Design of high intensity radio frequency quadrupole accelerator for Suzhou neutron source

Abstract

Neutrons are essential for material structure analysis and scientific research. The neutron source at Suzhou Laboratory employs a proton linear accelerator, with its low-energy section comprising two pulsed RFQ accelerators. In the beam dynamics design, operating at 324 MHz, two RFQs accelerate proton and negative hydrogen beams from 50 keV to 3 MeV, achieving a 98.3 % transmission efficiency over a 3.385 m electrode length. In the radio frequency (RF) design, a four-vane structure with Dipole Stabilizer Rods (DSRs) was adopted to mitigate mode mixing. Thirty-six tuners provide a ±2 MHz frequency tuning range, while optimized undercuts ensure field uniformity. Simulation of the entire cavity shows an eigenmode frequency of 323.95 MHz and a peak power loss of 203 kW. Multi-physics analysis indicates a cavity frequency shift of 20 kHz due to thermal deformation. This study presents the beam dynamics, RF structure, and multi-physics analysis, confirming that the RFQ design meets operational requirements.