Intense-laser generated fast electron transport in a large preplasma created by a long pulse laser

Understanding the generation and transport of fast electrons from intense laser-matter interactions is crucial for the Fast Ignition scheme. It has been shown that the plasma associated with the intrinsic prepulse of the intense laser light affects the fast electron generation as well as the fast electron transport. A short pulse laser experiment investigating these effects was carried out with a metal foil covered by a preformed long scale length plasma. Preplasmas were created using a separate long pulse laser, and their profile characterized. Fast electron generation and transport were diagnosed by measuring Kalpha X-ray fluorescence from a copper layer embedded in between two aluminum layers. Ring structured Kalpha X-ray patterns were observed with a monochromatic X-ray imaging system only when the preplasma was present. In this study, two 2D simulations are performed to understand how the preplasma affects the fast electron transport; radiation-hydrodynamics code h2d and hybrid PIC code LSP The preplasma condition (electron temperature and density) and the self-generated field profiles are estimated from h2d simulation at the timing when the short pulse is injected in the experiment. Then, these profiles are used in the LSP simulation as an initial condition to model the fast electron transport in the preplasma. The results of simulations will be compared to the experimental results in the presentation.