Investigation of quasi-cw interaction between $CO_2$ laser radiation and a graphite target in air

A quasi-cw plasma jet, initiated by $CO_2$-laser radiation of power density $0,1-2$ MW/cm${}^2$ on a graphite target in air, was investigated using spectroscopic, interferometric, and photometric diagnostic methods. The plasma jet was shown to consist of carbon vapor transparent to the laser radiation and propagating into the air surrounding the target without being appreciably heated by the laser radiation. The gasdynamics and thermal physics of the jet are discussed; they are of interest for the problems of laser processing of materials and the construction of laser jet engines.