Some effects of the rhodamine laser radiation on absorbing materials

The first investigations were made of the damage to absorbing materials caused by the radiation generated in a rhodamine 6G laser in the form of structure-free pulses. The laser was pumped by flashlamps and its output was in the form of 55-μsec pulses of 12 J energy. The maximum radiation power density was 3 · 10⁶ W/cm². This radiation produced a quasistationary supersonic plasma jet with a relatively large angle of divergence. A static shock wave was formed in this jet. The dome-shaped configuration of this wave was determined by the geometry of the plasma jet. High-speed spectroscopic cinematography established that the spectrum was excited mainly in the static shock wave. The discontinuous structure of the plasma jet was probably due to the explosive (bulk) nature of the evaporation of a solid. The frequency of ejection of plasma bunches from lead was ~1 MHz (this was achieved using laser radiation of ~3 · 10⁶ W/cm² power density). The velocity of the plasma jet was determined. The pressure in the interaction zone was estimated. Some features of the effect on the absorbing materials were analyzed.