Investigation of stimulated Raman scattering in longitudinal magnetized plasma by theory and kinetic simulation

Stimulated Raman scattering (SRS) in a longitudinal magnetized plasma is studied by theoretical analysis and kinetic simulation. The linear growth rate derived via one-dimensional fluid theory shows the dependence on the plasma density, electron temperature, and magnetic field intensity. One-dimensional particle-in-cell simulations are carried out to examine the kinetic evolution of SRS under low magnetic intensity of \omega _\rmc/\omega _0\lt 0.01. There are two density regions distinguished in which the absolute growth of enveloped electrostatic waves and spectrum present quite different characteristics. In a relatively low-density plasma (n_\rme\sim 0.20n_\rmc), the plasma wave presents typical absolute growth and the magnetic field alleviates linear SRS. While in the plasma whose density is near the cut-off point (n_\rme\sim 0.23n_\rmc), the magnetic field induces a spectral splitting of the backscattering and forward-scattering waves. It has been observed in simulations and verified by theoretical analysis. Due to this effect, the onset of reflectivity delays, and the plasma waves form high-frequency oscillation and periodic envelope structure. The split wavenumber \rm\Delta k/k_0 is proportional to the magnetic field intensity and plasma density. These studies provide novel insight into the kinetic behavior of SRS in magnetized plasmas.