Parametric Instabilities of Damped Modes in Inhomogeneous Plasmas.
COLORADO UNIV BOULDER DEPT OF ASTRO-GEOPHYSICS
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Using WKB analysis it is shown that for three-wave backscattering type parametric instabilities in inhomogeneous plasmas no spatial convective growth is possible for undamped modes. If one coupled mode is more heavily damped than the other, then spatial growth is possible in both forward and back-scattering. The spatial amplification factor is that obtained by Rosenbluth only if the pump power is sufficiently above a damping-determined threshold but below a threshold for temporal or absolute instability exists for the backscatter instabilities. For the parametric decay instability at omega sub 0 2omega sub pe in a finite spatial region only a temporal instability is found but no spatial convective growth. Author
- Plasma Physics and Magnetohydrodynamics