Experimental tests of a 25mm square-bore railgun

As a preliminary study on the electromagnetic propulsion, a 25 mm square-bore railgun with a travel-length of 1940 mm was fabricated and tested. Electrical circuit parameters of the PFN (Pulse Forming Network) and the railgun were determined from the discharges of the PFN with the railgun short-circuited at the breech or muzzle. Launch experiments were conducted to verify the basic performance of the constructed railgun. The aluminum armature of 30 gram in mass was accelerated up to 2000 m/s with a peak current of about 700 kA by simultaneous discharging of 8 capacitor bank modules. Contact problems and gouging phenomena were observed. Circuit equations coupled with the armature motion were modeled. By introducing appropriate friction forces the model showed a good prediction on the armature motion. This small scale railgun gave useful information for the preparation and design of the larger railgun with a medium caliber to be studied subsequently.