Backscattered spectra for stimulated Raman scattering in an inhomogeneous plasma

Using one-dimensional wave-coupling simulations, Raman scattering is investigated in a laser-irradiated plasma with a linear density profile. The quarter-critical density appears to have a dominant role in the Raman spectrum. In the case of no density modulation, a spectral broadening is observed and found to result from a coupling between the convective and absolute Raman, via pump depletion. The modulation of the plasma density by Raman and Brillouin driven ion waves appears to give rise to a multiple blue-shifted peak spectrum.