Parametric instabilities with finite wavelength pump

Technical Report · Mon Dec 01 04:00:00 EST 1975

OSTI ID:7228521

Fried, B D; Ikemura, T; Nishikawa, K; Schmidt, G

The general problem of parametric instabilities driven by a finite wavelength pump is investigated. For the particular case of a Langmuir wave pump, it is shown that resonant decay instabilities (forward or backward scattering in the one-dimensional case), with thresholds which vanish in the collisionless limit, can occur only for pump wavenumber k/sub 0/ greater than the critical value ((m/M)/sup 1///sup 2//..gamma..)k/sub D/, where m and M are the electron and the ion mass, respectively, and ..gamma.. is the specific heat ratio. For smaller wavenumbers, there is always a nonzero threshold, the instability being of modulation character for long wavelengths and almost purely growing for short wavelengths. Frequency locking for small k/sub 0/ and wavenumber locking for large k/sub 0/ are demonstrated. The results are generalized to the case where the coupled waves satisfy arbitrary dispersion relations and simple physical interpretations of the instabilities are given.

• Research Organization: California Univ., Los Angeles (USA). Dept. of Physics
• OSTI ID: 7228521
• Report Number(s): TID-27319
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
COUPLING
DECAY INSTABILITY
DISPERSION RELATIONS
INSTABILITY
LANGMUIR FREQUENCY
PARAMETRIC INSTABILITIES
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA WAVES
RESONANCE