Quasilinear evolution of the self-filamentation instability

Abstract

A thermally inhomogeneous plasma immersed in a strong uniform magnetic field may be unstable to the formation of current filaments aligned to the field propagating at the diamagnetic drift frequency. The quasilinear evolution of this self-filamentation is studied. Transverse magnetic fields generated by the currents bring into thermal contact unequal temperature surfaces leading to a relaxation of the thermal gradient. For weak gradients, the instability is shown to saturate at a constant amplitude while, for stronger gradients, periodic behavior is exhibited. The transition from saturation to periodic behavior is predicted analytically from a three-wave model. The anomalous heat transport resulting from the instability is assessed.