Implement and commissioning of the beam energy feedback system in BEPCII linac

TL;DR

This paper details the development and commissioning of a real-time beam energy feedback system at BEPCII linac, utilizing non-interceptive measurement and RF phase adjustment to stabilize beam energy and improve injection rates.

Contribution

It introduces China's first non-interceptive online beam energy measurement method and a practical energy adjustment mechanism for the BEPCII linac.

Findings

Effective stabilization of beam energy fluctuations.

Improved injection rate stability.

Successful real-time energy feedback implementation.

Abstract

In order to ensure the beam quality and meet the requirements introduced by the BEPCII storage ring, the beam energy feedback system has been developed at the exit of the linac. This paper describes the implementation and commissioning of this system in detail. The energy feedback system consists of an energy measurement unit, an application software and an execution unit. In order to ensure the real-time monitoring and adjustment of beam energy, we need to introduce a non-interceptive type of online beam energy measurement method which is on the first try in China and the effective mechanism of energy adjustment to achieve this goal. The adjustment of energy is achieved by adjusting the output microwave phase of the RF power source station. The system was put into operation in March 16th, 2016 and achieved the desired results. It can effectively eliminate the low point of the injection rate caused by the fluctuation of the beam center energy and has played an important role in maintaining a high constant injection rate.