RUNAWAY ELECTRONS AS A DIAGNOSTIC OF MAGNETIC FLUCTUATIONS IN THE EDGE PLASMA OF THE TEXAS EXPERIMENTAL TOKAMAK

Recent experimental and theoretical results are combined to explore the energy dependence of runaway and suprathermal electron diffusion. It is shown that a quasilinear theory containing both magnetic and electrostatic E X B-driven radial transport is consistent with the available experimental data, and supports the notion that magnetic turbulence dominates runaway diffusion but electrostatic turbulence dominates thermal diffusion in the edge plasma of the Texas Experimental Tokamak (TEXT) [Nucl. Technol./Fusion 1, 479 (1981)]. These observations further expand the possibilities for employing runaway or suprathermal electrons as a diagnostic of the underlying transport mechanisms in a tokamak plasma.