High-power transverse flow CW CO2 laser for material processing applications

A transverse flow transversely excited (TFTE) CW CO2 with a maximum output power about 15kW has been developed. This is excited by pulser sustained DC discharge applied between a pair of multi-pins anodes and a common tubular cathode. Though the laser power in convective cooled CO2 laser scales proportionally with the volumetric gas flow, it did not increase in this laser when the volumetric gas flow was increased by increasing the electrode separation keeping the flow velocity constant. The discharge voltage too remained almost unchanged with increase of the electrode separation. These observations are explained considering the electrical discharge being controlled by ionization instability. Laser materials processing applications often demand programming facilities for laser power modulation. A four-stage cascaded multilevel DC-DC converter-based high-frequency switch mode power supply has been developed to modulate the output power of the laser. Laser was operated up to 15kW output power in four different modes viz. continuous wave mode, pulse periodic mode, single shot mode and processing velocity-dependent power mode with 1.2kHz modulation bandwidth. We describe briefly the laser system, the SMPS, and the temporal behavior of laser beam.