The effect of high‐Z atomic radiators on the x‐ray emission rate from a laser‐produced nitrogen plasma

The effect of a small admixture of high‐Z atomic radiators on the radiation rate of a laser‐produced nitrogen plasma has been experimentally studied for application to a nitrogen recombination soft x‐ray laser. The experiments used a miniature supersonic gas jet as a laser target that is capable of producing an on‐axis density of 1×1019 atoms/cm3. Nitrogen gas was seeded with 1%, 2%, and 5% (by number) of Ar, Kr, and Xe and irradiated with 31 J, 3 ns full width at half maximum pulses of 1054 nm light. The time‐dependent intensity of x rays between 114 and 140 A was measured from these plasmas and it was found that the e−1 decay time decreased with increasing Z and with the concentration of the high‐Z radiator. Several time‐integrated N VII spectral lines relevant to a nitrogen soft x‐ray laser are plotted against the measured e−1 decay time and it was found that the N VII line at 133.8 A is observed to be unusually bright as compared to the N VII 4‐2 and 2‐1 transitions, suggesting that enhanced recombina...

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