The radio-frequency design of an iris-type coupler for the CPHS radio-frequency quadrupole

The Compact Pulsed Hadron Source （CPHS） project is a university-based proton accelerator platform （13 MeV,16 kW,50 mA peak current,0.5 ms pulse width at 50 Hz） for multi-disciplinary neutron and proton applications.The CPHS linac consists of a 3 MeV radio-frequency quadrupole （RFQ） linac and a 13 MeV drift tube linac （DTL）.Both the RFQ and DTL share a 325 MHz,2.1 MW klystron source.A single iris-type radio-frequency （RF） coupler is used to feed 537 kW of RF power to the RFQ cavity.Three-dimensional electromagnetic models of the ridge-loaded tapered waveguide （RLWG） and the coupler-cavity system are presented,and the design process and results of the RLWG and iris plate are described in detail.