Parametric excitation of convective cell modes and nonlinear stabilization of purely-growing instability

Abstract

Parametric coupling of lower-hybrid pump waves with purely-damped convective cell modes generates enhanced electrostatic fluctuations in a magnetized plasma. The threshold electric field for exciting a purely-growing instability is found. In order to consider the saturation of the parametric instability, the authors have invoked a nonlinear mechanism which involves scattering of charged particles by suprathermal fluctuations. An expression for the effective collision frequency is also obtained, which characterizes the HF power dissipation in the plasma as well as the heating. Attempts have been made to correlate the results with some experimental data.