Experimental and theoretical investigation of localized CO2 laser interaction with fused silica during the process of surface damage mitigation

Chao Tan, Linjie Zhao, Mingjun Chen, Jian Cheng, Chunya Wu, Qi Liu, Hao Yang, Zhaoyang Yin, Wei Liao

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28 Citations (SciVal)

Abstract

Localized CO2 laser repairing of surface damage on fused silica optics has been successfully applied in high-power laser system in the field of controllable nuclear fusion. In order to accurately predict the surface topography evolution and to reveal the intrinsic physical mechanism during the process of laser mitigation, experiments of localized CO2 laser mitigation were firstly carried out to analyze the features of mitigated craters under different laser powers. Then a multi-physics coupled mathematical model was developed based on the fluid control equation, heat and mass transfer equation and material phase transition kinetics to investigate the thermodynamic and kinetic behaviors of laser interaction with silica. The model considered the effects of Marangoni convection, gravity, capillary force and vaporization recoil pressure, as well as the nonlinear variation of physical parameters of silica material with respect to temperature. The results showed that with the increase of laser power, the material ablation and the appearance of raised rim occurred simultaneously. The depth of the mitigated crater increased sharply when the threshold for material ablation was attained, while the lateral dimension increased linearly. The vaporization recoil pressure was found to be the dominant factor for the formation of Gaussian crater with the raised rim feature. The capillary force caused the material at the edge of the molten pool to have a tendency to reflow after laser shutting down, but it was too small to change the surface topography. This work could significantly contribute to the understanding of laser mitigation process, which laid the foundation for the accurate prediction and evaluation of surface quality of CO2 laser repaired fused silica surface.

Original languageEnglish
Article number102936
JournalResults in Physics
Volume16
Early online date10 Jan 2020
DOIs
Publication statusPublished - 31 Mar 2020

Funding

This work was supported by the National Natural Science Foundation of China (Grant Nos. 51775147 , 51705105 ); Science Challenge Project (Grant No. TZ2016006-0503-01 ); Young Elite Scientists Sponsorship Program by CAST (No. 2018QNRC001), China Postdoctoral Science Foundation funded project (Grant Nos. 2018T110288, 2017M621260); Self-Planned Task (Grant Nos. SKLRS201718A, SKLRS201803B) of State Key Laboratory of Robotics and System (HIT).

FundersFunder number
China Association for Science and Technology for the Young Elite Scientists Sponsorship Program
National Natural Science Foundation of China51705105, 51775147
China Postdoctoral Science Foundation2017M621260, 2018T110288
Harbin Institute of Technology
China Academy of Space Technology2018QNRC001
State Key Laboratory of Robotics and System
Science Challenge Project of ChinaTZ2016006-0503-01

    Keywords

    • CO laser
    • Damage mitigation
    • Fused silica
    • Physical mechanism
    • Surface topography evolution

    ASJC Scopus subject areas

    • General Physics and Astronomy

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