Collisional model of quasilinear transport driven by toroidal electrostatic ion temperature gradient modes
Journal article, 2009

The stability of ion temperature gradient (ITG) modes and the quasilinear fluxes driven by them are analyzed in weakly collisional tokamak plasmas using a semianalytical model based on an approximate solution of the gyrokinetic equation, where collisions are modeled by a Lorentz operator. Although the frequencies and growth rates of ITG modes far from threshold are only very weakly sensitive to the collisionality, the $a/L_{Ti}$ threshold for stability is affected significantly by electron-ion collisions. The decrease in collisionality destabilizes the ITG mode driving an inward particle flux, which leads to the steepening of the density profile. Closed analytical expressions for the electron and ion density and temperature responses have been derived without expansion in the smallness of the magnetic drift frequencies. The results have been compared with gyrokinetic simulations with GYRO and illustrated by showing the scalings of the eigenvalues and quasilinear fluxes with collisionality, temperature scale lengt, and magnetic shear.

ion temperature gradient mode

turbulent transport

quasilinear flux




Istvan Pusztai

Chalmers, Department of Radio and Space Science, Non-Linear Electrodynamics

Tünde Fülöp

Chalmers, Department of Radio and Space Science, Non-Linear Electrodynamics

Jeff Candy

General Atomics

R.J. Hastie

Euratom Ukaea Fusion Association

Physics of Plasmas

1070-664X (ISSN) 1089-7674 (eISSN)

Vol. 16 7 072305- 072305

Subject Categories

Fusion, Plasma and Space Physics



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