Analysis of induced stress on materials exposed to laser-plasma radiation during high-intensity laser experiments

In this work, we investigate the damage produced in materials when exposed to a laser-generated plasma. The plasma was generated by interaction of a high-intensity laser with Oxygen. We demonstrate that the stress induced on the target surface of a Tantalum target (typical materials used as Plasma Facing Material) after 10 h of plasma exposure is equivalent to the stress induced during 1 h of conventional laser ablation using a pulsed 0.5 J laser. In both cases we obtain a surface erosion in the tens of μm, and a change in the surface roughness in the tens of nm for the stressed materials. The erosion rate of 1 nm/s, explained in terms of surface fragmentation at thermodynamic equilibrium, generates a slow damage to the materials exposed to the plasma. Our method allows indicating safety parameters for the maintenance of materials used in high-intensity laser experiments.