Plasma and Fusion Research

Volume 11, 2403006 (2016)

Regular Articles

Saturation Mechanism of Decaying Ion Temperature Gradient Driven Turbulence with Kinetic Electrons
Yasuhiro IDOMURA
Japan Atomic Energy Agency, 178-4 Wakashiba, Kashiwa, Chiba 277-0871, Japan
(Received 5 November 2015 / Accepted 7 December 2015 / Published 24 February 2016)

Abstract

We present full-f gyrokinetic simulations of the ion temperature gradient driven (ITG) turbulence including kinetic electrons. By comparing decaying ITG turbulence simulations with adiabatic and kinetic electron models, an impact of kinetic electrons on the ITG turbulence is investigated. It is found that significant electron transport occurs even in the ITG turbulence, and both ion and electron temperature profiles are relaxed. In steady states, both cases show upshifts of nonlinear critical ion temperature gradients from linear ones, while their saturation mechanisms are qualitatively different. In the adiabatic electron case, the ITG mode is stabilized by turbulence driven zonal flows. On the other hand, in the kinetic electron case, passing electrons transport shows fine resonant structures at mode rational surfaces, which generate corrugated density profiles. Such corrugated density profiles lead to fine radial electric fields following the neoclassical force balance relation. The resulting E × B shearing rate greatly exceeds the linear growth rate of the ITG mode.

Keywords

full-f gyrokinetic model, ion temperature gradient driven turbulence, kinetic electron

DOI: 10.1585/pfr.11.2403006

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