Two Langmuir Wave Parametric Decay Instability Driven and Trapped by a Self-Trapped Electromagnetic Pump

抄録

The conditions under which an incident, x-z polarized strong pump electromagnetic wave propagating in the z-direction is self-trapped as an equilibrium filament in an initially uniform plasma are found for a Gaussian pump profile as exp [−(x−x_m)²⁄2d_x²]. Coupled equations describing the parametric coupling of two electron Langmuir waves due to the spatially aperiodic inhomogeneity of the self-trapped pump filament amplitude are then derived. Moreover, an analysis of the eigenvalue problem arising from these equations demonstrates a possibility that decay Langmuir waves can be trapped as temporally growing waves in a density cavity created by the inhomogeneous pump when the pump amplitude exceeds the threshold rather less than that for the decay instability of Jackson-type.