174 / 2023-04-15 10:53:23

Two-plasmon-decay instability in the non-eigenmode regime in laser plasma interaction

laser plasma interaction，two-plasmon-decay instability，hot electrons generation，non-eigenmode

It is shown theoretically that two-plasmon-decay instability (TPD) in plasma can be excited in the non-eigenmode regime, where the plasma density is larger than the quarter critical density.  This appears when the laser amplitude is larger than a certain threshold value, which increases with plasma density. In this case, the excited electrostatic mode has a constant frequency around half of the incident light frequency. The theoretical model indicates that the threshold of non-eigenmode TPD is nearly twice higher than non-eigenmode SRS. The theoretical model is validated by particle-in-cell simulations. The simulation results show that the non-eigenmode mode TPD has a higher threshold amplitude for the pump laser than the non-eigenmode mode of stimulated Raman scattering (SRS) excited in the plasma region above the quarter critical density. The excitation of the non-eigenmode TPD can generate hot electrons with higher energy than the non-eigenmode SRS.