High-frequency structure design and RF stability analysis of a 4-vane radio frequency quadrupole with pi-mode stabilizer loops

TL;DR

This paper presents the design optimization and RF stability analysis of a 176 MHz 4-vane RFQ with pi-mode stabilizer loops, enabling high-stability proton acceleration for neutron source applications.

Contribution

It introduces a novel RFQ design with PISLs that improves RF stability and simplifies operational tolerances compared to previous designs.

Findings

Achieved acceleration of 80 mA proton beam from 65 keV to 2.5 MeV over 5.3 m

Designed RFQ operates at 176 MHz with 10% duty cycle

PISLs enhance RF stability and reduce alignment requirements

Abstract

Compact accelerator-based neutron source facilities are garnering attention and play an important and expanding role in material and engineering sciences, as well as in neutron science education and training. Neutrons are produced by bombarding a low-energy proton beam onto a beryllium or lithium target. In such an accelerator-based neutron source, a radio frequency quadrupole (RFQ) is usually utilized to accelerate a high-intensity proton beam to a few MeV. This study mainly covers the high-frequency structure design optimizations of a 4-vane RFQ with pi-mode stabilizer loops (PISLs) and its RF stability analysis. A 176 MHz RFQ accelerator is designed to operate at a 10% duty factor and could accelerate an 80 mA proton beam from 65 keV to 2.5 MeV within a length of 5.3 m. The adoption of PISLs ensures high RF stability, eases the operation of the accelerator, and implies less stringent alignment and machining tolerances.