Saturated x-ray lasers at 196 and 73 Å pumped by a picosecond traveling-wave excitation -: art. no. 053810

Traveling-wave irradiation with a laser pulse of duration similar to1 picosecond has been shown to achieve saturated operation of Ne- and Ni-like x-ray lasers. Gain at 196 Angstrom was confirmed by observation of both forward and backward x-ray laser beams from a germanium plasma under ideal and nonideal traveling-wave conditions at a small signal gain of >40 cm(-1). Saturation was observed for targets >4 mm long consistent with a model of laser amplification along the plasma medium and with the output of a detailed ray-tracing post-processor coupled to a hydrodynamic and atomic physics code. Ni-like samarium targets, pumped under ideal traveling-wave conditions exhibited a small signal gain of similar to 19 cm(-1) at 73 Angstrom with saturation observed for targets 8 mm long.