Commissioning experiences with the spoke-based CW superconducting proton linac

The 10-MeV Accelerator-Driven Subcritical (ADS) system Injector-I test stand at the Institute of High Energy Physics (IHEP) is a testing facility dedicated to demonstrating the feasibility of the spoke-based superconducting (SC) linear accelerator (linac) for the ADS project in China. The injector adopted a four-vane copper structure radio frequency quadrupole (RFQ) with an output energy of 3.2 MeV and an SC section accommodating 14 β _g =0.12 single spoke cavities, 14 SC solenoids, and 14 cold beam position monitors (BPMs). A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave (CW) beam were successfully shooting through. The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections. This paper describes the results achieved, the difficulties encountered, and the experiences obtained during commissioning.