Characteristics of output beam from unstable-cavity in a tabletop x-ray laser pumped by a pulse-train YAG laser

摘要

X-ray lasing of Li-like Al transition, 3d-4f (15.47 nm), has been improved by using a plane-concave unstable cavity. It was found that the beam profile of the cavity output was almost circular and its divergence was about 3 mrad, that was narrower than that of spontaneous x-ray emission from the plasma. The absolute intensity was estimated to be about 1×10~8 photons/shot from the two different measurements.