Evidence of plasma fluctuations and their effect on the growth of stimulated Brillouin and stimulated Raman scattering in laser plasmas

Conference · Sat Nov 01 04:00:00 EST 1997

OSTI ID:650324

Montgomery, D S; Fernandez, J C; Cobble, J A ^[1]

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1. and others

The reflectivity levels of stimulated Brillouin scattering (SBS) in recent large scale length laser plasma experiments is much lower than expected for conditions where the convective gain exponent is expected to be large. Long wavelength velocity fluctuations caused during the plasma formation process, or by parametric instabilities themselves, have been proposed as a mechanism to detune SBS in these experiments and reduce its gain. Evidence of large velocity fluctuation levels is found in the time-resolved SBS spectra from these experiments, and correlates with observed changes in the reflectivity of both SBS and stimulated Raman scattering (SRS). The authors present evidence of fluctuations which increase as the plasma density systematically increases, and discuss their effect on the growth of parametric instabilities.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 650324
• Report Number(s): LA-UR--97-4830; CONF-971103--; ON: DE98004244
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BRILLOUIN EFFECT
INSTABILITY GROWTH RATES
LASER-PRODUCED PLASMA
PARAMETRIC INSTABILITIES
PLASMA WAVES
RAMAN EFFECT