Interaction of CO2 laser radiation with a relaxing breakdown plasma

An investigation was made of the development of breakdown under the influence of CO₂ laser pulses in a decaying air breakdown plasma created by an independent source. When the laser pulses were delayed by 0.1–15 ms relative to the moment of initiation of the plasma, the intensity corresponding to the breakdown threshold was more than two orders of magnitude less than the breakdown threshold of cold air. The breakdown threshold depended nonmonotonically on the laser pulse delay. The experimental results were compared with theoretical calculations of the plasma formation threshold.