Improvements on the design of search coil magnetometer for space experiments

Search coils despite of their bulk, are still used on space experiments thanks to their ability to measure weak magnetic fields and also to their robustness. This paper will focus on the search coil modeling and design. We propose an original shape of the magnetic core allowing an improvement of their performances. Models for the demagnetizing factor for this shape as well as for the winding behavior are proposed. Then, we present a formulation of the optimization problem needed to achieve a low mass sensor. This is a critical issue for space instruments. The optimization problem is solved by using a Newton algorithm combined with an efficient formulation of the cost function. Finally, we discuss the solution obtained via this optimization procedure and indicate the performances of the sensor. A sensitivity as low as 15fT/root Hz at a few kHz is obtained.