New developments of hybrid single cavity at IMP

A Hybrid single cavity (HSC) linac, which is formed by combining a radio frequency quadrupole (RFQ) structure and a drift tube (DT) structure into one interdigital-H (IH) cavity, is fabricated and assembled as a proof of principle (PoP) type injector for cancer therapy synchrotron according to the culmination of several years' researches^[1-4]. It also can be operated as a CW (continuous wave) test injector of neutron source for boron neutron capture therapy. The injection method of the HSC linac adopt a direct plasma injection scheme (DPIS), which is considered to be the only method for accelerating an intense current heavy ion beam produced by a laser ion source (LIS). The input beam current of the HSC was designed to be 20 milli ampere (mA) C⁶⁺ ions, which could be produced by a LIS. According to numerical simulations, the HSC linac could accelerate a 6-mA C⁶⁺ beam which meets requirement of the needed particle number for cancer therapy use (10^{8 ∼ 9}ions/pulse). The injection system adopted HSC injector with the method of DPIS can make the existing multi-turn injection system and the stripping system unnecessary, and also can make the beam pipe of the existing synchrotron magnets downsize which could reduce the whole cost of synchrotron (estimated millions dollars). Details of the measurements and the developments in IMP are reported in this paper. (authors)