  thumb|right|285px|naval surface warfare center test firing in january 2008 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 rail.c. s. rashleigh and r. a. marshall, electromagnetic acceleration of macroparticles to high velocities, j. appl. phys. 49(4), april 1978. railguns have long existed as experimental technology but the mass, size and cost of the required power supplies have prevented railguns from becoming practical military weapons. however, in recent years, significant efforts have been made towards their development as feasible military technology. for example, in the late 2000s, the u.s. navy tested a railgun that accelerates a 3.2&nbsp;kg (7 pound) projectile to hypersonic velocities of approximately , about . they gave the project the latin motto "velocitas eradico", latin for "i, [who am] speed, eradicate". in addition to military applications, railguns have been proposed as non-rocket spacelaunch technology for spacecraft;nasa considering rail gun launch system to the stars on universetoday.com by nancy atkinson on september 14, 2010 however, unless the launching track was particularly long, and the acceleration required spread over a much longer time, such launches would necessarily be restricted to unmanned spacecraft. ==basics==  thumb|285px|schematic diagram of a railgun the armature may be an integral part of the projectile, but it may also be configured to accelerate a separate, electrically isolated or non-conducting projectile. solid, metallic sliding conductors are often the preferred form of railgun armature but "plasma" or "hybrid" armatures can also be used. a plasma armature is formed by an arc of ionised gas that is used to push a solid, non-conducting payload in a similar m
Artillery_by_type Electromagnetic_components Emerging_technologies Spacecraft_propulsion