title: The beam energy feedback system for Beijing electron positron collider II linac.
abstract: A beam-energy feedback system has been developed for the injection linac to meet the beam quality needed for the Beijing electron positron collider II storage ring. This paper describes the implementation and commissioning of this system in detail. The system consists of an energy measurement unit, application software, and an actuator unit. A non-intersecting beam energy monitor was developed to allow real-time online energy adjustment. The beam energy adjustment is achieved by adjusting the output microwave phase of the RF power source station. The phase control mechanism has also been modified, and a new control method taking the return difference of the phase shifter into account is used to improve the system's performance. This system achieves the design aim and can adjust the beam center energy with a rate of 2 Hz. With the energy feedback system, the stability of the injection rate is better; the fluctuation range is reduced from 20 mA/min to 10 mA/min, while the stability of the beam center energy is maintained within ±0.1%.
authors.affiliation: Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: S
authors.identifier: 0000000176148157
authors.initials: S
authors.lastname: Wang
authors.affiliation: Centre for High Energy Physics, University of the Punjab, Lahore 45590, Pakistan.
authors.forename: M
authors.initials: M
authors.lastname: Iqbal
authors.affiliation: Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Chi
authors.affiliation: Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: R
authors.initials: R
authors.lastname: Liu
authors.affiliation: Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: X
authors.initials: X
authors.lastname: Huang