Magnetic Disturbance Due to The Hemispherical Hole in The Ground for A Building at The Magnetic Test Site

摘要

The attitude of magnetized spacecraft is affected by the earth's magnetic field. In order to test magnetic characteristics of spacecraft, satellites, sounding rocket payloads and their subsystems, the calibration of magnetometers, and others, the Japan Aerospace Exploration Agency (JAXA) has established a Spacecraft Magnetic Test Site (SMTS) having zero magnetic field (the maximum permissible flux density is ±2.5nT in sphere with the diameter of 2.3m). This is realized without using a magnetically shielded room by means of the main coil of a 3-axis Brumbeck system, which can cancel the uniform earth's magnetic field when combined with a nonmagnetic noise source space (NNSS) whose radius from the SMTS is more than 300m. DC magnetic disturbance due to buildings and AC disturbance due to human controlled activities such as the movement of electric trains and cars decay sufficiently in the NNSS. However, the extremely weak magnetic field in the nonmagnetic space is affected by the magnetic disturbance due to buildings, underground piping, and so on. A method using the 3-D finite element analysis (FEA) for evaluating the magnetic disturbance due to buildings in name NNSS is proposed and verified by comparing the results with actual measurements [1] [2]. In this paper, the magnetic disturbance inside and in the vicinity of the SMTS is investigated by comparing the results of 3-D FEA with measurements.