Development of Plasma X-Ray Amplifiers Based on Solid Targets for the Injector-Amplifier Scheme

Summary

Results of experimental studies aimed at generation and diagnostics of advanced soft X-ray amplifiers, produced from solid targets, are presented. 2D profiles of electron density of short plasma columns, generated by ~300-ps laser pulses under various illuminating conditions, were investigated by near-field distribution of the plasma self-emission, and by X-ray laser backlighting at 21 nm, accessing in the given geometry electron densities of 1022 cm^-3. The obtained data indicate that by employing line focus with concave intensity profile it is possible to generate laterally highly uniform plasma columns of width ~500 °m, potentially suitable as amplifiers with negligible lateral refraction. By X-ray laser backlighting we further probed the morphology and gain region of test Zn plasmas, pumped by a sequence of a loosely focused weak prepulse and tightly focused main pulse, separated by 5.5 ns. The data clearly show the beneficial role of the prepulse in lateral homogenization of the plasma, and reveal narrow ~50-°m gain region.