Coilgun
A coilgun (not to be confused with a railgun) is a type of magnetic accelerator gun (MAG) or magnetic accelerator cannon (MAC). It uses one or more electromagnetic coils to accelerate a magnetic shell to very high velocities. The name "Gauss gun" is a reference to Carl Friedrich Gauss, who formulated mathematical descriptions of the electromagnetic effect used by magnetic accelerators. Coilguns work according to the same magnetic principle as the Gauss gun, but their methods vary: both guns use an attractive magnetic force to accelerate the projectile, but Gauss guns use electromagnets while coilguns use solenoids.[1]
Overview
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Many hobbyists use low-cost rudimentary designs to experiment with coilguns, for example using photoflash capacitors from a disposable camera as the energy source, and a low inductance coil to propel the projectile forward.
Construction
A coilgun, as the name implies, consists of a coil of wire (or solenoid) with a ferromagnetic projectile placed at one of its ends. A large current is pulsed through the coil and a strong magnetic field forms, pulling the projectile to the center of the coil. When the projectile nears this point, the coil is switched off and a next coil can be switched on, progressively accelerating the projectile down successive stages. In common coilgun designs, the "barrel" of the gun is made up of a track that the projectile rides on, with the driver coils around the track. Power is supplied to the coils from some sort of fast discharge storage device, typically a battery of high-capacity high voltage capacitors designed for fast energy discharge.
A superconducting coilgun called a quench gun could be created by successively quenching a line of adjacent coaxial superconducting coils forming a gun barrel, generating a wave of magnetic field gradient travelling at any desired speed. A travelling superconducting coil might be made to ride this wave like a surfboard. The device would be a mass driver or linear synchronous motor with the propulsion energy stored directly in the drive coils.
Main Coilgun Types
There are two main types or setups of a coilgun, single stage and multistage. A single stage coilgun uses just one coil to propel a ferromagnetic projectile. A multistage coilgun uses multiple coils in succession to progressively increase the speed of the projectile. The animated figure above is an example of a multistage coilgun, as it uses more than one coil to increase the speed of the projectile.
Potential uses
Like railguns and ram accelerators, coilguns have been proposed for use in delivering payloads to space.
A coilgun has no moving parts other than the projectile, and the only noise produced is by the projectile moving. These attributes may make it attractive as a weapon.
Limitations
Despite heavy research and development by the amateur and professional community, great obstacles have yet to be overcome. One of the greatest limitations to the coil gun is the rate at which the ferromagnetic projectile becomes fully saturated by the magnetic field and the rate at which it looses its magnetic saturation. Once a ferromagnetic object becomes completely saturated the amount of force in which it can be attracted stops to increase. The rate at which the projectile looses its saturation is critical; as this rate is constant, greater distances betweens drive coils are needed to compensate for this rate. As the projectile increases in speed it reaches drive coils at progressively faster rates. Without compensation for desaturation time their will be less and less effect to the velocity of the projectile; resulting in exponentially lower efficiency per drive coil stage as the projectile travels down the line. Once the amount of force exerted to the projectile is less then or equal to the amount resistance exerted on the projectile due to air friction and friction in the barrel the projectile will no longer gain in velocity.
Coilguns in science fiction
Coilguns are a popular device in science fiction, especially sci-fi role playing and video games, where they go under such names Gauss cannon, Gauss rifle, or Magnetic Accelerator Cannon. The examples are numerous. One example is presented in Neal Asher's recent novel, The Voyage of the Sable Keech, in which an alien spaceship deploys a coilgun in orbit around the planet central to the storyline, to attempt to destroy a target within the a deep ocean on that planet.
References
- ^ B. N. Turman and R. J. Kaye, EM Mortar Technology Development For Indirect Fire, Sandia National Laboratories, Albuquerque, NM, 87185-1182
External links
- Another Coil Gun Site
- Gauss Pistol Site
- Thinkbotics EM-15 Coil Gun Rifle
- Coilgun for Robosapien
- SciToys Gauss Rifle (Not a Coil Gun)
- The Gauss Rifle Mark I (Not a coil gun)
- How to make a simple gauss gun (Not a coil gun)
Posting of links to advertisements of products for sale will not be tolerated! Non Coilgun links will be marked/or deleted accordingly