Intra-beam scattering and beam lifetime in a candidate lattice of the soft X-ray diffraction-limited storage ring for the upgraded SSRF

New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits. Intra-beam scattering (IBS) and Touschek scattering in such facilities are significant and require attention because of their ultra-low emittance. Therefore, cure strategies need to be carefully studied to obtain high-quality photon beams. For the Shanghai Synchrotron Radiation Facility Upgrade (SSRF-U), a candidate lattice of the storage ring, reaching the soft X-ray diffraction limit, was designed and presented for the first time in this study. The emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine configurations. The gains with RF frequencies of 100 MHz and 500 MHz were compared. Along with a better filling pattern, a more suitable RF frequency was adopted in the SSRF-U. The variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using simulations. Optimal beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus determined. The fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained parameters. Additionally, the Touschek scattering and beam lifetime were calculated, and an acceptable total beam lifetime was obtained.

Automated summary

New-generation synchrotron light sources aim to provide brighter radiation by reducing beam emittance, but intra-beam scattering and Touschek scattering are significant challenges. The study on the Shanghai Synchrotron Radiation Facility Upgrade focused on determining optimal machine configurations and parameters for achieving acceptable beam lifetime.