1 kHz Oscillation of short-pulse CO2 laser pumped by longitudinal discharge without pre-ionization

Commonly, a gas laser pumped by a pulsed discharge requires a pre-ionization system to form a uniform discharge at a high repetition rate like 1 kHz. In this paper, however, a longitudinally excited CO2 laser without any pre-ionization system operated at a repetition rate of 1 kHz. The discharge tube was made of an alumina ceramic tube with an inner diameter of 8 mm, an outer diameter of 16 mm and a length of 80 cm, and two metallic electrodes attached to the two ends of the tube, and did not have a pre-ionization system or a fast gas flow system. The CO2 laser produced short pulses with a spike pulse width of 200 ns, a pulse tail length of 150 μs, a spike pulse to pulse tail energy ratio of 1:112, a laser energy of 35.2 mJ, and a circular Gaussian-like beam at a repetition rate of 1 kHz, a CO2/N2/He gas mixing ratio of 1:1:5, a gas pressure of 4.6 kPa and an input energy of 738 mJ to the circuit generating fast, high-voltage pulses. The dependence of the laser energy on the repetition rate, the CO2/N2/He gas mixing ratio, and the input energy was investigated.