10 Hz Grazing Incidence Pumped Ni-like Mo Laser at 18.9 nm with 150 mJ Pump Energy

摘要

The first demonstration of the grazing incidence pumping (GRIP) scheme for laser-driven x-ray lasers (XRLs) is described utilizing 2-pulse pumping. A long pulse is incident normal to the target to produce a plasma with a particular density profile. Then a short pulse is incident at a grazing angle, chosen to optimally couple the short pulse laser energy into the specific density region where the inversion process will occur. The short pulse is simultaneously absorbed and refracted at a maximum electron density specified by the chosen pump angle then turns back into the gain region. The increased path length gives improved absorption allowing a reduction in the drive energy required for lasing. A Ni-like Mo XRL at 18.9 nm has been demonstrated with only 150 mJ total pump energy and a repetition rate of 10 Hz. We report high gains of 60 cm(sup -1) and the achievement of gain saturation for targets of 4 mm length.