
Author(s):
N. Nakajima

Title:
Thermal Diffusion by Stochastic Electromagnetic Fluctuations
Date of publication:
Oct. 2006

Key words:
21 IAEA Fusion Energy Conference , TH/P212

Abstract:
A new simple systematic method has been developed to analytically evaluate the thermal diffusion coefficient of guiding center test particles brought by coexisting homogeneously stochastic electrostatic and electromagnetic fluctuations. As a most simple case, thermal diffusion coefficients for electrons and ions are analytically obtained in a large aspect straight tokamak with a small gyroradius and negligible magnetic shear and negligible equilibrium vec{E} x vec{B} flow shear. Those analytical formulae are applicable to the range beyond socalled quasilinear limit; thermal diffusion coefficient are squarely (linearly) proportional to fluctuation amplitudes in the quasilinear (beyond quasilinear) region. It is shown that the thermal diffusion of electrons (ions) is mainly dominated by magnetic (electrostatic) fluctuations in the experimentally relevant situations, even if both magnetic and electrostatic fluctuations coexist. It is also shown that the resonant electrons do not diffuse when the electric field parallel to the unperturbed magnetic field lines is negligible, even if electrostatic and electromagnetic fluctuations coexist.

