Beam commissioning of the coupled RFQ-SFRFQ cavity

Abstract

We developed a novel compact structure, called a Coupled RFQ-SFRFQ (CRS), to accelerate a 0.8 MeV helium beam for a materials irradiation project. A high accelerating efficiency was achieved by replacing the accelerating section of the radio frequency quadrupole (RFQ) with a separated-function radio frequency quadrupole (SFRFQ) structure, in a single cavity. Following the electromagnetic simulations, RF measurement of the CRS cavity was performed, including low RF power and high RF power measurement. Recently, beam experiments on the CRS linac indicated that the maximum accelerated beam current could reach 2 mA with an energy of 0.8 MeV and energy spread (FWHM) of 3.1%. The experimental measurement results showed good consistency with the beam dynamics simulations.

Design and cold measurements of a coupled RFQ-SFRFQ cavity

“…In addition, other structures such as the spatially periodic radio frequency quadrupole focused structure was used to improve the acceleration efficiency of RFQ [10,11]. We have built an 26 MHz coupled RFQ-SFRFQ in a single cavity and successfully carried out the beam commissioning [12,13]. The lower 𝑞/𝐴 ratio ions have a slower energy gain and are accelerated at a lower frequency.…”