Convective gain of parametric instabilities: An experimentalist's viewpoint

Conference · Tue Jan 21 04:00:00 EST 1992

OSTI ID:5609312

Batha, S H; Batha, B H ^[1]

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1. California Univ., Davis, CA (United States). Plasma Physics Research Inst. Lawrence Livermore National Lab., CA (United States)

Assumptions made in the analytic formulation of convective-gain calculations limit the applicability of previous results to actual target experiments. In this manuscript, work in progress to extend the well-known coupled-mode analysis of convective, parametric instabilities is presented. The primary assumption is that various plasma and wave attributes are allowed to vary throughout the plasma. Previous analytic calculations assumed that these quantities did not vary from their value at the instability matching point. This is an appropriate assumption when the instability grows over a few wavelengths around the matching point, but is unreasonable when applied to plasmas which are thousands of laser wavelengths long. As will be seen, this assumption may give an incorrect value of the gain. The primary result of this work is derived in section III and is an expression for the gain coefficient of a convective instability assuming spatially-varying wave and plasma quantities. The effects of this result are illustrated by numerically evaluating the equation for stimulated Raman forward scattering in section IV. The emphasis of this manuscript is on the comparison to an experiment and the proposal of a linear saturation mechanism as presented in section V. The emphasis of a complementary work is on the connection of the present numerical work with previous analytic results and comparing the predicted convective gain of forward and backward SRS. The analysis begins with a derivation of the coupled-wave equations which are chosen to model the evolution of a convective, parametric instability.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5609312
• Report Number(s): UCRL-JC-109722; CONF-911131--1; ON: DE92009526
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340 -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
700411* -- Inertial Confinement Devices-- (1992-)
AMPLIFICATION
CONFINEMENT
CONVECTION
DIFFERENTIAL EQUATIONS
ENERGY TRANSFER
EQUATIONS
GAIN
HEAT TRANSFER
INERTIAL CONFINEMENT
INSTABILITY
LASER-PRODUCED PLASMA
MASS TRANSFER
MAXWELL EQUATIONS
NOVA FACILITY
PARAMETRIC INSTABILITIES
PARTIAL DIFFERENTIAL EQUATIONS
PLASMA
PLASMA CONFINEMENT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES