Analysis of the damaging effect of laser-plasma accelerated shrapnels on the optical shield

The practical implementation of the laser ignited thermonuclear fusion brings also the whole variety of technical challenges which have to be solved in foreseeable future in order to implement new scale fusion facilities operating in high-rep regime (and not only for them). One of these tasks represent a problem related to the shielding of the final optics and other vulnerable equipment placed inside the interaction chamber[1,2,3] in the case when solid targets (hohlraums, fast ignition targets with cones, and others) are irradiated by high-energy lasers, producing plasma and vapors which can split target into fragments and accelerate the non-evaporated parts to velocities a few folds of km/s and even more (achieving a hyper-velocities over 10 km/s, corresponding to the velocities of the space-debris micro-particles). This way accelerated particles (generally in range from few tens or hundred milligrams to several micrograms) can reach energies capable to destroy a glass plate made of Fused Silica, BK7, or similar kinds of crown glasses up to several millimeters thickness. This may result in serious damage or even destruction of the diagnostic and optical components located in the path of the shrapnel or other objects with similar possible damaging effect[3]. In this contribution a recent analysis of the laser-plasma accelerated fragments originated from Cu target irradiated by the Prague Asterix Laser System (PALS) first harmonics (1315 nm) with pulse duration 350 ps and energy 605 J, as well as the examination of the parameters of target fragments and the level of the damage of the final optical shield will be presented. (author)