Muzzle Voltage of Railgun in Zero Velocity and Launch Experiments

The muzzle voltage in a solid-armature railgun is an important diagnosis. Changes of the muzzle voltage usually contain information on the condition of the rail/armature interface. This paper reports on the zero velocity experiment in 1m railgun and the launch experiments in 3 m railgun (both with 30 mm square-bore). Comparing the experiments and theoretical analysis of muzzle voltage, it is shown that: (a) In zero velocity experiments, muzzle voltage is the sum of armature resistance voltage and the rail/armature interface resistor voltage; (b) In launch experiments, measurement of muzzle voltage is the sum of armature head resistance voltage drop, motional electromotive force of armature head and voltage drop of rail/armature-head interface resistance; (c) In launch experiments, large changes of the muzzle voltage can show the transition occurs, but stable muzzle voltage can't prove the transition does not occur. Because good contact at the front of the armature may mask transition occurring at the armature's rear.