Carbon-dioxide laser with high power per unit length

A CO2-N2-He laser is described in which the discharge plasma was excited in the volume between two coaxial silica tubes by means of a radial r.f. field. Additional power was fed into the plasma by a longitudinal d.c. field applied to internal electrodes. With an outer tube 46.5 mm in diameter and 1.2m long, an output power of 250W was obtained at 12% efficiency.