1) Spacecraft propulsion 2) Type of Artillery
Found on
https://www.crosswordclues.com/clue/railgun
A railgun is an electrically powered electromagnetic projectile launcher based on similar principles to the homopolar motor. A railgun comprises a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rai...
Found on
http://en.wikipedia.org/wiki/Railgun
No exact match found.
