Collisional model of quasilinear transport driven by toroidal electrostatic ion temperature gradient modes
- Department of Radio and Space Science, Chalmers University of Technology, and Euratom-VR Association, SE-41296 Goeteborg (Sweden)
- General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)
- EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)
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{sub 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 length, and magnetic shear.
- OSTI ID:
- 21277299
- Journal Information:
- Physics of Plasmas, Vol. 16, Issue 7; Other Information: DOI: 10.1063/1.3168611; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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