Modellizzazione del contributo magnetico di dispositivi di satelliti scientifici.

This thesis wants to improve the models used in the Magnetic Cleanliness Facility (MCF) in Thales Alenia Space - Torino, with the aim of estimating the magnetic field of Scientific Satellites. The MCF is composed by a turning table on which the Devices Under Test (DUTs) are placed and by two magnetometers that make a continuous reading synchronized with an angular transmitter while the table is rotating. The turning table is placed inside a magnetic coil facility which compensate the Earth magnetic field on the DUT. The aim of the compensation is only to eliminate induced magnetization on the DUT, because for the sensors the uniform fields are eliminated by using only the difference of the two sensors measures. Starting from this gradiometric measure we developed a single displaced dipole model which, using the combined data of two measures on at least two different planes, is able to give the complete position and magnetic dipole vectors. This is a great improvement over the model already existing on the facility, which could take into account only a measure on the plane and consequently is able to give only two components of the dipole moment and its height. We developed also a model with two dipoles which is more problematic by nature. The model we implemented is unable to give good prediction if the two dipoles are too near one to each other. The algorithm may be improved, but there will always be a distance below which the algorithm cannot distinguish them. In real life scenario this it is not a great deal because the two-dipoles model is needed only when the single dipole approximation is not valid. Some other models may be used (this thesis presents also the theoretical advantages and limits of the spherical harmonics expansion), nevertheless, for the actual requirements and typical DUT, the single dipole model provide a satisfying approximation and a good improvement of the model already present on the MCF.