Non-linear self consistency of microtearing modes

Abstract

The self-consistency of a microtearing turbulence is studied in non-linear regimes where the ergodicity of the flux lines determines the electron response. The current which sustains the magnetic perturbation via the Ampere law results from the combined action of the radial electric field in the frame where the island chains are static, and of the thermal electron diamagnetism. Numerical calculations show that at usual values of beta pol in Tokamaks the turbulence can create a diffusion coefficient of order nu th rho i2 where rho i is the ion larmor radius and nu th the electron ion collision frequency. On the other hand, collisionless regimes involving special profiles of each mode near the resonant surface seem possible.