Transient electromagnetic fields generated in experiments at the PHELIX laser facility

Large-amplitude electromagnetic radiofrequency fields are created by the charge-separation induced in interactions of high-intensity, short-pulse lasers with solid targets and have intensity that decreases with the distance from the target. Alternatively, it was experimentally proved very recently that charged particles emitted by petawatt laser-target interactions can be deposited on a capacitor-collector structure, far away from the target, and lead to the rapid (nanosecond-scale) generation of large quasi-static electric fields (MV/m), over wide regions. We demonstrate here the generation of both these fields in experiments at the PHELIX laser facility, with approximately 20 J energy and approximately 10(19) W/cm(2) intensity, for picoseconds laser pulses, interacting with pre-ionized polymer foams of near critical density. Quasi-static fields, up to tens of kV/m, were here observed at distances larger than 1 m from the target, with results much higher than the radiofrequency component. This is of primary importance for inertial-confinement fusion and laser-plasma acceleration and also for promising applications in different scenarios.