Session 7E - Space and Basic.
ORAL session, Thursday morning, November 14
Majestic Ballroom, Adam's Mark
A modeling procedure for macroscopic systems is proposed which is based on the large separation of space and time scales between the macro scales and the microscopic correlation lengths of the induced Langmuir tubulence excited by instabilities such as SRS, TPD and IADI. As a first example we have modeled in 1D the propagation of the pump wave and the modification of the intially linear density profile by the turbulence induced near critical density by the IADI ( ion acoustic decay instabilty) and the related modulational instabilty. The effect of the induced turbulence on the equation for the pump propagation is reduced to an effective (or anomalous) absorption coefficient and a frequency shift parameter, obtained from homogeneous simulations. The density profile is perturbed primarily by the ponderomotive pressure of the induced turbulence. Solution of the resulting mesoscale equations shows a dramatic, time dependent, alteration of the usual linear Airy profile. An application to SRS is proposed in which the standard envelope equation for the daughter Langmuir wave is modified by turbulence-induced anomalous aborption and frequency shift parameters which can be obtained from homogeneous simulations. * Research supported by the USDOE and by NSF grant #ATM-9503147