Design and investigation of various magnetic torquers

Martynas Kisielius DESIGN AND INVESTIGATION OF VARIOUS MAGNETIC TORQUERS Summary Cubesat type of satellites are one of the most popular means of space exploration due to their low production costs and relatively short design time. One of the ways to orient these satellites in space is to use magnetorquers. Magnetic coils are arranged perpendicular to each other and, due to their interaction with Earth's magnetic field magnetic torque arises thus steering the satellite about two axes perpendicular to the Earth's magnetic field. There are two main types of coils: without cores or with a ferromagnetic core. Depending on the purpose of the mission, its technical demands coils parameters are set and therefore the type of coil and its dimensions are decided. An overview of the main parameters of magnetorquers used on Cubesat missions over the past few years were done: power, magnetic moment, mass, and the dimensions of a ferromagnetic core were set. It was also decided aluminum and copper coils with and without core to be investigated, thus finding out which ferromagnetic core is to be used to meet the requirements. Using the Stoletov curve approximation method, the magnetic permeability dependence on the number of turns and the required mass of cores were calculated. In order to determine which coils are to be used, the dependence of their mass on power was investigated. It has been determined that to achieve the task parameters the most suitable use is aluminum rods with nickel-manganese 700 core. It has also been observed that for the same parameters, copper coils without core needs at least 4.35 W, aluminum 2.93W power. According to the size and weight of a known magnetorquer rotary weighing tray were designed via computerized design program FreeCAD to smoothly change the specimen and suppress the oscillations due to the turning. The structure allowed to measure the dipole moment generated by a magnetorquer p_m=0,53 A•m2. In order to verify the accuracy of the measurement and approxi-mation of the Stoletov's curve, all dependence were calcuted thus finding theoretical dipole moment p_m=0,6546 A•m2