Decay instability of laser radiation in a magnetoplasma

Abstract

The self-generated mega-Gauss magnetic fields in laser pellet fusion plasmas open some potential channels of parametric decay of laser radiation. In the vicinity of the cutoff, the pump decays efficiently into (i) lower hybrid and upper hybrid modes, (ii) ion acoustic and upper hybrid modes, (iii) fast ion wave and plasma wave, and (iv) Bernstein mode and plasma wave. At higher pump powers, nonlinear Landau damping and cyclotron damping by electrons possess large growth rates. These instabilities are also relevant to tokamak-type plasmas where nonlinear effects are important in the vicinity of the upper hybrid resonance.