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Journal Articles

Saturation mechanism of decaying ion temperature gradient driven turbulence with kinetic electrons

Idomura, Yasuhiro

Plasma and Fusion Research (Internet), 11, p.2403006_1 - 2403006_5, 2016/02

BB2015-1300.pdf:0.58MB

In this work, we address saturation mechanisms of decaying turbulence induced by the ion temperature gradient driven trapped electron mode. In the simulation, turbulent transport is quenched in the nonlinear quasi-steady phase, where temperature profiles exceeding linear critical temperature gradient parameters are formed. This kind of nonlinear critical temperature gradient is sustained by radial electric fields with strong shear, which is generated by corrugated density profiles. It is found that the density profile structure is related to electrons transport near low order mode rational surfaces, where non-adiabatic response of passing electrons becomes important.

Journal Articles

$$delta f$$ simulations of microturbulence

Idomura, Yasuhiro

Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.581 - 592, 2005/08

A gyrokinetic particle simulation is a powerful tool in studying tokamak microturbulence. A $$delta f$$ method, which is a standard method in recent gyrokinetic particle simulations, dramatically improved an efficiency of a particle simulation by reducing a particle noise, and full torus turbulence simulations are enabled. In this paper, the $$delta f$$ method is reviewed, and issues in full torus gyrokinetic particle simulations are discussed.

Journal Articles

Gyrokinetic simulations of tokamak micro-turbulence including kinetic electron effects

Idomura, Yasuhiro; Tokuda, Shinji; Kishimoto, Yasuaki

Journal of Plasma and Fusion Research SERIES, Vol.6, p.17 - 72, 2004/00

A global gyrokinetic toroidal particle code for a 3D nonlinear simulation (GT3D) has been developed for a comprehensive study of the ion and electron anomalous transport arising from the ion temperature gradient driven - trapped electron mode (ITG-TEM) turbulence in tokamak plasmas. In the preliminary linear ITG-TEM calculations, basic properties of ITG-TEM modes are confirmed. Adding trapped electrons not only increases the growth rate of the ITG mode, but also produces another unstable electron mode, the TEM mode, which is unstable even at $$eta_i = 0$$. The dominant mode changes from the ITG mode to the TEM mode depending on $$k_theta$$ and $$eta_i$$. In linear benchmark calculations using Cyclone base case parameters, eigenfrequencies obtained from GT3D, GTC(PPPL-UCI) and FULL(PPPL) show reasonable quantitative agreement.

Journal Articles

Effects of trapped electrons on pressure-gradient-driven kinetic modes with negative magnetic shear

Yamagiwa, Mitsuru; *

Plasma Physics and Controlled Fusion, 40(9), p.1673 - 1678, 1998/00

 Times Cited Count:1 Percentile:4.22(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Effects of radial gradient of the Shafranov shift on the kinetic ballooning and drift-type modes in high-performance tokamaks

*; Yamagiwa, Mitsuru

Canadian Journal of Physics, 75(9), p.599 - 604, 1997/09

no abstracts in English

Oral presentation

Formations of radial electric fields and critical temperature gradients in ion temperature gradient driven trapped electron mode turbulence

Idomura, Yasuhiro

no journal, , 

Decaying turbulence simulations of ion temperature gradient driven (ITG) turbulence with adiabatic electrons and ion temperature gradient driven trapped electron mode (ITG-TEM) turbulence with kinetic electrons are performed using a full-f gyrokinetic code. Nonlinear critical temperature gradients exceeding linear critical temperature gradients are observed in both simulations, and mechanisms to sustain them are investigated. It is found that unlike zonal flows in the ITG turbulence, the ITG-TEM turbulence produces corrugated electron density profiles, which form radial electric fields with strong shear following a force balance relation.

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