Electron thermal conductivity in an ergodic magnetic limiter

Abstract

The magnetic field perturbations which create an ergodic magnetic limiter also create enhanced thermal conductivity for electrons. This conductivity is calculated using an MHD model which includes drift heat flow in toroidal geometry. For parameters relevant to the ergodic magnetic limiter, the enhanced thermal conductivity is determined mainly by mode coupling of the radial magnetic field perturbations and is found to be ~ 103 times larger than the classical value.

Overview of magnetic structure induced by the TEXTOR-DED and the related transport

“…The transport in fully developed ergodic regions of the magnetic field lines can be described by the quasilinear theory. It predicts the flat temperature profile at the plasma edge due to the large effective transverse diffusion in the ergodic zone [64,65]. However, the quasilinear theory was not able to describe the small-scale temperature structures in the ergodic zone measured in the experiments on the tokamaks TEXT, Tore Supra and CSTN-II [6,11,66]: it has been observed the stationary (quasi) periodic radial, poloidal and toroidal structures with the magnitude of oscillations about 5-20 eV.…”