Combustion initiation system

Abstract

A combustion initiation system includes an initiating device for producing, containing and propelling a combustion initiating plasma having an energy density approaching that produced by combustion of the fuel itself, and is suitable for initiating combustion in relatively lean mixtures of various types of fuels. A high voltage power supply delivers electrical energy by a coaxial cable to the initiating device which communicates with a fuel mixture in a combustion area such as the combustion chamber of an ordinary internal combustion engine. The initiating device includes a capacitive portion for storing a large quantity of electrical energy therein derived from the power supply, and an electrode portion integral with the capacitive portion which comprises a pair of concentric, rod shaped electrodes for producing a high energy, umbrella shaped plasma discharge, using the inverse pinch technique. Due to the close proximity between the capacitive and electrode portions of the initiating device, rapid energy transfer from the former to the latter creates high magnetic pressures which transform the discharge into a high energy plasma jet which is delivered well into the combustion area.

What is claimed is: 
     
       1. A device for generating a high energy plasma jet for initiating combustion of fuel, comprising: a first electrode including a rod shaped member and a tip on one extremity of said rod shaped member; .[.and.].   a second electrode electrically insulated from said first electrode and including an annular portion circumscribing the longitudinal axis of said rod shaped member,   said tip being substantially spaced along said longitudinal axis from said annular portion of said second electrode,   said tip and said annular portion defining an annular space therebetween across which electrical current may flow to produce an annularly shaped electrical discharge for initiating combustion of said fuel, the longitudinal spacing between said tip and said annular .[.position.]. .Iadd.portion .Iaddend.being sufficient to allow said discharge to generate .[.a generally cylindrical.]. .Iadd.an .Iaddend.electromagnetic field .[.surrounding said discharge and sufficient in strength to temporarily radially confine.]. .Iadd.for urging .Iaddend.said discharge .Iadd.radially outward from said longitudinal axis; and   means continuous with said first and second electrodes for temporarily storing a quantity of electrical energy therein sufficient to produce said electrical discharge, said device having an inherent inductance sufficiently low to result in the discharge of the stored quantity of electrical energy across said annular space within 60 nanoseconds .Iaddend..   
     
     
       2. The device of claim 1, wherein said first and second electrodes are disposed concentric with respect to said longitudinal axis of said rod shaped member. 
     
     
       3. The device of claim 2, wherein said tip includes a conically shaped outer surface, the outer periphery of said surface being spaced essentially equidistant from said longitudinal axis of said rod member. 
     
     
       4. The device of claim 3, wherein said conically shaped surface forms an angle with respect to a plane extending normal to said longitudinal axis of said rod shaped member, said angle being in the range of between 15 and 90 degrees. 
     
     
       5. The device of claim 3, wherein said tip includes an annularly shaped, flat face contiguous with said conically shaped surface and adjacent the outer periphery of said tip, said annularly shaped flat face forming an angle with respect to said longitudinal axis of said rod shaped member between 0 and 45 degrees. 
     
     
       6. The device of claim 2, wherein said tip includes a hemispherically shaped outer surface. 
     
     
       7. The device of claim 2 wherein said annularly shaped portion of said second electrode includes a first annularly shaped, essentially flat section circumscribing said rod shaped member and immediately adjacent the latter, and a second annularly shaped, essentially flat section circumscribing said first section, said first and second flat sections forming an angle with respect to each other in the range of 0 to 45 degrees. 
     
     
       8. The device of claim 2, wherein said rod shaped member includes a bore extending longitudinally therethrough. 
     
     
       9. The device of claim 2, wherein said annularly shaped portion of said second electrode forms a disk shaped surface circumscribing the circumferential side walls of said rod shaped member. 
     
     
       10. The device of claim 2, wherein said first electrode further includes a tip on one extremity of said rod shaped member, said tip including an annular flange extending radially outward beyond the circumferential side walls of said rod shaped member, and an outer, elongate tip portion longitudinally aligned with said rod shaped member contiguous with said flange. 
     
     
       11. The device of claim 2, wherein said annular portion of said second electrode is disposed adjacent one extremity of said first electrode, said rod shaped member including a cylindrically shaped intermediate section and an annularly shaped flange on .[.the opposite.]..Iadd., said one .Iaddend.extremity thereof, the diameter of said flange being greater than the diameter of said intermediate section of said rod. 
     
     
       12. The device of claim 11, wherein said .[.opposite.]. .Iadd.one .Iaddend.extremity of said rod shaped member terminats in a conically shaped surface. .[.13. The device of claim 2, including means formed integral with said first and second electrodes for temporarily storing a quantity of electrical energy therein sufficient to produce a high energy 
     
     
        plasma jet for initiating combustion of said fuel..]. 14. The device of claim .[.13.]. .Iadd.1.Iaddend., wherein said storing means comprises a capacitor having a pair of spaced-apart, electrical storage plates, one of said plates being contiguous to and coupled with said one electrode, the other of said pair of plates being contiguous to and coupled with said 
     
     
        second electrode. 15. The device of claim 14 wherein said pair of electrical storage plates have a dielectric material interposed therebetween, said dielectric material being selected from the group 
     
     
        consisting of ceramic, water, oil, glycerene, or isopropyl alcohol. 16. The device of claim 15, wherein said rod shaped member is disposed between said tip and said pair of capacitor plates, and each of said capacitor plates of said pair thereof are of generally star shaped cross 
     
     
        section. 17. The device of claim 14, wherein said one capacitor plate of said pair thereof is connected to the opposite extremity of said rod 
     
     
        shaped member. 18. The device of claim 1, including a layer of electrically insulative material surrounding the cylindrical sidewalls of said rod .[.shape.]. .Iadd.shaped .Iaddend.member and interposed between 
     
     
        said annular portion of said second electrode and said rod member. 19. The device of claim 18, wherein said tip is essentially circular in cross section, the circular periphery of said tip extending radially outward beyond the cylindrical sidewalls of intermediate sections of said rod member, whereby the diameter of said tip exceeds the diameter of said 
     
     
        intermediate sections of said rod member. 20. The device of claim 19, wherein the outside diameter of said layer of insulative material is less 
     
     
        in magnitude than the diameter of said tip. 21. An improved device for initiating combustion of fuel in a combustion chamber using a high energy plasma jet, comprising: first and second electrodes communicating with said combustion chamber and defining .[.a.]. .Iadd.an .Iaddend.annular discharge gap therebetween across which .Iadd.a preselected quantity of .Iaddend.electrical energy may be transferred, .Iadd.said preselected quantity of electrical energy being sufficient in magnitude to produce a high energy plasma jet resulting in the initiation of combustion of said fuel, .Iaddend.said first and second electrodes being configured to produce .[.a generally cylindrical.]. .Iadd.a current flow which creates an .Iaddend.electromagnetic field for .[.radially confining the transfer of electrical energy between said electrodes during said transfer;.]. .Iadd.urging the transfer of electrical energy between said electrodes radially outward; and, .Iaddend.   means contiguous with said first and second electrodes and immediately adjacent said combustion chamber for temporarily storing .[.a.]. .Iadd.said preselected .Iaddend.quantity of electrical energy therein .[.sufficient in magnitude to create said high energy plasma jet.].,   said storing means being adapted for electrically coupling with a source of electrical power and electrically connected with each of said first and second electrodes.Iadd., said device having an inherent inductance sufficiently low to result in the discharge of said preselected quantity   
     
     
        across said discharge gap within 60 nanoseconds.Iaddend.. 22. The device of claim 21 wherein: said first and second electrodes are concentrically disposed with respect to each other about a longitudinal axis,   said second electrode being annular in shape and circumscribing portions of said first electrode,   said first electrode being elongate and including a tip portion on one end thereof, said tip portion being spaced from said second electrode along said longitudinal axis, said discharge gap being defined by an annular space surrounding said first electrode between said tip portion and said   
     
     
        second electrode. 23. The device of claim 22, wherein said tip portion is essentially circular in cross section and the periphery of said tip portion extends radially outward from said longitudinal axis beyond the 
     
     
        longitudinal sidewalls of said first electrode. 24. The device of claim 23, wherein said second electrode forms an annular cavity surrounding 
     
     
        essentially the entire length of said first electrode. 25. The device of 
     
     
        claim 24, wherein said annular cavity is dish shaped. 26. The device of claim 22, wherein said second electrode extends radially outward from said longitudinal axis, the interior perimeter of said second electrode being 
     
     
        radially spaced from said first electrode. 27. The device of claim 22, including a layer of electrical insulative material surrounding at least parts of said first electrode including said portions thereof and extending from said tip portion toward the other end of said first 
     
     
        electrode. 28. The device of claim 21, wherein said first electrode is 
     
     
        essentially cylindrical in shape. 29. The device of claim 28, wherein said .Iadd.first .Iaddend.electrode includes a bore extending longitudinally 
     
     
        therethrough. 30. The device of claim 21 wherein said storing means comprises a capacitor including a pair of spaced apart electrical energy storage plates respectively coupled with said first and second electrodes. 
     
     
        1. The device of claim 30, wherein each of said storage plates is 
     
     
        essentially star shaped in cross-section. 32. The device of claim 30, wherein said pair of storage plates are each symmetrically disposed about 
     
     
        said longitudinal axis. 33. The device of claim 32, wherein said first electrode includes a tip portion on one end thereof distal from said 
     
     
        second electrode, said tip portion being generally conical in shape. 34. The device of claim 32, wherein said pair of storage plates are 
     
     
        respectively formed integral with said first and second electrodes. 35. A system for sequentially initiating combustion of a plurality of predefined quantities of fuel, comprising: high voltage generating means adapted to be operably coupled with a source of electrical energy for producing a high electrical voltage;   electrical energy storage means operably coupled with said high voltage generating means for storing a predetermined quantity electrical energy;   a plurality of combustion initiation devices respectively associated with said plurality of said predefined quantities of fuel and spaced distal from said energy storage means, each of said devices including a capacitive portion for storing said predetermined quantity of electrical energy therein and an electrode portion formed integral with said capacitive portion, each said devices being operable to .Iadd.discharge said predetermined quantity of electrical energy through said electrode portion within approximately 60 nanoseconds, said predetermined quantity of electrical energy being sufficient in magnitude to .Iaddend.produce a high energy plasma jet for initiating combustion of the corresponding quantity of fuel, the electrode portion of each of said devices comprising a first electrode including a rod shaped member having a tip on one end thereof and a second electrode electrically insulated from said first electrode and including an annular portion circumscribing the longitudinal axis of said rod shaped member, said tip being substantially spaced from said annular portion, said tip and said annular portion defining an annular space therebetween across which electrical current may be transferred to produce an .[.annularly shaped.]. electrical discharge, the longitudinal spacing between said tip and said annular portion being sufficient to allow said discharge to generate .[.a generally cylindrical.]. .Iadd.an electrical current flow producing an .Iaddend.electromagnetic field .[.enveloping said discharge, said field being.]. sufficient in strength .[.to temporarily radially restrain said discharge whereby to increase the energy density of said discharge.]. .Iadd.for moving said discharge, said predetermined quantity of electrical energy being sufficient to produce said magnetic field.Iaddend.; and   timing control means operably coupled with said electrical energy storage means and with each of said initiation devices for selectively coupling said electrical energy storage means with said initiation devices in a predetermined timed .[.sequency.]. .Iadd.sequence .Iaddend.whereby to sequentially deliver said predetermined quantity of electrical energy from said storage means to individual ones of said capacitive portions of said   
     
     
        initiation devices. 36. The system of claim 35, wherein: said second electrode is disposed concentric with respect to said first electrode about said longitudinal axis, and   said first electrode includes a layer of electrically insulative material covering said rod shaped member and extending between said tip and said   
     
     
        annular portion of said second electrode. 37. The system of claim 36, wherein said rod shaped member is essentially circular in cross section, the diameter of said tip being greater in magnitude than the diameter of intermediate sections of said rod shaped member between said tip and said 
     
     
        annular portion of said second electrode. 38. The system of claim 37, 
     
     
        wherein said tip is generally conical in shape. 39. The system of claim 36, wherein said annular portion of said second electrode extends radially outward from said longitudinal axis, the inner periphery of said annular portion being spaced from the longitudinal sidewalls of said rod shaped 
     
     
        member. 40. The system of claim 36 wherein said insulative material is 
     
     
        selected from the group consisting of glass or ceramic. 41. The system of claim 35, wherein said capacitive portion of each of said devices comprises a pair of electrically conductive, spaced apart plates defining a capacitor and respectively contiguous with said first and second 
     
     
        electrodes. 42. The system of claim 41, wherein each of said plates is symmetrically disposed about said longitudinal axis, said plates being respectively electrically connected to said annular portion of said second 
     
     
        electrode and to the opposite extremity of said rod shaped member. 43. The system of claim 41, including a layer of dielectric substance interposed 
     
     
        between said plates. 44. The system of claim 43, wherein said dielectric substance is one selected from the group consisting of water, oil, 
     
     
        glycerine, isopropyl alcohol or ethylene glycol. 45. The system of claim 41, wherein each of said plates comprises a plurality of sections, each of said sections extending essentially radially outward from said 
     
     
        longitudinal axis. 46. The system of claim 35, wherein said high voltage generation means is capable of producing an output of at least 
     
     
        approximately 15,000 volts. 47. The system of claim 35, where said high 
     
     
        voltage generating means comprises a pulse type voltage generator. 48. The system of claim 35, wherein said high voltage generating means includes an output for delivering high voltage electrical energy thereto, said storage means being electrically coupled to said output of said generating means, said timing control means comprising: distribution circuit means coupled with each of said initiation devices and with said storage means for selectively distributing electrical energy from said storage means to the corresponding one of said initiation   
     
     
        devices. 49. The system of claim 48, wherein distribution circuit means comprises a plurality of electrical circuits respectively associated with said initiation devices, each of said circuits comprising an electronic switch connected between said storage means and the respectively associated initiation device, and an electronic trigger operably coupled 
     
     
        with said switch for controlling the latter. 50. The system of claim 49, wherein said timing control means further includes: first control means operably coupled with said storage means for controlling the discharge of electrical energy stored in said storage means from the latter to said distribution circuit means, and   second control means operably coupled with said first control means and with each of said electrical circuits for selectively delivering a control signal simultaneously to a selected one of said electrical circuits and to   
     
     
        said first control means. 51. The system of claim 50, wherein said first control means comprises a pair of spaced apart electrical terminals defining a spark gap therebetween and a third electrical terminal coupled with said second control means for inducing electrical breakdown of the 
     
     
        medium between said pair of electrical terminals. 52. The system of claim 50, wherein said second control means comprises: a first electrical terminal adapted to be coupled with a source of electrical power,   a plurality of electrical terminals respectively coupled with said electrical circuits, and   means for selectively coupling said first electrical terminal with one of   
     
     
        said plurality of electrical terminals. 53. The system of claim 50, wherein said timing control means further includes an inductor operably 
     
     
        coupled between said first and second control means. 54. The system of claim 35, wherein said high voltage generating means is provided with an input and there is further provided: a source of electrical power operably coupled with said high voltage   
     
     
        generating means. 55. The system of claim 54, wherein said source of electrical energy comprises a battery and means operably coupled with said 
     
     
        battery for recharging the latter. 56. The system of claim 35, including a coaxial electrical cable operably coupled between each of said initiation devices and said timing control means, said cable comprising an inner and outer conductor, said inner and outer conductors being operably coupled with the capacitive portion of the corresponding initiation device. 
     
     
        .Iadd. 7.  Apparatus for initiating combustion of fuel, comprising: first and second electrodes defining a gap across which a preselected quantity of electrical energy may be discharged, the magnitude of said preselected quantity of electrical energy being sufficient to form a high energy plasma for initiating combustion of said fuel; and   capacitor means substantially contiguous with said first and second electrodes for storing said preselected quantity of electrical energy, the inductance of said electrodes and said capacitor means being sufficiently low to allow said preselected quantity of electrical energy to be discharged across said gap within 60 nanoseconds..Iaddend. .Iadd.58. The apparatus of claim 57, wherein said first and second electrodes are symmetric about a common axis. .Iaddend. .Iadd.59. The apparatus of claim 58, wherein said discharge gap is annular in shape and is disposed coaxial with and longitudinally along said common axis. .Iaddend. .Iadd.60. The apparatus of claim 57, wherein said capacitor means includes first and second storage plates respectively connected to said first and second electrodes. .Iaddend. .Iadd.61. The apparatus of claim 57, including means coupled with said capacitor means for charging said capacitor means with said preselected quantity of electrical energy in less than approximately   
     
     
        10 microseconds. .Iaddend. .Iadd.62.  The apparatus of claim 58, wherein said preselected quantity of electrical energy stored in said capacitor means produces an electrical current through said electrodes sufficient in magnitude to create an inverse pinch electrical discharge across said gap and between said electrodes, and to develop a magnetic pressure for moving said discharge radially outward from said axis, the quantity of said electrical current being given by ##EQU5## 
     
     
        .Iaddend. .Iadd.63.  A device for initiating combustion of a gaseous air-fuel mixture in a combustion chamber using a high energy plasma, comprising: first and second electrodes symmetric about a reference axis and defining an electrical discharge gap; and   means coupled with said electrodes for storing a preselected quantity of electrical energy sufficient in magnitude to produce an electrical discharge between said electrodes across said gap, said discharge resulting in the initiation of combustion of said gaseous air-fuel mixture,   said electrodes and said storing means defining an electrical discharge circuit in said device, said discharge circuit having an inherent inductance and being configured to minimize said inherent inductance and thereby maximize the magnitude of magnetic power generated by the current flowing in said discharge circuit,   the inherent inductance of said discharge circuit being sufficiently low to result in the transfer of preselected quantity of electrical energy from said storing means to the electrical discharge in less than approximately   
     
     
        60 nanoseconds. .Iaddend. .Iadd.64.  The device of claim 63, wherein: said first and second electrodes and said discharge gap are coaxial, said discharge gap being annular in shape and extending longitudinally along said axis,   said preselected quantity of electrical power and said magnetic power being sufficient in magnitude to create an inverse pinch electrical discharge between said electrodes across said gap. .Iaddend.