BNL, Upton, New York, USA
We have developed an orbit correction / feedback program to unify the existing orbit-related feedback systems for stable beam operation at NSLS-II. Until recently only a handful of beamlines have been benefiting from long-term orbit stability provided by a local bump agent program. To expand this to all the beamlines as well as correct more frequently, a new slow orbit feedback program called unified orbit feedback (UOFB) was written from scratch that works with the fast orbit feedback transparently, while accumulated fast corrector strength is continuously shifted to the slow correctors and RF frequency is adjusted for circumference change. UOFB can lock 3 different types of local bumps to the target offsets/angles for days: those for insertion device (ID) sources with only ID RF beam position monitors (BPM) or mixtures of ID RF BPMs and X-ray BPMs, and those for bending magnet sources with arc BPMs between which orbit correctors, dipoles and quadrupoles exist. Furthermore, this feed-back can accommodate beamline user requests to enable / disable the feedback loop for their beamline and to change bump target setpoints without turning off the loop.
