Kinetic analysis of rare gas metastable production and optically pumped Xe lasers

Abstract

Optically pumped all-rare-gas lasers use metastable rare gas atoms as the lasing species in mixtures with He or Ar buffer gas. The metastables are generated in a glow discharge, and we report model calculations for the optimal production of Ne*, Ar*, Kr* and Xe*. Discharge efficiency was estimated by solving the Boltzmann equation. Laser efficiency, gain and output power of the CW optically pumped Xe laser were assessed as functions of heavier rare gas content, pressure, optical pump intensity and the optical path length. It was found that, for efficient operation the heavier rare gas content has to be of the order of one percent or less, and the total pressure—in the range 0.3–1.5 atm. Output power and specific discharge power increase approximately linearly with pump intensity over the output range from 300–500 W cm−2. Ternary mixtures Xe:Ar:He were found to be the most promising. Total laser efficiency was found to be nearly the same for pumping the 2p8 or 2p9 state, reaching 61%–70% for a pump intensity of ~720 W cm−2 when the Xe fraction was in the range 0.001 ÷ 0.01 and Ar fraction—0.1 ÷ 0.5. However, when the 2p8 state was pumped, the maximum total efficiency occurred at larger pressures than for pumping of the 2p9 state. The discharge power density required to sustain a sufficient Xe* number density was in the range of tens of watts per cubic centimeter for 50% Ar in the mixture.

Rydberg states population via three-body and dissociative recombination in low-temperature plasmas of rare gas mixtures

“…In accordance with formulas(15),(20) and (29) the recombination cross sections s en and rate constants b n res of electron capture to a given atomic nl-sublevel depend on the widths, G e  nl , of the autoionizing Rydberg state of a quasimolecule BA( f, nl). Thus, to evaluate the cross sections and rate constants (37) one should replace the value of + ), (20) and (29) with the effective coupling parameter…”

“…The plasmas of rare gas mixtures are of great interest for many applications in plasma physics, optoelectronics, laser physics and material processing, including VUV radiation sources [1,2], control of electromagnetic wave propagation [3], alternating current plasma displays [4,5], microplasma arrays [6,7], plasma etching [8], development of optically pumped rare gas lasers [9,10] and high-power xenon lasers [11,12]. The kinetics of electronic transitions and excited level population in such plasmas are the topics of ongoing experimental [13][14][15][16][17] and theoretical [18][19][20][21] studies. Recombination is one of the key elementary processes in plasmas [22][23][24].…”

Kinetics of Metastable Argon Optical Excitation and Gain in Ar/He Microplasmas

“…Relevant prior research includes investigations of collisional state-to-state energy transfer kinetics, , collisional line broadening rates, − the kinetics of discharge production of Ar­(1s 5 ) metastables, ,− and kinetics-based models of scaling the laser output to elevated powers. − Various laser and discharge design configurations have also been investigated. − In this paper, we describe experimental measurements and kinetics analysis of spatially resolved small-signal gain produced by optical pumping of Ar­(1s 5 ) generated in microplasma arrays, as well as diode-pumped lasing, following the transition sequence illustrated in Figure . Analysis of the optical gain results required additional research to characterize the spatially resolved microdischarge temperatures and collisional line-broadening dynamics, and to verify the relevant microplasma spectroscopy and branching ratios; those results are provided in the Supporting Information.…”

Demonstration of a diode-pumped dual-wavelength metastable krypton laser

“…Until now, most research on DPRGLs has been carried out using Ar* as the gain medium [ 15 – 18 ] and a little on the Xe* laser [ 5 , 19 , 20 ] . The only research for the Kr* laser is on concept verification and kinetics investigation [ 1 , 21 ] , and no study using high-power diode pumping has been reported.…”