Recent advances in soft-x-ray laser research

Soft x-ray laser experiments at the Lawrence Livermore National Laboratory, Nova laser will be described. Much of the work involves the study of collisionally pumped Ne-like and Ni-like lasers1 although some studies of recombination pumped and resonantly photo-pumped x-ray lasers will be discussed. These experiments have produced nickel-like collisionally pumped x-ray lasers at wavelengths near to, and below that of the K absorption edge of carbon (43.76-Å)2. Recent work has concentrated on the development of the Ni-like Ta amplifier as a high power source at 44.83- Å. Amplification occurs in a laser produced plasma created by irradiating a thin foil of Ta with two beams of the Nova laser. Up to 8 gainlengths have been demonstrated so far, with a gain coefficient of 3 cm–1 and a gain duration of 250 psec. The Ni-like Ta amplifier at 44.83- Å lies at the edge of the water window, and provides the basis for the design of an x-ray laser source that should fulfill some of the requirements for holography of living cells. It remains to optimize the coherent output power of the amplifier to use it as a source for future x-ray holography experiments. Experiments utilizing normal incidence x-ray optics to enhance the power output from this laser will be described.