EP2747117B1 - Device for generating microwaves with dual cathodes - Google Patents

Device for generating microwaves with dual cathodes Download PDF

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Publication number
EP2747117B1
EP2747117B1 EP13197779.5A EP13197779A EP2747117B1 EP 2747117 B1 EP2747117 B1 EP 2747117B1 EP 13197779 A EP13197779 A EP 13197779A EP 2747117 B1 EP2747117 B1 EP 2747117B1
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European Patent Office
Prior art keywords
cathode
potential
anode
generation device
emission
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EP13197779.5A
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German (de)
French (fr)
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EP2747117A2 (en
EP2747117A3 (en
Inventor
Jean-Pierre Brasile
Dominique Fasse
Anne-Sophie Chauchat
Patrick Sirot
Dominique Jousse
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Thales SA
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Thales SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes
    • H01J23/05—Cathodes having a cylindrical emissive surface, e.g. cathodes for magnetrons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/50—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field
    • H01J25/52—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode
    • H01J25/58—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode having a number of resonators; having a composite resonator, e.g. a helix
    • H01J25/587—Multi-cavity magnetrons

Definitions

  • the present invention relates to a device for generating microwave waves, of the type comprising an anode and a first cathode, separated by an interaction space, the first cathode being adapted to emit first electrons in the interaction space when subjected. to an electric field of intensity greater than a first threshold value, and the anode being adapted to attract said first electrons
  • Wave generation devices of this type include in particular magnetrons, klystrons, and MILOs (for “Magnetically Insulated Line Oscillator”).
  • a device for generating microwave waves comprising an anode and a cathode separated by an interaction space, this device further comprising a waveguide disposed opposite an orifice passing through the anode and extending from an outer surface of the anode to the outside of the generating device is known to " Rapid Start of Oscillations in a Magnetron with a "Transparent" Cathode ", Mikhail Fuks and Edl Schamiloglu, Physical Review Letters, November 10, 2005 (2005-11-10), XP055250125, URL: http: //journals.aps.org/ prl / pdf / 10.1103 / PhysRevLett.95.205101 .
  • These devices cannot emit a wave of both high power and long duration, due to the risk of forming a short circuit between the anode and the cathode in the interaction space. So, some of these devices are designed to generate long duration, low power waves, others are designed to generate medium power long pulses, and the rest of these devices are designed to generate high power short pulses. .
  • Known generation devices therefore generally do not have great flexibility of operation, in the sense that they are not suitable for emitting only one type of wave.
  • Transmission equipment for example microwave weapons, suitable for transmitting both continuous waves of low power and short pulses of high power, for example with a view to electronic warfare. Because of their very wide operating range, this equipment requires the use of several generation devices to power it.
  • An objective of the invention is therefore to provide a generation device that is compact and exhibits great operating flexibility.
  • the invention relates to a generation device of the aforementioned type, comprising a second cathode, interposed between the first cathode and the anode and adapted to emit second electrons into the interaction space when subjected to a electric field of intensity greater than a second threshold value, the anode being adapted to attract said second electrons, and a supply circuit electrical cathode, adapted to establish a potential difference between the cathodes.
  • the second threshold value is strictly greater than the first threshold value.
  • the generation device 10 comprises a microwave tube 12 and at least one, in the example shown a plurality of waveguide (s) 14.
  • the microwave tube 12 comprises a first cathode 16, a second cathode 18, an anode 20, and a circuit 21 ( Figure 2 ) power supply of the cathodes 16, 18.
  • the cathodes 16, 18 are separated from the anode 20 by an interaction space 22.
  • the supply circuit 21 of the cathodes is adapted to bring each cathode, respectively 16, 18, to an electric potential, respectively V 1 ; V 2 , less than the electrical potential V 0 of the anode 20 when the tube 12 is supplied with electrical energy, so that there is a potential difference between the anode 20 and each cathode, respectively 16, 18.
  • This difference of potential generates an electric field E inside the interaction space 22, oriented from the anode 20 towards the cathodes 16, 18.
  • the microwave tube 12 also comprises a focusing device 76 for focusing electrons emitted by the cathodes 16, 18 inside the interaction space 22.
  • the focusing device 76 is adapted to generate a magnetic field B at 1. interior of the interaction space 22.
  • the electric E and magnetic B fields are oriented perpendicular to each other. They each respect the conditions of synchronism imposed by the geometry of the tube 12. They are adapted to one another to give the electrons emitted by the cathodes 16, 18 a cycloidal movement in the interaction space 22.
  • the first cathode 16 is adapted to emit the first electrons in the interaction space 22, intended for the anode 20, under the effect of the electric field E, provided that this electric field has an intensity greater than a first threshold value E 1 .
  • the first cathode 16 is in particular suitable for continuously emitting electrons over a period of more than 1 ⁇ s when it is subjected to the electric field E.
  • the first cathode 16 is advantageously, as shown in Figure 2 , a field emission cathode with electron emitting microtips.
  • Such cathodes are known, for example from FR-A-2 734 076 .
  • This cathode 16 comprises, in a known manner, a conductive substrate 24, for example made of silicon, having an active face 26 on which microtips 28 are arranged.
  • the active face 26 is covered with an insulating layer 30, for example made of carbon dioxide. silicon, separating it from a conductive grid 32.
  • the microtips 28 are housed in respective cavities 34 formed in the insulating layer 30. These cavities 34 communicate with the interaction space 22 through corresponding openings provided in the grid 32. The ends of the microtips 28 opposite to the substrate 24 come in contact with the interaction space 22. flush with the outer surface of the grille 32.
  • the dimension of the cavities 34, and therefore of the microtips, is of the order of a micron in height and width.
  • the density of microtips 28 is of the order of 10,000 to 100,000 microtips per mm 2 of active face 26. It will be noted that, for reasons of legibility of the Figures, the proportions have not been observed on the figure. Figure 2 .
  • the microtips 28 are preferably formed by carbon nanotubes.
  • Positive biasing means (not shown) of gate 32 are connected between substrate 24 and gate 32. These means are suitable for varying the voltage between substrate 24 and gate 32 on command between a first value, less than a voltage. threshold, in which the flow of electrons emitted by the cathode 16 is zero, and a second value, greater than the threshold voltage, in which the cathode 16 produces a current of electrons.
  • microtips 28 are not distributed uniformly over the active face 26. They are grouped within emission zones 36 of the cathode 16. These emission zones 36 are distant from each other.
  • the substrate 24 is cylindrical, preferably cylindrical of revolution, and extends along a longitudinal axis Z.
  • the microtips 28 are distributed over the entire periphery of the cylinder.
  • Each emission zone 36 is elongated parallel to the longitudinal axis Z.
  • the first cathode 16 is a thermoelectronic cathode, adapted to emit electrons into the interaction space if and only if the field E is greater than the first threshold value E 1 and the cathode 16 is heated to a temperature greater than a threshold value.
  • the cathode 16 is then made of tungsten, or of pyrolytic carbon.
  • the first cathode 16 is a mixture of tungsten and Sc 2 O 3 , as described in the document ZHAO Jinfeng, Scandia-added Tungsten Dispenser Cathode Fabrication for THz Vacuum Integrated Power Amplifiers, Terahertz Science and Technology December 2011, vol. 4, n ° 4, pages 240-252 ..
  • the first cathode 16 is at a distance D from the anode 20.
  • the second cathode 18 is suitable for emitting second electrons in the interaction space 22, destined for the anode 20, under the effect of the electric field E, provided that this electric field has an intensity greater than one second threshold value E 2 .
  • the second threshold value E 2 is preferably different from the first threshold value E 1 .
  • the second threshold value E 2 is strictly greater than the first threshold value E 1 .
  • the second cathode 18 is interposed between the first cathode 16 and the anode 20.
  • the second cathode 18 is tubular and surrounds the first cathode 16.
  • the cathodes 16, 18 are concentric. They are each centered on the longitudinal axis Z.
  • the first electrons emitted by the first cathode 16 must therefore pass through the second cathode 18 to reach the anode 20.
  • the second cathode 18 delimits, as visible on the figure.
  • Figure 2 a plurality of windows 40 each interposed between the first cathode 16 and the anode 20. Each window 40 is delimited between two emission regions 42 of the second cathode 28.
  • Each of said windows 40 is arranged opposite one of the emission zones 36 of the first cathode 16.
  • the number of electrons emitted by the first cathode 16 striking the second cathode 18 is reduced, which makes it possible to increase the efficiency of the generation device 10.
  • the second cathode 18 is advantageously a “transparent” cathode.
  • Such cathodes are known, for example from US 2008/0246385 .
  • the second cathode 18 thus comprises a tubular body 44 extending around the axis Z, from a first end 46 for connection to the supply circuit 21 to a second free end 48.
  • Body 44 is formed from a material having good electrical conductivity, typically copper.
  • a plurality of bars 50 extend parallel to the Z axis from the free end 48, opposite the body 44. Each bar 50 constitutes an emission region 42 of the second cathode 18.
  • Each bar 50 is typically made of pyrolytic carbon, tungsten or molybdenum. These materials have in fact in common the fact that they have good electrical and thermal conductivity, that they degas little and that they are rigid, which makes them particularly suitable for the production of bars 50. Pyrolytic carbon having a low density in addition, its use makes it possible to lighten the generation 10 device.
  • the bars 50 are regularly distributed around the Z axis. They define between them a cavity 52 for receiving the first cathode 16, centered on the Z axis.
  • the bars 50 are spaced from each other. For each pair of consecutive bars 50, a void 54 is thus left between these bars 50.
  • This void 54 constitutes a window 40 of the second cathode 18. It allows the passage of electrons emitted by the first cathode 16, as well as the passage of electromagnetic fields so that they penetrate inside the second cathode 18.
  • the bars 50 have a cylindrical shape of revolution.
  • the bars 50 have any other suitable shape, for example a prism shape. It will be noted that the use of bars 50 in the form of prisms makes it possible to lengthen the period during which the second cathode 18 can continuously emit electrons.
  • the end 56 of the bars 50 opposite the body 44 is left free.
  • a member for connecting the bars 50 to one another typically a ring, connects said ends 56, so as to reinforce the second cathode 18.
  • the second cathode 18 is typically a field emission cathode.
  • the second cathode 18 is advantageously suitable for emitting electrons in the interaction space 22 with a current density greater than 10 A / cm 2 .
  • the second cathode 18 is at a distance d from the anode 20.
  • the anode 20 is tubular. It has an interior surface 60, and an exterior surface 62, opposite the interior surface 60. It is formed from a conductive material, typically steel, graphite or copper.
  • the interior surface 60 delimits a plurality of resonant cavities 63, 64. These resonant cavities 63, 64 are adapted to amplify an electromagnetic wave formed by the circulation of electrons emitted by the cathodes 16, 18 in the interaction space 22.
  • the anode 20 delimits at least one, in the example shown a plurality, of orifice (s) passing through 65 opening into the interior surface 60 and into the exterior surface 62.
  • the anode 20 is preferably, as shown, coaxial with the first cathode 16.
  • the microwave tube 12 is of the magnetron type.
  • the anode 20 is disposed radially around the cathodes 16, 18, and the cavities 63, 64 are distributed over the periphery of the anode 20.
  • the anode 20 comprises a cylindrical body 66 and a plurality of fins 68 each extending radially towards the cathode 20.
  • the cylindrical body 66 defines the outer surface 62 and a portion of the inner surface 60.
  • Each fin 68 protrudes from the cylindrical body 66 inwardly of the anode 20 and delimits a portion of the interior surface 60.
  • Each fin 68 is oriented longitudinally.
  • cylindrical is here to be understood in the broad sense and covers both cylinders of revolution and cylinders with a square, hexagonal, or other section.
  • Each cavity 63, 64 is symmetrical relative to a median longitudinal plane of the cavity 63, 64.
  • This median longitudinal plane includes the longitudinal axis Z.
  • Each cavity 63, 64 opens into a substantially cylindrical central space 70 extending at the center of the anode 20.
  • the central space 70 extends longitudinally.
  • the cathodes 16, 18 are arranged substantially in the center of the central space 70.
  • the remainder of the central space 70 constitutes the interaction space 22.
  • the plurality of resonant cavities 63, 64 comprises a plurality of large resonant cavities 63 and small resonant cavities 64, arranged alternately around the central space 70.
  • the radial section of each small cavity resonator 64 is smaller than the radial section of each large cavity resonator 63.
  • Each large cavity 63 is delimited by two fins 68 and by the cylindrical body 66.
  • Each small cavity 64 is delimited inside a fin 68 by a radial orifice opening into the central space 70.
  • the anode 20 thus has a configuration of the “rising sun” type. This configuration makes it possible to limit the risk of oscillations on parasitic frequencies, and thus to increase the efficiency of the device 10.
  • each large cavity 63 constitutes an output resonant cavity
  • each small resonant cavity 64 constitutes an intermediate resonant cavity.
  • the cavities 63, 64 are arranged so that the number of intermediate cavities 64 disposed between two consecutive outlet cavities 63 is equal for each pair of consecutive outlet cavities 63.
  • Each through orifice 65 opens into a respective outlet cavity 63.
  • No through orifice 65 opens into one of the intermediate cavities 64.
  • the outlet cavities 63 are identical to each other and the intermediate cavities 64 are identical to each other.
  • all of the resonant cavities are outlet cavities 63.
  • an emission zone 42 of the second cathode 18 is disposed substantially opposite said exit cavity 63.
  • said emission zone 42 is not strictly aligned with the exit cavity. 63, but is offset on an upstream side of the median longitudinal plane of the cavity 63.
  • upstream is to be understood with reference to a direction of circulation of the electrons in the interaction space 22, as will be detailed later.
  • an emission zone 42 of the second cathode 18 is arranged substantially opposite each cavity 63, 64 of the anode 20.
  • the anode 20 also comprises two rings (not shown) for longitudinal closure of the cavities 63, 64. Each ring thus defines a longitudinal end of the anode 20.
  • the respective positions of the cathodes 16, 18 on the one hand and of the anode 20 on the other hand are reversed, that is to say that the cathodes 16, 18 are arranged radially around the anode 20.
  • the microwave tube 12 is of the MILO type.
  • the interaction space 22, as well as the resonant cavities 63, 64, are kept under vacuum.
  • the focusing 76 typically comprises an electromagnet extending around the anode 20, in particular two electromagnets each extending around the anode 20 and arranged longitudinally on either side of the waveguides 14.
  • the focuser 76 is powered by an electrical power supply 78 of the generation device 10.
  • the third power supply 78 is adapted to deliver a current I to the focuser 76.
  • Each waveguide 14 is disposed opposite an orifice 65 passing through the anode 20, and extends from the exterior surface 62 of the anode 20 towards the exterior of the generation device 10.
  • the power supply circuit 21 is adapted to establish a significant potential difference, that is to say greater than 10%, between the cathodes 16, 18, and to supply the cathodes 16, 18 selectively with direct voltage or with voltage. impulse.
  • the supply circuit 21 comprises a direct voltage supply 100, a pulsed voltage supply 102, and an electric circuit 104 electrically connecting the supplies 100, 102 to the cathodes 16, 18.
  • the DC voltage supply 100 is suitable for generating a stable high voltage, preferably between 50 and 100kV. It is typically constituted by a stabilized mains supply.
  • the pulse voltage supply 102 is for example a Marx generator. It is electrically connected to the direct voltage supply 100 by a first switch 110 for controlling the electrical supply of the supply 102 by the supply 100.
  • Switch 110 is adapted to toggle between a closed configuration, in which it electrically connects an output of the DC power supply 100 to an input of the pulse power supply 102, and an open configuration, in which the output of the DC power supply 100 and the input of the pulse supply 102 are electrically isolated from each other
  • the electrical circuit 104 comprises a first electrical connection 112 electrically connecting the DC power supply 102 to the cathodes 16, 18, a second electrical connection 114 electrically connecting the pulse power supply 102 to the cathodes 16, 18, a second switch 116 for controlling the first electrical connection 112, and a voltage offset module 118 of the second cathode 18 with respect to the first cathode 16.
  • the second switch 116 is specific to the first electrical link 112. It is adapted to switch between a closed configuration, in which it electrically connects the DC power supply 100 to the cathodes 16, 18, and an open configuration, in which it electrically isolates the continuous supply 100 of the cathodes 16, 18.
  • the voltage shift module 118 is common to the first and second electrical links 112, 114. It comprises a voltage consuming member 120, interposed between the cathode 18 and the power supplies 100, 102, and a short circuit 122 for bypassing the voltage. organ 120.
  • the member 120 is adapted to consume a voltage substantially equal to the product of the potential difference between the first cathode 16 and the anode 20 times the d / D ratio.
  • the organ 120 is typically a resistor.
  • the short circuit 122 includes a third switch 124, to selectively open or close the short circuit 122.
  • the generation device 10 also comprises a module 80 for controlling the power supply circuit 21 and the power supply 78.
  • This control module 80 is programmed to control the power supply circuit 21, in particular the power supplies 100, 102 and the switches 110, 116, 124, as well as the power supply 78 according to several operating modes of the generation device 10. These operating modes are summarized in the table presented in Figure 5 .
  • the control module 80 is programmed to control the supply circuit 21 in a first operating mode (Mode 1) of the generation device 10, so that it takes the electric potential V 1 of the first cathode 16 to a first setpoint potential V 1.1 , and the electric potential V 2 of the second cathode 18 at a second setpoint potential V 2.1 .
  • control module 80 is programmed to control the DC power supply 100 so that it generates an electric voltage at the first electric potential V 1,1 , order the closing of the second switch 116, and order the opening of the first and third switches 110, 124.
  • the first setpoint potential V 1.1 is less than the electric potential V 0 of the anode 20.
  • the first setpoint potential V 1.1 is less than a first emission potential W 1 of the first cathode 16 , below which the first cathode 16 emits first electrons, and greater than a second emission potential W 2 of the second cathode 18, below which the first cathode 16 emits first electrons.
  • the first emission potential W 1 is equal to V 0 - D ⁇ E 1 .
  • the second emission potential W 2 is equal to V 0 - d ⁇ E 2 .
  • the second setpoint potential V 2.1 is less than the electrical potential V 0 of the anode 20, and greater than the first setpoint potential V 1.1 .
  • the second setpoint potential V 2.1 is adapted to minimize the disturbance induced by the second cathode 18 on the electric field created in the interaction space 22 by the first cathode 16 brought to the first setpoint potential V 1 , 1 .
  • the second setpoint potential V 2.1 is adapted so that the electric field created in the interaction space 22 by the first cathode 16 is brought to the first setpoint potential V 1.1 in the absence of the second cathode 18 is substantially equal to the electric field created in the interaction space 22 by the first cathode 16 brought to the first setpoint potential V 1,1 in the presence of the second cathode 18 brought to the second setpoint potential V 2 , 1 .
  • the second setpoint potential V 2.1 is substantially equal to V 0 - V 0 - V 1.1 D ⁇ d .
  • substantially equal is meant that the potential V 2.1 is between 90% and 110% of the aforementioned value.
  • the control module 80 is programmed to control the supply circuit 21 in the first operating mode (Mode 1) so as to maintain the first cathode 16 at the first setpoint potential V 1.1 for more than 1 ⁇ s.
  • the control module 80 is also programmed to control the power supply circuit 21, in particular the power supplies 100, 102 and the switches 110, 116, 124, as well as the power supply 78, in a second operating mode (Mode 2) of the generation device 10, so as to cyclically vary the electric potential V 1 of the first cathode 16 between the potential V 0 and a third potential setpoint V 1.2 , strictly less than the first setpoint potential V 1.1 , keeping the ratios (V 0 -V 1 ) / (V 0 -V 2 ) and (V 0 -V 1 ) / I substantially constant .
  • control module 80 is programmed to control the closing of the first switch 110, to control the opening of the second and third switches 116, 124, and to control the pulse supply 102 so that it generates a varying electrical voltage. cyclically between the potential V 0 and the third reference potential V 1.2 .
  • the third setpoint potential V 1,2 is greater than the second emission potential W 2 .
  • the control module 80 is further programmed to control the power supply circuit 21, in particular the power supplies 100, 102 and the switches 110, 116, 124 ,, in a third operating mode (Mode 3) of the generation device 10 , so that it causes the potential V 2 of the second cathode 18 to vary cyclically between the potential V 0 , and a fourth setpoint potential V 2.2 strictly less than the third setpoint potential V 1.2 , the potential V 1 of the first cathode 16 being at all times substantially equal to the potential V 2 of the second cathode 18, that is to say between 90% and 110% of the potential V 2 .
  • a third operating mode Mode 3
  • control module 80 is programmed to control the closing of the first and third switches 110, 124, to control the opening of the second switch 116, and to control the pulse supply 102 so that it generates a varying electrical voltage. cyclically between the potential V 0 and the fourth reference potential V 2.2 .
  • the fourth electrical reference potential V 2.2 is lower than the second emission potential W 2 .
  • the control module 80 is finally programmed to control the power supply 78 in the third operating mode (Mode 3) so that the ratio (V 0 -V 2 ) / I is kept substantially constant.
  • the generation device 10 further comprises a control interface 82.
  • This interface 82 comprises means 84 for selecting an operating mode of the generation device 10, and means 86 for sending an instruction to launch the mode. operating mode selected on the control module 80.
  • the control interface 82 is typically intended to serve as an interface with a computer system.
  • the selection means 84 comprise input / output ports known to those skilled in the art.
  • the generation device 10 is stopped.
  • the first and second cathodes 16, 18 are at the same potential as the anode 20, and the longitudinal magnetic field B is zero.
  • the generation device 10 is switched to the first operating mode.
  • the generation device 10 being stopped beforehand, this switching corresponds to a start-up of the generation device 10 in the first operating mode.
  • the first operating mode is selected by means of the control interface 82, which issues an instruction to launch the first operating mode to the control module 80.
  • the control module 80 receiving said instruction to launch of the first operating mode, sends a setpoint to the DC power supply 100 to generate an electric voltage at the first setpoint potential V 1.1 , closes the second switch 116, and opens the switches 110, 124. It also starts the power supply 78, with the instruction to inject a current I into the focusing device 76, adapted so that the focusing device 76 generates a longitudinal magnetic field B of intensity adapted to maintain the microwave tube 12 in oscillating mode.
  • the conditions which the longitudinal magnetic field B must verify for this purpose are known to those skilled in the art.
  • the first cathode 16 is thus brought to the first setpoint potential V 1.1
  • the second cathode 18 is brought to the second setpoint potential V 2.1.
  • a negative potential difference is therefore established between the anode 20 on the one hand and each cathode 16, 18 on the other hand.
  • This potential difference generates a radial electric field E oriented from the anode 20 towards the cathodes 16, 18.
  • This radial electric field E has an intensity greater than the first threshold value E 1 but less than the second threshold value E 2 . Under the effect of this electric field E, each emission zone 36 of the first cathode 16 emits first electrons in the interaction space 22.
  • each emission zone 36 is placed opposite a window 40 of the second cathode 18, the first electrons are little hampered by the second cathode 18 in order to reach the interaction space 22.
  • the first electrons rotate around the cathodes 16, 18 in space interaction 22, grouping together in packets.
  • the direction of rotation of the first electrons is determined in a known manner by the orientation of the electric field E and of the magnetic field B.
  • This displacement of the first electrons generates a radiofrequency electromagnetic wave in the microwave tube 12.
  • This wave is amplified thanks to the resonant cavities. 63, 64 and is captured to be used, for example to power a microwave weapon antenna, thanks to the waveguides 14.
  • This first step is followed by a second step of switching the generation device 10 into the second operating mode.
  • the second operating mode is selected by means of the control interface 82, which issues an instruction to launch the second operating mode to the control module 80.
  • the control module 80 receiving said instruction to launch of the second operating mode, closes the first switch 110, opens the second switch 116, and communicates a setpoint to the pulse supply 102, instructing it to generate an electric voltage varying cyclically between the potential V 0 and the third potential of setpoint V 1.2 .
  • the control module 80 also communicates a new setpoint to the power supply 78, instructing it to vary the current I while maintaining the ratio I / (V 0 -V 1 ) constant.
  • the potential V 1 of the first cathode 16 thus varies cyclically between the potential V 0 and the third setpoint potential V 1,2
  • the potential V 2 of the second cathode 18 also varies cyclically, the ratio (V 0 -V 1 ) / (V 0 -V 2 ) remaining substantially constant. Consequently, the radial electric field E takes on a variable intensity, varying between a maximum intensity, greater than the first threshold value E 1 and less than the second threshold value E 2 , and a minimum intensity, substantially zero.
  • each emission zone 36 of the first cathode 16 emits first electrons in the interaction space 22. As described above, these first electrons generate a radiofrequency wave in the microwave tube 12 while moving in the interaction space 22.
  • the duration of the cycles of variation of the first potential V 1 is adapted so that the electric field E goes back below the first threshold value E 1 when the electromagnetic energy accumulated in the interaction space 22 reaches a trigger threshold d 'a short circuit between the first cathode 16 and the anode 20.
  • This second operating mode thus allows the emission of waves of higher powers than in the first operating mode.
  • the transmission time must be reduced accordingly.
  • This second step is followed by a third step of switching the generation device 10 into the third operating mode.
  • the third operating mode is selected by means of the control interface 82, which sends an instruction to launch the third operating mode to the control module 80.
  • the control module 80 receiving said instruction to launch of the third operating mode, closes the third switch 124, and communicates a new setpoint to the pulse supply 102, instructing it to generate an electric voltage varying cyclically between the potential V 0 and the fourth setpoint potential V 2.2 .
  • the control module 80 also communicates a new setpoint to the power supply 78, instructing it to vary the current I while maintaining the ratio I / (V 0 -V 2 ) constant.
  • the potentials V 1 and V 2 of the cathodes 16, 18 thus both vary cyclically between the potential V 0 and the fourth setpoint potential V 2.2 , said potentials V 1 , V 2 remaining substantially equal to one another. . Consequently, the radial electric field E takes on a variable intensity, varying between a maximum intensity greater than the second threshold value E 2 , and a minimum intensity, substantially zero.
  • each emission region 42 of the second cathode 18 emits second electrons in the interaction space 22. As described above, these second electrons generate a radiofrequency wave in the microwave tube 12 while moving in the interaction space 22.
  • each emission region 42 Due to the punctuality of each emission region 42, the second emitted electrons are already distributed in packets, which makes it possible to accelerate the generation of the radiofrequency wave.
  • the first and second cathodes 16, 18 being substantially at the same potential, there is no electric field between the two.
  • the first cathode 16 is therefore in permanently subjected to an electric field of zero intensity, so that it does not emit electrons.
  • the duration of the cycles of variation of the second potential V 2 is adapted so that the electric field E goes back below the second threshold value E 2 when the electromagnetic energy accumulated in the interaction space 22 reaches a trigger threshold d 'a short circuit between the second cathode 16 and the anode 20.
  • This third operating mode thus allows the emission of waves of higher powers than in the second operating mode. However, the transmission time must be reduced accordingly.
  • the generation device 10 is stopped.
  • the control module 80 controls the stopping of the supply circuit 21 and of the supply 78.
  • Each cathode 16, 18 stabilizes at a potential substantially equal to the potential V 0 of the anode 20, and the longitudinal magnetic field B takes on a zero value.
  • the generation device 10 is connected to a source (not shown) for supplying the interaction space 22 with electromagnetic wave via one of the waveguides 14.
  • This source is in operation. particularly suitable for emitting an electromagnetic wave with a predetermined frequency and / or phase.
  • This source is typically a magnetron or a klystron.
  • the generation device 10 is then started in the first operating mode, the source supplying the interaction space 22. Under the effect of the wave electromagnetic emitted by the source, the wave generated by the generation device 10 is set on the frequency and on the phase of said electromagnetic wave.
  • the generation device 10 is started, the source is stopped. The generation device 10 is then switched to the second operating mode and then, optionally, to the third operating mode. At each changeover, the wave generated by the generation device 10 keeps the frequency and the phase of the wave previously emitted in the interaction space 22.
  • the second cathode 18 is cylindrical of revolution and is formed of two parts 90, 92 rotating with respect to one another around the longitudinal axis Z between a first configuration of the cathode 18, shown in FIG. Figure 7 , and a second configuration of the cathode 18, shown in Figure 8 .
  • the second cathode 18 also comprises means for driving (not shown) a first 90 of the two parts 90, 92 in rotation relative to the second part 92.
  • the two parts 90, 92 are connected to the supply circuit 21 so as to be brought to substantially the same electric potential.
  • Each part 90, 92 carries one half of the emission regions 42 of the second cathode 18.
  • the emission regions 42 are regularly distributed along the circumference of the second cathode 18. In other words, each emission region 42 is equidistant from the two other emission regions 42 of which it is. is the closest.
  • the emission regions 42 are grouped together in pairs of adjacent emission regions 42.
  • each emission region 42 is adjacent to another emission region 42 and at a distance from the other emission regions 42.
  • each emission region 42 carried by the first part 90 is adjacent. to an emission region 42 carried by the second part 92, the emission regions 42 carried by each part 90, 92 remaining at a distance from each other.
  • the number of windows 40 is halved, due to the absence of a window 40 between the adjacent emission regions 42.
  • the remaining windows 40 are larger than in the first configuration, which makes it possible to promote the passage of the first electrons when the first cathode 16 emits.
  • each pair of adjacent emission regions 42 is equivalent to a single emission sector of the cathode 18.
  • the microwave tube 12 is a magnetron
  • the second cathode 18 is of the “transparent cathode” type, as described above.
  • the body 44 is formed of two cylinders 94, 96 oriented longitudinally and fitted one inside the other.
  • the inner cylinder 94 belongs to the first part 90.
  • the outer cylinder 96 belongs to the second part 92.
  • the inner cylinder 94 is integral with three of the six bars 50 of the cathode 18. These are regularly distributed along the circumference of the inner cylinder 94. In other words, they are arranged at the vertices of an equilateral triangle. Said bars 50 are fixed relative to each other.
  • the outer cylinder 96 is integral with the three remaining bars 50. These are regularly distributed along the circumference of the outer cylinder 96. In other words, they are arranged at the vertices of an equilateral triangle. Said bars 50 are fixed relative to each other.
  • each of the bars 50 secured to the inner cylinder 94 and the bars 50 secured to the outer cylinder 96 are substantially equidistant from the longitudinal axis Z.
  • each of the bars 50 secured to the inner cylinder 94 is carried by a projection 98 projecting radially. outwardly from the outer peripheral surface of the inner cylinder 94.
  • each of the bars 50 integral with the outer cylinder 96 is carried by a projection projecting radially inwardly from the inner surface of the outer cylinder 96. .
  • This variant can be generalized to a case where the second cathode 18 comprises N parts each carrying P / N emission regions 42, where P is the total number of emission regions 42 of the second cathode 18, said parts being rotatable. relative to the others around the longitudinal axis Z between a first configuration of the second cathode 18, in which all the emission regions 42 are spaced from each other, and a second configuration of the second cathode 18, in which at least two of the emission regions 42 are adjacent.
  • This variant of the invention makes it possible to increase the efficiency of the generation device 10 when it is in the first or the second operating mode, by reducing the interactions between the first electrons and the second cathode 18.
  • this variant further increases the flexibility of the generation device 10 by making it possible to generate waves, when the generation device 10 is in the third mode of operation, over a wide range of frequencies.
  • the second cathode 18 is also formed of two parts, each carrying one half of the emission regions 42 of the second cathode 18, but these parts are not rotatable with respect to one another. 'other.
  • a switch makes it possible to selectively electrically connect only one of said parts or both parts simultaneously, to the supply circuit 21.
  • this variant makes it possible to operate the magnetron in ⁇ mode and in 2 ⁇ mode.

Description

La présente invention concerne un dispositif de génération d'ondes hyperfréquences, du type comprenant une anode et une première cathode, séparées par un espace d'interaction, la première cathode étant adaptée pour émettre des premiers électrons dans l'espace d'interaction lorsque soumise à un champ électrique d'intensité supérieure à une première valeur seuil, et l'anode étant adaptée pour attirer lesdits premiers électronsThe present invention relates to a device for generating microwave waves, of the type comprising an anode and a first cathode, separated by an interaction space, the first cathode being adapted to emit first electrons in the interaction space when subjected. to an electric field of intensity greater than a first threshold value, and the anode being adapted to attract said first electrons

Les dispositifs de génération d'ondes de ce type sont connus et incluent notamment les magnétrons, les klystrons, et les MILOs (pour « Magnetically Insulated Line Oscillator » en anglais).Wave generation devices of this type are known and include in particular magnetrons, klystrons, and MILOs (for “Magnetically Insulated Line Oscillator”).

Aussi, un dispositif de génération d'ondes hyperfréquences comprenant une anode et une cathode séparée par un espace d'interaction, ce dispositif comprenant en outre un guide d'ondes disposé en regard d'un orifice traversant de l'anode et s'étendant depuis une surface extérieure de l'anode vers l'extérieur du dispositif de génération est connu de " Rapid Start of Oscillations in a Magnetron with a "Transparent" Cathode", Mikhail Fuks and Edl Schamiloglu, Physical Review Letters, 10 novembre 2005 (2005-11-10), XP055250125, URL:http://journals.aps.org/prl/pdf/10.1103/ PhysRevLett.95.205101 .Also, a device for generating microwave waves comprising an anode and a cathode separated by an interaction space, this device further comprising a waveguide disposed opposite an orifice passing through the anode and extending from an outer surface of the anode to the outside of the generating device is known to " Rapid Start of Oscillations in a Magnetron with a "Transparent" Cathode ", Mikhail Fuks and Edl Schamiloglu, Physical Review Letters, November 10, 2005 (2005-11-10), XP055250125, URL: http: //journals.aps.org/ prl / pdf / 10.1103 / PhysRevLett.95.205101 .

Ces dispositifs ne peuvent pas émettre une onde, à la fois, de forte puissance et de longue durée, du fait du risque de formation d'un court-circuit entre l'anode et la cathode dans l'espace d'interaction. Ainsi, certains de ces dispositifs sont conçus pour générer des ondes de longue durée et de faible puissance, d'autres sont conçus pour générer des impulsions longues de moyenne puissance, et le reste de ces dispositifs est conçu pour générer des impulsions courtes de forte puissance.These devices cannot emit a wave of both high power and long duration, due to the risk of forming a short circuit between the anode and the cathode in the interaction space. So, some of these devices are designed to generate long duration, low power waves, others are designed to generate medium power long pulses, and the rest of these devices are designed to generate high power short pulses. .

Les dispositifs de génération connus ne présentent donc généralement pas une grande souplesse de fonctionnement, en ce sens qu'ils ne sont adaptés pour n'émettre qu'un seul type d'onde.Known generation devices therefore generally do not have great flexibility of operation, in the sense that they are not suitable for emitting only one type of wave.

On connaît des équipements d'émission, par exemple les armes hyperfréquences, adaptés pour émettre à la fois des ondes continues de faible puissance et des impulsions courtes de forte puissance, par exemple en vue de la guerre électronique. Du fait de leur très large plage de fonctionnement, ces équipements nécessitent l'utilisation de plusieurs dispositifs de génération pour les alimenter.Transmission equipment is known, for example microwave weapons, suitable for transmitting both continuous waves of low power and short pulses of high power, for example with a view to electronic warfare. Because of their very wide operating range, this equipment requires the use of several generation devices to power it.

On comprend que la présence de ces multiples dispositifs de génération constitue un obstacle à la miniaturisation des équipements d'émission.It will be understood that the presence of these multiple generation devices constitutes an obstacle to the miniaturization of transmission equipment.

Un objectif de l'invention est donc de proposer un dispositif de génération compact et présentant une grande souplesse de fonctionnement.An objective of the invention is therefore to provide a generation device that is compact and exhibits great operating flexibility.

A cet effet, l'invention a pour objet un dispositif de génération du type précité, comprenant une deuxième cathode, intercalée entre la première cathode et l'anode et adaptée pour émettre des deuxièmes électrons dans l'espace d'interaction lorsque soumise à un champ électrique d'intensité supérieure à une deuxième valeur seuil, l'anode étant adaptée pour attirer lesdits deuxièmes électrons, et un circuit d'alimentation électrique des cathodes, adapté pour établir une différence de potentiel entre les cathodes. La deuxième valeur seuil est strictement supérieure à la première valeur seuil.To this end, the invention relates to a generation device of the aforementioned type, comprising a second cathode, interposed between the first cathode and the anode and adapted to emit second electrons into the interaction space when subjected to a electric field of intensity greater than a second threshold value, the anode being adapted to attract said second electrons, and a supply circuit electrical cathode, adapted to establish a potential difference between the cathodes. The second threshold value is strictly greater than the first threshold value.

Dans des modes de réalisation préférés de l'invention, le dispositif de génération présente l'une ou plusieurs des caractéristiques suivantes, prise(s) isolément ou suivant toute(s) combinaison(s) techniquement possible(s) :

  • la première cathode est une cathode à émission de champ à micropointes émettrices d'électrons,
  • la première cathode est adaptée pour émettre continûment des électrons sur une durée supérieure à 1 µs,
  • la deuxième cathode est adaptée pour délivrer une densité de courant supérieure à 10 A/cm2,
  • la deuxième cathode comprend une pluralité de régions d'émission définissant entre elles au moins une fenêtre, interposée entre la première cathode et l'anode,
  • les régions d'émission de la deuxième cathode définissent entre elles plusieurs fenêtres, et la première cathode comprend une pluralité de zones d'émission distantes les unes des autres, chaque zone d'émission de la première cathode étant disposée en regard de l'une des fenêtres de la deuxième cathode,
  • l'anode est tubulaire et s'étend suivant un axe, chaque cathode étant entourée par l'anode en étant sensiblement centrée sur l'axe,
  • il comprend un module de commande du circuit d'alimentation des cathodes, programmé pour porter le potentiel électrique de la première cathode à un premier potentiel de consigne, inférieur à un potentiel d'émission de la première cathode, et pour porter le potentiel électrique de la deuxième cathode à un deuxième potentiel de consigne inférieur au potentiel de l'anode et supérieur au premier potentiel de consigne, lorsque le dispositif de génération est dans un premier mode de fonctionnement,
  • la différence de potentiel entre le deuxième potentiel de consigne et le potentiel de l'anode est sensiblement égale à U 1 D × d ,
    Figure imgb0001
     où U1 est la différence de potentiel entre la premier potentiel de consigne et le potentiel de l'anode, D est la distance entre l'anode et la première cathode, et d est la distance entre l'anode et la deuxième cathode,
  • le module de commande est programmé pour maintenir le potentiel électrique de la première cathode au premier potentiel de consigne pendant une durée supérieure à 1 µs dans le premier mode de fonctionnement,
  • le module de commande est programmé pour porter le potentiel électrique de la deuxième cathode à un troisième potentiel de consigne, inférieur à un potentiel d'émission de la deuxième cathode, lorsque le dispositif de génération est dans un autre mode de fonctionnement, le potentiel électrique de la première cathode étant sensiblement égal au potentiel électrique de la deuxième cathode,
  • le module de commande est programmé pour faire varier cycliquement le potentiel électrique de la deuxième cathode entre le troisième potentiel de consigne et le potentiel de l'anode, lorsque le dispositif de génération est dans l'autre mode de fonctionnement.
  • l'anode est tubulaire et s'étend suivant un axe, chaque cathode étant entourée par l'anode en étant sensiblement centrée sur l'axe, et le dispositif de génération comprend un focalisateur pour former un champ magnétique dans l'espace d'interaction, orienté suivant l'axe, le module de commande étant adapté pour commander une alimentation du focalisateur de façon à faire varier cycliquement l'intensité du champ magnétique, lorsque le dispositif de génération est dans le deuxième mode de fonctionnement, entre une intensité maximale lorsque le potentiel électrique de la deuxième cathode est égal au troisième potentiel de consigne, et une intensité nulle lorsque le potentiel électrique de la deuxième cathode est au potentiel de l'anode.
In preferred embodiments of the invention, the generation device has one or more of the following characteristics, taken in isolation or in any technically possible combination (s):
  • the first cathode is a field emission cathode with electron emitting microtips,
  • the first cathode is suitable for continuously emitting electrons over a period of more than 1 µs,
  • the second cathode is suitable for delivering a current density greater than 10 A / cm 2 ,
  • the second cathode comprises a plurality of emission regions defining between them at least one window, interposed between the first cathode and the anode,
  • the emission regions of the second cathode define between them several windows, and the first cathode comprises a plurality of emission zones distant from each other, each emission zone of the first cathode being arranged opposite one windows of the second cathode,
  • the anode is tubular and extends along an axis, each cathode being surrounded by the anode while being substantially centered on the axis,
  • it comprises a control module for the supply circuit of the cathodes, programmed to bring the electric potential of the first cathode to a first reference potential, lower than an emission potential of the first cathode, and to raise the electric potential of the second cathode at a second reference potential lower than the potential of the anode and higher than the first reference potential, when the generation device is in a first operating mode,
  • the potential difference between the second setpoint potential and the potential of the anode is approximately equal to U 1 D × d ,
    Figure imgb0001
     where U 1 is the potential difference between the first setpoint potential and the potential of the anode, D is the distance between the anode and the first cathode, and d is the distance between the anode and the second cathode,
  • the control module is programmed to maintain the electric potential of the first cathode at the first setpoint potential for a period greater than 1 µs in the first operating mode,
  • the control module is programmed to bring the electric potential of the second cathode to a third reference potential, lower than an emission potential of the second cathode, when the generating device is in another operating mode, the electric potential of the first cathode being substantially equal to the electric potential of the second cathode,
  • the control module is programmed to cyclically vary the electric potential of the second cathode between the third setpoint potential and the potential of the anode, when the generating device is in the other operating mode.
  • the anode is tubular and extends along an axis, each cathode being surrounded by the anode while being substantially centered on the axis, and the generating device comprises a focuser for forming a magnetic field in the interaction space , oriented along the axis, the control module being adapted to control a power supply of the focusing so as to cyclically vary the intensity of the magnetic field, when the generating device is in the second operating mode, between a maximum intensity when the electric potential of the second cathode is equal to the third setpoint potential, and zero intensity when the electric potential of the second cathode is at the potential of the anode.

D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description qui va suivre, donnée uniquement à titre d'exemple et faite en se référant aux dessins annexés, sur lesquels :

  • la Figure 1 est une vue en coupe radiale d'un dispositif de génération selon l'invention,
  • la Figure 2 est une vue en élévation et en coupe partielle d'une première et d'une deuxième cathode du dispositif de génération de la Figure 1,
  • la Figure 3 est une vue en perspective de la deuxième cathode de la Figure 2, selon une première variante de l'invention,
  • la Figure 4 est un schéma électrique d'un circuit d'alimentation des première et deuxième cathodes de la Figure 2,
  • la Figure 5 est un tableau présentant divers modes de fonctionnement du dispositif de génération de la Figure 1,
  • la Figure 6 est une vue en perspective et en coupe selon un plan marqué VI-VI sur la Figure 7 de la deuxième cathode de la Figure 2, selon une deuxième variante de l'invention,
  • la Figure 7 est une vue de dessus de la cathode de la Figure 6, dans une première configuration, et
  • la Figure 8 est une vue similaire à la Figure 7, dans une deuxième configuration de la cathode.
Other characteristics and advantages of the invention will become apparent on reading the description which follows, given solely by way of example and made with reference to the appended drawings, in which:
  • the Figure 1 is a radial sectional view of a generation device according to the invention,
  • the Figure 2 is an elevational view in partial section of a first and a second cathode of the device for generating the Figure 1 ,
  • the Figure 3 is a perspective view of the second cathode of the Figure 2 , according to a first variant of the invention,
  • the Figure 4 is an electrical diagram of a power supply circuit for the first and second cathodes of the Figure 2 ,
  • the Figure 5 is a table showing various modes of operation of the device for generating the Figure 1 ,
  • the Figure 6 is a perspective and sectional view on a plane marked VI-VI on the Figure 7 of the second cathode of the Figure 2 , according to a second variant of the invention,
  • the Figure 7 is a top view of the cathode of the Figure 6 , in a first configuration, and
  • the Figure 8 is a view similar to Figure 7 , in a second configuration of the cathode.

Comme visible sur la Figure 1, le dispositif de génération 10 selon l'invention comprend un tube hyperfréquence 12 et au moins un, dans l'exemple représenté une pluralité de, guide(s) d'ondes 14. Le tube hyperfréquence 12 comprend une première cathode 16, une deuxième cathode 18, une anode 20, et un circuit 21 (Figure 2) d'alimentation électrique des cathodes 16, 18.As visible on the Figure 1 , the generation device 10 according to the invention comprises a microwave tube 12 and at least one, in the example shown a plurality of waveguide (s) 14. The microwave tube 12 comprises a first cathode 16, a second cathode 18, an anode 20, and a circuit 21 ( Figure 2 ) power supply of the cathodes 16, 18.

Les cathodes 16, 18 sont séparées de l'anode 20 par un espace d'interaction 22. Le circuit d'alimentation 21 des cathodes est adapté pour porter chaque cathode, respectivement 16, 18, à un potentiel électrique, respectivement V1; V2, inférieur au potentiel électrique V0 de l'anode 20 lorsque le tube 12 est alimenté en énergie électrique, de sorte qu'il existe une différence de potentiel entre l'anode 20 et chaque cathode, respectivement 16, 18. Cette différence de potentiel génère un champ électrique E à l'intérieur de l'espace d'interaction 22, orienté de l'anode 20 vers les cathodes 16, 18.The cathodes 16, 18 are separated from the anode 20 by an interaction space 22. The supply circuit 21 of the cathodes is adapted to bring each cathode, respectively 16, 18, to an electric potential, respectively V 1 ; V 2 , less than the electrical potential V 0 of the anode 20 when the tube 12 is supplied with electrical energy, so that there is a potential difference between the anode 20 and each cathode, respectively 16, 18. This difference of potential generates an electric field E inside the interaction space 22, oriented from the anode 20 towards the cathodes 16, 18.

Le tube hyperfréquence 12 comprend également un focalisateur 76 pour focaliser des électrons émis par les cathodes 16, 18 à l'intérieur de l'espace d'interaction 22. A cet effet, le focalisateur 76 est adapté pour générer un champ magnétique B à l'intérieur de l'espace d'interaction 22.The microwave tube 12 also comprises a focusing device 76 for focusing electrons emitted by the cathodes 16, 18 inside the interaction space 22. For this purpose, the focusing device 76 is adapted to generate a magnetic field B at 1. interior of the interaction space 22.

Les champs électrique E et magnétique B sont orientés perpendiculairement l'un à l'autre. Ils respectent chacun les conditions de synchronisme imposées par la géométrie du tube 12. Ils sont adaptés l'un à l'autre pour conférer aux électrons émis par les cathodes 16, 18 un mouvement cycloïdal dans l'espace d'interaction 22.The electric E and magnetic B fields are oriented perpendicular to each other. They each respect the conditions of synchronism imposed by the geometry of the tube 12. They are adapted to one another to give the electrons emitted by the cathodes 16, 18 a cycloidal movement in the interaction space 22.

La première cathode 16 est adaptée pour émettre des premiers électrons dans l'espace d'interaction 22, à destination de l'anode 20, sous l'effet du champ électrique E, à condition que ce champ électrique ait une intensité supérieure à une première valeur de seuil E1.The first cathode 16 is adapted to emit the first electrons in the interaction space 22, intended for the anode 20, under the effect of the electric field E, provided that this electric field has an intensity greater than a first threshold value E 1 .

La première cathode 16 est en particulier adaptée pour émettre continûment des électrons sur une durée supérieure à 1 µs lorsqu'elle est soumise au champ électrique E.The first cathode 16 is in particular suitable for continuously emitting electrons over a period of more than 1 μs when it is subjected to the electric field E.

A cet effet, la première cathode 16 est avantageusement, comme représenté sur la Figure 2, une cathode à émission de champ à micropointes émettrices d'électrons. De telles cathodes sont connues, par exemple de FR-A-2 734 076 .For this purpose, the first cathode 16 is advantageously, as shown in Figure 2 , a field emission cathode with electron emitting microtips. Such cathodes are known, for example from FR-A-2 734 076 .

Cette cathode 16 comprend, de façon connue, un substrat conducteur 24, par exemple en silicium, ayant une face active 26 sur laquelle sont disposées des micropointes 28. La face active 26 est recouverte d'une couche isolante 30, par exemple en oxyde de silicium, la séparant d'une grille 32 conductrice. Les micropointes 28 sont logées dans des cavités respectives 34 ménagées dans la couche isolante 30. Ces cavités 34 communiquent avec l'espace d'interaction 22 par des ouvertures correspondantes prévues dans la grille 32. Les extrémités des micropointes 28 opposées au substrat 24 viennent en affleurement de la surface extérieure de la grille 32.This cathode 16 comprises, in a known manner, a conductive substrate 24, for example made of silicon, having an active face 26 on which microtips 28 are arranged. The active face 26 is covered with an insulating layer 30, for example made of carbon dioxide. silicon, separating it from a conductive grid 32. The microtips 28 are housed in respective cavities 34 formed in the insulating layer 30. These cavities 34 communicate with the interaction space 22 through corresponding openings provided in the grid 32. The ends of the microtips 28 opposite to the substrate 24 come in contact with the interaction space 22. flush with the outer surface of the grille 32.

La dimension des cavités 34, et donc des micropointes, est de l'ordre du micron en hauteur et en largeur. La densité de micropointes 28 est de l'ordre de 10 000 à 100 000 micropointes par mm2 de face active 26. On notera que, pour des raisons de lisibilité des Figures, les proportions n'ont pas été respectées sur la Figure 2.The dimension of the cavities 34, and therefore of the microtips, is of the order of a micron in height and width. The density of microtips 28 is of the order of 10,000 to 100,000 microtips per mm 2 of active face 26. It will be noted that, for reasons of legibility of the Figures, the proportions have not been observed on the figure. Figure 2 .

Les micropointes 28 sont de préférence constituées par des nanotubes en carbone.The microtips 28 are preferably formed by carbon nanotubes.

Des moyens (non représentés) de polarisation positive de la grille 32 sont connectés entre le substrat 24 et la grille 32. Ces moyens sont adaptés faire varier sur commande la tension entre le substrat 24 la grille 32 entre une première valeur, inférieure à une tension seuil, dans laquelle le flux d'électrons émis par la cathode 16 est nul, et une deuxième valeur, supérieure à la tension seuil, dans laquelle la cathode 16 produit un courant d'électrons.Positive biasing means (not shown) of gate 32 are connected between substrate 24 and gate 32. These means are suitable for varying the voltage between substrate 24 and gate 32 on command between a first value, less than a voltage. threshold, in which the flow of electrons emitted by the cathode 16 is zero, and a second value, greater than the threshold voltage, in which the cathode 16 produces a current of electrons.

De tels moyens de polarisation sont connus.Such polarization means are known.

Les micropointes 28 ne sont pas réparties uniformément sur la face active 26. Elles sont groupées au sein de zones d'émission 36 de la cathode 16. Ces zones d'émission 36 sont distantes les unes des autres.The microtips 28 are not distributed uniformly over the active face 26. They are grouped within emission zones 36 of the cathode 16. These emission zones 36 are distant from each other.

Dans l'exemple représenté, le substrat 24 est cylindrique, de préférence cylindrique de révolution, et s'étend suivant un axe longitudinal Z. Les micropointes 28 sont réparties sur toute la périphérie du cylindre. Chaque zone d'émission 36 est allongée parallèlement à l'axe longitudinal Z.In the example shown, the substrate 24 is cylindrical, preferably cylindrical of revolution, and extends along a longitudinal axis Z. The microtips 28 are distributed over the entire periphery of the cylinder. Each emission zone 36 is elongated parallel to the longitudinal axis Z.

En variante, la première cathode 16 est une cathode thermoélectronique, adaptée pour émettre des électrons dans l'espace d'interaction si et seulement si le champ E est supérieur à la première valeur de seuil E1 et la cathode 16 est chauffée à une température supérieure à une valeur seuil. La cathode 16 est alors en tungstène, ou en carbone pyrolytique.As a variant, the first cathode 16 is a thermoelectronic cathode, adapted to emit electrons into the interaction space if and only if the field E is greater than the first threshold value E 1 and the cathode 16 is heated to a temperature greater than a threshold value. The cathode 16 is then made of tungsten, or of pyrolytic carbon.

En variante encore, la première cathode 16 est en mélange de tungstène et de Sc2O3, comme décrit dans le document ZHAO Jinfeng, Scandia-added Tungsten Dispenser Cathode Fabrication for THz Vacuum Integrated Power Amplifiers, Terahertz Science and Technology décembre 2011, vol. 4, n°4, pages 240-252 ..As a further variant, the first cathode 16 is a mixture of tungsten and Sc 2 O 3 , as described in the document ZHAO Jinfeng, Scandia-added Tungsten Dispenser Cathode Fabrication for THz Vacuum Integrated Power Amplifiers, Terahertz Science and Technology December 2011, vol. 4, n ° 4, pages 240-252 ..

La première cathode 16 est à une distance D de l'anode 20.The first cathode 16 is at a distance D from the anode 20.

De retour à la Figure 1, la deuxième cathode 18 est adaptée pour émettre des deuxièmes électrons dans l'espace d'interaction 22, à destination de l'anode 20, sous l'effet du champ électrique E, à condition que ce champ électrique ait une intensité supérieure à une deuxième valeur de seuil E2.Back to the Figure 1 , the second cathode 18 is suitable for emitting second electrons in the interaction space 22, destined for the anode 20, under the effect of the electric field E, provided that this electric field has an intensity greater than one second threshold value E 2 .

La deuxième valeur de seuil E2 est de préférence différente de la première valeur de seuil E1. En particulier, la deuxième valeur de seuil E2 est strictement supérieure à la première valeur de seuil E1.The second threshold value E 2 is preferably different from the first threshold value E 1 . In particular, the second threshold value E 2 is strictly greater than the first threshold value E 1 .

La deuxième cathode 18 est intercalée entre la première cathode 16 et l'anode 20.The second cathode 18 is interposed between the first cathode 16 and the anode 20.

En particulier, la deuxième cathode 18 est tubulaire et entoure la première cathode 16.In particular, the second cathode 18 is tubular and surrounds the first cathode 16.

De préférence, les cathodes 16, 18 sont concentriques. Elles sont chacune centrée sur l'axe longitudinal Z.Preferably, the cathodes 16, 18 are concentric. They are each centered on the longitudinal axis Z.

Les premiers électrons émis par la première cathode 16 doivent donc traverser la deuxième cathode 18 pour atteindre l'anode 20. A cet effet, la deuxième cathode 18 délimite, comme visible sur la Figure 2, une pluralité de fenêtres 40 chacune interposée entre la première cathode 16 et l'anode 20. Chaque fenêtre 40 est délimitée entre deux régions d'émission 42 de la deuxième cathode 28.The first electrons emitted by the first cathode 16 must therefore pass through the second cathode 18 to reach the anode 20. For this purpose, the second cathode 18 delimits, as visible on the figure. Figure 2 , a plurality of windows 40 each interposed between the first cathode 16 and the anode 20. Each window 40 is delimited between two emission regions 42 of the second cathode 28.

Chacune desdites fenêtres 40 est disposée en regard de l'une des zones d'émission 36 de la première cathode 16. Ainsi, le nombre d'électrons émis par la première cathode 16 heurtant la deuxième cathode 18 est réduit, ce qui permet d'augmenter le rendement du dispositif de génération 10.Each of said windows 40 is arranged opposite one of the emission zones 36 of the first cathode 16. Thus, the number of electrons emitted by the first cathode 16 striking the second cathode 18 is reduced, which makes it possible to increase the efficiency of the generation device 10.

En référence à la Figure 3, la deuxième cathode 18 est avantageusement une cathode « transparente ». De telles cathodes sont connues, par exemple de US 2008/0246385 .With reference to the Figure 3 , the second cathode 18 is advantageously a “transparent” cathode. Such cathodes are known, for example from US 2008/0246385 .

La deuxième cathode 18 comprend ainsi un corps 44 tubulaire s'étendant autour de l'axe Z, depuis une première extrémité 46 de raccordement au circuit d'alimentation 21 jusqu'à une deuxième extrémité 48 libre. Le corps 44 est formé dans un matériau ayant une bonne conductivité électrique, typiquement en cuivre.The second cathode 18 thus comprises a tubular body 44 extending around the axis Z, from a first end 46 for connection to the supply circuit 21 to a second free end 48. Body 44 is formed from a material having good electrical conductivity, typically copper.

Une pluralité de barreaux 50 s'étendent parallèlement à l'axe Z depuis l'extrémité libre 48, à l'opposée du corps 44. Chaque barreau 50 constitue une région d'émission 42 de la deuxième cathode 18.A plurality of bars 50 extend parallel to the Z axis from the free end 48, opposite the body 44. Each bar 50 constitutes an emission region 42 of the second cathode 18.

Chaque barreau 50 est typiquement en carbone pyrolytique, en tungstène ou en molybdène. Ces matériaux ont en effet en commun de présenter une bonne conductivité électrique et thermique, de dégazer peu et d'être rigides, ce qui les rend particulièrement adaptés pour la réalisation des barreaux 50. Le carbone pyrolytique ayant une outre une faible densité, son utilisation permet d'alléger le dispositif de génération 10.Each bar 50 is typically made of pyrolytic carbon, tungsten or molybdenum. These materials have in fact in common the fact that they have good electrical and thermal conductivity, that they degas little and that they are rigid, which makes them particularly suitable for the production of bars 50. Pyrolytic carbon having a low density in addition, its use makes it possible to lighten the generation 10 device.

Les barreaux 50 sont régulièrement répartis autour de l'axe Z. Ils délimitent entre eux une cavité 52 de réception de la première cathode 16, centrée sur l'axe Z.The bars 50 are regularly distributed around the Z axis. They define between them a cavity 52 for receiving the first cathode 16, centered on the Z axis.

Les barreaux 50 sont espacés les uns des autres. Pour chaque paire de barreaux 50 consécutifs, un vide 54 est ainsi laissé entre ces barreaux 50. Ce vide 54 constitue une fenêtre 40 de la deuxième cathode 18. Il permet le passage des électrons émis par la première cathode 16, ainsi que le passage des champs électromagnétiques pour qu'ils pénètrent à l'intérieur de la deuxième cathode 18.The bars 50 are spaced from each other. For each pair of consecutive bars 50, a void 54 is thus left between these bars 50. This void 54 constitutes a window 40 of the second cathode 18. It allows the passage of electrons emitted by the first cathode 16, as well as the passage of electromagnetic fields so that they penetrate inside the second cathode 18.

On notera que, dans l'exemple représenté, les barreaux 50 ont une forme cylindrique de révolution. En variante, les barreaux 50 ont toute autre forme appropriée, par exemple une forme de prisme. On notera que l'utilisation de barreaux 50 en forme de prismes permet d'allonger la durée pendant laquelle la deuxième cathode 18 peut émettre continûment des électrons.It will be noted that, in the example shown, the bars 50 have a cylindrical shape of revolution. As a variant, the bars 50 have any other suitable shape, for example a prism shape. It will be noted that the use of bars 50 in the form of prisms makes it possible to lengthen the period during which the second cathode 18 can continuously emit electrons.

De même, dans l'exemple représenté, l'extrémité 56 des barreaux 50 opposée au corps 44 est laissée libre. En variante, un organe de liaison des barreaux 50 les uns aux autres, typiquement un anneau, relie lesdites extrémités 56, de façon à renforcer la deuxième cathode 18.Likewise, in the example shown, the end 56 of the bars 50 opposite the body 44 is left free. As a variant, a member for connecting the bars 50 to one another, typically a ring, connects said ends 56, so as to reinforce the second cathode 18.

La deuxième cathode 18 est typiquement une cathode à émission de champ.The second cathode 18 is typically a field emission cathode.

La deuxième cathode 18 est avantageusement adaptée pour émettre des électrons dans l'espace d'interaction 22 avec une densité de courant supérieure à 10 A/cm2.The second cathode 18 is advantageously suitable for emitting electrons in the interaction space 22 with a current density greater than 10 A / cm 2 .

La deuxième cathode 18 est à une distance d de l'anode 20.The second cathode 18 is at a distance d from the anode 20.

De retour à la Figure 1, l'anode 20 est tubulaire. Elle présente une surface intérieure 60, et une surface extérieure 62, opposée à la surface intérieure 60. Elle est formée dans un matériau conducteur, typiquement en acier, en graphite ou en cuivre.Back to the Figure 1 , the anode 20 is tubular. It has an interior surface 60, and an exterior surface 62, opposite the interior surface 60. It is formed from a conductive material, typically steel, graphite or copper.

La surface intérieure 60 délimite une pluralité de cavités résonnantes 63, 64. Ces cavités résonnantes 63, 64 sont adaptées pour amplifier une onde électromagnétique formée par la circulation des électrons émis par les cathodes 16, 18 dans l'espace d'interaction 22.The interior surface 60 delimits a plurality of resonant cavities 63, 64. These resonant cavities 63, 64 are adapted to amplify an electromagnetic wave formed by the circulation of electrons emitted by the cathodes 16, 18 in the interaction space 22.

L'anode 20 délimite au moins un, dans l'exemple représenté une pluralité, d'orifice(s) traversant 65 débouchant dans la surface intérieure 60 et dans la surface extérieure 62.The anode 20 delimits at least one, in the example shown a plurality, of orifice (s) passing through 65 opening into the interior surface 60 and into the exterior surface 62.

L'anode 20 est de préférence, comme représenté, co-axiale avec la première cathode 16.The anode 20 is preferably, as shown, coaxial with the first cathode 16.

Dans l'exemple représenté, le tube hyperfréquences 12 est du type magnétron. Ainsi, l'anode 20 est disposée radialement autour des cathodes 16, 18, et les cavités 63, 64 sont réparties sur la périphérie de l'anode 20.In the example shown, the microwave tube 12 is of the magnetron type. Thus, the anode 20 is disposed radially around the cathodes 16, 18, and the cavities 63, 64 are distributed over the periphery of the anode 20.

En particulier, l'anode 20 comprend un corps cylindrique 66 et une pluralité d'ailettes 68 s'étendant chacune radialement vers la cathode 20. Le corps cylindrique 66 délimite la surface extérieure 62 et une partie de la surface intérieure 60. Chaque ailette 68 fait saillie depuis le corps cylindrique 66 vers l'intérieur de l'anode 20 et délimite une partie de la surface intérieure 60. Chaque ailette 68 est orientée longitudinalement.In particular, the anode 20 comprises a cylindrical body 66 and a plurality of fins 68 each extending radially towards the cathode 20. The cylindrical body 66 defines the outer surface 62 and a portion of the inner surface 60. Each fin 68 protrudes from the cylindrical body 66 inwardly of the anode 20 and delimits a portion of the interior surface 60. Each fin 68 is oriented longitudinally.

On notera que le terme « cylindrique » est ici à entendre au sens large et couvre aussi bien des cylindres de révolution que des cylindres à section carrée, hexagonale, ou autre.It will be noted that the term “cylindrical” is here to be understood in the broad sense and covers both cylinders of revolution and cylinders with a square, hexagonal, or other section.

Chaque cavité 63, 64 est symétrique relativement à un plan longitudinal médian de la cavité 63, 64. Ce plan longitudinal médian inclut l'axe longitudinal Z.Each cavity 63, 64 is symmetrical relative to a median longitudinal plane of the cavity 63, 64. This median longitudinal plane includes the longitudinal axis Z.

Chaque cavité 63, 64 débouche dans un espace central 70 sensiblement cylindrique s'étendant au centre de l'anode 20. L'espace central 70 s'étend longitudinalement. Les cathodes 16, 18 sont disposées sensiblement au centre de l'espace central 70. Le reste de l'espace central 70 constitue l'espace d'interaction 22.Each cavity 63, 64 opens into a substantially cylindrical central space 70 extending at the center of the anode 20. The central space 70 extends longitudinally. The cathodes 16, 18 are arranged substantially in the center of the central space 70. The remainder of the central space 70 constitutes the interaction space 22.

Dans l'exemple représenté, la pluralité de cavités résonnantes 63, 64 comprend une pluralité de grandes cavités résonnantes 63 et de petites cavités résonnantes 64, disposées en alternance les unes des autres autour de l'espace central 70. La section radiale de chaque petite cavité résonnante 64 est inférieure à la section radiale de chaque grande cavité résonnante 63.In the example shown, the plurality of resonant cavities 63, 64 comprises a plurality of large resonant cavities 63 and small resonant cavities 64, arranged alternately around the central space 70. The radial section of each small cavity resonator 64 is smaller than the radial section of each large cavity resonator 63.

Chaque grande cavité 63 est délimitée par deux ailettes 68 et par le corps cylindrique 66. Chaque petite cavité 64 est délimitée à l'intérieur d'une ailette 68 par un orifice radial débouchant dans l'espace central 70. L'anode 20 présente ainsi une configuration du type « soleil levant » (en anglais « rising sun »). Cette configuration permet de limiter le risque d'oscillations sur des fréquences parasites, et ainsi d'augmenter le rendement du dispositif 10.Each large cavity 63 is delimited by two fins 68 and by the cylindrical body 66. Each small cavity 64 is delimited inside a fin 68 by a radial orifice opening into the central space 70. The anode 20 thus has a configuration of the “rising sun” type. This configuration makes it possible to limit the risk of oscillations on parasitic frequencies, and thus to increase the efficiency of the device 10.

Selon une variante, chaque grande cavité 63 constitue une cavité résonnante de sortie, et chaque petite cavité résonnante 64 constitue une cavité résonnante intermédiaire. Les cavités 63, 64 sont disposées de sorte que le nombre de cavités intermédiaires 64 disposées entre deux cavités de sortie 63 consécutives soit égal pour chaque paire de cavités de sortie 63 consécutives.According to a variant, each large cavity 63 constitutes an output resonant cavity, and each small resonant cavity 64 constitutes an intermediate resonant cavity. The cavities 63, 64 are arranged so that the number of intermediate cavities 64 disposed between two consecutive outlet cavities 63 is equal for each pair of consecutive outlet cavities 63.

Chaque orifice traversant 65 débouche dans une cavité de sortie 63 respective.Each through orifice 65 opens into a respective outlet cavity 63.

Aucun orifice traversant 65 ne débouche dans une des cavités intermédiaires 64.No through orifice 65 opens into one of the intermediate cavities 64.

De préférence, les cavités de sortie 63 sont identiques les unes aux autres et les cavités intermédiaires 64 sont identiques les unes aux autres.Preferably, the outlet cavities 63 are identical to each other and the intermediate cavities 64 are identical to each other.

En variante, toutes les cavités résonnantes sont des cavités de sortie 63.As a variant, all of the resonant cavities are outlet cavities 63.

Pour chaque cavité de sortie 63, une zone d'émission 42 de la deuxième cathode 18 est disposée sensiblement en face de ladite cavité de sortie 63. De préférence, ladite zone d'émission 42 n'est pas rigoureusement alignée avec la cavité de sortie 63, mais est décalée d'un côté amont du plan longitudinal médian de la cavité 63. Le terme « amont » est à entendre en référence à un sens de circulation des électrons dans l'espace d'interaction 22, comme cela sera détaillé plus loin.For each exit cavity 63, an emission zone 42 of the second cathode 18 is disposed substantially opposite said exit cavity 63. Preferably, said emission zone 42 is not strictly aligned with the exit cavity. 63, but is offset on an upstream side of the median longitudinal plane of the cavity 63. The term “upstream” is to be understood with reference to a direction of circulation of the electrons in the interaction space 22, as will be detailed later.

En variante, une zone d'émission 42 de la deuxième cathode 18 est disposée sensiblement en face de chaque cavité 63, 64 de l'anode 20.As a variant, an emission zone 42 of the second cathode 18 is arranged substantially opposite each cavity 63, 64 of the anode 20.

L'anode 20 comprend également deux anneaux (non représentés) de fermeture longitudinale des cavités 63, 64. Chaque anneau délimite ainsi une extrémité longitudinale de l'anode 20.The anode 20 also comprises two rings (not shown) for longitudinal closure of the cavities 63, 64. Each ring thus defines a longitudinal end of the anode 20.

Dans une autre variante (non représentée), les positions respectives des cathodes 16, 18 d'une part et de l'anode 20 d'autre part sont inversées, c'est-à-dire que les cathodes 16, 18 sont disposées radialement autour de l'anode 20. Dans une troisième variante (non représentée), le tube hyperfréquence 12 est du type MILO.In another variant (not shown), the respective positions of the cathodes 16, 18 on the one hand and of the anode 20 on the other hand are reversed, that is to say that the cathodes 16, 18 are arranged radially around the anode 20. In a third variant (not shown), the microwave tube 12 is of the MILO type.

L'espace d'interaction 22, ainsi que les cavités résonnantes 63, 64, sont maintenus sous vide.The interaction space 22, as well as the resonant cavities 63, 64, are kept under vacuum.

Le focalisateur 76 comprend typiquement un électroaimant s'étendant autour de l'anode 20, en particulier deux électroaimants s'étendant chacun autour de l'anode 20 et disposés longitudinalement de part et d'autre des guides d'ondes 14.The focusing 76 typically comprises an electromagnet extending around the anode 20, in particular two electromagnets each extending around the anode 20 and arranged longitudinally on either side of the waveguides 14.

Le focalisateur 76 est alimenté par une alimentation électrique 78 du dispositif de génération 10. La troisième alimentation 78 est adaptée pour délivrer un courant I au focalisateur 76.The focuser 76 is powered by an electrical power supply 78 of the generation device 10. The third power supply 78 is adapted to deliver a current I to the focuser 76.

Chaque guide d'onde 14 est disposé en regard d'un orifice traversant 65 de l'anode 20, et s'étend depuis la surface extérieure 62 de l'anode 20 vers l'extérieur du dispositif de génération 10.Each waveguide 14 is disposed opposite an orifice 65 passing through the anode 20, and extends from the exterior surface 62 of the anode 20 towards the exterior of the generation device 10.

Le circuit d'alimentation 21 est adapté pour établir une différence de potentiel significative, c'est-à-dire supérieure à 10%, entre les cathodes 16, 18, et pour alimenter les cathodes 16, 18 sélectivement en tension continue ou en tension impulsionnelle.The power supply circuit 21 is adapted to establish a significant potential difference, that is to say greater than 10%, between the cathodes 16, 18, and to supply the cathodes 16, 18 selectively with direct voltage or with voltage. impulse.

A cet effet, en référence à la Figure 4, le circuit d'alimentation 21 comprend une alimentation en tension continue 100, une alimentation en tension impulsionnelle 102, et un circuit électrique 104 raccordant électriquement les alimentations 100, 102 aux cathodes 16, 18.For this purpose, with reference to the Figure 4 , the supply circuit 21 comprises a direct voltage supply 100, a pulsed voltage supply 102, and an electric circuit 104 electrically connecting the supplies 100, 102 to the cathodes 16, 18.

L'alimentation en tension continue 100 est adaptée pour générer une haute tension stable, de préférence comprise entre 50 et 100kV. Elle est typiquement constituée par une alimentation secteur stabilisée.The DC voltage supply 100 is suitable for generating a stable high voltage, preferably between 50 and 100kV. It is typically constituted by a stabilized mains supply.

L'alimentation en tension impulsionnelle 102 est par exemple un générateur de Marx. Elle est raccordée électriquement à l'alimentation en tension continue 100 par un premier interrupteur 110 de pilotage de l'alimentation électrique de l'alimentation 102 par l'alimentation 100.The pulse voltage supply 102 is for example a Marx generator. It is electrically connected to the direct voltage supply 100 by a first switch 110 for controlling the electrical supply of the supply 102 by the supply 100.

L'interrupteur 110 est adapté pour basculer entre une configuration fermée, dans laquelle il raccorde électriquement une sortie de l'alimentation continue 100 à une entrée de l'alimentation impulsionnelle 102, et une configuration ouverte, dans laquelle la sortie de l'alimentation continue 100 et l'entrée de l'alimentation impulsionnelle 102 sont isolées électriquement l'une de l'autreSwitch 110 is adapted to toggle between a closed configuration, in which it electrically connects an output of the DC power supply 100 to an input of the pulse power supply 102, and an open configuration, in which the output of the DC power supply 100 and the input of the pulse supply 102 are electrically isolated from each other

Le circuit électrique 104 comprend une première liaison électrique 112 raccordant électriquement l'alimentation continue 102 aux cathodes 16, 18, une deuxième liaison électrique 114 raccordant électriquement l'alimentation impulsionnelle 102 aux cathodes 16, 18, un deuxième interrupteur 116 de commande de la première liaison électrique 112, et un module 118 de décalage en tension de la deuxième cathode 18 par rapport à la première cathode 16.The electrical circuit 104 comprises a first electrical connection 112 electrically connecting the DC power supply 102 to the cathodes 16, 18, a second electrical connection 114 electrically connecting the pulse power supply 102 to the cathodes 16, 18, a second switch 116 for controlling the first electrical connection 112, and a voltage offset module 118 of the second cathode 18 with respect to the first cathode 16.

Le deuxième interrupteur 116 est spécifique à la première liaison électrique 112. Il est adapté pour basculer entre une configuration fermée, dans laquelle il raccorde électriquement l'alimentation continue 100 aux cathodes 16, 18, et une configuration ouverte, dans laquelle il isole électriquement l'alimentation continue 100 des cathodes 16, 18.The second switch 116 is specific to the first electrical link 112. It is adapted to switch between a closed configuration, in which it electrically connects the DC power supply 100 to the cathodes 16, 18, and an open configuration, in which it electrically isolates the continuous supply 100 of the cathodes 16, 18.

Le module de décalage en tension 118 est commun aux première et deuxième liaisons électriques 112, 114. Il comprend un organe 120 consommateur de tension, interposé entre la cathode 18 et les alimentations 100, 102, et un court-circuit 122 de contournement de l'organe 120.The voltage shift module 118 is common to the first and second electrical links 112, 114. It comprises a voltage consuming member 120, interposed between the cathode 18 and the power supplies 100, 102, and a short circuit 122 for bypassing the voltage. organ 120.

L'organe 120 est adapté pour consommer une tension sensiblement égale au produit de la différence de potentiel entre la première cathode 16 et l'anode 20 par le rapport d/D. L'organe 120 est typiquement une résistance.The member 120 is adapted to consume a voltage substantially equal to the product of the potential difference between the first cathode 16 and the anode 20 times the d / D ratio. The organ 120 is typically a resistor.

Le court-circuit 122 comprend un troisième interrupteur 124, pour sélectivement ouvrir ou fermer le court-circuit 122.The short circuit 122 includes a third switch 124, to selectively open or close the short circuit 122.

En référence aux Figures 1, 2 et 4, le dispositif de génération 10 comprend également un module 80 de commande du circuit d'alimentation 21 et de l'alimentation 78. Ce module de commande 80 est programmé pour piloter le circuit d'alimentation 21, en particulier les alimentations 100, 102 et les interrupteurs 110, 116, 124, ainsi que l'alimentation 78 suivant plusieurs modes de fonctionnement du dispositif de génération 10. Ces modes de fonctionnement sont synthétisés dans le tableau présenté en Figure 5.With reference to Figures 1 , 2 and 4 , the generation device 10 also comprises a module 80 for controlling the power supply circuit 21 and the power supply 78. This control module 80 is programmed to control the power supply circuit 21, in particular the power supplies 100, 102 and the switches 110, 116, 124, as well as the power supply 78 according to several operating modes of the generation device 10. These operating modes are summarized in the table presented in Figure 5 .

Le module de commande 80 est programmé pour piloter le circuit d'alimentation 21 dans un premier mode de fonctionnement (Mode 1) du dispositif de génération 10, de façon à ce qu'il porte le potentiel électrique V1 de la première cathode 16 à un premier potentiel de consigne V1,1, et le potentiel électrique V2 de la deuxième cathode 18 à un deuxième potentiel de consigne V2,1.The control module 80 is programmed to control the supply circuit 21 in a first operating mode (Mode 1) of the generation device 10, so that it takes the electric potential V 1 of the first cathode 16 to a first setpoint potential V 1.1 , and the electric potential V 2 of the second cathode 18 at a second setpoint potential V 2.1 .

A cet effet, le module de commande 80 est programmé pour piloter l'alimentation continue 100 de sorte qu'elle génère une tension électrique au premier potentiel électrique V1,1, commander la fermeture du deuxième interrupteur 116, et commander l'ouverture des premier et troisième interrupteurs 110, 124.To this end, the control module 80 is programmed to control the DC power supply 100 so that it generates an electric voltage at the first electric potential V 1,1 , order the closing of the second switch 116, and order the opening of the first and third switches 110, 124.

Le premier potentiel de consigne V1,1 est inférieur au potentiel électrique V0 de l'anode 20. En particulier, le premier potentiel de consigne V1,1 est inférieur à un premier potentiel W1 d'émission de la première cathode 16, en deçà duquel la première cathode 16 émet des premiers électrons, et supérieur à un deuxième potentiel W2 d'émission de la deuxième cathode 18, en deçà duquel la première cathode 16 émet des premiers électrons. Le premier potentiel d'émission W1 est égal à V 0 - D × E 1. Le deuxième potentiel d'émission W2 est égal à V 0 - d × E 2 . The first setpoint potential V 1.1 is less than the electric potential V 0 of the anode 20. In particular, the first setpoint potential V 1.1 is less than a first emission potential W 1 of the first cathode 16 , below which the first cathode 16 emits first electrons, and greater than a second emission potential W 2 of the second cathode 18, below which the first cathode 16 emits first electrons. The first emission potential W 1 is equal to V 0 - D × E 1 . The second emission potential W 2 is equal to V 0 - d × E 2 .

Le deuxième potentiel de consigne V2,1 est inférieur au potentiel électrique V0 de l'anode 20, et supérieur au premier potentiel de consigne V1,1. En particulier, le deuxième potentiel de consigne V2,1 est adapté pour minimiser la perturbation induite par la deuxième cathode 18 sur le champ électrique créé dans l'espace d'interaction 22 par la première cathode 16 portée au premier potentiel de consigne V1,1. En d'autres termes, le deuxième potentiel de consigne V2,1 est adapté pour que le champ électrique créé dans l'espace d'interaction 22 par la première cathode 16 portée au premier potentiel de consigne V1,1 en l'absence de la deuxième cathode 18 soit sensiblement égal au champ électrique créé dans l'espace d'interaction 22 par la première cathode 16 portée au premier potentiel de consigne V1,1 en présence de la deuxième cathode 18 portée au deuxième potentiel de consigne V2,1.The second setpoint potential V 2.1 is less than the electrical potential V 0 of the anode 20, and greater than the first setpoint potential V 1.1 . In particular, the second setpoint potential V 2.1 is adapted to minimize the disturbance induced by the second cathode 18 on the electric field created in the interaction space 22 by the first cathode 16 brought to the first setpoint potential V 1 , 1 . In other words, the second setpoint potential V 2.1 is adapted so that the electric field created in the interaction space 22 by the first cathode 16 is brought to the first setpoint potential V 1.1 in the absence of the second cathode 18 is substantially equal to the electric field created in the interaction space 22 by the first cathode 16 brought to the first setpoint potential V 1,1 in the presence of the second cathode 18 brought to the second setpoint potential V 2 , 1 .

A cet effet, le deuxième potentiel de consigne V2,1 est sensiblement égal à V 0 − V 0 − V 1,1 D × d .

Figure imgb0002
Par « sensiblement égal », on entend que le potentiel V2,1 est compris 90% et 110 % de la valeur précitée. Ainsi, le champ électrique créé par la deuxième cathode 18 portée au deuxième potentiel de consigne V2,1 dans l'espace d'interaction 22 est sensiblement identique à celui créé par la première cathode 16 portée au premier potentiel de consigne V1,1. La perturbation induite par la deuxième cathode 18 sur la circulation des premiers électrons émis par la première cathode 16 est donc réduite.For this purpose, the second setpoint potential V 2.1 is substantially equal to V 0 - V 0 - V 1.1 D × d .
Figure imgb0002
 By “substantially equal” is meant that the potential V 2.1 is between 90% and 110% of the aforementioned value. Thus, the electric field created by the second cathode 18 brought to the second setpoint potential V 2.1 in the interaction space 22 is substantially identical to that created by the first cathode 16 brought to the first setpoint potential V 1.1 . The disturbance induced by the second cathode 18 on the circulation of the first electrons emitted by the first cathode 16 is therefore reduced.

Le module de commande 80 est programmé pour piloter le circuit d'alimentation 21 dans le premier mode de fonctionnement (Mode 1) de manière à maintenir la première cathode 16 au premier potentiel de consigne V1,1 pendant plus de 1 µs.The control module 80 is programmed to control the supply circuit 21 in the first operating mode (Mode 1) so as to maintain the first cathode 16 at the first setpoint potential V 1.1 for more than 1 μs.

Le module de commande 80 est également programmé pour piloter le circuit d'alimentation 21, en particulier les alimentations 100, 102 et les interrupteurs 110, 116, 124, ainsi que l'alimentation 78, dans un deuxième mode de fonctionnement (Mode 2) du dispositif de génération 10, de manière à faire varier cycliquement le potentiel électrique V1 de la première cathode 16 entre le potentiel V0 et un troisième potentiel de consigne V1,2, strictement inférieur au premier potentiel de consigne V1,1, en gardant les rapports (V0-V1)/(V0-V2) et (V0-V1)/I sensiblement constants.The control module 80 is also programmed to control the power supply circuit 21, in particular the power supplies 100, 102 and the switches 110, 116, 124, as well as the power supply 78, in a second operating mode (Mode 2) of the generation device 10, so as to cyclically vary the electric potential V 1 of the first cathode 16 between the potential V 0 and a third potential setpoint V 1.2 , strictly less than the first setpoint potential V 1.1 , keeping the ratios (V 0 -V 1 ) / (V 0 -V 2 ) and (V 0 -V 1 ) / I substantially constant .

A cet effet, le module de commande 80 est programmé pour commander la fermeture du premier interrupteur 110, commander l'ouverture des deuxième et troisième interrupteurs 116, 124, et piloter l'alimentation impulsionnelle 102 de sorte qu'elle génère une tension électrique variant cycliquement entre le potentiel V0 et le troisième potentiel de consigne V1,2.To this end, the control module 80 is programmed to control the closing of the first switch 110, to control the opening of the second and third switches 116, 124, and to control the pulse supply 102 so that it generates a varying electrical voltage. cyclically between the potential V 0 and the third reference potential V 1.2 .

En particulier, le troisième potentiel de consigne V1,2 est supérieur au deuxième potentiel d'émission W2.In particular, the third setpoint potential V 1,2 is greater than the second emission potential W 2 .

Le module de commande 80 est en outre programmé pour piloter le circuit d'alimentation 21, en particulier les alimentations 100, 102 et les interrupteurs 110, 116, 124,, dans un troisième mode de fonctionnement (Mode 3) du dispositif de génération 10, de manière à ce qu'il fasse varier cycliquement le potentiel V2 de la deuxième cathode 18 entre le potentiel V0, et un quatrième potentiel de consigne V2,2 strictement inférieur au troisième potentiel de consigne V1,2, le potentiel V1 de la première cathode 16 étant à tout instant sensiblement égal au potentiel V2 de la deuxième cathode 18, c'est-à-dire compris 90% et 110 % du potentiel V2.The control module 80 is further programmed to control the power supply circuit 21, in particular the power supplies 100, 102 and the switches 110, 116, 124 ,, in a third operating mode (Mode 3) of the generation device 10 , so that it causes the potential V 2 of the second cathode 18 to vary cyclically between the potential V 0 , and a fourth setpoint potential V 2.2 strictly less than the third setpoint potential V 1.2 , the potential V 1 of the first cathode 16 being at all times substantially equal to the potential V 2 of the second cathode 18, that is to say between 90% and 110% of the potential V 2 .

A cet effet, le module de commande 80 est programmé pour commander la fermeture des premier et troisième interrupteurs 110, 124, commander l'ouverture du deuxième interrupteur 116, et piloter l'alimentation impulsionnelle 102 de sorte qu'elle génère une tension électrique variant cycliquement entre le potentiel V0 et le quatrième potentiel de consigne V2,2.To this end, the control module 80 is programmed to control the closing of the first and third switches 110, 124, to control the opening of the second switch 116, and to control the pulse supply 102 so that it generates a varying electrical voltage. cyclically between the potential V 0 and the fourth reference potential V 2.2 .

En particulier, le quatrième potentiel électrique de consigne V2,2 est inférieur au deuxième potentiel d'émission W2.In particular, the fourth electrical reference potential V 2.2 is lower than the second emission potential W 2 .

Le module de commande 80 est enfin programmé pour piloter l'alimentation 78 dans le troisième mode de fonctionnement (Mode 3) de manière à ce que le rapport (V0-V2)/I soit maintenu sensiblement constant.The control module 80 is finally programmed to control the power supply 78 in the third operating mode (Mode 3) so that the ratio (V 0 -V 2 ) / I is kept substantially constant.

Le dispositif de génération 10 comprend en outre une interface de pilotage 82. Cette interface 82 comprend des moyens 84 de sélection d'un mode de fonctionnement du dispositif de génération 10, et des moyens 86 d'envoi d'une instruction de lancement du mode de fonctionnement sélectionné au module de commande 80.The generation device 10 further comprises a control interface 82. This interface 82 comprises means 84 for selecting an operating mode of the generation device 10, and means 86 for sending an instruction to launch the mode. operating mode selected on the control module 80.

L'interface de pilotage 82 est typiquement destinée à servir d'interface avec un système informatique. A cet effet, les moyens de sélection 84 comprennent des ports d'entrées/sorties connus de l'homme de l'art.The control interface 82 is typically intended to serve as an interface with a computer system. To this end, the selection means 84 comprise input / output ports known to those skilled in the art.

Un procédé de génération d'une onde hyperfréquence au moyen du dispositif de génération 10 va maintenant être décrit.A method of generating a microwave wave by means of the generating device 10 will now be described.

Initialement, le dispositif de génération 10 est à l'arrêt. Les première et deuxième cathodes 16, 18 sont au même potentiel que l'anode 20, et le champ magnétique longitudinal B est nul.Initially, the generation device 10 is stopped. The first and second cathodes 16, 18 are at the same potential as the anode 20, and the longitudinal magnetic field B is zero.

Dans une première étape, le dispositif de génération 10 est basculé dans le premier mode de fonctionnement. Le dispositif de génération 10 étant préalablement à l'arrêt, ce basculement correspond à un démarrage du dispositif de génération 10 dans le premier mode de fonctionnement.In a first step, the generation device 10 is switched to the first operating mode. The generation device 10 being stopped beforehand, this switching corresponds to a start-up of the generation device 10 in the first operating mode.

A cet effet, le premier mode de fonctionnement est sélectionné au moyen de l'interface de pilotage 82, qui émet une instruction de lancement du premier mode de fonctionnement à destination du module de commande 80. Le module de commande 80, recevant ladite instruction de lancement du premier mode de fonctionnement, envoie une consigne à l'alimentation continue 100 de générer une tension électrique au premier potentiel de consigne V1,1, ferme le deuxième interrupteur 116, et ouvre les interrupteurs 110, 124. Il démarre également l'alimentation 78, avec pour consigne d'injecter un courant I dans le focalisateur 76, adapté pour que le focalisateur 76 génère un champ magnétique longitudinal B d'intensité adaptée pour maintenir le tube hyperfréquences 12 en régime oscillant. Les conditions que doit dans ce but vérifier le champ magnétique longitudinal B, sont connues de l'homme du métier.To this end, the first operating mode is selected by means of the control interface 82, which issues an instruction to launch the first operating mode to the control module 80. The control module 80, receiving said instruction to launch of the first operating mode, sends a setpoint to the DC power supply 100 to generate an electric voltage at the first setpoint potential V 1.1 , closes the second switch 116, and opens the switches 110, 124. It also starts the power supply 78, with the instruction to inject a current I into the focusing device 76, adapted so that the focusing device 76 generates a longitudinal magnetic field B of intensity adapted to maintain the microwave tube 12 in oscillating mode. The conditions which the longitudinal magnetic field B must verify for this purpose are known to those skilled in the art.

La première cathode 16 est ainsi portée au premier potentiel de consigne V1,1, et la deuxième cathode 18 est portée au deuxième potentiel de consigne V2,1. Il s'établit donc une différence de potentiel négative entre l'anode 20 d'une part et chaque cathode 16, 18 d'autre part. Cette différence de potentiel génère un champ électrique radial E orienté de l'anode 20 vers les cathodes 16, 18. Ce champ électrique radial E a une intensité supérieure à la première valeur de seuil E1 mais inférieure à la deuxième valeur de seuil E2. Sous l'effet de ce champ électrique E, chaque zone d'émission 36 de la première cathode 16 émet des premiers électrons dans l'espace d'interaction 22.The first cathode 16 is thus brought to the first setpoint potential V 1.1 , and the second cathode 18 is brought to the second setpoint potential V 2.1. A negative potential difference is therefore established between the anode 20 on the one hand and each cathode 16, 18 on the other hand. This potential difference generates a radial electric field E oriented from the anode 20 towards the cathodes 16, 18. This radial electric field E has an intensity greater than the first threshold value E 1 but less than the second threshold value E 2 . Under the effect of this electric field E, each emission zone 36 of the first cathode 16 emits first electrons in the interaction space 22.

Chaque zone d'émission 36 étant disposée en regard d'une fenêtre 40 de la deuxième cathode 18, les premiers électrons sont peu gênés par la deuxième cathode 18 pour atteindre l'espace d'interaction 22.Since each emission zone 36 is placed opposite a window 40 of the second cathode 18, the first electrons are little hampered by the second cathode 18 in order to reach the interaction space 22.

Sous l'effet conjugué du champ électrique radial E et du champ magnétique longitudinal B, les premiers électrons tournent autour des cathodes 16, 18 dans l'espace d'interaction 22, en se groupant par paquets. Le sens de rotation des premiers électrons est déterminé de façon connue par l'orientation du champ électrique E et du champ magnétique B. Ce déplacement des premiers électrons génère une onde électromagnétique radiofréquence dans le tube hyperfréquence 12. Cette onde est amplifiée grâce aux cavités résonnantes 63, 64 et est captée pour être utilisée, par exemple pour alimenter une antenne d'arme hyperfréquence, grâce aux guides d'ondes 14.Under the combined effect of the radial electric field E and the longitudinal magnetic field B, the first electrons rotate around the cathodes 16, 18 in space interaction 22, grouping together in packets. The direction of rotation of the first electrons is determined in a known manner by the orientation of the electric field E and of the magnetic field B. This displacement of the first electrons generates a radiofrequency electromagnetic wave in the microwave tube 12. This wave is amplified thanks to the resonant cavities. 63, 64 and is captured to be used, for example to power a microwave weapon antenna, thanks to the waveguides 14.

Cette émission d'électrons générant une onde hyperfréquence continue indéfiniment, en l'absence de modification de la différence de potentiel entre l'anode 20 et chaque cathode 16, 18.This emission of electrons generating a microwave wave continues indefinitely, in the absence of modification of the potential difference between the anode 20 and each cathode 16, 18.

A cette première étape succède une deuxième étape de basculement du dispositif de génération 10 dans le deuxième mode de fonctionnement.This first step is followed by a second step of switching the generation device 10 into the second operating mode.

A cet effet, le deuxième mode de fonctionnement est sélectionné au moyen de l'interface de pilotage 82, qui émet une instruction de lancement du deuxième mode de fonctionnement à destination du module de commande 80. Le module de commande 80, recevant ladite instruction de lancement du deuxième mode de fonctionnement, ferme le premier interrupteur 110, ouvre le deuxième interrupteur 116, et communique une consigne à l'alimentation impulsionnelle 102, l'instruisant de générer une tension électrique variant cycliquement entre le potentiel V0 et le troisième potentiel de consigne V1,2.To this end, the second operating mode is selected by means of the control interface 82, which issues an instruction to launch the second operating mode to the control module 80. The control module 80, receiving said instruction to launch of the second operating mode, closes the first switch 110, opens the second switch 116, and communicates a setpoint to the pulse supply 102, instructing it to generate an electric voltage varying cyclically between the potential V 0 and the third potential of setpoint V 1.2 .

Le module de commande 80 communique également une nouvelle consigne à l'alimentation 78, l'instruisant de faire varier le courant I en maintenant le rapport I/(V0-V1) constant.The control module 80 also communicates a new setpoint to the power supply 78, instructing it to vary the current I while maintaining the ratio I / (V 0 -V 1 ) constant.

Le potentiel V1 de la première cathode 16 varie ainsi cycliquement entre le potentiel V0 et le troisième potentiel de consigne V1,2, et le potentiel V2 de la deuxième cathode 18 varie également cycliquement, le rapport (V0-V1)/(V0-V2) demeurant sensiblement constant. En conséquence, le champ électrique radial E prend une intensité variable, variant entre une intensité maximale, supérieure à la première valeur de seuil E1 et inférieure à la deuxième valeur de seuil E2, et une intensité minimale, sensiblement nulle.The potential V 1 of the first cathode 16 thus varies cyclically between the potential V 0 and the third setpoint potential V 1,2 , and the potential V 2 of the second cathode 18 also varies cyclically, the ratio (V 0 -V 1 ) / (V 0 -V 2 ) remaining substantially constant. Consequently, the radial electric field E takes on a variable intensity, varying between a maximum intensity, greater than the first threshold value E 1 and less than the second threshold value E 2 , and a minimum intensity, substantially zero.

A chaque fois que le champ électrique E est supérieur à la première valeur de seuil E1, chaque zone d'émission 36 de la première cathode 16 émet des premiers électrons dans l'espace d'interaction 22. Comme décrit précédemment, ces premiers électrons génèrent une onde radiofréquence dans le tube hyperfréquence 12 en se déplaçant dans l'espace d'interaction 22.Whenever the electric field E is greater than the first threshold value E 1 , each emission zone 36 of the first cathode 16 emits first electrons in the interaction space 22. As described above, these first electrons generate a radiofrequency wave in the microwave tube 12 while moving in the interaction space 22.

A chaque fois que le champ électrique E repasse sous la première valeur de seuil E1, l'émission de premiers électrons s'arrête. De préférence, la durée des cycles de variation du premier potentiel V1 est adaptée pour que le champ électrique E repasse sous la première valeur de seuil E1 lorsque l'énergie électromagnétique accumulée dans l'espace d'interaction 22 atteint un seuil déclenchement d'un court-circuit entre la première cathode 16 et l'anode 20.Each time the electric field E goes back below the first threshold value E 1 , the emission of first electrons stops. Preferably, the duration of the cycles of variation of the first potential V 1 is adapted so that the electric field E goes back below the first threshold value E 1 when the electromagnetic energy accumulated in the interaction space 22 reaches a trigger threshold d 'a short circuit between the first cathode 16 and the anode 20.

Ce deuxième mode de fonctionnement permet ainsi l'émission d'ondes de plus fortes puissances que dans le premier mode de fonctionnement. La durée d'émission doit cependant être réduite en conséquence.This second operating mode thus allows the emission of waves of higher powers than in the first operating mode. However, the transmission time must be reduced accordingly.

A cette deuxième étape succède une troisième étape de basculement du dispositif de génération 10 dans le troisième mode de fonctionnement.This second step is followed by a third step of switching the generation device 10 into the third operating mode.

A cet effet, le troisième mode de fonctionnement est sélectionné au moyen de l'interface de pilotage 82, qui émet une instruction de lancement du troisième mode de fonctionnement à destination du module de commande 80. Le module de commande 80, recevant ladite instruction de lancement du troisième mode de fonctionnement, ferme le troisième interrupteur 124, et communique une nouvelle consigne à l'alimentation impulsionnelle 102, l'instruisant de générer une tension électrique variant cycliquement entre le potentiel V0 et le quatrième potentiel de consigne V2,2.To this end, the third operating mode is selected by means of the control interface 82, which sends an instruction to launch the third operating mode to the control module 80. The control module 80, receiving said instruction to launch of the third operating mode, closes the third switch 124, and communicates a new setpoint to the pulse supply 102, instructing it to generate an electric voltage varying cyclically between the potential V 0 and the fourth setpoint potential V 2.2 .

Le module de commande 80 communique également une nouvelle consigne à l'alimentation 78, l'instruisant de faire varier le courant I en maintenant le rapport I/(V0-V2) constant.The control module 80 also communicates a new setpoint to the power supply 78, instructing it to vary the current I while maintaining the ratio I / (V 0 -V 2 ) constant.

Les potentiels V1 et V2 des cathodes 16, 18 varient ainsi tous deux cycliquement entre le potentiel V0 et le quatrième potentiel de consigne V2,2, lesdits potentiels V1, V2 demeurant sensiblement égaux l'un à l'autre. En conséquence, le champ électrique radial E prend une intensité variable, variant entre une intensité maximale supérieure à la deuxième valeur de seuil E2, et une intensité minimale, sensiblement nulle.The potentials V 1 and V 2 of the cathodes 16, 18 thus both vary cyclically between the potential V 0 and the fourth setpoint potential V 2.2 , said potentials V 1 , V 2 remaining substantially equal to one another. . Consequently, the radial electric field E takes on a variable intensity, varying between a maximum intensity greater than the second threshold value E 2 , and a minimum intensity, substantially zero.

A chaque fois que le champ électrique E est supérieur à la deuxième valeur de seuil E2, chaque région d'émission 42 de la deuxième cathode 18 émet des deuxièmes électrons dans l'espace d'interaction 22. Comme décrit précédemment, ces deuxièmes électrons génèrent une onde radiofréquence dans le tube hyperfréquences 12 en se déplaçant dans l'espace d'interaction 22.Whenever the electric field E is greater than the second threshold value E 2 , each emission region 42 of the second cathode 18 emits second electrons in the interaction space 22. As described above, these second electrons generate a radiofrequency wave in the microwave tube 12 while moving in the interaction space 22.

Du fait de la ponctualité de chaque région d'émission 42, les deuxièmes électrons émis sont déjà répartis en paquets, ce qui permet d'accélérer la génération de l'onde radiofréquence.Due to the punctuality of each emission region 42, the second emitted electrons are already distributed in packets, which makes it possible to accelerate the generation of the radiofrequency wave.

Les première et deuxième cathodes 16, 18 étant sensiblement au même potentiel, il n'existe pas de champ électrique entre les deux. La première cathode 16 est donc en permanence soumise à un champ électrique d'intensité nulle, de sorte qu'elle n'émet pas d'électron.The first and second cathodes 16, 18 being substantially at the same potential, there is no electric field between the two. The first cathode 16 is therefore in permanently subjected to an electric field of zero intensity, so that it does not emit electrons.

A chaque fois que le champ électrique E repasse sous la deuxième valeur de seuil E2, l'émission de deuxièmes électrons s'arrête. De préférence, la durée des cycles de variation du deuxième potentiel V2 est adaptée pour que le champ électrique E repasse sous la deuxième valeur de seuil E2 lorsque l'énergie électromagnétique accumulée dans l'espace d'interaction 22 atteint un seuil déclenchement d'un court-circuit entre la deuxième cathode 16 et l'anode 20.Each time the electric field E goes back below the second threshold value E 2 , the emission of second electrons stops. Preferably, the duration of the cycles of variation of the second potential V 2 is adapted so that the electric field E goes back below the second threshold value E 2 when the electromagnetic energy accumulated in the interaction space 22 reaches a trigger threshold d 'a short circuit between the second cathode 16 and the anode 20.

Ce troisième mode de fonctionnement permet ainsi l'émission d'ondes de plus fortes puissances que dans le deuxième mode de fonctionnement. La durée d'émission doit cependant être réduite en conséquence.This third operating mode thus allows the emission of waves of higher powers than in the second operating mode. However, the transmission time must be reduced accordingly.

Au terme de la troisième étape, le dispositif de génération 10 est arrêté. En d'autres termes, le module de commande 80 commande l'arrêt du circuit d'alimentation 21 et de l'alimentation 78. Chaque cathode 16, 18 se stabilise à un potentiel sensiblement égal au potentiel V0 de l'anode 20, et le champ magnétique longitudinal B prend une valeur nulle.At the end of the third step, the generation device 10 is stopped. In other words, the control module 80 controls the stopping of the supply circuit 21 and of the supply 78. Each cathode 16, 18 stabilizes at a potential substantially equal to the potential V 0 of the anode 20, and the longitudinal magnetic field B takes on a zero value.

Selon des variantes du procédé de génération :

  • le dispositif de génération est arrêté au terme de la première ou de la deuxième étape, et/ou
  • l'ordre des étapes est modifié : la troisième étape succède par exemple directement à la première étape, et est suivie de la deuxième étape, et/ou
  • le procédé débute par la deuxième ou la troisième étape, et/ou
  • le procédé ne comprend qu'une ou deux des trois étapes décrites ci-dessus.
According to variants of the generation process:
  • the generation device is stopped at the end of the first or second step, and / or
  • the order of the steps is modified: the third step follows for example directly from the first step, and is followed by the second step, and / or
  • the process begins with the second or third step, and / or
  • the method comprises only one or two of the three steps described above.

Grâce à l'invention décrite ci-dessus, il est possible de combiner un grand nombre de modes de fonctionnement différents au sein d'un même dispositif de génération compact. En particulier il est possible, au moyen du dispositif de génération, d'émettre aussi bien des ondes de faibles puissances sur des durées longues, que des ondes de fortes puissances sur des durées brèves. Ce dispositif de génération est ainsi tout particulièrement adapté à l'alimentation d'armes hyperfréquences.Thanks to the invention described above, it is possible to combine a large number of different operating modes within a single compact generation device. In particular, it is possible, by means of the generation device, to emit both low-power waves over long durations and high-power waves over short durations. This generation device is thus very particularly suitable for supplying microwave weapons.

En option, le dispositif de génération 10 est raccordé à une source (non représentée) d'alimentation de l'espace d'interaction 22 en onde électromagnétique par l'intermédiaire de l'un des guides d'ondes 14. Cette source est en particulier adaptée pour émettre une onde électromagnétique avec une fréquence et/ou une phase prédéterminée. Cette source est typiquement un magnétron ou un klystron.As an option, the generation device 10 is connected to a source (not shown) for supplying the interaction space 22 with electromagnetic wave via one of the waveguides 14. This source is in operation. particularly suitable for emitting an electromagnetic wave with a predetermined frequency and / or phase. This source is typically a magnetron or a klystron.

Le dispositif de génération 10 est alors démarré dans le premier mode de fonctionnement, la source alimentant l'espace d'interaction 22. Sous l'effet de l'onde électromagnétique émise par la source, l'onde générée par le dispositif de génération 10 se cale sur la fréquence et sur la phase de ladite onde électromagnétique.The generation device 10 is then started in the first operating mode, the source supplying the interaction space 22. Under the effect of the wave electromagnetic emitted by the source, the wave generated by the generation device 10 is set on the frequency and on the phase of said electromagnetic wave.

Une fois le dispositif de génération 10 démarré, la source est arrêtée. Le dispositif de génération 10 est ensuite basculé dans le deuxième mode de fonctionnement puis, optionnellement, dans le troisième mode de fonctionnement. A chaque basculement, l'onde générée par le dispositif de génération 10 conserve la fréquence et la phase de l'onde précédemment émise dans l'espace d'interaction 22.Once the generation device 10 is started, the source is stopped. The generation device 10 is then switched to the second operating mode and then, optionally, to the third operating mode. At each changeover, the wave generated by the generation device 10 keeps the frequency and the phase of the wave previously emitted in the interaction space 22.

Il est ainsi possible de maîtriser la fréquence et/ou la phase de l'onde générée par le dispositif de génération 10, en particulier lorsque celui-ci fonctionne dans le deuxième ou le troisième mode de fonctionnement, modes dans lesquels l'onde générée est de forte puissance, au moyen d'un pilote de faible puissance. Cela est particulièrement avantageux dans le cas où l'on voudrait associer plusieurs dispositifs de génération d'ondes de fortes puissances de manière à ce qu'ils émettent en phase.It is thus possible to control the frequency and / or the phase of the wave generated by the generation device 10, in particular when the latter operates in the second or the third operating mode, modes in which the generated wave is high power, by means of a low power pilot. This is particularly advantageous in the case where it is desired to combine several devices for generating high-power waves so that they emit in phase.

Une variante de l'invention est présentée sur les Figure 6 à 8. Dans cette variante, la deuxième cathode 18 est cylindrique de révolution et est formée de deux pièces 90, 92 rotatives l'une par rapport à l'autre autour de l'axe longitudinal Z entre une première configuration de la cathode 18, représentée sur la Figure 7, et une deuxième configuration de la cathode 18, représentée sur la Figure 8. La deuxième cathode 18 comprend également des moyens d'entraînement (non représentés) d'une première 90 des deux pièces 90, 92 en rotation relativement à la deuxième pièce 92.A variant of the invention is presented on Figure 6 to 8 . In this variant, the second cathode 18 is cylindrical of revolution and is formed of two parts 90, 92 rotating with respect to one another around the longitudinal axis Z between a first configuration of the cathode 18, shown in FIG. Figure 7 , and a second configuration of the cathode 18, shown in Figure 8 . The second cathode 18 also comprises means for driving (not shown) a first 90 of the two parts 90, 92 in rotation relative to the second part 92.

Les deux pièces 90, 92 sont raccordées au circuit d'alimentation 21 de manière à être portées sensiblement au même potentiel électrique.The two parts 90, 92 are connected to the supply circuit 21 so as to be brought to substantially the same electric potential.

Chaque pièce 90, 92 porte une moitié des régions d'émission 42 de la deuxième cathode 18.Each part 90, 92 carries one half of the emission regions 42 of the second cathode 18.

Dans la première configuration, les régions d'émission 42 sont régulièrement réparties le long de la circonférence de la deuxième cathode 18. En d'autres termes, chaque région d'émission 42 est à équidistance des deux autres régions d'émission 42 dont elle est le plus proche.In the first configuration, the emission regions 42 are regularly distributed along the circumference of the second cathode 18. In other words, each emission region 42 is equidistant from the two other emission regions 42 of which it is. is the closest.

Dans la deuxième configuration, les régions d'émission 42 sont regroupées par paires de régions d'émissions 42 adjacentes. En d'autres termes, chaque région d'émission 42 est adjacente à une autre région d'émission 42 et à distance des autres régions d'émission 42. En particulier, chaque région d'émission 42 portée par la première pièce 90 est adjacente à une région d'émission 42 portée par la deuxième pièce 92, les régions d'émission 42 portées par chaque pièce 90, 92 demeurant à distance les unes des autres.In the second configuration, the emission regions 42 are grouped together in pairs of adjacent emission regions 42. In other words, each emission region 42 is adjacent to another emission region 42 and at a distance from the other emission regions 42. In particular, each emission region 42 carried by the first part 90 is adjacent. to an emission region 42 carried by the second part 92, the emission regions 42 carried by each part 90, 92 remaining at a distance from each other.

Ainsi, lorsque la cathode 18 est dans la deuxième configuration, le nombre de fenêtres 40 est divisé par deux, du fait de l'absence de fenêtre 40 entre les régions d'émission 42 adjacentes. Toutefois, les fenêtres 40 restantes sont plus grandes que dans la première configuration, ce qui permet de favoriser le passage des premiers électrons lorsque la première cathode 16 émet.Thus, when the cathode 18 is in the second configuration, the number of windows 40 is halved, due to the absence of a window 40 between the adjacent emission regions 42. However, the remaining windows 40 are larger than in the first configuration, which makes it possible to promote the passage of the first electrons when the first cathode 16 emits.

En outre, chaque paire de régions d'émission 42 adjacentes est équivalente à un unique secteur d'émission de la cathode 18. Ainsi, dans le cas où le tube hyperfréquence 12 est un magnétron, comme décrit plus haut, il est possible de faire émettre la deuxième cathode 18 en ayant au choix un secteur d'émission, formé d'une seule région d'émission 42, en face de chaque cavité résonnante 63, 64, de façon à faire fonctionner le magnétron en mode 2π, ou un secteur d'émission, formé d'une paire de régions d'émission 42 adjacentes, en face d'une cavité résonnante 63, 64 sur deux, de façon à faire fonctionner le magnétron en mode π. Il est ainsi possible de faire varier la fréquence de l'onde générée lorsque le dispositif de génération 10 est dans le troisième mode de fonctionnementFurther, each pair of adjacent emission regions 42 is equivalent to a single emission sector of the cathode 18. Thus, in the case where the microwave tube 12 is a magnetron, as described above, it is possible to make emit the second cathode 18 by having a choice of an emission sector, formed of a single emission region 42, opposite each resonant cavity 63, 64, so as to operate the magnetron in 2π mode, or a sector emission, formed of a pair of adjacent emission regions 42, facing a resonant cavity 63, 64 out of two, so as to operate the magnetron in π mode. It is thus possible to vary the frequency of the wave generated when the generation device 10 is in the third operating mode.

Dans l'exemple représenté sur les Figures 6 à 8, la deuxième cathode 18 est du type « cathode transparente », comme décrit plus haut.In the example shown on Figures 6 to 8 , the second cathode 18 is of the “transparent cathode” type, as described above.

Le corps 44 est formé de deux cylindres 94, 96 orientés longitudinalement et emmanchés l'un dans l'autre. Le cylindre intérieur 94 appartient à la première pièce 90. Le cylindre extérieur 96 appartient à la deuxième pièce 92.The body 44 is formed of two cylinders 94, 96 oriented longitudinally and fitted one inside the other. The inner cylinder 94 belongs to the first part 90. The outer cylinder 96 belongs to the second part 92.

Le cylindre intérieur 94 est solidaire de trois des six barreaux 50 de la cathode 18. Ceux-ci sont régulièrement répartis le long de la circonférence du cylindre intérieur 94. En d'autres termes, ils sont disposés aux sommets d'un triangle équilatéral. Lesdits barreaux 50 sont fixes les uns par rapport aux autres.The inner cylinder 94 is integral with three of the six bars 50 of the cathode 18. These are regularly distributed along the circumference of the inner cylinder 94. In other words, they are arranged at the vertices of an equilateral triangle. Said bars 50 are fixed relative to each other.

Le cylindre extérieur 96 est solidaire des trois barreaux 50 restants. Ceux-ci sont régulièrement répartis le long de la circonférence du cylindre extérieur 96. En d'autres termes, ils sont disposés aux sommets d'un triangle équilatéral. Lesdits barreaux 50 sont fixes les uns par rapport aux autres.The outer cylinder 96 is integral with the three remaining bars 50. These are regularly distributed along the circumference of the outer cylinder 96. In other words, they are arranged at the vertices of an equilateral triangle. Said bars 50 are fixed relative to each other.

Les barreaux 50 solidaires du cylindre intérieur 94 et les barreaux 50 solidaires du cylindre extérieur 96 sont sensiblement à équidistance de l'axe longitudinal Z. A cet effet, chacun des barreaux 50 solidaires du cylindre intérieur 94 est porté par une saillie 98 faisant saillie radialement vers l'extérieur depuis la surface périphérique extérieure du cylindre intérieur 94. En variante (non représentée), chacun des barreaux 50 solidaires du cylindre extérieur 96 est porté par une saillie faisant saillie radialement vers l'intérieur depuis la surface intérieure du cylindre extérieur 96.The bars 50 secured to the inner cylinder 94 and the bars 50 secured to the outer cylinder 96 are substantially equidistant from the longitudinal axis Z. For this purpose, each of the bars 50 secured to the inner cylinder 94 is carried by a projection 98 projecting radially. outwardly from the outer peripheral surface of the inner cylinder 94. Alternatively (not shown), each of the bars 50 integral with the outer cylinder 96 is carried by a projection projecting radially inwardly from the inner surface of the outer cylinder 96. .

Cette variante est généralisable à un cas où la deuxième cathode 18 comporte N pièces portant chacune P/N régions d'émissions 42, où P est le nombre total de régions d'émission 42 de la deuxième cathode 18, lesdites pièces étant rotatives les unes par rapport aux autres autour de l'axe longitudinal Z entre une première configuration de la deuxième cathode 18, dans laquelle toutes les régions d'émission 42 sont à distance les unes des autres, et une deuxième configuration de la deuxième cathode 18, dans laquelle au moins deux des régions d'émission 42 sont adjacentes.This variant can be generalized to a case where the second cathode 18 comprises N parts each carrying P / N emission regions 42, where P is the total number of emission regions 42 of the second cathode 18, said parts being rotatable. relative to the others around the longitudinal axis Z between a first configuration of the second cathode 18, in which all the emission regions 42 are spaced from each other, and a second configuration of the second cathode 18, in which at least two of the emission regions 42 are adjacent.

Cette variante de l'invention permet d'augmenter le rendement du dispositif de génération 10 lorsqu'il est dans le premier ou le deuxième mode de fonctionnement, en réduisant les interactions entre les premiers électrons et la deuxième cathode 18.This variant of the invention makes it possible to increase the efficiency of the generation device 10 when it is in the first or the second operating mode, by reducing the interactions between the first electrons and the second cathode 18.

En outre, cette variante augmente encore la flexibilité du dispositif de génération 10 en permettant de générer des ondes, lorsque le dispositif de génération 10 est dans le troisième mode de fonctionnement, sur une large plage de fréquences.Furthermore, this variant further increases the flexibility of the generation device 10 by making it possible to generate waves, when the generation device 10 is in the third mode of operation, over a wide range of frequencies.

Dans une autre variante (non représentée), la deuxième cathode 18 est également formée de deux pièces, portant chacune une moitié des régions d'émission 42 de la deuxième cathode 18, mais ces pièces ne sont pas rotatives l'une par rapport à l'autre. Un commutateur permet de sélectivement raccorder électriquement une seule desdites pièces ou les deux pièces simultanément, au circuit d'alimentation 21. De même que la précédente variante, cette variante permet de faire fonctionner le magnétron en mode π et en mode 2π.In another variant (not shown), the second cathode 18 is also formed of two parts, each carrying one half of the emission regions 42 of the second cathode 18, but these parts are not rotatable with respect to one another. 'other. A switch makes it possible to selectively electrically connect only one of said parts or both parts simultaneously, to the supply circuit 21. Like the previous variant, this variant makes it possible to operate the magnetron in π mode and in 2π mode.

On notera que, dans les exemples donnés ci-dessus, les valeurs de potentiels exprimés, en particulier les valeurs des potentiels d'émission W1, W2, et la valeur du deuxième potentiel de consigne V2,1, sont bâtis sur une approximation selon laquelle le champ électrique serait sensiblement constant dans tout l'espace d'interaction 22. L'homme du métier saura ajuster ces valeurs au moyen de tests de routine pour qu'elles correspondent plus justement à la réalité de la répartition du champ électrique dans l'espace d'interaction 22.It will be noted that, in the examples given above, the values of potentials expressed, in particular the values of the emission potentials W 1 , W 2 , and the value of the second reference potential V 2.1 , are built on a approximation according to which the electric field would be substantially constant throughout the entire interaction space 22. Those skilled in the art will know how to adjust these values by means of routine tests so that they correspond more precisely to the reality of the distribution of the electric field in the interaction space 22.

Claims (14)

  1. Device (10) for generating ultrahigh frequency waves, comprising an anode (20) and a first cathode (16), separated by an interaction space (22), the first cathode (16) being adapted to emit first electrons into the interaction space (22) when subjected to an electric field (E) with an intensity greater than a first threshold value, and the anode (20) being adapted to attract said first electrons, the generation device (10) comprising furthermore at least one waveguide (14) disposed opposite a through-opening (65) of the anode (20) and extending from an exterior surface (62) of the anode (20) towards the exterior of the generation device (10), characterised in that it comprises a second cathode (18), intercalated between the first cathode (16) and the anode (20) and adapted to emit second electrons into the interaction space (22) when subjected to an electrical field (E) with an intensity greater than a second threshold value strictly greater than the first threshold value, the anode (20) being adapted to attract said second electrons, and in that it comprises a circuit (21) for electrical supply of the cathodes (16, 18), adapted to establish a potential difference between the cathodes (16, 18).
  2. Generation device (10) according to claim 1, in which the first cathode (16) is a cathode for emission of a field of electron-emitting micropoints.
  3. Generation device (10) according to claim 1 or 2, in which the first cathode (16) is adapted to emit electrons continuously over a time greater than 1 µs.
  4. Generation device (10) according to any of the preceding claims, in which the second cathode (18) is adapted to deliver a current density greater than 10 A/cm2.
  5. Generation device (10) according to any of the preceding claims, in which the second cathode (18) comprises a plurality of emission regions (42) defining between them at least one window (40), interposed between the first cathode (16) and the anode (20).
  6. Generation device (10) according to claim 5, in which the emission regions (42) of the second cathode (18) define between them several windows (40), and the first cathode (16) comprises a plurality of emission zones (36) remote from each other, each emission zone (36) of the first cathode (16) being disposed opposite the one of the windows (40) of the second cathode (18).
  7. Generation device (10) according to any of the preceding claims, in which the anode (20) is tubular and extends following an axis (Z).
  8. Generation device (10) according to claim 7, in which each cathode (16, 18) is surrounded by the anode (20) by being substantially centred on the axis (Z).
  9. Generation device (10) according to any of the preceding claims, comprising a module (80) for control of the supply circuit (21) of the cathodes (16, 18), programmed to bring the electrical potential (V1) of the first cathode (16) to a first reference potential (V1,1), less than an emission potential (W1) of the first cathode (16), and to bring the electrical potential (V2) of the second cathode (18) to a second reference potential (V2,2) less than the potential (V0) of the anode (20) and greater than the first reference potential (V1,1) when the generation device (10) is in a first functioning mode.
  10. Generation device (10) according to claim 9, in which the potential difference between the second reference potential (V2,2) and the potential (V0) of the anode (20) is substantially equal to U 1 D × d
    Figure imgb0005
     where U1 is the potential difference between the first reference potential (V1,1) and the potential (V0) of the anode, D is the distance between the anode (20) and the first cathode (16) and d is the distance between the anode (20) and the second cathode (18).
  11. Generation device (10) according to claim 9 or 10, in which the control module (80) is programmed to maintain the electrical potential (V1) of the first cathode (16) at the first reference potential (V1,1) for a time greater than 1 µs in the first functioning mode.
  12. Generation device (10) according to any of claims 9 to 11, in which the control module (80) is programmed to bring the electrical potential (V2) of the second cathode (18) to a third reference potential (V2,2), less than an emission potential (W2) of the second cathode (18) when the generation device (10) is in another functioning mode, the electrical potential (V1) of the first cathode (16) being substantially equal to the electrical potential (V2) of the second cathode (18).
  13. Generation device (10) according to claim 12, in which the control module (80) is programmed to make the electrical potential (V2) of the second cathode (18) vary cyclically between the third reference potential (V2,2) and the potential (V0) of the anode (20) when the generation device (10) is in the other functioning mode.
  14. Generation device (10) according to claim 13, in which the anode (20) is tubular and extends following an axis (Z), each cathode (16, 18) being surrounded by the anode (20) by being substantially centred on the axis (Z), and the generation device (10) comprises a focusing device (76) in order to form a magnetic field (B) in the interaction space (22), orientated following the axis (Z), the control module (80) being adapted to control a supply (78) of the focusing device (76) so as to make the intensity of the magnetic field (B) vary cyclically, when the generation device (10) is in the second functioning mode, between a maximum intensity when the electrical potential (V2) of the second cathode (18) is equal to the third reference potential (V2,2), and a zero intensity when the electrical potential (V2) of the second cathode (18) is at the potential (V0) of the anode (20).
EP13197779.5A 2012-12-19 2013-12-17 Device for generating microwaves with dual cathodes Active EP2747117B1 (en)

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FR1203487A FR2999797B1 (en) 2012-12-19 2012-12-19 DUAL CATHODE HYPERFREQUENCY WAVE GENERATING DEVICE

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US9711315B2 (en) * 2015-12-10 2017-07-18 Raytheon Company Axial strapping of a multi-core (cascaded) magnetron

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US2217860A (en) * 1937-03-22 1940-10-15 Farnsworth Television & Radio Split cathode multiplier
US5578906A (en) 1995-04-03 1996-11-26 Motorola Field emission device with transient current source
US7893621B2 (en) * 2007-01-24 2011-02-22 Stc.Unm Eggbeater transparent cathode for magnetrons and ubitrons and related methods of generating high power microwaves
FR2970114B1 (en) * 2010-12-29 2013-04-05 Thales Sa HYPERFREQUENCY WAVE GENERATING DEVICE HAVING A CATHODE OF WHICH EACH END IS CONNECTED TO A VOLTAGE SOURCE

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FR2999797B1 (en) 2016-04-15

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