Abstract

A new heavy-ion linac within a continuous-wave (CW) 4-rod radio-frequency quadrupole (RFQ) was designed and constructed as the injector for the separated-sector cyclotron (SSC) at the Heavy Ion Research Facility at Lanzhou (HIRFL). In this paper, we present the development of and the beam commissioning results for the 53.667 MHz CW RFQ. In the beam dynamics design, the transverse phase advance at zero current, σ0⊥, is maintained at a relatively high level compared with the longitudinal phase advance (σ0∥) to avoid parametric resonance. A quasi-equipartitioning design strategy was applied to control the emittance growth and beam loss. The installation error of the electrodes was checked using a FARO 3D measurement arm during the manufacturing procedure. This method represents a new approach to measuring the position shifts of electrodes in a laboratory environment and provides information regarding the manufacturing quality. The experimental results of rf measurements exhibited general agreement with the simulation results obtained using CST code. During on-line beam testing of the RFQ, two kinds of ion beams (Ar408+ and O165+) were transported and accelerated to 142.8 keV/u, respectively. These results demonstrate that the SSC-Linac has made a significant progress. And the design scheme and technology experiences developed in this work can be applied to other future CW RFQs.20 MoreReceived 22 May 2015DOI:https://doi.org/10.1103/PhysRevAccelBeams.19.010402This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Physical SystemsAccelerator applicationsPulsed-power acceleratorsAccelerators & Beams

Highlights

  • The Heavy Ion Research Facility at Lanzhou (HIRFL) accelerator complex was upgraded with a multifunctional cooler storage ring (CSR) at the end of 2007 [1]

  • Several innovative design concepts and fabrication procedures were implemented in the production of this radio-frequency quadrupole (RFQ)

  • Several advanced fabrication technologies were applied for the construction of the RFQ, including precise machining and one-step high-temperature brazing

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Summary

INTRODUCTION

The HIRFL accelerator complex was upgraded with a multifunctional cooler storage ring (CSR) at the end of 2007 [1]. The heavy ions coming from the SFC must be first injected into the SSC, accelerated to 10.06 MeV=u, and transported into the CSR This operating scheme results in low beam efficiency, especially for heavy ions [2]. The SSC-Linac RFQ, which operates in CW mode to match the operation of the SSC, can accelerate particles with charge-to-mass ratios between 1=3–1=7 from 3.728 keV=u to 143 keV=u As designed, this machine will transport 238U34þ beams at a current of 0.5 pmA. A wide safety margin would be preferable for different ion species and beam intensities because the high charge state will enhance the space charge force These requirements pose challenges in the beam dynamics and in the design of the cooling of the structure and in ensuring stable long-term operation.

DESIGN AND SIMULATION
Beam dynamics design
Rf structure design
General characteristics of the rf design
Power consumption and cooling design
Manufacture and assembly
Mechanical measurements
Rf measurements of RFQ
Rf performance of the cavity
Measurements of the electric field flatness
Measurement of the dipole components
High-power conditioning
Beam commissioning
Findings
SUMMARY AND OUTLOOK
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