Numerical Simulation of Pre-formed Plasma Generated by Low Intensity Pre-Pulse Before Main Heating Laser in Fast-Ignition

We investigated the plasma expansion of the inner surface of the cone used for the fast-ignition scheme of the inertial confinement fusion (ICF). LFEX laser [1] in Osaka University is high intense and short pulse laser system, which has 10$^{19}$W/cm$^{2}$ to 10$^{20}$W/cm$^{2}$, and ps pulse duration. However, it has also low intense pre-pulse with the contrast ranging from 10$^{5}$ to 10$^{8}$. It is high enough to ablate the inner surface of the cone wall used for fast ignition target. We developed the two-dimensional simulation code (Star-2D) [2], and simulate plasma expansion of the inner surface of the cone. We will discuss our simulation results, and also effects of the pre-plasma expansion on fast electron production. On the other hand, our code has been applied to simulate the laser-produced plasmas for Extreme-Ultraviolet research, and its accuracy has been tested with various experiments. We will also discuss the accuracy of our simulations. \\[4pt] [1] H. Azechi et at., in EPS. \\[0pt] [2] A. Sunahara et al., \textit{Journal of Physics: Conference Series }112(2008) 042048-1-4.