A theory of electron energy confinement in tokamaks

A one-dimensional thermal transport code has been employed to study electron energy confinement in tokamaks. At each time step of the computations, each point in the profile is examined to determine whether it is linearly stable to either the dissipative trapped electron mode or the internal kink and tearing modes. If the point is determined to be unstable, an anomalously large electron thermal conductivity is turned on in the vicinity of that point. The electron temperature profile is found to relax to a marginally stable state. Our code predicts the scaling of confinement time with density in Alcator, and the scaling of temperature half-width with q (a) in Tokamak Fontenay aux Roses.