High gain table-top transient collisional X-ray lasers

Summary form only given, as follows. In the last few years, there has been rapid progress in the development of higher efficiency laser-pumped X-ray lasers which has led to a significant reduction in the energy required to produce a population inversion. At LLNL, we are continuing research on table-top transient collisional excitation schemes generated by high power (15 TW), 500 fs pulses from the COMET laser. Strong lasing has been demonstrated on various Ne-like and Ni-like ion X-ray lasers operating in the 130-320 /spl Aring/ range using typically 5-10 J of laser energy on target. Ultra high gains up to 55/cm have been observed allowing the possibility of achieving gain saturation and X-ray laser output energy of 1-10 /spl mu/J with target lengths of a few millimeters. Recent experiments show enhanced output of the X-ray laser when the short laser pulse irradiates the target in a traveling wave geometry. The high gain region in the plasma has been determined using multi-layer coated optics imaging and is compared with simulations to better understand the generation of the transient X-ray laser.