Realization of compact permanent-magnet-based multibend-achromat lattice with magnetic crosstalk compensations

Electron storage rings based on multibend-achromat (MBA) lattices can achieve exceptionally low natural emittances. At the Paul Scherrer Institute in Switzerland, the Swiss Light Source facility underwent an upgrade project, replacing its triple-bend achromat ring with a seven-bend achromat ring. Due to the compact nature of MBA lattices, magnetic fields can be influenced by neighboring magnets. These magnetic crosstalk effects turned out to be significant during the design phase: the integral fields of the magnets could be altered by several percent. We present how we incorporated compensations for these effects into the design and how we tuned the magnets prior to installation. The crosstalk compensations were validated through the accelerator commissioning.