High Repetition Rate Long-pulsed UV-preionized TE CO₂ Laser

This paper gives a particular study on the output characteristics of a UV-preionizedlong-pulsed TE CO₂ laser excited by Pulser/sustainer discharge under various gas mixtures, gaspressures or discharge voltages. The main experimental results are as follows:(1) Improved the mechanical structure of the laser resonator. The new designedmirror-supporting structure can form a rigid laser resonator which can be easily adjusted and canoperate stably under different gas pressures.(2) Designed a novel excitation circuit. A series inductor is introduced into the originalPusler/sustainer discharge circuit used in the long-pulsed TE CO2 laser. Experiments show thatthe new designed scheme can significantly enhance the preionization capabilities of the Pulserdischarge and greatly increase the laser output pulse energies.(3) Experimented five output coupling mirrors with reflectivity of 17%, 25%, 50%, 70%, or80%. With the 50% one, the 26us discharge current width laser can generate the maximum pulseenergy with gas mixture CO₂:N₂:He=5.3:21.3:73.4.(4) Tested 20 kinds of different gas mixtures in the long pulse TE CO₂ laser with dischargecurrent width of 26us. Results show that the discharge can be more stable when the ratioB=CO₂/N₂ is less than 0.4. And the laser with less content of CO₂+N₂ in the gas mixtureneeds lower preionization voltage, discharges more stably, suits for relatively higher mixturepressure and produces larger power under repetition rate operation.(5) Obtained detailed measurements of the laser outputs with 3 different discharge widths16.65us, 26.88us, 50.75us and 4 different gas mixtures, respectively. These measurements showthat the width of the laser pulse profile is nearly the same as the theoretical discharge currentwidth determined by PFN. In the 50.75us case, the fluctuation of the discha-ge current waveformduring the sustainer discharge tends to be less than that of the other two. Compared with that of26.88us or 50.75us, the laser with a discharge pulse width of 16.65us has re(?)atively longer fallingtime in the output laser pulse profile and needs higher voltage for efficiently preionization.(6) Obtained stable operation under high repetition rate with various long pulse discharges.For 40kPa of the gas mixture CO₂:N₂:He=4: 20: 76, the laser can generate 335W, 307W, 271Wat 100Hz with an input pulse energy of 32.66J in the discharge width of 16.65us, 26.88us, 50.75usrespectively.##原图像不清晰...