Four-rod RFQ beam dynamics design of PKUNIFTY upgrade

The Peking University neutron imaging facility (PKUNIFTY), an RFQ-based neutron source, aims at developing industrial applications. During the past 3 y operation, some problems have appeared, such as RF sparking for the RFQ high power operation, full power level instability of RF transmitter, and the misalignment of RFQ electrodes assembling and deformation. The PKUNIFTY upgrade endeavors to adopt a modest inter-voltage beam dynamics design. The new beam dynamics design of 201.5 MHz RFQ of PKUNIFTY, which accelerates 35 mA of D⁺ from 50 keV to 2.0 MeV at 10% duty factor, is performed. The averaged D⁺ beam will be about 3 mA. The source will deliver a fast neutron yield of 2.5 × 10¹² n/s via the deuteron-beryllium reaction, which is about 10 times higher than the current status. (authors)