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A Reduced Transport Model for Ion Heat Diffusivity by Gyro-Kinetic Analysis with Kinetic Electrons in Helical Plasmas

Shinichiro TODA, Motoki NAKATA, Masanori NUNAMI, Akihiro ISHIZAWA¹⁾, Tomo-Hiko WATANABE²⁾ and Hideo SUGAMA

National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan

1)

Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan

2)

Department of Physics, Nagoya University, Furo-cho, Nagoya, Aichi 464-8602, Japan

(Received 14 April 2017 / Accepted 27 July 2017 / Published 30 August 2017)

Abstract

A high ion temperature plasma in the Large Helical Device is examined in the case in which the ion temperature gradient mode is unstable. The nonlinear gyro-kinetic simulation is performed to evaluate the turbulent ion heat diffusivity with the kinetic electron response. It is clarified that the decay time of zonal flows [S. Ferrando-Margalet et al., Phys. Plasmas 14, 122505 (2007)] decreases radially outward due to the trapped electron and the ion energy transport increases outward. To reduce the computational cost for applying to the dynamical transport simulation, an extended transport model for the ion heat diffusivity in terms of the mixing length estimate and the characteristic quantity for the linear response of zonal flows is proposed.

Copyright (c) 2017 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

transport model, zonal flow, gyro-kinetic simulation, turbulence, helical plasma

DOI: 10.1585/pfr.12.1303035

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