A gasdynamic CO.sub.2 -laser in which the lasing medium is being cooled by expansion in a Laval nozzle, is operated in a way to amplify the cooling effect. This increased cooling is accomplished by introducing liquid droplets into the expanding lasing medium. These droplets are entrained by the flowing medium whereby the droplets are taken along with a speed corresponding approximately to the speed of the expanding lasing medium. The amplification of the cooling is accomplished by the evaporation of these droplets.

In a gasdynamic laser in which the hot flowing lasing medium (e.g. CO.sub.2 --N.sub.2) is cooled by expansion in a Laval nozzle 1, liquid droplets are introduced into the expanding lasing medium to increase the cooling effect. The liquid can be water, preferably heavy water, from a container 4 pressurized by the laser medium in plenum 6 and introduced from pipes 3 into a region immediately before the nozzle neck 2 so as to be atomized and accelerated through the neck 2. Evaporation occurs downstream of the neck and causes an increase in the cooling. The droplets preferably have a size in the range 1-20 .mu.m and may contain dissolved CO.sub.2. The droplets may be dispersed in a super cooled gas which is then injected into the lasing medium.

A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

A laser amplifier system amplifies pulses in a single "stage" from .about.10.sup.-9 joules to more than 10.sup.-3 joules, with average power of 1-10 watts, and beam quality M.sup.2 <2. The laser medium is cooled substantially below room temperature, as a means to improve the optical and thermal characteristics of the medium. This is done with the medium inside a sealed, evacuated or purged cell to avoid moisture or other materials condensing on the surface. A "seed" pulse from a separate laser is passed through the laser medium, one or more times, in any of a variety of configurations including single-pass, multiple-pass, and regenerative amplifier configurations.

Disclosed is a gas laser utilizing radio frequency discharge excitation in the area of sonic or supersonic/subsonic transfer gas flow. The laser uses various types of gases and mixtures of gases as the active medium and provides for RF or UV pre-ionization of the gaseous medium before using radio frequency discharge excitation. The gas is supplied into a receiver, and has downstream therefrom a supersonic nozzle for acceleration of the active gaseous flow to high subsonic or supersonic speeds in order to provide intensive dynamic cooling of the active gas medium. The gas is excited using radio frequency discharge excitation in the critical area of the supersonic nozzle or downstream therefrom. The radio frequency discharge and excitation can also occur within the optical resonator region which is located within the supersonic area of the nozzle. The present invention provides compact, efficient and super-powerful continuous, quasi-continuous and pulse laser systems with wavelengths from 2.03 mkm to 10.6 mkm with a high quality output beam. The present laser advice may be utilized in scientific, commercial, aerospace and free space applications.