Electron transport and instabilities in laser plasma interaction

The propagation of laser-driven, relativistic electron beams in plasmas is a phenomenon of relevance in astrophysical scenarios, particularly concerning the problem of the generation of strong, spatially extended and sustained magnetic fields in astrophysical jets. We report on experiments where the transport of hot electron currents through foam has been studied using the proton imaging technique. Strong filamentation has been observed, possibly due to electromagnetic instabilities of the Weibel type. A multitude of tubelike filamentary structures is also observed to form behind the front of a plasma created by irradiating solid-density wire targets with a high-intensity ($I\sim $10$^{19}$ W/cm$^{2})$, picosecond-duration laser pulse. These filaments exhibit a remarkable degree of stability, persisting for several tens of picoseconds, and appear to be magnetized over a length corresponding to several filament radii.