Multi-physics analysis and experiment of a CW four-rod RFQ

The new injector SSC-LINAC is under design and construction to improve the efficiency and intensity of beams for the Separated-Sector Cyclotron (SSC). This will be accomplished with a normal conducting radio-frequency quadrupole (RFQ) accelerator. To match with the SSC, the RFQ must be operated on Continuous Wave (CW) mode with a frequency of 53.667 MHz. A four-rod structure was adopted for small dimensions of the cavity. While, it was a huge challenge on CW mode. A multi-physics theoretical analysis, including RF, thermal, structural and frequency shift coupling analysis, have been completed in response to the safe and stable operation of the RFQ. The experimental measurement of frequency shift has been also completed, which is consistent with the simulation. In this paper, the results of theoretical analysis and experiment are reported in detail.