Interaction of relativistic laser pulses with near-critical density plasma*

We perform fundamental studies using the relativistic-intensity Titan laser (LLNL) interacting with very low-density foam targets, to study a near-critical density plasma. The interactions are characterized through simultaneous measurements of electron and proton spectra and beam divergence, the reflected and transmitted optical light and the generated x-ray radiation. Trends with plasma density are cross-correlated across different diagnostics to investigate the transition electron heating mechanisms and channeling behavior. Two dimensional particle-in-cell simulations are performed to give better physical understanding of these phenomenon.