Theory and simulation of stimulated Raman scatter at near-forward angles

Computer simulations in two dimensions of Raman near‐forward scatter are presented to show the linear and nonlinear behavior of this instability in a high‐temperature, low‐density plasma. Modifications to one‐dimensional theory are discussed, as is the angular dependence of the spatial growth rate. In the simulations, the amount of laser energy scattered into various angles is examined and the subsequent heating of the electrons is discussed. Results with mobile ions are presented as well. It is found that, for the strongly driven parameter regime examined, some stimulated Brillouin scattering is observed early in time until the ions heat up and quench the instability. However, the ion motion does not substantially change the level of stimulated Raman scattered light in these simulations.