The impedance of the laser head of a 100-W copper-vapor laser is investigated. The laser head is of a coaxial geometry, which is commonly used for longitudinally electrically excited, pulsed-gas lasers. The plasma conductivity is estimated using the available data on plasma parameters. The effect of radial gradient of the gas temperature and electron density is considered. The tube inductance and capacitance are estimated and the combined effect is demonstrated. The skin effect is considered. A method to calculate the exact influence of the skin effect on the tube impedance is presented. The full calculation procedure is demonstrated for the case of a 100-W, 8-cm-diameter, copper-vapor laser. The consequent impedance is used to calculate the laser current under given excitation conditions. Very good agreement exists between the calculated and measured laser current. The metal-sleeve diameter is found that is optimal for power matching. >

Analysis of the impedance of a coaxial, large-bore copper-vapor laser

Comprehensive investigations of the lasing characteristics in the double-pulse regime, of the characteristics of excitation pulses, and of the decay of metastable active levels during the discharge afterglow were made using a copper vapor laser with a 12-mm diameter 40-cm long discharge tube and operating in the self-heating regime. It was found that under conditions close to efficient lasing, the recovery of the lasing ability during the second pulse was mainly determined by the decay of the metastable levels.

Decay of metastable states and its influence on the lasing characteristics of a copper vapor laser

A study was made of the spatial kinetics of the decay of metastable atoms, resolved over the radius of a copper vapor gas discharge tube, under conditions typical of the self-heating regime. The investigations were carried out for a time interval of 1–100μsec after the excitation pulse, with a radial resolution of 2–3 mm, in the entire lasing temperature range. A profile of the population of the metastable states having a minimum on the axis transformed into a profile with a maximum on the discharge axis during the interpulse time interval. An analysis was made of the possible processes during the afterglow of the discharge and estimates were obtained of the electron density and temperature in the laser plasma.

Relaxation of metastable atoms during the afterglow in a copper vapor laser

Pulsed metal vapour lasers (PMVLs), utilising transitions from resonance to metastable levels in atoms and atomic ions (r-m lasers), especially copper vapour laser (CVL), are now among the most efficient and powerful gas lasers in the visible and near IR regions of spectrum. They are widely used in many important applications. Consequently, they were subject of many investigations. Nevertheless, understanding of basic kinetic processes controlling operation of these lasers is still not satisfactory. As the result it is difficult to predict attainable output power, efficiency and other characteristics of the lasers. This is a result of considerable experimental difficulties associated with experimental investigations of kinetics in PMVL.

Kinetics of Metal Vapour and Metal Halide Lasers

The paper presents the results of the research and development of the CuBr laser with continuous control of each pulse energy. The prototype consists of a large volume CuBr active element with an unstable cavity, two high voltage pulses generators and control system. The HBr additive was used to increase the laser energy-frequency characteristics. Control of laser pulses energy has been provided by high-voltage preionization pulses. The linear control of output power from 5 W to 0 have been demonstrated. The metastable atom population is the major factor in the energy control. The dependence of the preionization pulse energy for full suppression on the active media operating mode (CuBr concentration, pumping energy etc.) was studied. The ratio between excitation pulse energy and preionization pulse energy for full suppression of the lasing changing from 18 to 25.

Continuous control of CuBr laser pulse energy

The method of resonance absorption of the 510.6 nm line was used to determine the density n/sub m/ of the 4s/sup 2/ /sup 2/D/sub 5//sub ///sub 2/ metastable level of the copper atoms during the interpulse periods of a Cu laser, in the neon buffer gas pressure range of 10--50 kPa. At pressures exceeding 10 kPa an increase in n/sub m/ was observed (following rapid decay) over a period 5--10 ..mu..sec after the current pulse. A numerical solution of the problem of relaxation of the plasma parameters showed that the complex nature of the variation in n/sub m/ can be explained by a combination of a number of processes including recovery of the concentration of the copper atoms in the ground state and relaxation of the temperature and density of the electrons.

Relaxation of the 4s2 2D5/2 metastable level of the copper atom in the afterglow of a pulsed discharge in a copper vapor laser

The relaxation of the metastable 4s2 2D5/2 level of a copper atom in the afterglow of a pulse discharge in a copper-vapor laser

The values of the average gas temperature as a function of the type and pressure of buffer gas and the power per unit length injected into the discharge were determined experimentally based on the change in the gas pressure in a copper-vapor longitudinally pumped laser with the pulsed periodic discharge switched off for a short time. The profiles of the gas temperature and its average value are calculated taking into account the nonuniformity of the discharge for three different model distributions of the energy input over the cross section of the gas discharge tube. Comparison of experiments with the calculations showed that the nonuniformity of the discharge strongly affects the averge gas temperature.

L. A. Selezneva

Papers

Relaxation of the 4s2 2D5/2 metastable level of the copper atom in the afterglow of a pulsed discharge in a copper vapor laser

The relaxation of the metastable 4s2 2D5/2 level of a copper atom in the afterglow of a pulse discharge in a copper-vapor laser

Nonuniformity of a discharge in a copper-vapor laser and its effect on the gas temperature