Design and test of a superconducting RFQ for heavy ions

摘要

A prototype SRFQ resonator optimized for a velocity of (beta)=0.03 and a charge to mass ratio (q/M) of 1/6 has been designed, fabricated and tested. This is a short RFQ structure (only 2(beta)(lambda) long) operating at 57.4MHz. The resonator is made of copper, and a 1.5(mu)m thick layer of electroplated Pb-2at.%Sn is used as the superconductor. The electrical characteristics of the resonator derived from detailed 3-D numerical simulations using the MAFIA codes, and also from measurements on the actual resonator are described. The multipactoring levels could be processed away with ease. Quality factor (Q) > 1 (times) 10(sup 8) is obtained for E(sub a) up to 1 MV/m. Other parameters relevant to superconducting operation are also presented.