Electron temperature and transverse instability in laser-driven near-critical- density plasma shock waves

Abstract We employed particle-in-cell (PIC) simulations to investigate the transverse instability of collisionless shock waves and its impact on ion acceleration. The instability is induced by an intense laser interacting with a near-critical-density plasma. In the longitudinal regime, the shock wave is highly stable at a low electron temperature and propagates at a constant velocity. The numerical simulations show that under identical parameters, electron temperatures in two-dimensional (2D) simulations are higher than those in one-dimensional (1D) cases, which can be attributed to additional transverse acceleration in 2D configurations. A higher electron temperature leads to enhanced dispersion of ion acoustic waves, which impedes the formation of shock waves. The transverse instability (dominated by the Rayleigh-Taylor (RT) instability in our scenario) at the shock front can enhance the production of high-energy electrons. We further analyzed the origin and impact of this RT instability, and find that the laser-induced magnetic field enables a specific wave mode to outcompete other modes. The rapid growth of the transverse instability breaks the structural integrity of the shock wave, and ultimately disrupts the associated proton acceleration process.