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.