Ramp tuning of the APS booster synchrotron magnet power supplies

The acceleration cycle of the Advanced Photon Source (APS) booster synchrotron is completed within 250 ms and is repeated at 2 Hz. The currents in the quadrupole and sextupole magnets must track the dipole current to within tight tolerances if the beam is to remain stable during acceleration. In order to meet the performance specifications, a monitoring system, online with the main control system, is used to measure machine performance and adapt power supply reference waveforms from cycle to cycle. The system optimizes the tracking between the power supplies, thus minimizing transient effects and taking care of any slow drifts. Tuning algorithms are described and their performance evaluated. Practical considerations are also discussed.