RELAXATION CALCULATION OF MAGNETIC FIELDS PRODUCED BY DISTRIBUTED CURRENTS IN PRESENCE OF IRON WITH A VARIABLE PERMEABILITY

摘要

The solutions obtained previously for the magnetic field produced by a spiral sector FFAG magnet in which the pole face windings are distributed in spiral and radial grooves have been extended to include the effects of a finite variable permeability in the iron. A unified method is presented for the construction of the algorisms. The cases treated are sufficiently general that both radial gaps as well as radial return current slots are included. This allows the potential to be graded along the spiral poles with a grading distance equal to the distance between radial return slots and with a grading distance equal to the distance between the radial gaps.