FINITE DIFFERENCE METHOD FOR CALCULATING MAGNETIC FIELD COMPONENTS OFF-MEDIAN PLANE USING MEDIAN PLANE FIELD DATA

摘要

Given a magnet with midplane symmetry, the field is totally determined if one knows the field in the midplane. A new finite difference method for calculating the field from discrete data in the midplane is described. Because data to be processed are obtained from measurements with noise, the method for evaluating derivatives is required to suppress the high frequency signals effectively, while maintaining reasonable accuracy for low frequencies. First-order and second-order differentiators for a uniform mesh are designed. As a test, they are applied to the magnetic field produced by two magnetized-iron bars where the exact analytical expression for the magnetic field is known and also they are applied to the same field data when a small amount of noise is superimposed. And, finally, they are applied to the measured magnetic field of the K1200 superconducting cyclotron. (C) 1995 Academic Press, Inc. [References: 12]