Generation Mechanisms of Multi-MeV Electrons in Ultra-intense Laser Plasma Interactions and Applications*

We report on the analysis of recent data taken with a magnetic electron spectrometer on the TITAN laser at LLNL. The experiments consisted of ultra-intense laser pulses incident on solid planar targets at various angles, with and without intentional pre-pulses. We find that a few key parameters, namely the slope and the maximum electron energy, scale with laser intensity in a way that is somewhat different than simple ponderomotive scaling would predict, and discuss various mechanisms that may explain the discrepancy. We then consider two applications of these high energy electrons: as a bremsstrahlung source and a method to generate positrons. LLNL-ABS-405449.