An experiment to demonstrate a nitrogen recombination X-ray amplifier using high-density planar gas jet laser target. Final report

The results of an experiment to search for lasing in atomic transitions at x-ray energies in N{sub 2} gas target plasmas using ultra-short laser pulses is presented. Particular emphasis was placed on a search for a predicted 24.7 nm optical-field-ionization (OFI) induced lasing line from the Li-like nitrogen (N{sup 4+}, 3d {yields} 2p) transition. The excitation laser was a multi-terawatt Cr:LiSrAlF{sub 6} laser system operating at a wavelength of 825 nm and a pulse duration of 135 fs located at the Lawrence Livermore National Laboratory. Experimental conditions were optimized and a series of Li-like (including the 24.7 rm N{sup 4+} 3d {yields} 2p) lines were observed and identified. Further experimental studies are required before an attempt at measurement of any potential lasing gain can be made