Development of a Diagnostic Technique to Track Magnetized Projectiles in Opaque Media

A new diagnostic method to measure the trajectory and orientation of a magnetized projectile traveling through opaque media in-situ has been developed. An array of magnetic field sensing coils placed around a projectile flight path produces raw voltage data that, upon analysis, yields the trajectory of the projectile. This paper discusses the theory of operation of the diagnostic, presents the analysis used to convert voltage signals to trajectory information, gives design details of the sensor array, and presents two representative experiments. In these experiments projectiles were launched from a 50-mm gun at a velocity of about 1 km/s. In both cases the projectiles perforated a 35 inch long, right circular cylinder filled with sand. Data from 24 sensing coils were recorded and analyzed to determine the trajectory and orientation of the projectiles from well before they impacted the opaque material until well after target exit. To test the validity of the method high-speed digital video cameras recorded the projectiles’ entry and exit for the same sand targets. Trajectory and orientations from the magnetic tracking technique compared well to camera observations.