Experimental investigations on the Stimulated Raman Scattering (SRS) in a magnetized environment*

SRS plays a detrimental role in inertial confinement fusion (ICF) caused by a loss of energy and preheat of the fuel by suprathermal electrons generated through the decay of electron plasma waves (EPW). However, recent numerical work [1] has shown that SRS can be mitigated by a moderate external magnetic field. Such behavior of SRS in a pre-magnetized plasma has not been experimentally confirmed. With the development of applied magnetic fields for use in laser-plasma experiments, investigation on the effect of a magnetic field on SRS is now possible. We have introduced a new platform designed to investigate the mitigation of SRS at OMEGA-EP, which takes advantage of the MIFEDS pulse-power coil to pre-magnetize the plasma. The Sub-Aperture Backward Scatter (SABS) diagnostic was fielded to time resolve reflected light from Backward-SRS (BSRS). The first results of SABS show clear evidence of the reflected light resulting from the BSRS in the kinetic regime, kλ_D ~ 0.3 where k is the EPW wavenumber and λ_D is the Debye length.

In addition, the aspect of the generation of hot electrons by SRS and how it is affected by an external magnetic field will be addressed in a series of experiments at JLF, which will be also discussed.