Lasing to ground state of ions in discharge created plasma in microcapillary

The objective of this paper is to present the results of recent experiments on lasing to ground state in H-like LiIII ions in microcapillary plasma. The experiments were conducted at both Princeton University and NRL. Two methods were used to fill the microcapillaries with plasma: ablation of microcapillary walls when irradiated with a low power laser beam of a few ns duration, or fast electrical discharge. Powerful subpicosecond laser beams (with wavelength of 0.25 μm at Princeton University and 1.053 μm at NRL) were used for longitudinal pumping of microcapillary plasma following by the fast recombination and gain generation in the transition to ground state of hydrogen-like LiIII ions. In these experiments the dependence of the gain on the specific method of the preplasma creation, electric discharge versus low-power laser, pumping laser wavelength (0.248 μm versus 1.053 μm), and the geometry of the experiment (microcapillary dimensions and electrode design) were investigated. Results of these investigations are presented and discussed with the particular emphasis on the experiments with the 1 μm subpicosecond laser pumping of discharge-produced microcapillary plasma.