A waveguide overloaded cavity kicker for the HLS II longitudinal feedback system

TL;DR

This paper presents the design, simulation, and measurement of a waveguide overloaded cavity kicker for the HLS II feedback system, improving stability and reducing power requirements.

Contribution

It introduces a novel waveguide overloaded cavity kicker design with optimized frequency and bandwidth for HLS II, including simulation and experimental validation.

Findings

Optimized kicker achieves desired frequency and bandwidth.

Higher shunt impedance reduces feedback power.

Measurements confirm simulation accuracy.

Abstract

In the upgrade project of Hefei Light Source (HLS II), a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively. We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator. The beam pipe of the kicker is racetrack shape so as to avoid a transition part to the octagonal vacuum chamber. The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code. The higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement. Before the kicker cavity was installed in the storage ring, a variety of measurements were carried out to check its performance. All these results of simulation and measurement are presented.