Z Effects on Laser Energy Absorption and Fast Electron Transport in Fast Ignition ICF

We report on a systematic study of the Z-effects on laser energy absorption and energy coupling using multilayer solid targets consisting of interaction and transport layers made of different Z materials and fluorescent layers in planar and cone geometries. The experiment was carried out on the Titan laser (0.7 ps, 150 J, 10$^{20}$ W/cm$^{2}$ peak intensity). Results show several clear trends: i)electron flux transport systematically decreased with increasing $Z$, ii)increase in the laser intensity reduced the laser energy conversion to fast electrons in the planar geometry for high Z material and iii)in cone geometry, coupling was reduced 1.5x compared to flat targets when a 2x lower intensity was used. Detailed results will be presented.