esign and high power testing of offline conditioning cavity for CiADS RFQ high power coupler

o verify the rationality of the design of the power coupler for the RFQ cavity and to reduce contamination of the cavity, the low loss offline conditioning cavity was designed and high power test was conducted. The offline cavity was composed of two coupling ports and two tuners. Furthermore, the loss of the cavity could be minimized by the installation angle of the coupling ring and the insertion depth of the tuner. Electromagnetic structural and multiphysics simulations of the cavity were conducted, and the minimal theoretical power loss of the cavity was 4.3%. When the frequency variation of cavity was 110kHz, the theoretical power losses increased to 10%. Therefore, the tuner was always in motion during conditioning. Multiphysics simulations showed that the increased temperature of the cavity did not affect the frequency variation. When the offline high power conditioning platform was completed, the transmission performance of the conditioning system was measured. The power loss was 6.3%, larger than the theoretical calculation value. The conditioning employed efficient automatic range scanning and standing wave resonant conditioning methods. In order to fully condition the power coupler, 13 standing wave points were selected. The maximum continuous wave power is greater than 20kW, better than the expected target.