Generation of narrow divergence electron beams in relativistic laser-plasma interactions*

The evacuation of plasma from channels formed during the interaction of intense laser pulses with under-dense plasma is attractive for a number of applications, particularly fast ignition inertial fusion. We investigated the channel formation using proton radiography as the diagnostic tool. We observed the interactions of ultra-intense laser pulse (120J/ 15ps/ 1053nm) with a large scale-length plasma which was formed by the expansion of a plastic foil target by preheating with a laser pulse comprising 200J/ 1ns/ 527nm, focused to 400-diameter. This experiment was set-up to mimic the coronal plasma experienced during the compression phase of a directly driven implosion. The results showed that laser-induced electron beam were guided by self-generated magnetic field.