Simulation of ion generation and dynamics for Fast Ignition*

The ePLAS$^{1}$ implicit/hybrid code is being used to model fast ion generation in a variety of studies involving picosecond time scales on the Titan, and Omega EP lasers. Applied to Cu foils 200 $\mu $m in radius and 20 $\mu $m thick, under 1 ps of 5 x 10$^{19}$ W/cm$^{2}$ laser illumination in a 10 $\mu $m radius spot, ePLAS shows (in particle electron mode) the generation of 10$^{17}$ cm$^{3}$ ion beams travelling 80 $\mu $m by 2.9 ps. The corresponding calculation for a hydrogen foil (with fluid hot electrons) shows a forward 10$^{18}$ cm$^{3}$ beam crossing $\sim $250 $\mu $m. Such calculations complete in 24 min on a 2 GHz PC. The talk will detail the expansion of Titan-driven deuterium beams from a 25 $\mu $m foil. For EP we explore ion beams from hemispheres with 400 $\mu $m curvature radius, again with a $\sim $25 $\mu $m thickness under 1 kJ, 40 $\mu $m diameter, 10 ps illumination. We compare the ion flows calculated for fluid vs. particle ions, and discuss the energy spectrum calculated with PIC. 1. R. J. Mason, JCP \textbf{71,} 429 (1987), and R. J. Mason, PRL \textbf{96,} 035001 (2006). \newline \newline *Research supported in part by the USDOE under SBIR Grant DE-FG02-07ER84723.