Latest developments in the CO2 laser remediation process of LMJ optics supported by COMSOL numerical modelling

Laser-induced surface damage of fused silica components a crucial point for high-energy laser systems like the French Laser MégaJoule (LMJ), will be addressed. Surface damage, originating from high-energy photon interacting with optics, is initially small but can rapidly expand under successive laser irradiation. CO2 laser processing is effective for mitigation but sensitive to material properties and laser intensity fluctuations, leading to negative effects like surface deformation and debris formation. Collaborative efforts between CEA-CESTA and Institut Fresnel have developed a CO2 laser mitigation technique involving microablation of damaged sites. This work focuses on reducing post-processing negative effects and increasing performance, such as the LIDT of cones. We will discuss the use of numerical simulations and measures for insight and guidance in improving processing parameters.