion has been developed for the analysis of global mode structures. The analytical expression of the η (ratio between the density and temperature gradient lengths) threshold value for linear ITG instability has been obtained from the local dispersion relation, whose dependency on the ion temperature comes from the FLR effect. Dependency of the threshold by the global analysis is reproduced by the local analysis with appropriate selection of the perpendicular wavenumber. Break of the Boltzmann relation by the FLR effect is not strong as to generate another unstable branch of the ITG mode.

Keywords

gyro-fluid model, finite-Larmor-radius effect, linear device, ion-temperature-gradient instability, dispersion relation

DOI: 10.1585/pfr.14.1401158

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