气氛环境对真空窗口紫外激光诱导损伤阈值的影响机制

基于氟橡胶圈密封测试了熔石英真空窗口在351 nm激光辐照下的激光诱导损伤阈值（LIDT），实验发现真空窗口和氟橡胶圈紧密接触后LIDT下降约50%，氟橡胶圈经多次挤压后，其对真空窗口LIDT的影响显著减弱，在此基础上对比了大气、103 Pa和10?2～10?1 Pa下真空窗口的LIDT，结果显示随着气压降低真空窗口LIDT显著下降且气压再次升高后其LIDT未有提升。基于铟丝密封对比测试了真空窗口在不同气压下的LIDT，结果未发现气体含量差异对真空窗口LIDT的影响。对比两种密封材料测试结果，认为真空窗口LIDT下降是由氟橡胶圈污染引起，且低气压下有机物释放加剧。

Influence mechanism of atmosphere on the damage threshold induced by ultraviolet laser in vacuum window

Vacuum window (VW) damage is the bottleneck restricting the load capacity of high-power laser device, and the influence of vacuum environment is worthy of attention. Firstly, based on the fluororubber ring seal, the laser-induced damage threshold (LIDT) of fused silica VW irradiated by the 351 nm laser was measured. It is found that the LIDT of the VW decreases by about 50% after the close contact with the fluororubber ring. After repeated extrusion, the influence of the fluororubber ring on the LIDT of the VW is significantly weakened. On this basis, the LIDTs of the VW under atmosphere, 103 Pa and 10?2～10?1 Pa are compared. The results show that the LIDT of vacuum window decreases significantly with the decrease of air pressure, and the LIDT does not increase after the air pressure rises again. In addition, the LIDT of the VW under different air pressure is tested based on indium ring sealing, while the effect of air pressure difference on the LIDT is not found. Comparing the results of the two sealing materials, it is considered that the LIDT decreasing of the VW is mainly caused by the release of organic contamination from fluororubber ring and the release of organic matter will be intensified under low pressure.