Comparison of methods for calculating the magnetic moment of the cores of electromagnets of spacecraft control systems

Abstract

The relevance of determining the magnetic moment of the core of a DC electromagnet of spacecraft control systems is shown. The review of methods for calculating the magnetic moment of a cylindrical core by demagnetizing factors and integral equations is made. Methods based on the use of demagnetizing factors are considered in more detail, their comparative analysis is made, and the field of application is investigated depending on the level of the external magnetic field and the relative length of the core. It has been established that the field of application of experimentally determined demagnetizing factors is limited by the range (60–100) of the relative length of the core and the upper limit of the level of an external magnetic field of strength 10000 A/m, and for other variants of relative lengths and levels, additional experiments are necessary. The determination of the demagnetizing factors under the assumption of the uniformity of magnetization is possible if the relative length of the core and the level of an external magnetic field exceed, respectively, the values of 100 and 40000 A/m. The use of demagnetizing factors under the assumption of constant magnetic permeability for cores of relative length not less than 60 with the level of an external magnetic field whose strength does not exceed 10000 A/m is not sufficiently substantiated, since its values may differ by an order of magnitude at different points of the core. The drawbacks of the method of demagnetization factors are noted and the necessity of using the method of integral equations is justified.