Interaction of near-IR laser radiation with plasma of a continuous optical discharge

The interaction of 1.07-mu m laser radiation with plasma of a continuous optical discharge (COD) in xenon and argon at a pressure of p = 3-25 bar and temperature of T = 15 kK has been studied. The threshold power required to sustain COD is found to decrease with increasing gas pressure to P (t) < 30 W in xenon at p > 20 bar and to P (t) < 350 W in argon at p > 15 bar. This effect is explained by an increase in the coefficient of laser radiation absorption to 20-25 cm(-1) in Xe and 1-2 cm(-1) in Ar due to electronic transitions between the broadened excited atomic levels. The COD characteristics also depend on the laser beam refraction in plasma. This effect can be partially compensated by a tighter focusing of the laser beam. COD is applied as a broadband light source with a high spectral brightness.