Effects of weak turbulence on parametric processes in an unmagnetized plasma

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5476231

Takeshita, S

A system of equations describing the parametric process is derived from kinetic equations. The effect of the external radiation is represented as ponderomotive force in the electron kinetic equation. Langmuir and ion-acoustic turbulences are modeled as fluctuating background electric field and plasma density. Langmuir turbulence lowers the effective plasma frequency. The turbulence also may drive an oscillating two stream instability (OTSI), and may enhance the coupling process of longitudinal waves. Due to the lowering of the plasma frequency, the best matching pump frequency for two-plasmon decay is lowered. The frequency of the reflected light of Raman scattering is increased. The thresholds of parametric decay and Raman scattering abruptly drop when OTSI is driven. The threshold of parametric decay is further reduced because of the enhanced coupling. Ion-acoustic turbulence does not interact strongly with ion-acoustic modes of parametric processes. The ion-acoustic turbulence, however, randomly generates the spatial regions characterized by plasma frequencies ranging from slightly lower to higher than the average. Long wavelength turbulence creates the regions that are best tuned to different pump frequencies for parametric decay. For the whole plasma, the best matching frequency now has a width rather than one value, as in the case of quiescent plasma. The short wavelength turbulence creates these regions within a typical wavelength of an ion-acoustic mode of parametric processes.

• Research Organization: Michigan Univ., Ann Arbor (USA)
• OSTI ID: 5476231
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700105* -- Fusion Energy-- Plasma Research-- Plasma Kinetics-Theoretical-- (-1987)
EQUATIONS
INSTABILITY
ION ACOUSTIC WAVES
ION WAVES
KINETIC EQUATIONS
PARAMETRIC ANALYSIS
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
PLASMA WAVES
TWO-STREAM INSTABILITY