The conditions for the formation of stable volume discharges at atmospheric pressure in CO2–laser mixtures with an increased content of carbon dioxide and providing the generation of laser radiation pulses in the form of a "giant peak" with a base duration of up to 100 nanoseconds and a radiation energy of up to 1.5 J are determined. With the help of a selective resonator, a discrete rearrangement of radiation on individual vibrational–rotational transitions in the wavelength range of 9.2–10.8 μm is realized. The operation of the TEA–CO2 laser at pulse repetition frequencies up to 50 Hz is ensured.
The results of an experimental investigation of the "electrical wind" as a means of convective renewal of gas mixtures in the gas–discharge gaps in CO2–laser mixtures at superatmospheric (1–12 Atm) pressures are presented. It is established that for a fixed value of the current of a unipolar corona discharge, the speed of the "electrical wind" does not depend on the pressure, but is determined by the chemical composition of the working mixture. The maximum values of the "electrical wind" velocity were achieved in pure carbon dioxide and molecular nitrogen and their values are 3.2 and 2.9 m∙s –1. In typical CO2:N2:He laser mixtures = 1:1:3 – 1:1:6 the values of the speed of the "electrical wind" are in the range from 2.5 to 1.5 m∙s –1. It is reported about the design and generation characteristics of a small–sized sealed–off metal–ceramic CO2 laser of superatmospheric pressure with an "electrical wind" operating at pulse repetition frequencies up to 25 Hz. At an operating pressure of 12 atmospheres and the excitation zone of the volumetric pump discharge V =18∙0.8∙0.8 cm3 achieved the maximum radiation energy in a pulse of 0.8 J with a duration of up to 10 nanoseconds.
The influence of the structure of the electrodes on the attainment of the maximum pulse repetition rates and the level of the average radiation power in TEA–N2 lasers is studied. It is shown that the use of sectioned cathodes promotes the formation of volumetric discharges at increased pulse repetition rates. The use of a cathode structure in the form of a set of pins with individual excitation of volume discharges in each gap, together with the use of preliminary ionization of gas mixtures by VUV radiation, ensures that the maximum pulse repetition rates of up to 10–12 kHz in N2:He mixtures are achieved. The maximum average radiation power of 6 W was achieved at a pulse repetition rate of 5 kHz for an N2:He mixture with an optimal component ratio of 30:730 at a total pressure of 760 Torr.
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