16-10-2012, 05:46 PM
RAILGUN
PRINCIPLE OF OPERATION:
A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the Lorentz force. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts with the strong magnetic fields generated by the rails and thus accelerates the projectile.
BACKGROUND:
Railguns are being pursued as weapons with projectiles that do not contain explosives, but are given extremely high velocities: 3500 m/s or more (for comparison, the M16 rifle has a muzzle speed of 975-1025 m/s, Or A.K. 47 has a muzzle speed of 710 m/s), which would make their kinetic energy equal or superior to the energy yield of an explosive-filled shell of greater mass. This would allow more ammunition to be carried and eliminate the hazards of carrying explosives in a tank or naval weapons platform. Also, by firing at higher velocities railguns have greater range, less bullet drop and less wind drift, bypassing the inherent cost and physical limitations of conventional guns - "the limits of gas expansion prohibit launching an unassisted projectile to velocities greater than about 1.5 km/s and ranges of more than 50 miles [80 km] from a practical conventional gun system."
IMPLEMENTATION & APPLICATIONS:
Naval forces are also interested in railgun research. Current ship guns store their explosive shells in a large magazine underneath the gun. If a shell from a hostile happens to penetrate into the armory and explode, it is quite likely to cause all of the shells in the magazine to detonate, usually destroying the ship. However if the ship is instead equipped with railguns, the magazine would need only to store the non-explosive tungsten bullets. Additionally, the compact railgun projectiles would require less space to store than the shells used for current guns. Electricity for the railgun could be supplied from an on-board compulsator, which in turn could be powered by the ship's engines. However the main advantage for naval forces is range; the US Navy plans to deploy railguns with ranges over 250 miles (400 km) on naval vessels as early as 2012.
There is interest in using railguns as mass drivers for space exploration and mining. Also, railguns may be used to initiate fusion reactions, by firing pellets of fusible material at each other. The impact would create immense temperatures and pressures, allowing nuclear fusion to occur. However current railguns are not yet sufficient to achieve the energies required.
Railguns have also been used to research impacts on orbiting satellites. Railguns can simulate the high velocity of a low mass projectile such as a lost nut or bolt in a zero gravity environment. This allows engineers to verify computer models, test, and develop proper enclosures to protect satellite electronics.