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At present, to solve a number of technological problems and to conduct various researches, electhcdischarge C°2 ' operaling in continuous and repetitively-pulsed (RP) modes with powers of up to 10 kW are used. The demand for 10-1000 kW lasers sets a problem of stable high-energy deposition into an active medium of rat1r large (hundreds ofliters) volume. Co2laserswith diffusion cooling usually employ a self- sustained discharge in tubes. In such a scheme, maximum power depends on the tube length only rather than on radius and constitutes 100 W/m. A number of setups - "Kometa", "Kardamon", are based on this principle, the top power of which won't exceed several kW. In TRINFI an MKTL-1O laser with the output power of 14 has been developed. The drawbacks of this type of lasers are short service life, difficulties in operation because of the oil cooling of the tubes as well as fragility of the structure. That's why high power lasers use airfuel mixture convective cooling by a gas flowing through a discharge area 2• Amongthe lasers ofthis type we can mention: LT1-2 (TRIMTI), Slavyanka (NIIEFA), LT-S (Shatura). They feature a triple mixture circulation through the entire loop, aclive-medium low pressure (30-60 Torr) and resonator alignment with the discharge area. The parameters of the most widely used LT1-2 lasers are shown in Table 1 . i.asers with a closed loop have a decrease in output power because of changes in mixture composition due to chemical pmcesses. The solution to this problem resides in partial renovation of the working gas mixture (03-1%) or in addition of stabilizing substances to the laser mxture. The best experimental results were obtained with the additive: 1.7%CO+1.4%H Fig.1 shows that the extent of CO2 dissociation with such an addition is only 20% within 4 hours of operation1.
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