Nonlinear spreading of Farley-Buneman waves

Abstract

Nonlinear coupling of Farley-Buneman (FB) waves is studied using the method of modulational decay instabilities. Dispersion relation for the growth of the secondary Farley-Buneman waves has been derived. It is shown that the primary wave is unstable with respect to the modulational instability decay, producing the secondary waves with a finite flow angle with respect to the direction of the electron E×B flow. This process leads to the nonlinear spreading of the primary FB waves into the linearly stable region which is consistent with the previous numerical simulations and some observations.