Theory of double resonance parametric excitation in plasmas. Part 2
Abstract
Using a simpler formalism than in the original paper on this subject, we verify the earlier result that, for a pump frequency separation Δ approximately equal to twice the ion acoustic frequency Ω, the use of two long-wavelength pumps can reduce the threshold for parametric excitation of ion-acoustic waves when, and only when, the Langmuir wave damping rate γ is much larger than Ω. The threshold is then reduced by a factor of order Ω/Ω, the optimum value of t being 2Ω -Γ for equal pump amplitudes, where Γ is the ion-acoustic wave damping rate and Γ Ω. The analysis presented in a recent paper is shown to be valid only for γ Ω, where the threshold reduction is quite small, vanishing in the limit of weak ion-acoustic wave damping (Te/Ti 1).
- Publication:
-
Journal of Plasma Physics
- Pub Date:
- October 1980
- DOI:
- 10.1017/S0022377800022856
- Bibcode:
- 1980JPlPh..24..315F
- Keywords:
-
- Coupled Modes;
- Electrostatic Waves;
- Ion Acoustic Waves;
- Plasma Resonance;
- Wave Attenuation;
- Wave Excitation;
- Damping;
- Frequency Response;
- Pumping;
- Thresholds;
- Wave Dispersion;
- Plasma Physics