DIAGNOSTICS OF THE ACTIVE MEDIUM OF A HOM OGENEOUS CO2 GASDYNAMIC LASER BY THE LASER SPECTROGRAPH METHOD

The gains were measured for the lines in the traditional bands 00(0)1- 10(0)0 and 00(0)1-02(0)0, in the second band of the 00(0)2-10(0)1 sequ ence, and in the hot band 01(1)1-11(1)0 emitted by the active medium o f a quasi-cw homogeneous CO2 gasdynamic laser. The experimental result s were fitted to a generalised theoretical model to find the translati onal and vibrational temperatures, and the concentration of the active molecules. It was found that, under the conditions in the active medi um in the homogeneous gasdynamic laser, the use of water vapour (fract ion of H2O approximately 2%) as a relaxant gas resulted in fast VT-rel axation and the translational temperature was equal (with the limits o f a 3% error) to the vibrational temperature T-2 of the bending mode. Under the same conditions the Fermi resonance between the 10(0)0 and 0 2(0)0 levels did not ensure the Boltzmann distribution of the populati ons of these levels: so that the vibrational temperature of the symmet ric mode T-1 was higher than T-2 and the difference between them incre ased to 0.5T(2) when the initial pressure was reduced. Dissociation of the CO2 molecules was not detected in the active medium of the homoge neous gasdynamic laser (the proportion of CO2 was 0.11 +/- 0.01, which agreed-within the limits of an error not exceeding 10%-with the value deduced from thermodynamic calculation).