A Railgun Test Bench and Standardized Methodology for Muzzle Voltage Noise Analysis

This paper presents the design, development, and initial testing results of a small-bore railgun and test bench for the study of muzzle voltage traces. An analysis of the noise observed on voltage traces taken from the muzzle during motional and locked-armature operations is presented and discussed. The average velocities for a 3.38-g projectile were 50 m/s over a series of 21 tests. The railgun is powered by a sequentially fired pulse-forming network consisting of six electrolytic capacitor banks. Typical current and voltage characteristics are approximately 20-kA peak current at 275 V for a 6-ms pulse train length. Noise root-mean-square voltage and noise margins are extracted from the muzzle voltage waveforms and discussed. This investigation also develops a quantitative method to analyze muzzle voltage noise, which can be applied to any electromagnetic launcher. The technique reveals a new and interesting result that shows noise levels were greatest during early pulses of the firing sequence and generally decreased with subsequent pulses. This demonstrates that the technique has the potential to provide insight into the nature of the armature-rail sliding contact.