Ultralow-Alpha Operation with three Families of Sextupoles at the KARA Ring

For more than two decades, the Karlsruhe Research Ac- celerator (KARA) — KIT’s synchrotron radiation source and accelerator test facility — has been routinely operated in short-pulse mode, which involves reducing the momentum compaction factor [1]. Recent advances, such as enhanced stability provided by new magnet power supplies [2], have enabled us to surpass previous limitations in achieving ex- tremely small momentum compaction factors. Based on lattice simulations and the introduction of a single additional sextupole magnet we successfully suppressed the longitudi- nal chromaticity, allowing the “zero-current” bunch length at KARA to be reduced from the previous 2 ps to below 1 ps. We also report on the measurements of the characterization of this improved operating mode.