Fan, M.X. Chen, Q. Gong, K.Y. Li, A.H. Li, B. Liu, H.C. Qu, P.H. Wang, Y. Wu, X.L. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-THPO038 English 767-770 THPO038 DTL coupling cavity vacuum operation Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-THPO038 http://jacow.org/linac2018/papers/thpo038.pdf There are four Drift Tube Linac (DTL) tanks in China Spallation Neutron Source (CSNS) Project. Each DTL tank requires a power coupler with a peak power of 2 MW and a duty cycle of 1.5% for beam operation. After approximately two years machining, all four couplers were already installed in the tunnel before year 2017. Up to now, the first phase of beam tuning has been completed, the maximum transmission power of the coupler exceeds 1.7 MW with a pulse width of 650 μs and a repetition rate of 25 Hz, meanwhile, the vacuum is maintained on the order of 10⁻⁶ Pa during the operation and no breakdown was observed. This paper describes the architecture, the fabrication, the low power test results and the high power conditioning process of the coupler. Some problems encountered are also presented.