EMISSION-SPECTROSCOPY OF A CARBON PLASMA FORMED BY LASER-ABLATION OF GRAPHITE - II - ABLATION BY A CO2-LASER AND ALSO SIMULTANEOUSLY BY XECL AND CO2-LASERS

The method of time-resolved emission spectroscopy was used to investig ate the radiation emitted by a carbon plasma plume formed as a result of vacuum ablation of graphite by pulsed CO2 laser radiation. The spec trum of the radiation changed drastically in the course of emission fr om the plasma. The spectrum revealed successive appearance of various luminescence components contributed by C+ ions, C-2 radicals, and micr oparticles. This spectrum differed considerably from that observed for a plasma formed by ablation with an XeCl laser, mainly because of the difference between the laser radiation wavelengths. Under certain con ditions it was found that additional heating, with CO2 laser radiation , of a plasma formed by ablation of graphite with XeCl laser radiation altered greatly the emission spectrum. The changes indicated a higher degree of particle atomisation and a higher proportion of ions in suc h a plasma, compared with the plasma produced by one laser.