Diagnostic Capabilities for Electromagnetic Railguns

In the past 30 years, there have been significant advances in the development of modeling and simulation algorithms for electromagnetic railguns. The development of instrumentation capable of measuring the physical parameters that occur during a high-velocity launch, however, has not kept pace with the advances in modeling capabilities. In addition, there has been an increase in the size and complexity of existing railguns, and therefore it has become necessary to find instrumentation that has the flexibility to conform to the variations present from one railgun to the next, to aid in the cross-utilization of instrumentation across the community. This paper will describe results from Georgia Tech and U.S. Navy to evaluate diagnostic techniques that measure different phenomena at higher resolution in both time and space in order to provide the data needed to validate railgun models. The diagnostics described here address all aspects of railgun testing, including the launcher, projectile, and pulsed power supplies and all phases of the evaluation process from validation of modeling and simulation tools to structural health monitoring. Specific quantities for which diagnostics will be described include temperature, electric and magnetic field sensors, and strain measurements. Examples of electromagnetic sensors that will be presented include colossal magnetoresistance sensors, which respond to changes in a magnetic field with a change in resistance, and a slab-coupled optical sensor for detecting electric fields. Test results from railguns at both Georgia Tech and the French-German Institute in Saint-Louis will be described.