The study of laser-induced flare discharge on dielectric and semiconductor macroparticles in vacuum: plasma production and ablative acceleration

An injector was used that allowed the multiple triggering of a beam of particles (of a size of several to 100 μm) in a region where laser irradiation was focused. By varying the experimental conditions, the particles could be either completely or partially evaporated and strongly accelerated by ablation. The maximum measured velocities were 4×10⁶ cm/s, plasma velocities were about (1-2)×10 ⁷ cm/s, and the temperature was about 100-150 eV. Only 30% of the substance (particles of B₄C with dimensions greater than 40 μm) was evaporated before destruction. The particles of B₄ C that were smaller than 30 μm were completely evaporated under a laser power density of about 10¹² W/cm² and a half-duration of 30 ns. For the particles smaller than 100 μm and made of materials with a low evaporation temperature, such as paraffin, LiH, and polystyrene, no accelerated fragments were detected, i.e. these particles were completely evaporated during less than 10 ns