A new helical coupling microwave antenna excited high-powerCO2 laser using a cylindrical resonant cavity

A new helical coupling antenna which was installed into a cylindrical microwave cavity (2.45 GHz) has been investigated to obtain high-power CO₂ laser operation. Laser experiments using a system of swirling fast axial gas flow parallel to the beam have been performed. The geometric properties of the helical antenna and the gas flow structures were optimized by using numerical codes analyzing the electric fields and gas flow dynamics. The swirling flow of the laser gas mixtures of CO₂-N₂-He=0.7-5-19 was caused in the discharge tube by an 8-slit nozzle. It is shown that the electric field obtained by the proper design of the helical coupling coil yields homogeneous discharges. The maximum output power and the efficiency (RF to laser power conversion ratio) was obtained as 1010 W and 15%, respectively, at a gas pressure of 45 torr and a gas flow rate of 57 kg/h