Threshold and simulations of absolutely unstable stimulated Raman backscattering for relativistic phase velocities

Recent laser-driven high energy density experiments have generated very high (>10 keV) electron temperatures in under dense plasma conditions that suggest the necessity of relativistic treatment in simulations. Stimulated Raman Scattering, the interaction of light waves with these Langmuir waves, is of great interest, as the relativistic dispersion relation for high phase velocity Langmuir waves has reduced damping compared to the conventional treatment. In continuation from previous work, we conduct physics studies on these Langmuir waves using the relativistic Vlasov equations. Previous simulations confirmed that higher plasma temperatures with relativistic treatment displayed reduced electron potential damping in a collisionless plasma. Given this, it is assumed that relativity will also influence the absolute threshold of uniform plasma parametric instabilities. Moreover, we conduct Raman simulations to demonstrate the amount of backscattering. Using these simulations, we can observe the effect relativity has on backscattering.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore

National Laboratory under Contract DE-AC52-07NA27344.