Abstract :
Single-pass gain at 10.6 microns has been studied parametrically in nonflowing CO2or buffered CO2amplifying media. The gain profile across the amplifier diameter and integrated gain both were determined. Parameters varied included buffer gas type, mixture ratio, gas pressure, amplifier bore, discharge current, and wall temperature. Tube bores of 12, 22, and 34 mm and buffer gases of H2, He, Ne, A, O2, and N2were studied. For CW laser amplifiers, optimum gain is relatively independent of current density, but decreases with wall temperature. A pressure-diameter product of about 4 torr-cm was found to hold for CO2, CO2:He, and CO2:N2amplifying media at optimum gain. The gain depends strongly on the CO2partial pressure and is relatively insensitive to the buffer gas pressure. The highest gain, 1.7 db/meter, was achieved in helium buffered CO2amplifiers with a diameter, of 22 mm or less. Addition of N2to the optimum CO2:He mixture reduced the gain. The maximum gain decreased slowly with the amplifier diameter. Addition of hydrogen to CO2quenched the inversion of CO201°0 - 00°1 levels. No gain saturation was detected for a 30 db range of input signal power, from a milliwatt to a few watts. Pulsed gain measurements are also presented.
