Development of the 3MeV RFQ for the Compact Pulsed Hadron Source at Tsinghua University

We pre­sent, in this paper, the physics and me­chan­i­cal de­sign of a Radio Fre­quen­cy Quadrupole (RFQ) ac­cel­er­a­tor for the Com­pact Pulsed Hadron Source (CPHS) at Ts­inghua Uni­ver­si­ty. The 3-me­ter-long RFQ will ac­cel­er­ate pro­tons from 50 keV to 3 MeV at an RF fre­quen­cy of 325 MHz. In the physics de­sign we have pro­grammed the in­ter-vane volt­age as a func­tion of beam ve­loc­i­ty, to op­ti­mize the per­for­mance of the RFQ, by tai­lor­ing the cav­i­ty cross sec­tion and vane-tip ge­om­e­try as a func­tion of lon­gi­tu­di­nal po­si­tion while lim­it­ing the peak sur­face elec­tric field to 1.8 Kil­patrick. There will be no Medi­um-En­er­gy-Beam-Trans­port (MEBT) fol­low­ing the RFQ. The fo­cus­ing at the high en­er­gy end of the RFQ and at the en­trance of the DTL have been tai­lored to pro­vide con­tin­u­ous restor­ing forces in­de­pen­dent of the beam cur­rent. In sim­u­la­tions of the pro­ton beam in the RFQ, using the code PARMTE­QM, we ob­serve trans­mis­sion ex­ceed­ing 97%. The RFQ is me­chan­i­cal­ly sep­a­rat­ed into three sec­tions to fa­cil­i­tate ma­chin­ing and braz­ing. We have ma­chined a test sec­tion and the final RFQ ac­cel­er­a­tor is now under con­struc­tion. We will de­scribe the sta­tus of the RFQ sys­tem in this paper.