Particle-in-cell simulations of laser plasma instabilities and hot electron generation in shock ignition regime*

Experiments conducted on the OMEGA EP laser facility with high-intensity, multi-kJ UV laser (1×10¹⁶ W/cm², 1.25 kJ, 1 ns) interacting with a long scalelength keV corona plasma have shown strongly directional hot electrons with moderate temperature (~45 keV), quite favorable for electron assisted shock ignition. To understand the underlying physics, we performed 2-dimensional particle-in-cell (PIC) simulations with a long density range (0.01~0.3n_c) using the OSIRIS code to study the laser plasma instabilities (LPI) and resultant hot electron generation in the experiments. The simulation results show that the hot electrons are mainly generated by two-plasmon decay (TPD) near the n_c/4 surface with half angle of 30 degrees, temperature of 40 keV and ~3% of the laser energy, which agree with the experiments. In the lower density region (< 0.1n_c), stimulated Brillouin scattering (SBS) reflects significant amount of laser energy and suppresses stimulated Raman scattering (SRS). Their competition is susceptible to whether a laser speckle or plane wave is used. More details of the simulation results will be presented in the meeting.