Detection of Armature-Rail Contact Instabilities in Electromagnetic Launchers

This article deals with the detection of asymmetrical current distribution and the inspection of the rail-armature contact during the launch operation of electromagnetic rail launchers. The method puts in relationship electromagnetic quantities and geometric distances adopting search loops in symmetric position to the rails and offers an auxiliary geometrical interpretation representing the mutual inductances between each loop and the railgun by equivalent geometrical loci. For this purpose, we provide an analytical description for a case study with infinitely long straight wires, in the quasi-static approximation. An experimental analysis is carried out in static conditions on a railgun prototype available at the University of Pisa for different positions of the armature. Besides, we report an uncertainty analysis of the obtained measurement results, performed via a Monte Carlo simulation. Finally, we extend our analysis to the case of dynamic experiments performed with two different armatures to further validate the proposed approach.