The development of the 13.5 MHz kicking cavity at the entrance of the bunch compressor for a new planned high intensity neutron source

Abstract

A kicking cavity working at an ultralow resonant frequency has been proposed as the key component at the entrance of the bunch compressor for a newly planned neutron source. This neutron source currently under construction at the Northwest Institute of Nuclear Technology is designed to generate short neutron pulses at high intensity and repetition rates. With the development of the High Intensity Neutron Source which is a combined facility of a 100 mA-162.5 MHz-30 MeV proton linac and the 1 ns bunch compressor, a 13.5 MHz proof-of-principle kicking cavity was designed. In the light of the theoretical analysis, an effective way to accomplish the target frequency is increasing the equivalent inductance and capacitance. Subsequently, a new structure incorporating a pair of deflecting plates, a coil and an insulating holder was developed. By optimizing its geometry, cavity’s radio frequency properties have been improved with a focus on inductance, stray capacitance, frequency sensitivity, rf electric breakdown and power dissipation. The trajectories and transverse phase space were simulated, confirming that the beam could be deflected smoothly through the cavity with the maximum kicking angle. A model cavity was then fabricated, surface treated and cold tested. Finally, a comparative analysis of theoretical estimation, simulated and tested results is conducted to corroborate the consistency of the outcomes.