Magnetic Disturbance Due to the Hemispherical Hole in the Ground for a Building at the Magnetic Test Site

摘要

At the Japan Aerospace Exploration Agency, a zero magnetic field is required to test the magnetic characteristics of spacecrafts, satellites and to calibrate magnetometers. This zero-magnetic field is realized by means of a three-axis coil system which can cancel the uniform earth's magnetic field, but cannot cancel magnetic disturbance because of no magnetically shielded room. Therefore, the magnetic disturbance within and in the vicinity of the zero-magnetic field of a Spacecraft Magnetic Test Site (SMTS) is investigated by comparing the results of three-dimensional (3-D) finite-element analysis with measurements. Distributions of the magnetic disturbance due to three hemispherical objects-the roof, the foundation made of concrete, and the hole in the ground for the SMTS building-are analyzed and compared with those measured by a proton magnetometer. Consequently, it is shown that the hemispherical hole in the ground for the SMTS building, which has weak magnetism and is a little higher than that of concrete, generates a weak magnetic disturbance in the zero-magnetic field of the SMTS