Design of the Button-Type Beam Position Monitor for the Electron Storage Ring of Hefei Advanced Light Facility

There are large number of button-type beam position monitors (BPMs) installed on the electron storage ring of the Hefei Advanced Light Facility (HALF), which primarily used for measuring the beam position and closed orbit. This paper presents the design of the button-type BPM for the diffraction-limited storage ring of the HALF. Firstly, the design of the button-type BPM, including materials and geometric structures, is based on the requirements of the measurement system. Subsequently, simulations and numerical analyses are applied to evaluate the pickup signal strength and sensitivity of the button-type BPM. Furthermore, 3D electromagnetic simulations are employed to get the wakefield losses when the electron beam passed through the button-type BPM. Based on the wakefield loss factor, the temperature distribution and mechanical thermal deformation caused by the dissipation of beam wakefield power on the geometric structure of the button-type BPM are analysed. The results of the multiphysics field simulations consist of electromagnetic, thermal, and mechanical aspects of the button-type BPM model show that the design of the BPMs satisfy the beam position measurement for the HALF. The mechanical structure and key component materials for the fabrication of the button-type BPM for the HALF storage ring were determined.