Fast electron generation in cones with ultraintense laser pulses

Experimental results from copper cones irradiated with ultraintense laser light are presented. Spatial images and total yields of CuKα fluorescence were measured as a function of the laser focusing properties. The fluorescence emission extends into the cone approximately 300μm from the cone tip and cannot be explained by ray tracing including cone wall absorption. In addition, the total fluorescence yield from cones is an order of magnitude higher than for equivalent mass foil targets. Indications are that the physics of the laser-cone interaction is dominated by preplasma created from the long duration, low-energy prepulse from the laser.