ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
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(ring) 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(ring) is observed to be unusually bright as compared to the N VII 4-2 and 2-1 transitions, suggesting that enhanced recombination effects are possibly being seen. In addition, theoretical calculations of the N VII first- and second-excited state population dynamics are presented that predict a population inversion in recombining nitrogen, indicating a small signal gain of 4.4 cm−1. It is concluded that a low-Z soft x-ray laser is feasible using a laser-heated gas jet target and that possible gain enhancement might be possible by adding high-Z radiators to increase the cooling rate of the plasma.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.356251
