On measuring the electron heat diffusion coefficient in atokamak from sawtooth oscillation observations

A number of new methods are discussed for determining the electron heat conduction coefficient χ e in a tokamak from the experimental observation of the space-time evolution of the temperature perturbations induced by internal disruptions. In the Oak Ridge Tokamak (ORMAK) the various average values of χ e and the radial dependence of χ e are found to be consistent with and more precise than the χ e (r) determined by conventionally analysing the electron power balance equation. The net result of these measurements is to conclusively prove that the dominant radial electron heat transport mechanism in tokamaks is a microscopic, diffusive process.