Review of Ni-like ion Xx-ray laser research at Lawrence Livermore NationalLaboratory

We have demonstrated saturated output on several nickel-like ion X-ray lase rs ranging from niobium to silver by using a psec, high-power, chirped-puls e-amplification, tabletop laser. These results have been achieved at wavele ngths from 20.3 to 13.9 nm on the Ni-like 3d(9)4d(1)S(o) --> 3d(9)4p(1)P(1) laser line using a total of 5 to 7 J of energy in a traveling wave excitat ion scheme. Strong amplification is also observed for Ni-like Sn at 11.9 nm . Gain of 41 cm(-1), gain-length product of 18, and output energy of 12 muJ are measured for the Ni-like Pd line at 14.7 nm. For Ni-Iike Mo, experimen ts are done using multilayer mirrors to obtain two-dimensional images of th e output aperture of the laser and to measure the total laser energy as a f unction of various parameters such as the delay between the short and long pulses and the energy of the two pulses. For Mo we measure an output energy of 2 muJ and a gain-length product of 16.6. To model the Mo experiments, t he LASNEX code is used to calculate the hydrodynamic evolution of the plasm a and provide the temperatures and densities to the XRASER code, which then does the kinetics calculations to determine the gain. The temporal and spa tial evolution of the plasma is studied both with and without radiation tra nsport included for the 4f and 4p --> 3d Ni-like Mo resonance lines. High g ains are predicted and observed for both the 3d(9)4d(1)S(o) --> 3d(9)4p(1)P (1) laser line at 18.9 nm and the 3d(9)4f(1)P(1) --> 3d(9)4d(1)P(1) photopu mped line at 22.6 nm. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.