摘要
Stimulated Raman scattering(SRS)in plasma in a non-eigenmode regime is studied theoretically and numerically.Different from normal SRS with the eigen electrostatic mode excited,the non-eigenmode SRS is developed at plasma density ne>0.25nc when the laser amplitude is larger than a certain threshold.To satisfy the phase-matching conditions of frequency and wavenumber,the excited electrostatic mode has a constant frequency around half of the incident light frequency ω0/2,which is no longer the eigenmode of electron plasma wave ωpe.Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero.Super-hot electrons are produced by the non-eigen electrostatic wave.Our theoretical model is validated by particle-in-cell simulations.The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than 10^15 W/cm^2.
基金
This work was supported by the Natural Science Foundation of Shanghai(No.19YF1453200)
the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDA25050800 and XDA25050100)
the National Natural Science Foundation of China(Nos.11775144 and 1172109)
the National Science and Technology Innovation Foundation of the Chinese Academy of Sciences(No.CXJJ-20S015).