Time-resolved measurements of population densities in a Sr<sup>+</sup>recombination laser

Abstract

Time-resolved Sr I and Sr II population densities have been measured in an Sr+ recombination laser. The results indicate that the Sr vapor is fully ionized during the longitudinal discharge pulse and that 3 percent of this ionization persists until the start of the next pulse some 265 μs later. A lower limit of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.3-2.6 \times 10^{20}</tex> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> was placed on the electron density during the 180 A current pulse. The steady-state Sr I ground state population showed strong radial gradients, and the estimated population of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.3 \times 10^{20}</tex> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> was lower than that anticipated from vapor pressure considerations. The data were used to discriminate between two proposed mechanisms for laser emission from Sr+ and confirm the dominance of the recombination mechanism.