Physical design of a compact 2 MeV deuteron radio-frequency quadrupole

This paper describes the physical design of a radio-frequency quadrupole (RFQ) accelerator for a compact accelerator-driven neutron source. The 325-MHz RFQ accelerates a 30-mA deuteron beam from 50 keV to 2 MeV, which is directly matched to the drift-tube linac (DTL) without a separate beam matching section. The objective of this design is to obtain a short RFQ with a tolerable transmission and power consumption. Using a modified four-section procedure, the inter-vane voltage is ramped with RFQ longitudinal position to obtain the required short length, and the focusing strength is varied to suppress beam loss. The RFQ has a length of 193.2 cm, with a peak power consumption of 186 kW, and a beam transmission of 94.1%.