Limiting Energy Inputs in the Non-Self-Sustained Discharge of a CO2-Flow Laser

At present the non-self-sustained discharge supported by a beam of fast electrons is being widely used to excite laser media at high pressures1,2. The principal characteristics of the discharge (the limiting value of the E/N, the limiting discharge current density j) significantly depend on the composition of gas mixtures and the discharge-burning duration. In particular, the limiting values of E/N abruptly decrease with the increased duration of a pumping pulse τρ (in a gas-flow discharge, τρ is the time in which the gas passes through the discharge region), reaching, at technologically convenient values ~ 1 ms, such magnitudes that the amount of energy spent to excite the upper laser levels decreases3. In this case, the discharge instability substantially reduces the possibility of optimization of the device parameters.