Commissioning of the 7 MeV H[formula omitted] linac injector for a 200 MeV proton synchrotron

Abstract

This paper describes the beam commissioning progress of the 7 MeV H− linac injector for the proton synchrotron of Xi’an 200 MeV Proton Application Facility (XiPAF). To fulfill a flux of 105∼108p/cm2/s with a uniformity better than 90% on a 3 cm × 3 cm sample size at the experimental station, the number of the accumulated protons in each cycle in the synchrotron is designed to be larger than 2 × 1011. The protons are acquired from the H− beam stripped by the carbon foil, which enables transverse space painting during injection. The maximum pulse length of the injected beam is 40μs. With an estimation of 40 for the intensity gain factor, the injected beam is required to have a peak current of higher than 1 mA, with the normalized transverse emittance of 90% particles less than 6 and 4 πmm mrad for the horizontal and vertical planes, respectively, and the momentum spread of 90% particles within ±0.45%. The injector mainly consists of an H− ion source, a low energy beam transport line (LEBT), a 3 MeV radio frequency quadrupole (RFQ) accelerator, a 7 MeV interdigital H-mode drift tube linac (IH-DTL), and an injection beam transport line. After several stages of beam commissioning, the linac injector has reached a pulsed peak current of 2.5 mA, with normalized emittance (90% particles) less than 4.4 and 2.2 πmm mrad, 90% momentum spread less than ±0.55%, which lays a good foundation for the beam commissioning of the synchrotron.