Design of a New Type of Variable-Frequency Radio-Frequency Quadrupole Linac with a Folded-Coaxial Resonator

Abstract

A new type of variable-frequency radio-frequency quadrupole (RFQ) linac that will be constructed as a new injector for the RIKEN heavy-ion linac (RILAC) is proposed. It is designed to accelerate ions with mass-to-charge ratios of 7 to 28 at up to 450 keV per charge by varying its operational frequency from 17 to 35 MHz. The resonator has a folded-coaxial structure, and the resonant frequency is changed by a movable shorting plate. As a result of a low-power test on a half-scale model, the required rf power is found to be 6 kW at 17 MHz, and it increases to 34 kW at 35 MHz in cw operation.