USH237H - Armature for small caliber electromagnetic launch projectile - Google Patents
Armature for small caliber electromagnetic launch projectile Download PDFInfo
- Publication number
- USH237H USH237H US06/895,014 US89501486A USH237H US H237 H USH237 H US H237H US 89501486 A US89501486 A US 89501486A US H237 H USH237 H US H237H
- Authority
- US
- United States
- Prior art keywords
- projectile
- hole
- securing
- armature
- body portion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B6/00—Projectiles or missiles specially adapted for projection without use of explosive or combustible propellant charge, e.g. for blow guns, bows or crossbows, hand-held spring or air guns
- F42B6/006—Projectiles for electromagnetic or plasma guns
Definitions
- 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 ⁇ 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.
- the invention concerns a small caliber projectile for electromagnetic launchers, which reduces projectile armature and rail erosion.
- a projectile 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.
- Another object of the invention is to provide an improved armature for a small caliber electromagnetic launch projectile weapon.
- Another object of this invention is to provide a projectile arrangement for launching by an electromagnetic launching mechanism.
- FIG. 1 illustrates an electromagnetic launch projectile
- FIG. 2 shows a frontal view of a cathode coated washer
- FIG. 3 shows a side, sectional view of the washer in FIG. 2;
- FIG. 4 shows an exploded view of a projectile in accordance with the present invention
- FIG. 5A shows a first alternate body portion of a projectile
- FIG. 5B shows a second alternate body portion for a projectile.
- FIG. 1 shows a projectile for launching with electromagnetic launchers.
- the projectile (10) includes an armature (12) consisting of approximately 60 copper washers (14).
- the washers (14) are stacked together and held in place between forward and rear phenolics (18, 20).
- an arc drop during launch occurs, which at the multi-kiloampere rail current, causes excessive heating and material erosion to the rail and armature.
- FIG. 2 An embodiment according to this invention, is illustrated in FIG. 2.
- a washer (22) typically comprised of a refractory metal such as tungsten, molybdenum, tantalum or rhenium is shown in frontal view.
- the thin film ring (26) is comprised of, a barium, strontium carbonate cathode coating mixture, as one example, deposited on the washer (22) surface.
- FIG. 3 shows a cross-section of the FIG. 2 device.
- the thin film (ring 26) of thickness (28), normal to the surface of the washer (22), will determine the separation between any adjacent washers. This aspect is discussed with respect to FIG. 4.
- FIG. 4 depicts a projectile in accordance with the present invention.
- the projectile (30) includes a series of washers (22) having thin film ring cathodes (26), the series of washers comprising a body portion.
- the front of the projectile (30) is a nose (32) having a threaded hole (34).
- a tail section (36) has a hole (38) through which a threaded device (40) passes.
- the threaded device (40) may comprise a screw or bolt which mates with the threaded hole (34) of the nose (32) such that the body portion (in this embodiment the series of washers (22)) and tail (36) are secured to the nose (32).
- the washer stack could be replaced with a porous (FIG. 5a) or wafer structure (FIG. 5b) in which low work function material embedded in a refractory metal matrix, comprises the entire body portion.
- the low work function material is drawn to the surface of the rail-armature interface by the heat generated by the electric arcing at the rail-armature interface.
- the low work function material reaches the surface of a rail-armature interface to reduce arc drop.
- the washer stack could include one or more copper uncoated washers interdispersed to provide the optimum benefits of thermal conductivity from the copper and the optimum amount of electron emission from the coated washers.
- An armature realized in accordance with FIG. 4 will reduce rail-armature arcing losses by lowering the work function of the armature surface.
- the cathode material activates the low work function metal (cesium, barium, strontium calcium or strontium) is chemically released.
- the separation between the washers provided by the thickness of the coating also functions as a capillary drawing the low work function metal towards the armature surface.
- the low work function metal coats the bare refractory metal surface lowering the overall armature work function.
- the washer stack with its layers of thermally isolating thin film rings (26) separating individual washers also serve to constrain the heating of the projectile to the armature region.
- a plasma comprised of electrons and ions, forms in the rail-armature interstice having a low arc drop characteristic of an alkali metal discharge. This plasma will appear behind the projectile as well as the interstice. The plasma should provide an additional force of the self-generated current density of the plasma interacting with the current it carries.
- the specific design of the armature and the spacing of the rail-armature interstice will determine the proportunate contributions of the J ⁇ B and/or plasma forces acting on the projectile.
- a cathode coating may be easily deposited, by a spray gun, evaporation or through impregnation techniques.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- Plasma Technology (AREA)
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
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×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.
Other objects and attendant advantages of this invention will become apparent from a study of the attached specification and a viewing of the drawings in which:
FIG. 1 illustrates an electromagnetic launch projectile;
FIG. 2 shows a frontal view of a cathode coated washer;
FIG. 3 shows a side, sectional view of the washer in FIG. 2;
FIG. 4 shows an exploded view of a projectile in accordance with the present invention;
FIG. 5A shows a first alternate body portion of a projectile; and
FIG. 5B shows a second alternate body portion for a projectile.
FIG. 1 shows a projectile for launching with electromagnetic launchers. The projectile (10) includes an armature (12) consisting of approximately 60 copper washers (14). The washers (14) are stacked together and held in place between forward and rear phenolics (18, 20). With such a projectile (10), an arc drop during launch occurs, which at the multi-kiloampere rail current, causes excessive heating and material erosion to the rail and armature.
An embodiment according to this invention, is illustrated in FIG. 2. A washer (22) typically comprised of a refractory metal such as tungsten, molybdenum, tantalum or rhenium is shown in frontal view. Accordingly, the thin film ring (26) is comprised of, a barium, strontium carbonate cathode coating mixture, as one example, deposited on the washer (22) surface.
FIG. 3 shows a cross-section of the FIG. 2 device. Here, it is evident that the thin film (ring 26) of thickness (28), normal to the surface of the washer (22), will determine the separation between any adjacent washers. This aspect is discussed with respect to FIG. 4.
FIG. 4 depicts a projectile in accordance with the present invention. The projectile (30) includes a series of washers (22) having thin film ring cathodes (26), the series of washers comprising a body portion. The front of the projectile (30) is a nose (32) having a threaded hole (34). A tail section (36) has a hole (38) through which a threaded device (40) passes. The threaded device (40) may comprise a screw or bolt which mates with the threaded hole (34) of the nose (32) such that the body portion (in this embodiment the series of washers (22)) and tail (36) are secured to the nose (32).
The washer stack could be replaced with a porous (FIG. 5a) or wafer structure (FIG. 5b) in which low work function material embedded in a refractory metal matrix, comprises the entire body portion. The low work function material is drawn to the surface of the rail-armature interface by the heat generated by the electric arcing at the rail-armature interface. The low work function material reaches the surface of a rail-armature interface to reduce arc drop. The washer stack could include one or more copper uncoated washers interdispersed to provide the optimum benefits of thermal conductivity from the copper and the optimum amount of electron emission from the coated washers.
An armature realized in accordance with FIG. 4 will reduce rail-armature arcing losses by lowering the work function of the armature surface. When the cathode material activates the low work function metal (cesium, barium, strontium calcium or strontium) is chemically released. The separation between the washers provided by the thickness of the coating also functions as a capillary drawing the low work function metal towards the armature surface. There the low work function metal coats the bare refractory metal surface lowering the overall armature work function. The washer stack with its layers of thermally isolating thin film rings (26) separating individual washers also serve to constrain the heating of the projectile to the armature region.
A plasma, comprised of electrons and ions, forms in the rail-armature interstice having a low arc drop characteristic of an alkali metal discharge. This plasma will appear behind the projectile as well as the interstice. The plasma should provide an additional force of the self-generated current density of the plasma interacting with the current it carries. The specific design of the armature and the spacing of the rail-armature interstice will determine the proportunate contributions of the J×B and/or plasma forces acting on the projectile.
A cathode coating may be easily deposited, by a spray gun, evaporation or through impregnation techniques.
Other substitutions and modifications to the invention will become apparent to those skilled in the art, which do not depart from the scope of the invention.
Claims (18)
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.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/895,014 USH237H (en) | 1986-08-06 | 1986-08-06 | Armature for small caliber electromagnetic launch projectile |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/895,014 USH237H (en) | 1986-08-06 | 1986-08-06 | Armature for small caliber electromagnetic launch projectile |
Publications (1)
Publication Number | Publication Date |
---|---|
USH237H true USH237H (en) | 1987-03-03 |
Family
ID=25403831
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/895,014 Abandoned USH237H (en) | 1986-08-06 | 1986-08-06 | Armature for small caliber electromagnetic launch projectile |
Country Status (1)
Country | Link |
---|---|
US (1) | USH237H (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5005484A (en) * | 1986-05-09 | 1991-04-09 | Rheinmetall Gmbh | Projectile for firing from an electromagnetic projectile acceleration device |
US5191164A (en) * | 1991-04-01 | 1993-03-02 | The United States Of America As Represented By The Department Of Energy | Hybrid armature projectile |
US5237904A (en) * | 1988-01-05 | 1993-08-24 | Kuhlmann Wilsdorf Doris | Armature/projectile for a single or multi-turn rail gun |
FR2706112A1 (en) * | 1993-03-29 | 1994-12-09 | Fmc Corp | Arc plasma injectors in series. |
US20050155487A1 (en) * | 2003-12-24 | 2005-07-21 | Frasca Joseph F. | Improvements to Electromagnetic Propulsion Devices |
US20070156140A1 (en) * | 2003-05-01 | 2007-07-05 | Ali Baily | Method of fusing biomaterials with radiofrequency energy |
US20100194212A1 (en) * | 2008-08-23 | 2010-08-05 | George Arthur Proulx | Railgun system |
US8438767B2 (en) * | 2006-10-24 | 2013-05-14 | P-Bar Co., Llc | Expanding projectile |
-
1986
- 1986-08-06 US US06/895,014 patent/USH237H/en not_active Abandoned
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5005484A (en) * | 1986-05-09 | 1991-04-09 | Rheinmetall Gmbh | Projectile for firing from an electromagnetic projectile acceleration device |
US5237904A (en) * | 1988-01-05 | 1993-08-24 | Kuhlmann Wilsdorf Doris | Armature/projectile for a single or multi-turn rail gun |
US5191164A (en) * | 1991-04-01 | 1993-03-02 | The United States Of America As Represented By The Department Of Energy | Hybrid armature projectile |
FR2706112A1 (en) * | 1993-03-29 | 1994-12-09 | Fmc Corp | Arc plasma injectors in series. |
US20070156140A1 (en) * | 2003-05-01 | 2007-07-05 | Ali Baily | Method of fusing biomaterials with radiofrequency energy |
US20050155487A1 (en) * | 2003-12-24 | 2005-07-21 | Frasca Joseph F. | Improvements to Electromagnetic Propulsion Devices |
US7077047B2 (en) * | 2003-12-24 | 2006-07-18 | Joseph Franklin Frasca | Electromagnetic propulsion devices |
US8438767B2 (en) * | 2006-10-24 | 2013-05-14 | P-Bar Co., Llc | Expanding projectile |
US20100194212A1 (en) * | 2008-08-23 | 2010-08-05 | George Arthur Proulx | Railgun system |
US8109190B2 (en) * | 2008-08-23 | 2012-02-07 | George Arthur Proulx | Railgun system |
US8387509B1 (en) * | 2008-08-23 | 2013-03-05 | George Arthur Proulx | Railgun system |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Oks et al. | Development of plasma cathode electron guns | |
USH237H (en) | Armature for small caliber electromagnetic launch projectile | |
EP0200035B1 (en) | Electron beam source | |
US6373023B1 (en) | ARC discharge initiation for a pulsed plasma thruster | |
WO2017216802A1 (en) | Inline screw feeding vacuum arc thruster | |
US3397337A (en) | Flash X-ray dielectric wall structure | |
JP5357879B2 (en) | Apparatus for reducing the application of positively charged ions to a surface portion, and ion accelerator | |
CN115898802B (en) | Hall thruster, space device comprising same and use method thereof | |
JPH03500109A (en) | Plasma switch with disordered chromium cold cathode | |
US3315125A (en) | High-power ion and electron sources in cascade arrangement | |
US3744247A (en) | Single grid accelerator for an ion thrustor | |
US4563828A (en) | Detonator mechanism for cartridges, particularly for cartridges used in manual weapons | |
US8587227B2 (en) | Electrostatic ion accelerator arrangement | |
US5008585A (en) | Vacuum arc sources of ions | |
US3308329A (en) | Thermionic emissive cathode with end structure for emissive suppression | |
US3843901A (en) | Multi-beam cathode ray tube construction | |
GB1578167A (en) | Ion generating source | |
US3862449A (en) | Ion sleeve for arc lamp electrode | |
US5089707A (en) | Ion beam generating apparatus with electronic switching between multiple cathodes | |
US5191164A (en) | Hybrid armature projectile | |
GB2123934A (en) | Electromagnetic projectile launcher with explosive-start and plasma drive | |
US3552124A (en) | Ion thrustor accelerator system | |
US2858470A (en) | Cathode for electron discharge devices | |
US11990307B2 (en) | Electron gun | |
US10863612B2 (en) | System for generating a plasma jet of metal ions |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |