A pulsed excitation was used to study high peak power generation in CO2and CO2-mixture flowing gas lasers. A rotating mirror was used as aQswitch with a variable delay between excitation pulse and mirror alignment. A variation of the time delay and multiple-exposure photographs can permit a measure of the population inversion versus time to be photographed. High-voltage pulses were used with higher than usual gas pressures to generate peak powers of about 30 kW. Peak power was shown to be primarily dependent on CO2partial pressure in CO2-He and CO2-N2mixtures.