S.A. Starostin

RF discharge in CO2 laser mixtures at moderate pressures

The voltage-power characteristics and spatial structure of an RF discharge in the mixtures of CO2 and N2 molecular gases with He at total pressures of tens of torr are studied. One-dimensional numerical simulations of an RF discharge are carried out within two approaches: (i) the distribution function and the related kinetic coefficients are assumed to be functions of the local reduced field, and (ii) the kinetic coefficients are functions of the electron mean energy, which is calculated with allowance for both electron heat conduction and diffusion. The latter approach is shown to better describe the existing experimental dependence of the discharge voltage and the phase shift between the discharge current and voltage on the driving power.

Catalyst enhanced high power radio frequency excited CO2 slab laser

A substantial improvement in the specific laser output power (up to 30%) and efficiency (up to 50%) of a radio frequency (rf) excited slab CO2 laser with a distributed gold catalyst is observed when a large amount of CO (more than 60% of CO2 concentration) is added to the laser gas mixture. A maximum output power of 160 W with an efficiency of 17% was obtained from a laser with an active volume of 2×15×370 mm3. Gas mixtures with a high CO concentration combined with a distributed gold catalyst also accelerate the start-up time of rf pumped CO2 lasers considerably.

Effect of Resonant Radiation Transport on the Parameters of RF and DC Discharges in a He-Ar-Xe Mixture

A study is made of the effect of the transport of Xe 147-nm resonant radiation on the parameters of a low-temperature plasma of DC and RF discharges in gas mixtures used as the working medium in lasers based on infrared transitions in xenon. RF discharges are treated in the planar geometry typical of slab lasers. DC discharges in tubes are treated in cylindrical geometry. The trapping of resonant radiation is described using different approximate models: the decay time approximation for a plasma slab (the Holstein approximation) and the effective lifetime approximation (the Biberman approximation). The transport equation for resonant radiation is solved numerically. The effect of the radiation transport on both the current-voltage characteristics of a discharge and the spatial distribution of the excited Xe atoms is investigated. The current-voltage characteristics calculated for a DC discharge with allowance for the resonant radiation transport agree well with the experimental characteristics. It is found that, for an RF discharge, the effective lifetime approximation overestimates the density of the excited Xe atoms near the electrodes by several times and underestimates this density at the midplane of the discharge gap.

Misalignment effects in the resonator of a transverse RF excited Ar-He-Xe laser

Summary form only. A new continuous wave (CW) transverse radio frequency (RF) excited Ar-He-Xe laser was reported recently. Because of its potential advantages (very high gain, lasing in an atmospheric transmission window near 2 /spl mu/m and 4 /spl mu/m) this laser has attracted the attention of several research groups. It soon led to a substantial improvement of the laser performance resulting in an output power in the order of 10 watts.