Transient collisional excitation X-ray lasers with 1-ps tabletop drivers

Recent results are presented for I-ps driven X-ray laser amplification in Ne-like and Ni-like transient collisional excitation research at the Lawrence Livermore National Laboratory, Plasma formation, ionization and collisional excitation are optimized using two laser pulses of 600- and I-ps duration at tabletop energies of typically 5 J or less in each beam. Gain of 35 cm(-1) and higher has been measured on the 147 Angstrom 4d --> 4p J = 0 --> 1 transition of Ni-like Pd and is a direct consequence of the nonstationary population inversion produced by the high intensity picosecond pulse. We report the characterization of the X-ray laser properties including the transient gain lifetime and beam divergence for different Ne-like and Ni-like X-ray lasers.