TREA

Armature for small caliber electromagnetic launch projectile

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Information

  • Patent Grant
  • H237
  • Patent Number
    H237
  • Date Filed
    Wednesday, August 6, 1986
    38 years ago
  • Date Issued
    Tuesday, March 3, 1987
    37 years ago
  • Inventors
  • Original Assignees
  • Examiners
    • Tudor; Harold J.
    Agents
    • Lane; Anthony T.
    • Card, Jr.; Harold H.
    • Sachs; Michael C.
Information
Abstract
The invention concerns an electromagnetically launched projectile having anrmature comprised of refractory metal washers, each of which being coated with a thin film of cathode emitter material. The low work function metal generated by the heat of arcing rises to the armature surface through the capillaries formed between the armature washers. The arc occuring between the rail of the electromagnetic launcher and the armature is lowered due to the formation of a low voltage metallic discharge. The reduced arc drop lowers the erosion rate on the rails which reduces the rail damage resulting in increased firing rate and longer rail life.
Description
Claims
  • 1. A projectile means, for launching via an electromagnetic launching means, including:
  • a nose end;
  • a body portion having a material comprising a means for providing a low-work function relative to the electromagnetic launching means;
  • a tail end; and
  • a securing means for engaging the nose end, and for securing the body portion and tail end to the nose end.
  • 2. A projectile means as in claim 1, the body portion having an orifice through which the securing means passes.
  • 3. A projectile means as in claim 2, the material being porous.
  • 4. A projectile means as in claim 3, the body portion comprising one solid porous element.
  • 5. A projectile means as in claim 4, the nose end having a hole with which the securing means mates.
  • 6. A projectile means as in claim 5, the securing means comprising a threaded device, and the hole having threads into which the securing means is threaded to mate with the hole.
  • 7. A projectile means as in claim 3, the body portion comprising a series of adjacent wafers.
  • 8. A projectile means as in claim 7, the nose end having a hole with which the securing means mates.
  • 9. A projectile means as in claim 8, the securing means comprising a threaded device, and the hole having threads into which the securing means is threaded to mate with the hole.
  • 10. A projectile means as in claim 2, the body portion comprising a series of disc-like means separated from one another by the means for providing a low work function material.
  • 11. A projectile means as in claim 10, the disc-like means comprising a washer.
  • 12. A projectile means as in claim 11, the means for providing a low work function material bonded to at least one side of each washer.
  • 13. A projectile means as in claim 12, the means for providing a low work function material comprising a thin film ring attached to the washer side toward the circumference of the washer.
  • 14. A projectile means as in claim 13, the ring having a thickness normal to the washer side, which determines the separation between adjacent washers.
  • 15. A projectile means as in claim 14, the nose end having a hole with which the securing means mates.
  • 16. A projectile means as in claim 15, the securing means comprising a threaded device, and the hole having threads into which the securing means is threaded to mate with the hole.
  • 17. A projectile means as recited in claim 10, wherein each said washer is formed of refractory metal material with an electron emissive coating on the peripheral area thereof to provide spacing between the respective washers.
  • 18. A projectile means as in claim 10, wherein the disc-like means comprises a plurality of interdispersed refractory coated washers with copper washers.
GOVERNMENTAL INTEREST

The invention described herein may be made, used, or licensed by or for the Government for Governmental purposes, without the payment to me of any royalties thereon. A small caliber electromagnetic launcher typically comprises a projectile, a rail launcher and a power generating means. The electromagnetic launcher might be a linear induction motor, where the projectile is accelerated along rails by a J.times.B force, where J is current density and B is magnetic flux density. To generate such a force however requires current to travel on the rails and pass between the rails through a conducting portion of the projectile, this conduction portion being known as the projectile armature. The greatest limitation to electromagnetic launchers however is believed found in the capabilities of the armature of the projectile and rails. The arc drop (approximately 20 volts) occurring between the rail and armature during launch of the projectile, with the multi-kiloampere rail current, causes excessive heating and a material erosion. Clearly therefore any improvements in such mechanisms that would reduce the erosion, in armature and rail, and other advances to the art and science of rail gun weapons, would be of significant value for use in the field. The invention concerns a small caliber projectile for electromagnetic launchers, which reduces projectile armature and rail erosion. A projectile is presented having a nose; a body portion which functions as an armature when electromagnetically launched (e.g., as a rail gun); a tail end; and a threaded device which secures the body portion and tail to the nose via a threaded hole. The body portion comprises a series of washers to which a ring of low-work function material is bonded, the thickness of which determines the separation between adjacent washers. The material is a thin film of cathode coating. The body portion may also comprise a single solid porous refractory element with a low-work function material embedded within its pores, or a stack of coated wafers that could include some fraction of copper uncoated wafers interdispersed. Accordingly, the arc drop occurring at the rail-armature interface is reduced by the emission of surface electrons at low temperatures, thus reducing rail and armature erosion. Accordingly, it is an object of this invention to provide an improved rail gun, capable of withstanding rail and armature erosion. Another object of the invention is to provide an improved armature for a small caliber electromagnetic launch projectile weapon. And even another object of this invention is to provide a projectile arrangement for launching by an electromagnetic launching mechanism.