Physical design and multi-physics analysis of a 200 MHz continuous wave radio frequency quadrupole accelerator for a proton accelerator facility

Abstract

Based on the platform of a proton accelerator facility, a 200 MHz high intensity continuous wave (CW) radio frequency quadrupole (RFQ) accelerator has been designed at the Sino-French Institute of Nuclear Engineering and Technology of Sun Yat-Sen University, China. Employing the conventional four-vane structure, the RFQ can accelerate 20 mA proton beam from 20 keV to 2.5 MeV. In the beam dynamics design, the simulated transmission efficiency reaches 99.5% and the vane length is less than 4 m. In the electromagnetic design, for the long-term stable operation, Pi-mode Stabilizer Loops (PISLs) are utilized to achieve more than 10 MHz mode frequency separation and to decrease the effects of dipole modes. The 48 tuners are optimized to provide a range of ± 2 MHz frequency tuning. Additionally, the undercuts are optimized to ensure a good field flatness along the longitudinal direction. Based on the coolant channel design, the multi-physics analysis is performed to investigate the deformation and stress resulting from the dissipation of RF power within the cavity, as well as determine the temperature tuning coefficients of the coolants within the vane and wall. The entire design and analysis of PAFA-RFQ has been completed, and the scheme of the design can also be applied to the design of other RFQ cavities.