Cleanliness control of vacuum system in high-flux laser device
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摘要: 在高通量激光装置真空系统运行过程中,泵组润滑油在真空环境下产生的分子污染可能扩散沉积在光学系统元件表面,在高通量激光辐照下诱导损伤,降低光学元件负载能力。针对真空系统洁净度控制开展研究,构建了包括真空泵组优化、增加低温冷阱吸附、增加冷阱在线加热再生工艺的真空系统洁净度控制方法。实验研究结果表明:真空系统经过120 h连续运行后,平均24 h非挥发性残留物表面沉积量维持在2.86×10−9 g/cm2洁净水平,熔石英光学试片考核组和对照组在350 nm处的透过率以及12.3 J/cm2通量以下的损伤密度曲线基本一致,证明了该方法的有效性。Abstract: During the operation of vacuum system in high-flux laser device, molecular contamination generated by the pump lubricating oil in the vacuum environment may diffuse and deposit on the surface of optical system components, induce damage under high-flux laser irradiation, and reduce the devices’ load capacity. Research has been conducted on the cleanliness control of vacuum systems, and a series of technical measures have been developed to control the vacuum system cleanliness, including optimizing the vacuum pump group, increasing low-temperature cold trap adsorption, and adding online heating regeneration technology for the cold trap. The experimental research results show that after 120 h of continuous operation, the average surface deposition of non-volatile residues in the vacuum system reaches a clean level of 2.86 × 10−9 g/cm2 after 24 h; The transmittance at 350 nm and the damage density curve below 12.3 J/cm2 flux of the fused quartz optical test piece assessment group and control group are basically consistent, proving the effectiveness of this method.
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Key words:
- high-flux laser device /
- vacuum system /
- cleanliness /
- optical components /
- transmittance /
- damage density
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表 1 考核组和对照组条件对比
Table 1. Comparison of conditions between the assessment group and the control group
optical component group conditions control group placed vertically in a PTFE storage box in a class 100 laboratory, at atmospheric pressure, room temperature, and relative humidity of 60% static assessment
groupplaced vertically in the pipeline of vacuum clean validation experimental system in a class 10000 laboratory, the vacuum unit and cold trap are not running, at atmospheric pressure, room temperature, and relative humidity of 60%dynamic assessment
groupplaced vertically in the pipeline of vacuum clean validation experimental system in a class 10000 laboratory, the vacuum unit and cold trap are running,with a vacuum degree of 4.0 × 10−1 Pa and a working temperature of −100 ℃ for the cold trap表 2 非挥发性残留物表面沉积量实验结果
Table 2. Experimental results of surface deposition of non-volatile residues
optical component group total surface deposition of non-volatile
residues after 120 h/(g·cm−2)average surface deposition of non-volatile
residues over 24 h/(g·cm−2)static assessment group 2.20×10−9 4.40×10−10 dynamic assessment group 1.43×10−8 2.86×10−9 -
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