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.