Atomic energy of Canada Limited RFQ1 and the Sparker-CW proton RFQ's at CRNL

Abstract RFQ1 is a cw 270 MHz proton accelerator designed to accelerate 75 mA of protons to 600 keV. As part of the design process, the Sparker, a cw 270 MHz RFQ test structure, was used to study surface electric field limits. During the past year, Sparker experiments have shown that unmodulated OFHC copper RFQ vanes can be conditioned to operate with surface fields in excess of 38 MV/m cw, and 50 MV/m pulsed (2.3 and 3.0 times the Kilpatrick criterion respectively). These experiments provided important RFQ design information that has been used in the design of RFQ1 as described in the paper. Features of the RFQ1 mechanical design include: cooling for a 10 W/cm 2 surface heat flux, easy vane removal through slots in the sides of the tank, a copper racetrack membrane to provide the RF and vacuum seal between the vanes and the tank (permitting vane adjustment as well), and OFHC copper vane tips for reliable high gradient operation.