Persistent currents in LHC magnets

The field errors due to persistent currents in LHC (Large Hadron Collider) dipoles, quadrupoles, and correction windings are discussed. The errors due to variations in the magnetization are shown to be significant. The author discusses the influence of magnetic cycling, the contribution of the different parts of the dipole winding, and simple scaling with coil radius and field. The partial cancellation of the sextupole and decapole in the different winding regions indicates that an effort should be made to study other coil geometries. The calculations made show the importance of using magnet poles with the same magnetization