Performance Test of Low β 162.5 MHz Nitrogen Infused HWR Cavity

Beijing isotope-separation-on-line neutron rich beam facility (BISOL) for both basic science and application is a project proposed by China Institute of Atomic Energy and Peking University. The intense deuteron driver accelerator (IDD) of BISOL would adopt superconducting half wave resonator (HWR) with low β and high current. A β=0.09 HWR cavity was developed in Peking University which has the ability to accelerate deuteron beam with current of 50 mA even for IDD future update. The design, fabrication, surface treatment and low temperature RF performance test results of HWR cavity were presented in this paper. A surface treatment of low temperature nitrogen infusion was applied to this cavity to study the effect of nitrogen infusion on low frequency low β cavity. The results show that this tapered shape HWR cavity reaches high accelerating gradient of 17 MV/m at 2 K. After low temperature infusion, the quality factor Q₀ almost doubles when the gradient is 10 MV/m at 2 K.