EP1186211A1 - Plasma torch comprising electrodes separated by an air gap and igniter incorporating same - Google Patents

Plasma torch comprising electrodes separated by an air gap and igniter incorporating same

Info

Publication number
EP1186211A1
EP1186211A1 EP01919603A EP01919603A EP1186211A1 EP 1186211 A1 EP1186211 A1 EP 1186211A1 EP 01919603 A EP01919603 A EP 01919603A EP 01919603 A EP01919603 A EP 01919603A EP 1186211 A1 EP1186211 A1 EP 1186211A1
Authority
EP
European Patent Office
Prior art keywords
electrodes
plasma torch
torch
electrode
plasma
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.)
Withdrawn
Application number
EP01919603A
Other languages
German (de)
French (fr)
Inventor
Luc Brunet
Jean Mary Lombard
Jean François PIERROT
Jean-Luc Taillandier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nexter Munitions SA
Original Assignee
Giat Industries SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Giat Industries SA filed Critical Giat Industries SA
Publication of EP1186211A1 publication Critical patent/EP1186211A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
    • F42C19/00—Details of fuzes
    • F42C19/08—Primers; Detonators
    • F42C19/0823—Primers or igniters for the initiation or the propellant charge in a cartridged ammunition
    • F42C19/0826—Primers or igniters for the initiation or the propellant charge in a cartridged ammunition comprising an elongated perforated tube, i.e. flame tube, for the transmission of the initial energy to the propellant charge, e.g. used for artillery shells and kinetic energy penetrators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B5/00—Cartridge ammunition, e.g. separately-loaded propellant charges
    • F42B5/02—Cartridges, i.e. cases with charge and missile
    • F42B5/08—Cartridges, i.e. cases with charge and missile modified for electric ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
    • F42C19/00—Details of fuzes
    • F42C19/08—Primers; Detonators
    • F42C19/0807—Primers; Detonators characterised by the particular configuration of the transmission channels from the priming energy source to the charge to be ignited, e.g. multiple channels, nozzles, diaphragms or filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
    • F42C19/00—Details of fuzes
    • F42C19/08—Primers; Detonators
    • F42C19/0811—Primers; Detonators characterised by the generation of a plasma for initiating the charge to be ignited
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
    • F42C19/00—Details of fuzes
    • F42C19/08—Primers; Detonators
    • F42C19/0823—Primers or igniters for the initiation or the propellant charge in a cartridged ammunition
    • F42C19/083—Primers or igniters for the initiation or the propellant charge in a cartridged ammunition characterised by the shape and configuration of the base element embedded in the cartridge bottom, e.g. the housing for the squib or percussion cap
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/52—Generating plasma using exploding wires or spark gaps

Definitions

  • the technical field of the invention is that of plasma torches and more particularly torches used to ignite a propellant charge of an ammunition.
  • a plasma torch is a system that generates gases at high pressure (of the order of 500 MPa) and at high temperature (greater than 10,000 K) from a high voltage electrical discharge (from 20 kV) caused between two electrodes.
  • Plasma torches are used in industry to cut, for example, conductive materials, or to destroy certain products or materials, or to make metallic deposits. They are also used in the armament field to generate pressure allowing the firing of a projectile.
  • Known plasma torches comprise an anode and a cathode separated by a capillary tube made of a material which is both electrical insulator and capable of decomposing to generate a plasma (for example a plastic material).
  • the electrical discharge between anode and cathode is started by means of a copper or other conductive material fuse.
  • the electric arc thus created causes a plasma which ablates the wall of the capillary tube, which causes the generation of light gases at high pressure and high temperature.
  • These gases are used either to directly accelerate a projectile, or to vaporize a working fluid (for example water) which makes it possible to increase the volume of gas.
  • a working fluid for example water
  • the torch according to the invention has improved resistance to mechanical stress which increases its reliability.
  • it is simple in structure and can be manufactured at lower cost.
  • the torch according to the invention can be produced without difficulty with very different lengths.
  • the invention also relates to an igniter using such a plasma torch, an igniter making it possible to facilitate the diffusion of the plasma towards the propellant charge, and this for very different charging configurations from the point of view of mass or geometry.
  • the subject of the invention is a plasma torch comprising at least two electrodes separated by a cylindrical insulating case delimiting an internal volume, torch characterized in that the electrodes are separated by a distance sufficiently reduced so that an arc of ignition between the electrodes when a supply voltage supplied by a generator is applied between them, the distance between the electrodes and the supply voltage of the generator being chosen such that the electric field appearing between the electrodes is of the order of 1 egavolt / meter.
  • the torch may include a rear electrode and a front electrode, the rear electrode comprising an axial tip oriented towards the front electrode and the front electrode comprising a thinned crown oriented towards the rear electrode and an axial bore.
  • the axial drilling of the front electrode may have a nozzle profile comprising a converging conical profile open from the side of the rear electrode and followed by a divergent conical profile open towards the outside of the torch.
  • the torch may include a block of energetic material disposed between the electrodes.
  • the block may be annular.
  • the torch will generally include a metal body having an axial bore inside which the electrodes and the insulating case are arranged.
  • the bore of the body may include a shoulder on which the front electrode is applied, the insulating cylindrical case being in axial support, on the one hand on the front electrode and on the other hand on the rear electrode, a ring of insulating closure being screwed at a rear thread of the body and ensuring the axial connection of the electrodes and the insulating case with the body.
  • the closure ring may include a lip surrounding a thinned extension of the insulating case.
  • the front electrode may include a cylindrical surface on which the insulating case will be adjusted.
  • the torch may include a spacer ring coaxial with the insulating case and interposed between the front electrode and the energy unit, the latter being supported on a counterbore made on the insulating case.
  • the invention also relates to an igniter for ammunition which is characterized in that it comprises at least one such plasma torch.
  • the igniter may include a tubular diffuser pierced with at least one hole and integral with the torch at a front portion thereof so as to receive the plasma generated by the torch.
  • the diffuser may include at least two regularly distributed holes angularly and / or axially and drilled in radial directions of the diffuser.
  • FIG. 1 shows in longitudinal section a first embodiment of a torch according to the invention
  • 2 shows in longitudinal section a second embodiment of a torch according to the invention
  • FIG. 3 shows in longitudinal section an example of an igniter using a torch according to the invention.
  • a plasma torch 1 according to a first embodiment of the invention comprises a metallic tubular body 2, closed at a front part 2a by a thin cover 3 made of plastic or made of metal and sticks to the body 2.
  • the rear part 2b of the body 2 has an enlarged diameter so as to constitute a stop flange facilitating the fixing of the torch in a bore of a support (not shown) for example of an ammunition base.
  • the body 2 carries a thread 4.
  • the tubular body 2 will be covered over substantially its entire external surface by an insulator (not shown), for example by a vacuum deposition of 30 to 80 micrometers of a plastic material such as polyethylene or of another insulating material, like glass or ceramic. Such an arrangement improves the electrical insulation of the torch. We will avoid the deposition of plastic material only at the thread 4 so as not to interfere with the fixing of the body.
  • the body 2 has an axial bore 5 inside which is a cylindrical insulating case 6 made of a plastic material capable of becoming ablated, that is to say of generating light gases by the action of a plasma .
  • a cylindrical insulating case 6 made of a plastic material capable of becoming ablated, that is to say of generating light gases by the action of a plasma .
  • the case 6 could also be made of an energetic material, for example nitrocellulose.
  • Such a case is generally called a capillary in known plasma torches.
  • a metal electrode 7 and 8 are separated by the insulating case 6.
  • An annular front electrode 8 is applied against an internal counterbore 2c of the case 2. It has a peripheral shoulder 8a which is adjusted tightly with the body 2.
  • the front electrode 8 has an axial bore 11 and it also has a thinned crown 12 which is oriented towards the point 7b of the rear electrode 7.
  • the front 8 and rear 7 electrodes are separated axially by a distance D (or air gap) which is chosen such that (for the chosen electric voltage) the electric field between the electrodes is of the order of 1 megavolt / m.
  • D or air gap
  • the distance D will be 10 mm.
  • the axial bore 11 of the front electrode 8 also has a nozzle profile comprising a converging conical profile 13 which is open from the side of the rear electrode 7 and which is followed by a diverging conical profile 14 which is open towards the outside torch 1.
  • angles of the converging and diverging as well as the length of the nozzle will be easily determined by the skilled person according to the desired performance for the torch (speed and pressure desired for the plasma leaving the nozzle). These angles are of the order of 15 ° for the convergent 13 and 20 ° for the diverging 14 (half angles at the top of the cones).
  • the total length of the nozzle will be of the order of 15 mm.
  • the nozzle makes it possible to reduce the heat losses at the level of the plasma generated by the torch. In fact, the nozzle makes it possible to bring the gases located at the periphery back into the axis of the torch. These gases are thus heated by the plasma.
  • the rear electrode 7 also has a peripheral shoulder 7c which acts as a positioning stop for the rear electrode 7 relative to the body 2.
  • the ring 9 is made of an insulating material with high mechanical strength, for example polyoxymethylene.
  • the ring 9 comprises a tubular front part 9c which is adjusted in the bore 5 of the body 2. This front part forms a sealing lip ensuring, by its radial deformation, during the operation of the torch, the gas gas tightness by torch 1.
  • the insulating cylindrical case 6 is axially supported on
  • the case has a thinned extension 6a which is interposed between a cylindrical surface of the electrode 7 and the tubular front part 9c of the ring 9.
  • This front part comprises annular sealing lips 30 separated by annular grooves 31.
  • the lips 30 ensure by their radial deformation, during the operation of the torch, the gas tightness produced by the torch 1.
  • the grooves 31 form expansion chambers also improving sealing.
  • a first connection 20 is in electrical contact by an appropriate means (for example a spring touch not shown) with the rear electrode 7.
  • a second connection 21 is in electrical contact with the metal body 2 of the torch, for example by a spring touch resting on the rear part 2b thereof.
  • the body 2 is in electrical contact with the front electrode 8 by virtue of the tight adjustment of the shoulder 8a of the electrode in the bore 5 of the body 2.
  • the generator 19 is designed to be able to deliver an energy of the order of 1 million Joules under a voltage of approximately 20 kilo Volts. Such an arrangement ensures the presence between the electrodes of an electric field of 1 MegaVolt / meter which makes it possible to ignite the plasma without a fuse.
  • a generator is conventional and includes, for example, capacitors, an inductor, thy ⁇ stors and a stabilized power supply. This voltage is applied to the electrodes 7 and 8. Due to the pointed shapes of the ends of the electrodes and the reduced air gap separating the latter, an electric arc occurs between the electrodes 7 and 8. The arc is confined in the chamber 22 which is delimited by the insulating case 6 and the electrodes 7 and 8.
  • the high pressure (of the order of 100 Mega Pascals) which then prevails in this chamber will cause the ablation of the material of the case 6 and the creation of a plasma which will flow out of the body 2 through the nozzle 11.
  • the thin cover 3 will be broken from the initiation of the torch.
  • This plasma makes it possible, for example, to initiate a propellant charge of ammunition. It then provides the advantages usually associated with electric plasma ignition: pressure level higher than that of a conventional pyrotechnic ignition due to the supply of electrical energy by the generator. This results in a higher speed for the projectile.
  • the plasma can also be used for a civil application, such as cutting or destruction of materials, creation of security openings.
  • the nozzle 11 makes it possible to promote the axial flow of the plasma gases out of the torch 1 and to accelerate these gases. This limits the pressure level in the chamber 22 to an admissible value for the mechanical strength of the torch while accelerating the diffusion of the plasma, which increases for example the efficiency of the ignition of a propellant charge of ammunition. It is thus possible to obtain with the torch according to the invention a plasma speed of the order of 10,000 m / s.
  • the electrical energy that can be consumed is of the order of 1 Mega Joules for an air gap D between the electrodes of approximately 20 mm, and a voltage of 20 kilo volts.
  • the torch according to the invention therefore has an excellent size / efficiency ratio, while being simple in design and easy to manufacture.
  • FIG. 2 shows a second embodiment of a plasma torch according to the invention. This mode differs from the previous one in that a block 23 of energetic material is placed between the electrodes 7 and 8.
  • the block is produced by hot or cold compression of an energetic material such as nitrocellulose or else a pyrotechnic composition.
  • an energetic material such as nitrocellulose or else a pyrotechnic composition.
  • the following conventional compositions may be used as pyrotechnic composition: Boron / potassium nitrate (B / KN03), Aluminum / Potassium perchlorate (A1 / KC104), Aluminum / copper oxide (Al / CuO).
  • the block 23 is supported on a counterbore 24 produced on the insulating case 6.
  • a spacer ring 25 is arranged coaxially with the insulating case 6 and it is interposed between the front electrode 8 and the block 23.
  • the block 23 is positioned rigidly between the two electrodes. Its annular shape does not interfere with the formation of the discharge arc between the electrodes.
  • the block 23 has a bore delimited by profiles symmetrical conics forming a convergent followed by a divergent. Such an arrangement facilitates the ablation and / or combustion of the material of the block 23.
  • the pressure and the temperature established in the chamber 22 ensure the initiation of the block 23. This combustion makes it possible to increase the pressure level of the plasma.
  • the spacer ring 25 will preferably be made of the same material as the case 6. Thus it will ablate like the case and will participate in the formation of the plasma.
  • the spacer ring 25 shown in Figure 2 has one end 25a in a conical bevel which enters a housing of complementary shape formed on the electrode 8. Such an arrangement improves the gas tightness and prevents gas passage between the spacer 25 and the electrode 8.
  • the plasma torch shown in Figures 1 and 2 can be directly placed on an ammunition base. Such an embodiment is more particularly suited to the initiation of small or medium caliber ammunition
  • FIG. 3 shows an igniter 26 according to an embodiment of the invention.
  • This igniter incorporates a torch 1 according to one or the other embodiment described above, a torch which is not shown here in detail.
  • This igniter comprises a tubular diffuser 27 which is fixed by gluing or screwing on a cylindrical extension 28 of the torch 1.
  • the diffuser is made of a plastic material ablatable by plasma (such as polyoxymethylene) or else a combustible material, for example nitrocellulose. It is pierced with holes 29 regularly distributed angularly and axially and drilled in radial directions of the diffuser.
  • the holes 29 have a conical profile which is flared towards the outside of the body 2 to facilitate the evacuation of the gases from the plasma.
  • the diffuser receives the plasma generated by the torch 1 and it diffuses it in radial directions.
  • Such an embodiment is more particularly suitable for igniting ammunition of caliber greater than 50mm.
  • the length of the diffuser 27 may vary between 20 and 300 mm without significant loss of performance.
  • an energetic material making it possible to increase the pressure or the energy of the plasma.
  • a pyrotechnic composition a propellant powder or a propellant.
  • An axial channel could be provided in this energetic material.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Plasma Technology (AREA)

Abstract

The invention concerns plasma torch (1) comprising at least two electrodes (7, 8) separated by an insulating cylindrical case (6) defining an internal volume (22). Said torch is characterised in that the electrodes are separated by a sufficiently reduced distance (D) to allow the occurrence of a priming arc between the electrodes (7, 8) when a supply voltage fed by a generator (19) is applied between said electrodes. The invention is useful for producing igniters for ammunitions.

Description

TORCHE A PLASMA COMPORTANT DES ELECTRODES SEPAREES PAR UN ENTREFER ET ALLUMEUR INCORPORANT UNE TELLE TORCHE PLASMA TORCH COMPRISING ELECTRODES SEPARATED BY A GAP AND IGNITOR INCORPORATING SUCH A TORCH
Le domaine technique de l'invention est celui des torches à plasma et plus particulièrement des torches utilisées pour assurer l'allumage d'un chargement propulsif d'une munition.The technical field of the invention is that of plasma torches and more particularly torches used to ignite a propellant charge of an ammunition.
Une torche à plasma est un système qui permet d'engendrer des gaz à haute pression (de l'ordre de 500 MPa) et à haute température (supérieure à 10000 K) à partir d'une décharge électrique de haute tension (de l'ordre de 20 kV) provoquée entre deux électrodes.A plasma torch is a system that generates gases at high pressure (of the order of 500 MPa) and at high temperature (greater than 10,000 K) from a high voltage electrical discharge (from 20 kV) caused between two electrodes.
Les torches à plasma sont utilisées dans l'industrie pour réaliser par exemple la découpe de matériaux conducteurs, ou encore pour détruire certains produits ou matériels, ou pour effectuer des dépôts métalliques. Elles sont également utilisées dans le domaine de l'armement pour engendrer une pression permettant le tir d'un projectile.Plasma torches are used in industry to cut, for example, conductive materials, or to destroy certain products or materials, or to make metallic deposits. They are also used in the armament field to generate pressure allowing the firing of a projectile.
Les torches à plasma connues comprennent une anode et une cathode séparées par un tube capillaire réalisé en un matériau qui est à la fois isolant électrique et susceptible de se décomposer pour engendrer un plasma (par exemple une matière plastique). La décharge électrique entre anode et cathode est amorcée au moyen d'un fusible en cuivre ou autre matériau conducteur. L'arc électrique ainsi créé provoque un plasma qui réalise l'ablation de la paroi du tube capillaire, ce qui entraine la génération de gaz légers à haute pression et haute température.Known plasma torches comprise an anode and a cathode separated by a capillary tube made of a material which is both electrical insulator and capable of decomposing to generate a plasma (for example a plastic material). The electrical discharge between anode and cathode is started by means of a copper or other conductive material fuse. The electric arc thus created causes a plasma which ablates the wall of the capillary tube, which causes the generation of light gases at high pressure and high temperature.
Ces gaz sont utilisés soit pour accélérer directement un projectile, soit pour vaporiser un fluide de travail (par exemple de l'eau) qui permet d' accroître le volume de gaz.These gases are used either to directly accelerate a projectile, or to vaporize a working fluid (for example water) which makes it possible to increase the volume of gas.
On pourra par exemple considérer les brevets FR2754969 et FR2768810 qui décrivent des torches à plasma utilisées pour initier un chargement propulsif de munition.We could for example consider the patents FR2754969 and FR2768810 which describe plasma torches used to initiate a propellant charge of ammunition.
Un inconvénient des torches à plasma connues est la fragilité du fil fusible permettant d'amorcer le plasma. Un tel fil fusible a 0,1 à 0,5 mm de diamètre. Il est susceptible de se rompre comme suite aux contraintes thermiques et mécaniques (vibration, chocs) qui se produisent lors des phases de stockage ou de mise en oeuvre des éléments de munition.One drawback of known plasma torches is the fragility of the fusible wire enabling the plasma to be primed. Such a fusible wire has 0.1 to 0.5 mm in diameter. It is likely to rupture as a result of thermal and mechanical stresses (vibration, shocks) that occur during the storage or implementation phases of the ammunition elements.
De plus la fabrication des torches connues est rendue délicate et coûteuse par l'opération de montage d'un tel fusible.In addition, the manufacture of known torches is made delicate and expensive by the operation of mounting such a fuse.
C'est le but de l'invention de pallier de tels inconvénients .It is the object of the invention to overcome such drawbacks.
Ainsi la torche selon l'invention a une résistance aux contraintes mécaniques améliorée ce qui augmente sa fiabilité. De plus elle est de structure simple et peut être fabriquée a moindre coûts.Thus the torch according to the invention has improved resistance to mechanical stress which increases its reliability. In addition it is simple in structure and can be manufactured at lower cost.
La torche selon l'invention peut être réalisée sans difficulté avec des longueurs très différentes.The torch according to the invention can be produced without difficulty with very different lengths.
L'invention a également pour objet un allumeur mettant en oeuvre une telle torche a plasma, allumeur permettant de faciliter la diffusion du plasma vers le chargement propulsif et cela pour des configurations de chargement très différentes du point de vue masse ou géométrie.The invention also relates to an igniter using such a plasma torch, an igniter making it possible to facilitate the diffusion of the plasma towards the propellant charge, and this for very different charging configurations from the point of view of mass or geometry.
Ainsi l'invention a pour objet une torche a plasma comprenant au moins deux électrodes séparées par un etui cylindrique isolant délimitant un volume interne, torche caractérisée en ce que les électrodes sont séparées par une distance suffisamment réduite pour qu'il apparaisse un arc d'amorçage entre les électrodes lorsqu'une tension d'alimentation fournie par un générateur est appliquée entre ces dernières, la distance entre les électrodes et la tension d'alimentation du générateur étant choisies telles que le champ électrique apparaissant entre les électrodes soit de l'ordre de 1 egavolt/mètre . La torche pourra comprendre une électrode arrière et une électrode avant, l'électrode arrière comportant une pointe axiale orientée vers l'électrode avant et l'électrode avant comportant une couronne amincie orientée vers l'électrode arrière et un perçage axial. Le perçage axial de l'électrode avant pourra avoir un profil de tuyère comportant un profil conique convergent ouvert du côte de l'électrode arrière et suivi par un profil conique divergent ouvert vers l'extérieur de la torche. Suivant une variante de réalisation, la torche pourra comporter un bloc d'un matériau énergétique disposé entre les électrodes .Thus the subject of the invention is a plasma torch comprising at least two electrodes separated by a cylindrical insulating case delimiting an internal volume, torch characterized in that the electrodes are separated by a distance sufficiently reduced so that an arc of ignition between the electrodes when a supply voltage supplied by a generator is applied between them, the distance between the electrodes and the supply voltage of the generator being chosen such that the electric field appearing between the electrodes is of the order of 1 egavolt / meter. The torch may include a rear electrode and a front electrode, the rear electrode comprising an axial tip oriented towards the front electrode and the front electrode comprising a thinned crown oriented towards the rear electrode and an axial bore. The axial drilling of the front electrode may have a nozzle profile comprising a converging conical profile open from the side of the rear electrode and followed by a divergent conical profile open towards the outside of the torch. According to an alternative embodiment, the torch may include a block of energetic material disposed between the electrodes.
Le bloc pourra être annulaire. La torche comportera généralement un corps métallique présentant un alésage axial à l'intérieur duquel sont disposés les électrodes et l'étui isolant.The block may be annular. The torch will generally include a metal body having an axial bore inside which the electrodes and the insulating case are arranged.
L' alésage du corps pourra comporter un épaulement sur lequel est appliquée l'électrode avant, l'étui cylindrique isolant étant en appui axial, d'une part sur l'électrode avant et d'autre part sur l'électrode arrière, une bague de fermeture isolante étant vissée au niveau d'un taraudage arrière du corps et assurant la solidarisation axiale des électrodes et de l'étui isolant avec le corps. La bague de fermeture pourra comporter une lèvre entourant un prolongement aminci de l'étui isolant.The bore of the body may include a shoulder on which the front electrode is applied, the insulating cylindrical case being in axial support, on the one hand on the front electrode and on the other hand on the rear electrode, a ring of insulating closure being screwed at a rear thread of the body and ensuring the axial connection of the electrodes and the insulating case with the body. The closure ring may include a lip surrounding a thinned extension of the insulating case.
L' électrode avant pourra comporter une portée cylindrique sur laquelle sera ajusté l'étui isolant.The front electrode may include a cylindrical surface on which the insulating case will be adjusted.
La torche pourra comporter une bague entretoise coaxiale à l'étui isolant et interposée entre l'électrode avant et le bloc énergétique, ce dernier étant en appui sur un lamage réalisé sur l'étui isolant.The torch may include a spacer ring coaxial with the insulating case and interposed between the front electrode and the energy unit, the latter being supported on a counterbore made on the insulating case.
L'invention a également pour objet un allumeur pour munition qui est caractérisé en ce qu' il comprend au moins une telle torche à plasma.The invention also relates to an igniter for ammunition which is characterized in that it comprises at least one such plasma torch.
L' allumeur pourra comprendre un diffuseur tubulaire percé d'au moins un trou et solidaire de la torche au niveau d'une partie avant de celle ci de façon à recevoir le plasma engendré par la torche. Le diffuseur pourra comporter au moins deux trous régulièrement répartis angulairement et/ou axialement et percés suivant des directions radiales du diffuseur.The igniter may include a tubular diffuser pierced with at least one hole and integral with the torch at a front portion thereof so as to receive the plasma generated by the torch. The diffuser may include at least two regularly distributed holes angularly and / or axially and drilled in radial directions of the diffuser.
D'autres avantages de l'invention apparaîtront à la lecture de la description qui va suivre de différents modes de réalisation, description faite en référence aux dessins annexés et dans lesquels : la figure 1 représente en coupe longitudinale un premier mode de réalisation d'une torche selon l'invention, la figure 2 représente en coupe longitudinale un deuxième mode de réalisation d'une torche selon l'invention, la figure 3 représente en coupe longitudinale un exemple d' allumeur mettant en oeuvre une torche selon 1' invention.Other advantages of the invention will appear on reading the description which follows of different embodiments, description made with reference to the accompanying drawings and in which: FIG. 1 shows in longitudinal section a first embodiment of a torch according to the invention, 2 shows in longitudinal section a second embodiment of a torch according to the invention, FIG. 3 shows in longitudinal section an example of an igniter using a torch according to the invention.
En se reportant a la figure 1, une torche a plasma 1 selon un premier mode de réalisation de l'invention comprend un corps tubulaire métallique 2, obture au niveau d'une partie avant 2a par un opercule mince 3 réalise en matière plastique ou bien en métal et colle au corps 2.Referring to Figure 1, a plasma torch 1 according to a first embodiment of the invention comprises a metallic tubular body 2, closed at a front part 2a by a thin cover 3 made of plastic or made of metal and sticks to the body 2.
La partie arrière 2b du corps 2 présente un diamètre élargi de façon a constituer une collerette butée facilitant la fixation de la torche dans un alésage d'un support (non représente) par exemple d'un culot de munition. Pour permettre également cette fixation de la torche 1, le corps 2 porte un filetage 4.The rear part 2b of the body 2 has an enlarged diameter so as to constitute a stop flange facilitating the fixing of the torch in a bore of a support (not shown) for example of an ammunition base. To also allow this fixation of the torch 1, the body 2 carries a thread 4.
Le corps tubulaire 2 sera recouvert sur sensiblement toute sa surface externe par un isolant (non représente) , par exemple par un dépôt sous vide de 30 a 80 micromètres d'une matière plastique telle que du polyethylene ou encore d'un autre matériau isolant, tel du verre ou une céramique. Une telle disposition permet d'améliorer l'isolation électrique de la torche. On évitera le dépôt de matière plastique uniquement au niveau du filetage 4 afin de ne pas gêner la fixation du corps.The tubular body 2 will be covered over substantially its entire external surface by an insulator (not shown), for example by a vacuum deposition of 30 to 80 micrometers of a plastic material such as polyethylene or of another insulating material, like glass or ceramic. Such an arrangement improves the electrical insulation of the torch. We will avoid the deposition of plastic material only at the thread 4 so as not to interfere with the fixing of the body.
Le corps 2 présente un alésage axial 5 a l'intérieur duquel est dispose un etui cylindrique isolant 6 réalise en une matière plastique susceptible de s'ablater, c'est a dire d'engendrer des gaz légers par l'action d'un plasma. On pourra par exemple réaliser l'etui 6 en polyoxymethylene ou en polytetrafluorethylene . On pourrait également réaliser l'etui 6 en un matériau énergétique, par exemple en nitrocellulose.The body 2 has an axial bore 5 inside which is a cylindrical insulating case 6 made of a plastic material capable of becoming ablated, that is to say of generating light gases by the action of a plasma . We can for example make the case 6 of polyoxymethylene or polytetrafluorethylene. The case 6 could also be made of an energetic material, for example nitrocellulose.
Un tel etui est généralement appelé capillaire dans les torches a plasma connues.Such a case is generally called a capillary in known plasma torches.
Deux électrodes métalliques 7 et 8 (réalisées par exemple en un alliage cuivreux), sont séparées par l'etui isolant 6. Une électrode arrière 7, globalement cylindrique et de même axe que le corps 2, s'étend a l'intérieur de l'etui 6.Two metal electrodes 7 and 8 (made for example of a copper alloy) are separated by the insulating case 6. A rear electrode 7, generally cylindrical and of the same axis as the body 2, extends inside the case 6.
Elle présente une extrémité arrière 7a qui est affleurante au niveau d'une face arrière la de la torche. Son extrémité avant 7b forme une pointe permettant de constituer un pied pour l'arc électrique qui engendrera le plasma.It has a rear end 7a which is flush with a rear face 1a of the torch. Its front end 7b forms a point making it possible to constitute a foot for the electric arc which will generate the plasma.
Une électrode avant annulaire 8 se trouve appliquée contre un lamage interne 2c de l'etui 2. Elle présente un epaulement périphérique 8a qui est ajuste de façon serrée avec le corps 2. L'électrode avant 8 comporte un perçage axial 11 et elle présente aussi une couronne amincie 12 qui est orientée vers la pointe 7b de l'électrode arrière 7.An annular front electrode 8 is applied against an internal counterbore 2c of the case 2. It has a peripheral shoulder 8a which is adjusted tightly with the body 2. The front electrode 8 has an axial bore 11 and it also has a thinned crown 12 which is oriented towards the point 7b of the rear electrode 7.
Conformément a l'invention les électrodes avant 8 et arrière 7 sont séparées axialement par une distance D (ou entrefer) qui est choisie telle que (pour la tension électrique choisie) le champ électrique entre les électrodes soit de l'ordre de 1 megavolt/m. A titre d'exemple pour une tension entre électrodes de 10000 Volts, la distance D sera de 10 mm. Cet espacement réduit entre les électrodes ainsi que les formes pointues 7b et 12 des deux électrodes permet de favoriser la formation d'un arc électrique dans l'entrefer séparant les électrodes.In accordance with the invention the front 8 and rear 7 electrodes are separated axially by a distance D (or air gap) which is chosen such that (for the chosen electric voltage) the electric field between the electrodes is of the order of 1 megavolt / m. For example, for a voltage between electrodes of 10,000 volts, the distance D will be 10 mm. This reduced spacing between the electrodes and the pointed shapes 7b and 12 of the two electrodes makes it possible to promote the formation of an electric arc in the air gap separating the electrodes.
Il n'est donc pas nécessaire de prévoir un fil fusible d'amorçage reliant les électrodes. La tenue mécanique et la fiabilité de la torche selon l'invention est donc bien supérieure a celle des torches connues puisqu' aucune rupture de fusible n'est a craindre.It is therefore not necessary to provide a fuse ignition wire connecting the electrodes. The mechanical strength and reliability of the torch according to the invention is therefore much higher than that of known torches since no breaking of the fuse is to be feared.
Le perçage axial 11 de l'électrode avant 8 a également un profil de tuyère comportant un profil conique convergent 13 qui est ouvert du côte de l'électrode arrière 7 et qui est suivi par un profil conique divergent 14 qui est ouvert vers l'extérieur de la torche 1.The axial bore 11 of the front electrode 8 also has a nozzle profile comprising a converging conical profile 13 which is open from the side of the rear electrode 7 and which is followed by a diverging conical profile 14 which is open towards the outside torch 1.
Les angles des convergents et divergents ainsi que la longueur de la tuyère seront détermines aisément par l'Homme du Métier en fonction des performances recherchées pour la torche (vitesse et pression recherchée pour le plasma sortant de la tuyère) . Ces angles sont de l'ordre de 15° pour le convergent 13 et de 20° pour le divergent 14 (demi angles au sommet des cônes) .The angles of the converging and diverging as well as the length of the nozzle will be easily determined by the skilled person according to the desired performance for the torch (speed and pressure desired for the plasma leaving the nozzle). These angles are of the order of 15 ° for the convergent 13 and 20 ° for the diverging 14 (half angles at the top of the cones).
La longueur totale de la tuyère sera de l'ordre de 15 mm. La tuyère permet de diminuer les pertes thermiques au niveau du plasma engendré par la torche. En effet la tuyère permet de ramener dans l'axe de la torche les gaz situés en périphérie. Ces gaz se trouvent ainsi réchauffés par le plasma . L'électrode arrière 7 présente également un épaulement périphérique 7c qui joue le rôle de butée de positionnement de l'électrode arrière 7 par rapport au corps 2. L' épaulementThe total length of the nozzle will be of the order of 15 mm. The nozzle makes it possible to reduce the heat losses at the level of the plasma generated by the torch. In fact, the nozzle makes it possible to bring the gases located at the periphery back into the axis of the torch. These gases are thus heated by the plasma. The rear electrode 7 also has a peripheral shoulder 7c which acts as a positioning stop for the rear electrode 7 relative to the body 2. The shoulder
7c est en appui contre un lamage 9a d'une bague de fermeture isolante 9 qui porte un filetage 10 permettant son vissage au niveau d'un taraudage arrière du corps 2.7c is in abutment against a countersink 9a of an insulating closure ring 9 which carries a thread 10 allowing it to be screwed at the level of a rear thread of the body 2.
La bague 9 est réalisée en un matériau isolant à haute tenue mécanique, par exemple du polyoxymethylene. La bague 9 comporte une partie avant tubulaire 9c qui est ajustée dans l'alésage 5 du corps 2. Cette partie avant forme une lèvre d' etanchéité assurant, par sa déformation radiale, lors du fonctionnement de la torche, l' etanchéité aux gaz produits par la torche 1.The ring 9 is made of an insulating material with high mechanical strength, for example polyoxymethylene. The ring 9 comprises a tubular front part 9c which is adjusted in the bore 5 of the body 2. This front part forms a sealing lip ensuring, by its radial deformation, during the operation of the torch, the gas gas tightness by torch 1.
L' étui cylindrique isolant 6 est en appui axial surThe insulating cylindrical case 6 is axially supported on
1' épaulement 8a de l'électrode avant et sur l'électrode arrière 7. L'étui comporte un prolongement aminci 6a qui est intercalé entre une portée cylindrique de l'électrode 7 et la partie avant tubulaire 9c de la bague 9.1 shoulder 8a of the front electrode and on the rear electrode 7. The case has a thinned extension 6a which is interposed between a cylindrical surface of the electrode 7 and the tubular front part 9c of the ring 9.
Cette partie avant comporte des lèvres d' etanchéité annulaires 30 séparées par des gorges annulaires 31. Les lèvres 30 assurent par leur déformation radiale, lors du fonctionnement de la torche, l' etanchéité aux gaz produits par la torche 1. Les gorges 31 forment des chambres de détente améliorant également l' etanchéité .This front part comprises annular sealing lips 30 separated by annular grooves 31. The lips 30 ensure by their radial deformation, during the operation of the torch, the gas tightness produced by the torch 1. The grooves 31 form expansion chambers also improving sealing.
Ainsi le vissage de la bague 9 assure la solidarisation axiale des électrodes 7, 8 et de l'étui isolant 6 avec le corps 2.Thus the screwing of the ring 9 ensures the axial joining of the electrodes 7, 8 and of the insulating case 6 with the body 2.
Le fonctionnement de cette torche est le suivant. Un générateur électrique 19 est relie par des connexions électriques 20,21 a la torche 1. Une première connexion 20 est en contact électrique par un moyen approprié (par exemple un toucheau à ressort non représenté) avec l'électrode arrière 7. Une seconde connexion 21 est en contact électrique avec le corps 2 métallique de la torche, par exemple par un toucheau à ressort en appui sur la partie arrière 2b de celui ci .The operation of this torch is as follows. An electric generator 19 is connected by electrical connections 20, 21 to the torch 1. A first connection 20 is in electrical contact by an appropriate means (for example a spring touch not shown) with the rear electrode 7. A second connection 21 is in electrical contact with the metal body 2 of the torch, for example by a spring touch resting on the rear part 2b thereof.
Le corps 2 est en contact électrique avec l'électrode avant 8 grâce a l'ajustement serre de l' épaulement 8a de l'électrode dans l'alésage 5 du corps 2.The body 2 is in electrical contact with the front electrode 8 by virtue of the tight adjustment of the shoulder 8a of the electrode in the bore 5 of the body 2.
Le générateur 19 est conçu pour pouvoir délivrer une énergie de l'ordre de 1 million de Joules sous une tension d'environ 20 kilo Volts. Une telle disposition permet d'assurer la présence entre les électrodes d'un champ électrique de 1 MegaVolt/ ètre ce qui permet d'amorcer le plasma sans fusible. Un tel générateur est classique et comprend par exemple des capacités, une inductance, des thyπstors et une alimentation stabilisée. Cette tension est appliquée aux électrodes 7 et 8. Du fait des formes pointues des extrémités d' électrodes et de l'entrefer réduit séparant ces dernières, il se produit un arc électrique entre les électrodes 7 et 8. L' arc se trouve confine dans la chambre 22 qui est délimitée par l'etui isolant 6 et les électrodes 7 et 8. La pression importante (de l'ordre de 100 Mega Pascals) qui règne alors dans cette chambre va provoquer l'ablation du matériau de l'étui 6 et la création d'un plasma qui s'écoulera hors du corps 2 au travers de la tuyère 11. L'opercule mince 3 sera rompu des l'initiation de la torche.The generator 19 is designed to be able to deliver an energy of the order of 1 million Joules under a voltage of approximately 20 kilo Volts. Such an arrangement ensures the presence between the electrodes of an electric field of 1 MegaVolt / meter which makes it possible to ignite the plasma without a fuse. Such a generator is conventional and includes, for example, capacitors, an inductor, thyπstors and a stabilized power supply. This voltage is applied to the electrodes 7 and 8. Due to the pointed shapes of the ends of the electrodes and the reduced air gap separating the latter, an electric arc occurs between the electrodes 7 and 8. The arc is confined in the chamber 22 which is delimited by the insulating case 6 and the electrodes 7 and 8. The high pressure (of the order of 100 Mega Pascals) which then prevails in this chamber will cause the ablation of the material of the case 6 and the creation of a plasma which will flow out of the body 2 through the nozzle 11. The thin cover 3 will be broken from the initiation of the torch.
Ce plasma permet par exemple d'assurer l'initiation d'un chargement propulsif de munition. Il procure alors les avantages habituellement liés a l'allumage par plasma électrique : niveau de pression supérieur à celui d'un allumage pyrotechnique classique dû a l'apport d'énergie électrique par le générateur. Il en resuite une vitesse supérieure pour le projectile. Le plasma peut également être utilise pour un application civile, tel la découpe ou la destruction des matériaux, la réalisation d' ouvertures de sécurité .This plasma makes it possible, for example, to initiate a propellant charge of ammunition. It then provides the advantages usually associated with electric plasma ignition: pressure level higher than that of a conventional pyrotechnic ignition due to the supply of electrical energy by the generator. This results in a higher speed for the projectile. The plasma can also be used for a civil application, such as cutting or destruction of materials, creation of security openings.
La tuyère 11 permet de favoriser l'écoulement axial des gaz du plasma hors de la torche 1 et d'accélérer ces gaz. On limite ainsi le niveau de pression dans la chambre 22 a une valeur admissible pour la tenue mécanique de la torche tout en accélérant la diffusion du plasma ce qui accroît par exemple l'efficacité de l'allumage d'un chargement propulsif de munition. II est ainsi possible d'obtenir avec la torche selon l'invention une vitesse de plasma de l'ordre de 10000 m/s.The nozzle 11 makes it possible to promote the axial flow of the plasma gases out of the torch 1 and to accelerate these gases. This limits the pressure level in the chamber 22 to an admissible value for the mechanical strength of the torch while accelerating the diffusion of the plasma, which increases for example the efficiency of the ignition of a propellant charge of ammunition. It is thus possible to obtain with the torch according to the invention a plasma speed of the order of 10,000 m / s.
L' énergie électrique pouvant être consommée est de l'ordre de 1 Mega Joules pour un entrefer D entre les électrodes d'environ 20 mm, et une tension de 20 kilo volts. La torche selon l'invention présente donc un excellent rapport encombrement / efficacité, tout en étant de conception simple et facile a fabriquer.The electrical energy that can be consumed is of the order of 1 Mega Joules for an air gap D between the electrodes of approximately 20 mm, and a voltage of 20 kilo volts. The torch according to the invention therefore has an excellent size / efficiency ratio, while being simple in design and easy to manufacture.
La figure 2 montre un deuxième mode de réalisation d'une torche a plasma selon l'invention. Ce mode diffère du précèdent en ce qu'un bloc 23 d'un matériau énergétique est dispose entre les électrodes 7 et 8.Figure 2 shows a second embodiment of a plasma torch according to the invention. This mode differs from the previous one in that a block 23 of energetic material is placed between the electrodes 7 and 8.
Le bloc est réalise par compression a chaud ou a froid d'un matériau énergétique tel que de la nitrocellulose ou bien une composition pyrotechnique. On pourra utiliser comme composition pyrotechnique les compositions classiques suivantes : Bore/nitrate de potassium (B/KN03) , Aluminium/Perchlorate de potassium (A1/KC104), Aluminium/oxyde de cuivre (Al/CuO) .The block is produced by hot or cold compression of an energetic material such as nitrocellulose or else a pyrotechnic composition. The following conventional compositions may be used as pyrotechnic composition: Boron / potassium nitrate (B / KN03), Aluminum / Potassium perchlorate (A1 / KC104), Aluminum / copper oxide (Al / CuO).
Le bloc 23 est en appui sur un lamage 24 réalise sur l'etui isolant 6. Une bague entretoise 25 est disposée coaxialement a l'etui isolant 6 et elle est interposée entre l'électrode avant 8 et le bloc 23.The block 23 is supported on a counterbore 24 produced on the insulating case 6. A spacer ring 25 is arranged coaxially with the insulating case 6 and it is interposed between the front electrode 8 and the block 23.
Ainsi le bloc 23 se trouve positionne de façon rigide entre les deux électrodes. Sa forme annulaire permet de ne pas gêner la formation de l'arc de décharge entre les électrodes.Thus the block 23 is positioned rigidly between the two electrodes. Its annular shape does not interfere with the formation of the discharge arc between the electrodes.
Suivant le mode de réalisation représente sur la figure 2, le bloc 23 présente un alésage délimite par des profils coniques symétriques formant un convergent suivi d'un divergent. Une telle disposition facilite l'ablation et/ou la combustion du matériau du bloc 23.According to the embodiment shown in FIG. 2, the block 23 has a bore delimited by profiles symmetrical conics forming a convergent followed by a divergent. Such an arrangement facilitates the ablation and / or combustion of the material of the block 23.
Lors du fonctionnement d'une telle torche, la pression et la température établies dans la chambre 22 assurent l'initiation du bloc 23. Cette combustion permet d'accroître le niveau de pression du plasma.During the operation of such a torch, the pressure and the temperature established in the chamber 22 ensure the initiation of the block 23. This combustion makes it possible to increase the pressure level of the plasma.
La bague entretoise 25 sera réalisée de préférence dans le même matériau que l'étui 6. Ainsi elle s'ablatera comme l'étui et participera à la formation du plasma.The spacer ring 25 will preferably be made of the same material as the case 6. Thus it will ablate like the case and will participate in the formation of the plasma.
La bague entretoise 25 représentée à la figure 2 comporte une extrémité 25a en biseau conique qui pénètre dans un logement de forme complémentaire réalisé sur l'électrode 8. Une telle disposition permet d'améliorer l' etanchéité aux gaz et évite un passage de gaz entre l'entretoise 25 et 1' électrode 8.The spacer ring 25 shown in Figure 2 has one end 25a in a conical bevel which enters a housing of complementary shape formed on the electrode 8. Such an arrangement improves the gas tightness and prevents gas passage between the spacer 25 and the electrode 8.
La torche à plasma représentée aux figures 1 et 2 peut être directement mise en place sur un culot de munition. Un tel mode de réalisation est plus particulièrement adapté à l'initiation des munitions de petit ou moyen calibreThe plasma torch shown in Figures 1 and 2 can be directly placed on an ammunition base. Such an embodiment is more particularly suited to the initiation of small or medium caliber ammunition
(inférieur a 50mm).(less than 50mm).
La figure 3 montre un allumeur 26 suivant un mode de réalisation de l'invention.FIG. 3 shows an igniter 26 according to an embodiment of the invention.
Cet allumeur incorpore une torche 1 suivant l'un ou l'autre mode de réalisation décrit précédemment, torche qui n'est pas représentée ici en détails.This igniter incorporates a torch 1 according to one or the other embodiment described above, a torch which is not shown here in detail.
Cet allumeur comprend un diffuseur tubulaire 27 qui est fixe par collage ou vissage sur un prolongement cylindrique 28 de la torche 1. Le diffuseur est réalisé en une matière plastique ablatable par le plasma (telle que du polyoxymethylene) ou bien un matériau combustible, par exemple en nitrocellulose . Il est percé de trous 29 régulièrement répartis angulairement et axialement et perces suivant des directions radiales du diffuseur.This igniter comprises a tubular diffuser 27 which is fixed by gluing or screwing on a cylindrical extension 28 of the torch 1. The diffuser is made of a plastic material ablatable by plasma (such as polyoxymethylene) or else a combustible material, for example nitrocellulose. It is pierced with holes 29 regularly distributed angularly and axially and drilled in radial directions of the diffuser.
Les trous 29 ont un profil conique qui est évase vers l'extérieur du corps 2 pour faciliter l'évacuation des gaz du plasma . Le diffuseur reçoit le plasma engendré par la torche 1 et il le diffuse suivant des directions radiales.The holes 29 have a conical profile which is flared towards the outside of the body 2 to facilitate the evacuation of the gases from the plasma. The diffuser receives the plasma generated by the torch 1 and it diffuses it in radial directions.
Un tel mode de réalisation est plus particulièrement adapté à l'allumage de munitions de calibre supérieur à 50mm. Pour une dimension de torche 2 donnée, la longueur du diffuseur 27 pourra varier entre 20 et 300mm sans perte notable de performances.Such an embodiment is more particularly suitable for igniting ammunition of caliber greater than 50mm. For a given torch size 2, the length of the diffuser 27 may vary between 20 and 300 mm without significant loss of performance.
On pourra à titre de variante disposer à l'intérieur du diffuseur 27 un matériau énergétique permettant d' accroître la pression ou l'énergie du plasma. Par exemple une composition pyrotechnique, une poudre propulsive ou un propergol. Un canal axial pourra être prévu dans ce matériau énergétique .As a variant, it is possible to have inside the diffuser 27 an energetic material making it possible to increase the pressure or the energy of the plasma. For example a pyrotechnic composition, a propellant powder or a propellant. An axial channel could be provided in this energetic material.
On pourra également à titre de variante prévoir un trou axial à l'extrémité du diffuseur 27.Alternatively, it is also possible to provide an axial hole at the end of the diffuser 27.
Il est bien entendu possible d'associer l'une ou l'autre des torches des figures 1 ou 2 avec l'allumeur de la figure 3. It is of course possible to associate one or other of the torches of FIGS. 1 or 2 with the igniter of FIG. 3.

Claims

REVENDICATIONS
1. Torche à plasma (1) comprenant au moins deux électrodes (7,8) séparées par un étui cylindrique isolant (6) délimitant un volume interne, torche caractérisée en ce que les électrodes (7,8) sont séparées par une distance (D) suffisamment réduite pour qu'il apparaisse un arc d'amorçage entre les électrodes (7,8) lorsqu'une tension d'alimentation fournie par un générateur (19) est appliquée entre ces dernières, la distance (D) entre les électrodes (7,8) et la tension d'alimentation du générateur (19) étant choisies telles que le champ électrique apparaissant entre les électrodes soit de l'ordre de 1 Megavolt/metre .1. Plasma torch (1) comprising at least two electrodes (7,8) separated by an insulating cylindrical case (6) delimiting an internal volume, torch characterized in that the electrodes (7,8) are separated by a distance ( D) sufficiently reduced so that a priming arc appears between the electrodes (7,8) when a supply voltage supplied by a generator (19) is applied between them, the distance (D) between the electrodes (7,8) and the supply voltage of the generator (19) being chosen such that the electric field appearing between the electrodes is of the order of 1 Megavolt / meter.
2. Torche a plasma selon la revendication 1, caractérisée en ce qu'elle comprend une électrode arrière (7) et une électrode avant (8), l'électrode arrière (7) comportant une pointe axiale (7b) orientée vers l'électrode avant (8) et l'électrode avant comportant une couronne amincie (12) orientée vers l'électrode arrière (7) et un perçage axial2. plasma torch according to claim 1, characterized in that it comprises a rear electrode (7) and a front electrode (8), the rear electrode (7) comprising an axial tip (7b) oriented towards the electrode front (8) and the front electrode comprising a thinned crown (12) oriented towards the rear electrode (7) and an axial bore
(11) • 3. Torche a plasma selon la revendication 2, caractérisée en ce que le perçage axial (11) de l'électrode avant (8) a un profil de tuyère comportant un profil conique convergent (13) ouvert du côte de l'électrode arrière (7) et suivi par un profil conique divergent (14) ouvert vers l'extérieur de la torche (1) .(11) • 3. plasma torch according to claim 2, characterized in that the axial bore (11) of the front electrode (8) has a nozzle profile comprising a converging conical profile (13) open from the side of the 'rear electrode (7) and followed by a divergent conical profile (14) open towards the outside of the torch (1).
4. Torche à plasma selon une des revendications 1 a 3, caractérisée en ce qu'elle comporte un bloc (23) d'un matériau énergétique dispose entre les électrodes (7,8).4. Plasma torch according to one of claims 1 to 3, characterized in that it comprises a block (23) of an energetic material disposed between the electrodes (7,8).
5. Torche a plasma selon la revendication 4, caractérisée en ce que le bloc (23) est annulaire.5. A plasma torch according to claim 4, characterized in that the block (23) is annular.
6. Torche a plasma selon une des revendications 1 à 5, caractérisée en ce qu'elle comporte un corps métallique (2) présentant un alésage axial (5) a l'intérieur duquel sont disposes les électrodes (7,8) et l'etui isolant (6). 6. plasma torch according to one of claims 1 to 5, characterized in that it comprises a metal body (2) having an axial bore (5) inside which are arranged the electrodes (7,8) and the insulating case (6).
7. Torche a plasma selon la revendication 6, caractérisée en ce que l'alésage (5) du corps comporte un épaulement (2c) sur lequel est appliquée l'électrode avant (8), l'etui cylindrique isolant (6) étant en appui axial, d'une part sur l'électrode avant (8) et d'autre part sur l'électrode arrière (7), une bague de fermeture isolante (9) étant vissée au niveau d'un taraudage arrière du corps (2) et assurant la solidarisation axiale des électrodes (7,8) et de l'étui isolant (6) avec le corps (2).7. plasma torch according to claim 6, characterized in that the bore (5) of the body comprises a shoulder (2c) on which the front electrode (8) is applied, the insulating cylindrical case (6) being axial support, on the one hand on the front electrode (8) and on the other hand on the rear electrode (7), an insulating closure ring (9) being screwed at the level of a rear thread of the body (2) and ensuring the axial joining of the electrodes (7,8) and the insulating case (6) with the body (2).
8. Torche à plasma selon la revendication 7, caractérisée en ce que la bague de fermeture (9) comporte une lèvre (9c) entourant un prolongement (βa) aminci de l'étui isolant (6).8. Plasma torch according to claim 7, characterized in that the closure ring (9) comprises a lip (9c) surrounding a thinned extension (βa) of the insulating case (6).
9. Torche à plasma selon une des revendications 7 ou 8, caractérisée en ce que l'électrode avant (8) comporte une portée cylindrique sur laquelle est ajusté l'étui isolant (6) .9. plasma torch according to one of claims 7 or 8, characterized in that the front electrode (8) has a cylindrical surface on which is adjusted the insulating case (6).
10. Torche à plasma selon la revendication 9 et une des revendications 4 ou 5, caractérisée en ce qu'elle comporte une bague entretoise (25) coaxiale à l'étui isolant (6) et interposée entre l'électrode avant (8) et le bloc énergétique (23), ce dernier étant en appui sur un lamage (24) réalisé sur l'étui isolant (6).10. Plasma torch according to claim 9 and one of claims 4 or 5, characterized in that it comprises a spacer ring (25) coaxial with the insulating case (6) and interposed between the front electrode (8) and the energy unit (23), the latter being supported on a counterbore (24) produced on the insulating case (6).
11. Allumeur (26) pour munition, caractérisé en ce qu'il comprend au moins une torche à plasma (1) suivant une des revendications 1 à 10.11. Igniter (26) for ammunition, characterized in that it comprises at least one plasma torch (1) according to one of claims 1 to 10.
12. Allumeur suivant la revendication 11, caractérisé en ce qu'il comprend un diffuseur tubulaire (27) percé d'au moins un trou (29) et solidaire de la torche (1) au niveau d'une partie avant de celle ci de façon à recevoir le plasma engendré par la torche.12. Igniter according to claim 11, characterized in that it comprises a tubular diffuser (27) pierced with at least one hole (29) and integral with the torch (1) at a front part thereof so as to receive the plasma generated by the torch.
13. Allumeur suivant la revendication 12, caractérisé en ce que le diffuseur (27) comporte au moins deux trous (29) régulièrement répartis angulairement et/ou axialement et percés suivant des directions radiales du diffuseur. 13. Igniter according to claim 12, characterized in that the diffuser (27) comprises at least two holes (29) regularly distributed angularly and / or axially and drilled in radial directions of the diffuser.
EP01919603A 2000-04-11 2001-03-30 Plasma torch comprising electrodes separated by an air gap and igniter incorporating same Withdrawn EP1186211A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0004735A FR2807611B1 (en) 2000-04-11 2000-04-11 PLASMA TORCH COMPRISING ELECTRODES SEPARATED BY A GAP AND IGNITOR INCORPORATING SUCH A TORCH
FR0004735 2000-04-11
PCT/FR2001/000962 WO2001078470A1 (en) 2000-04-11 2001-03-30 Plasma torch comprising electrodes separated by an air gap and igniter incorporating same

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EP1186211A1 true EP1186211A1 (en) 2002-03-13

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EP01919603A Withdrawn EP1186211A1 (en) 2000-04-11 2001-03-30 Plasma torch comprising electrodes separated by an air gap and igniter incorporating same

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US (1) US6740841B2 (en)
EP (1) EP1186211A1 (en)
FR (1) FR2807611B1 (en)
IL (1) IL146546A0 (en)
WO (1) WO2001078470A1 (en)
ZA (1) ZA200109302B (en)

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Also Published As

Publication number Publication date
US6740841B2 (en) 2004-05-25
WO2001078470A1 (en) 2001-10-18
FR2807611A1 (en) 2001-10-12
US20020134767A1 (en) 2002-09-26
IL146546A0 (en) 2002-07-25
ZA200109302B (en) 2002-06-20
FR2807611B1 (en) 2002-11-29

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