%A Xing Liu(柳兴), Xin-Yi Lu(陆心怡), Huan Wang(王焕), Li-Xin Yan(颜立新), Ren-Kai Li(李任恺), Wen-Hui Huang(黄文会), Chuan-Xiang Tang(唐传祥), Ronic Chiche, and Fabian Zomer %T Continuous-wave optical enhancement cavity with 30-kW average power %0 Journal Article %D 2023 %J Chin. Phys. B %R 10.1088/1674-1056/ac873e %P 34206-034206 %V 32 %N 3 %U {https://cpb.iphy.ac.cn/CN/abstract/article_125530.shtml} %8 2023-02-14 %X Optical enhancement cavity (OEC) is a powerful tool for fundamental research and diagnostics. In this paper, the progress of a continuous-wave OEC to realize of megawatt cavity for a novel light source based on a steady-state microbunching (SSMB) mechanism, is reported. After efficiently suppressing all external noise and optimizing the alignment, mode-matching, and polarization matching, stable and long-term locking is achieved with the help of two feedback loops. The modal instability phenomenon caused by the surface thermoelastic deformation is observed. A pair of D-shape mirrors are utilized to remove the high-order modes. Finally, an intra-cavity average power of 30 kW is reached.