MITIGATION OF MAGNET HYSTERESIS EFFECTS AT LANSCE

We have developed a scheme to mitigate the effects of magnet hysteresis in a beamline with a complex arrangement of magnets. The complexity is due to the fact that two power supplies power eight magnets. While some of the magnets are powered by just one of the two supplies, others are excited with the currents from both supplies, with the magnetic fields from the two currents adding in some magnets and subtracting in others. The primary challenge in developing this scheme was the process of determining a reproducible current set point after heuristic optimization by operators. We have also observed the effects of hysteresis in quadrupoles and steering magnets, and have demonstrated that methods typically employed in accelerators are sufficient to mitigate the hysteresis effects in these magnets.