Fast-axial-flow CO2 slab laser with a narrow-gap RF discharge operating athigh pressure

A fast-axial-flow carbon dioxide laser is operated with a rectangular cross section, radio frequency excited, slab discharge. The narrow electrode gap and the series capacitance of the discharge tube walls produce excellent d ischarge stability at higher input power density and pressure than in conve ntional fast-axial-flow lasers. For a single-section test discharge, the ma ss flow per unit cross sectional area is improved by high-pressure operatio n and the mass flow choking effect at sonic gas exit velocity is avoided. F or CW operation, the discharge power density has been increased to 200 W.cm (-3) and laser operation demonstrated at a pressure of 500 torr. In pulsed operation at pressures of 300-400 torr, repetition frequencies of 15 kHz ha ve been achieved with the pulse duration reduced to 15-25 mu s, suitable fo r materials processing of low thermal conductivity materials.