Supra-thermal electron beam stopping power and guiding in dense plasmas

Fast-electron beam stopping mechanisms in media ranging from solid to warm dense matter have been investigated experimentally and numerically. Laser-driven fast electrons have been transported through solid Al targets and shock-compressed Al and plastic foam targets. Their propagation has been diagnosed via rear-side optical self-emission and K-alpha X-rays from tracer layers. Comparison between measurements and simulations shows that the transition from collision-dominated to resistive field-dominated energy loss occurs for a fast-electron current density similar to 5 x 10(11) A cm(-2). The respective increases in the stopping power with target density and resistivity have been detected in each regime. Self-guided propagation over 200 mu m has been observed in radially compressed targets due to similar to 1 kT magnetic fields generated by resistivity gradients at the converging shock front.