3-D Numerical Code for Field Calculations of Superconductive Magnets

Phase III upgrade of CESR includes super conducting magnets without iron. The magnets are built from super conducting wire loops wrapped on a pipe. Because of the high currents involved in super conducting magnets, the distortion of the magnetic elds at the rounded ends may not be negligible and should be calculated. The gradual decrease in the magnetic eld at the edges causes higher order multipoles, and the parasitic magnetic eld in the z direction at the edges might cause coupling. In order to study these problems a 3-D numerical code was developed. The code BST.c calculates the spatial magnetic elds generated by a wire carrying current. In particular, it calculates elds of wire loops wrapped on a pipe. The arrangement and dimensions of the loops can be easily modi ed to create dipoles, quadruples, skew magnets etc.. It has been used to calculate the magnetic elds inside and outside the magnets. The higher order multipoles are obtained by a Fourier transformation of the eld. It calculates local elds errors due to possible manufacturing imperfections. It also calculates the particle trajectories inside the magnet in order to investigate possible coupling between the horizontal and the vertical motion due to Bz at the ends. The e ective magnet length was calculated by numerical integration over the whole magnet.