Soft Magnets for Passive Attitude Stabilization of Small Satellites

Abstract

The spinning and oscillatory motions of small orbiting satellites can be damped exploiting the magnetic energy dissipation occurring in onboard soft magnetic strips, cyclically excited by the oscillation of the earth field component along their axis. In this paper we investigate the role played by the intrinsic magnetic properties of the material, the aspect ratio of the strips, and their mutual arrangement in achieving maximum energy dissipation under typical spacecraft working conditions. Grain-oriented Fe-Si, mumetal, and Fe-based amorphous alloys, all endowed with near-rectangular hysteresis loops, are considered. Their energy loss behaviour is calculated when, either as single strip samples or arranged into an array of strips, they are subjected to a slowly oscillating magnetic field of defined peak value, emulating the action of the earth magnetic field on the travelling satellite. The strip size and array layout leading to maximum energy loss are predicted. Amorphous alloys, combining high saturation magnetization with flexible hysteresis loop properties, are shown to lead to the best damping behaviour under both oscillating and spinning satellite motions. In the latter case the Fe-Si strips appear to provide comparably high damping effects, while inferior behaviour is always predicted with mumetal samples

Optimal geometry and materials for nanospacecraft magnetic damping systems

“…18) puts in evidence their pseudolinear behavior, where a very low remanence results from the large demagnetizing effect. We, therefore, expect that whatever the time history of H bias , the measured loss will evolve with little or no hysteretic behavior [27].…”

Passive magnetic attitude stabilization system of the EduSAT microsatellite

“…However, at the first step, permeable rods manufactured using Fe-Ni alloy (specifically Mumetal) were selected on the basis of previous flight experience and reference literature, and a review of the manufacturing process was performed. Currently, the idea is to perform an in-orbit test for different proposed materials on different satellites [11]. The following sections deal with the design and manufacturing processes proposed to improve the performance of the Mumetal magnetic strips.…”

Volume magnetization for system-level testing of magnetic materials within small satellites

“…The use of an excitation (magnetizing) & sense (or pickup) coil is an accepted method of hysteresis measurement [21]. Recent empirical testing of hysteresis rods for PMAC systems have been performed by two main groups: Ivanov et al [25] (also [26]) use a small excitation solenoid (only magnetizing one hysteresis rod), while Santoni et al [27] (also [28], [29]) use a larger excitation solenoid capable of magnetizing a large array of rods. We present a method of using the Helmholtz cage itself as the excitation coil, as it is able to supply a uniform magnetizing field in a large volume and in any direction.…”