Csns Linac Vacuum System and Quadrupole Mass Spectrometry Leak Detection

The composition and design of vacuum system of China Spallation Neutron Source(CSNS) linear accelerator are introduced.The leakage of Radio Frequency Quadrupole(RFQ) cavity was detected by helium mass spectrometer and quadrupole mass spectrometer.The leakage point was determined by analyzing the residual gas composition curves and comparing the pressure change curves of RFQ cavity before and after the leakage medium was applied.And then the RFQ cavity quickly obtained the pressure of 10^-6Pa after eliminating leakage,which met the requirements of the linear accelerator for pressure.