Study on the frequency tuning of half-wave resonator at IMP

TL;DR

This paper analyzes the frequency detuning of a superconducting half-wave resonator caused by helium pressure and Lorentz force, and proposes a tuning system to compensate for these effects, ensuring stable operation.

Contribution

It presents a detailed analysis of detuning mechanisms and designs a tuning system for a 162.5 MHz HWR to maintain frequency stability during operation.

Findings

The tuning system effectively compensates for frequency drift due to external vibrations.

Simulations show the cavity can be tuned to counteract helium pressure and Lorentz force effects.

The analysis provides insights into the mechanical deformation and frequency shift mechanisms.

Abstract

A 162.5 MHz superconducting half-wave resonator (HWR) with geometry beta of 0.09 is being developed for Injector II of China Accelerator Driven Sub-critical System (CADS) Project at the Institute of Modern Physics (IMP). The HWR section composed of 16 HWR cavities will accelerate the proton beam from 2.1 MeV to 10 MeV. The RF and mechanical coupled analysis are essential in geometry design in order to predict the deformation of the cavity walls and the frequency shift caused by the deformation. In this paper, the detuning caused by both bath helium pressure and Lorentz force is analysed and a tuning system has been investigated and designed to compensate the detuning by deforming the cavity along the beam axis. The simulations performed with ANSYS code show that the tuning system can adjust and compensate the frequency drift due to external vibrations and helium pressure fluctuation during operation.