Design and RF test of MEBT buncher cavities for C-ADS Injector II at IMP

To match the beam from the Radio Frequency Quadrupole (RFQ) accelerator to the Superconducting Half-wave Resonator (HWR) Linac, two room temperature (RT) double-gap Quarter-wave Resonator (QWR) bunchers are designed to be located in the Medium Energy Beam Transport Line (MEBT) for the C-ADS Injector II at IMP. Both cavities work at 162.5MHz, with β=0.067 and a beam aperture diameter of 40mm. The effective voltage of these two cavities needs to reach 135kV in Continuous Wave (CW) mode. In this paper, the RF design and thermal analysis of the cavities will be presented, along with the tuners and coupler consideration. The measured frequencies, Rsh/Q0, Q0 and voltage of the cavities agree well with the simulation result. Details of the RF test results including the full power tests of the cavities will be shown.