Railgun is a projectile launcher which works on the principles of electromagnetism. Rail gun is a weapon that uses neither explosive nor the propellant but accelerates the projectile with high kinetic energy due to magnetic forces. The explosive powered military guns are capable of gaining readily a velocity of 2 km per second but Rail guns can accelerate the projectile beyond 3 km/s readily and in this way it is superior to the conventionally used long range weapons. The additional advantages of the Rail gun include the absence of explosive or warheads and low cost of the projectiles.
It consists of two parallel rails on which a rod (armature) is capable of moving. The rails are connected with . When a conducting rod is placed over the rails, circuit is completed and current starts to flow, entering through one rail and exiting through the other. The whole arrangement is placed inside an external magnetic field. The rod is accelerated by the magnetic effects of the current through rod. The conducting rod experiences the Lorentz force, because it is subjected to electric as well as magnetic field simultaneously.
It is important to note that the rails and the armature should be made of highly conducting materials. The rails must be capable of accelerating the armature and to bear the increase in temperature due o friction of the projectile with the rails.
The working principle of the Rail gun is like the electric motor. But it differs from it in the aspects that it has no winding. Actually it consists of a single loop of wire and thus requires millions of amperes current. The projectile may be electrically insulated nonconductor or the armature may be the partial part of the projectile. Usually the armature is solid made of metal; however the hybrid or plasma armatures are also used. A typical military Railgun should achieve a velocity of nearly 2000 m/s to 3500 m/s.
In comparison with ordinary explosive propellant powered guns, the Railgun may achieve very high launching speeds with the benefit of prolonged firing range. Generally velocities if Rail gun are compare-able with the velocities achieved by the light gas guns. But it is important to note that the light gas gun is considered suitable for laboratory test whereas the Railgun is of the standard of the military weapons.
Launching Space crafts:
For launching a space craft from earth’s surface we need high accelerating forces which accelerate the rocket within a small range (i.e. few kilometers). Lengthy helical tracks or a huge ring design may also do the same job.
But this can be efficiently done with the help of Rail gun which under ideal circumstances costs 528 $ per kilogram compared with 5000 $/kg.
As a Weapon:
propellant enables it to accelerate the projectile to a very high velocity of above 2,500 m/s as compared to M16 rifle. The rifle has a muzzle velocity of 930 m/s.
We may also use the Rail gun as an anti-air craft gun.