Spontaneous excitation of convective cells by kinetic Alfvén waves

Abstract

Spontaneous excitation of convective cells by kinetic Alfvén waves in a uniform plasma is investigated analytically employing the nonlinear gyrokinetic equations. Self-consistent theoretical analysis demonstrates the novel results that excitation via modulational instability can only occur when the finite ion Larmor radius effects are properly included, and, furthermore, both the electrostatic and magnetostatic convective cells are excited simultaneously. Theoretical predictions are verified with direct numerical simulations; showing excellent agreement in the modulational growth rate and field structures. Significant implications of the present results to the cross-field transport in space and fusion plasmas are also briefly discussed.