Stimulated Raman scattering in laser plasma with non-thermal electron distribution

The threshold and growth rate of stimulated Raman scattering (SRS) in laser plasma with super-Gaussian-Maxwellian (SGM) distributed electrons are investigated based on the nonlinear dispersion relation derived from kinetic theory. The differences in SRS characteristics among electrons following the SGM, Maxwellian, and super-Gaussian distributions under the same effective kinetic temperature are analyzed numerically using experimental parameters. It is found that the SRS threshold increases with electron density. The threshold for Maxwellian-distributed electrons is significantly higher than that for super-Gaussian-distributed electrons and considerably lower than that for SGM-distributed electrons. When the incident laser intensity is weak, the electron density corresponding to the maximum growth rate increases with laser intensity and is highest for SGM-distributed electrons. However, when the incident laser intensity is sufficiently strong, the growth rate of SRS increases with electron density and reaches its maximum at one-fourth of the critical electron density. The growth rate for electrons with an SGM distribution is slightly higher than those for the other two distributions. These results are conducive to the understanding of SRS properties in laser-plasma interactions.

Graphical abstract