31 / 2023-04-03 12:18:13

Physical design of RFQ injector system for proton synchrotron

Proton therapy, 4-vane RFQ, APTR, fast-bunching

The APTR (Shanghai Advanced Proton Therapy Facility) project, proposed by the Shanghai Institute of Applied Physics (SINAP) of Chinese Academy of Sciences, has entered the commissioning stage. As the key techniques of APTR complex, the injector system has been upgraded to accelerate proton beam to 7.0 MeV in the context of comprehensive localization and miniaturization. In order to pre-accelerate, longitudinally bunch and transversely focus the low-energy continuous beam from ion source, a pre-injecting system Radio-Frequency Quadruple (RFQ) has been designed. Based on fast bunching strategy, this RFQ, operated at 325 MHz, accelerates proton particles to 3.0 MeV. The phase advance has been taken into consideration, and parametric resonance has been carefully avoided by adjusting the vane parameters. The whole transmission efficiency has been optimized to 98.0% to meet the machining requirements and the emittance growth in horizontal and vertical directions are about 1.1%, 3.3% along the whole cavity. This paper discusses the beam dynamics design schemes, main parameter selections, simulation results and tolerance analysis. It can provide important theoretical base for linear injection system of proton synchrotron-based therapy facility.