Study of relativistic electron beam production and transport in high-intensity laser interaction with a wire target by integrated LSP modeling

The results of a numerical study of high-intensity short-pulse laser interaction with wire targets are presented. Fast electron production and transport in solid density plasma is modeled using the implicit hybrid particle-in-cell code LSP [D. R. Welch et al., Phys. Plasmas 13, 063105 (2006)]. These simulations were performed with realistic target size and laser parameters and over times much longer than the laser pulse. Nonlinear interaction processes, i.e., microchanneling and density steepening, have been observed. The spectrum of the relativistic electrons produced has a reduced slope temperature compared to that predicted by ponderomotive scaling. Preformed underdense plasma has been found to bottleneck fast electrons due to the intense magnetic fields generated near the critical surface. In a thin long wire target, the overall propagation length of the fast electrons is about 160 mu m; however, surface fields guide a small fraction of electrons to longer distances. These results are in good agreement with the experiments and have demonstrated that the modeling of electron transport relevant to fast ignition can be pursued in an integrated manner. (C) 2008 American Institute of Physics.