Beam optimization of RFQ and SFRFQ combined accelerator at Peking University

TL;DR

This paper details the design, upgrade, and optimization of a combined RFQ and SFRFQ accelerator at Peking University, demonstrating effective beam acceleration and transport with improved performance.

Contribution

It presents the first successful integration and optimization of RFQ and SFRFQ structures at Peking University, including beam conditioning techniques for enhanced acceleration.

Findings

Maximum O+ beam current exceeded 3.2mA at 1.03MeV

Final beam energy reached 1.65MeV with 0.53mA current

Beam transport and conditioning were effectively optimized

Abstract

The Peking University Integral Split Ring Radio Frequency Quadrupole(ISR RFQ) accelerator was constructed in 1999 with a high duty factor 16.7% and repetition frequency 166Hz, and it was able to accelerate N+, O+,O-, C+ and He+ from 1.6kev/u to 65keV/u. It was later upgraded as an injector of the Separated Function RFQ (SFRFQ). The experiments indicated that the maximum accelerated O+ beam current could exceed 3.2mA with energy 1.03MeV and an energy spread (FWHM) 3.1%. Then the beam transports through a 1m-long magnetic triplet to the entrance of SFRFQ and is finally accelerated to 1.64MeV. The beam conditioning of RFQ were carefully optimized to satisfy the requirements of the SFRFQ. The combined accelerator eventually can deliver 0.53mA O+ beam with energy 1.65MeV, which has sufficiently demonstrated the feasibility of the SFRFQ structure.