EP0407558B1 - Mikrowellen-verstärker oder oszillator-anordnung - Google Patents

Mikrowellen-verstärker oder oszillator-anordnung Download PDF

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Publication number
EP0407558B1
EP0407558B1 EP90902637A EP90902637A EP0407558B1 EP 0407558 B1 EP0407558 B1 EP 0407558B1 EP 90902637 A EP90902637 A EP 90902637A EP 90902637 A EP90902637 A EP 90902637A EP 0407558 B1 EP0407558 B1 EP 0407558B1
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EP
European Patent Office
Prior art keywords
electron beam
use according
circuit
output circuit
previous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90902637A
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English (en)
French (fr)
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EP0407558A1 (de
Inventor
Guy Convert
Jean-Pierre Brasile
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/74—Tubes specially designed to act as transit-time diode oscillators, e.g. monotrons

Definitions

  • the present invention relates to the use of a microwave amplifier device, as well as an oscillator obtained from the previous device.
  • speed modulation electronic tubes such as klystrons or traveling wave tubes.
  • This type of tube includes an electron gun, providing an electron beam; the electrons in the beam undergo a periodic change in speed which brings them together in packets in certain areas of space; these packets then excite by impulse, according to their own period, the oscillations of a microwave circuit (resonant cavity or line) by borrowing the energy necessary for their own kinetic energy.
  • Document FR-A-2,070,322 describes an example of such a tube.
  • vircators which, unlike the previous tubes, take advantage of the space charge effects.
  • a current of electrons is injected into a space, most often equal to several times the maximum current that could actually cross this space.
  • This virtual cathode is unstable, that is to say it oscillates in space, thus creating electromagnetic fields.
  • Document US-A-4,730,170 describes an example of such a vircator. With such a device, it is possible to obtain high microwave powers and this, under a reduced volume.
  • the signal transmitted is of poor quality, that is to say that the power is transmitted on numerous modes in a series of simultaneous or successive frequencies, and the applications of this type of signals are quite reduced.
  • the conversion efficiency is poor (of the order of 2 to 3% at best) compared to the efficiency which it is possible to obtain with speed modulation tubes (often greater than 40%).
  • the present invention relates to the use of a device intended to produce microwave energy from an electron beam, which makes it possible to avoid the above limitations, that is to say a yield of converting the energy of the electron beam into microwave energy and a quality of the emitted signal comparable to those of speed modulation tubes, with a weight and in a volume comparable to those of vircators.
  • the subject of the invention is the use of a microwave amplifier device as defined by claim 1.
  • FIG. 1 therefore represents a first embodiment of the device used according to the invention, seen in longitudinal schematic section.
  • the generator according to the invention is a structure of revolution around a longitudinal axis ZZ. It comprises an electron gun 1, formed by a cathode 11 and an anode composed of an armature 20 and a screen 21.
  • the cathode 11 is in the form of a conductive cylinder of axis ZZ, whose circumference protrudes 10 so that the electrons emitted by this cathode form an annular beam, represented by a dotted area 8 in the figure.
  • the direction of propagation of the electrons of the beam 8 is shown by arrows.
  • the armature 20 of the anode consists of a hollow cylinder, of the same axis ZZ as the cathode; it is closed by an annular shoulder 23 and a screen 21 in the form of a disc, leaving an annular slot 22 for the passage of the electron beam 8 to remain; the screen 21 is for example fixed by three tabs on the shoulder 23.
  • the generator used according to the invention also comprises an output microwave circuit 4 which is, in this embodiment, of the coaxial type, formed by an internal conductive cylinder 5 and an external conductor 40, arranged in the extension of the armature 20 , between which is defined an annular space 44.
  • the output circuit is substantially symmetrical of the electron gun 1 with respect to a plane normal to the plane of the figure, that is to say that the outer conductor 40 has a shoulder 43 annular and a screen 41 bearing, for example by legs, on the shoulder 43 and defining with this shoulder a circular slot 42 for the passage of the electron beam 8; the latter is received by an annular projection 50 of the inner conductor 5.
  • zone 3 Between the elements 21, 23 on the one hand, and 41, 43 on the other hand, there is a zone 3 called the injection region; this zone is laterally limited by extensions 25 and 45 of the walls 20 and 40 respectively, without contact with each other so as to form a slot 71 between them.
  • the generator according to the invention further comprises a microwave modulation circuit 7, which is in this embodiment of the coaxial type; the central conductor of the circuit is formed by the wall 40 and the external conductor by a wall 70 in the form of a hollow cylinder, always of axis ZZ, defining with the wall 40 an annular space 74, the outer conductor 70 coming to be connected to part 25 of the frame 20.
  • the application to the cathode 11 of a negative voltage with respect to that of the anode causes the emission of the annular electron beam 8.
  • the armature 20, the screen 21 and the elements of the output circuit 4 are at ground potential and a voltage -V o is applied to the cathode 11.
  • a longitudinal magnetic field (along the ZZ axis) is preferably applied to the structure, using means not shown, to focus the beam 8 thus produced.
  • the mechanism for forming a virtual cathode is recalled below. Inside an electron beam there is a charge of space: on the axis of the beam, the potential and the speed of the electrons are lower than at the periphery. If the density of electrons and consequently the transported current increase, the potential and the speed of the electrons decrease until zero: the electrons then form a heap, negatively charged, called virtual cathode.
  • This electron cluster oscillates on the longitudinal axis, giving rise to an electromagnetic field. The frequency of the oscillations depends in particular on the injection current and it is commonly measured in Gigahertz.
  • the maximum current intensity beyond which the electrons form a virtual cathode is a function of the potential of the electron beam as well as of the dimensions of the beam and of the injection region 3; more precisely, the maximum current for a given electron beam is lower when the injection zone 3 is of larger diameter.
  • the dimensions of the device (electron gun and injection zone) and the current of the electron beam are chosen so that it is slightly less than the maximum current likely to travel through region 3, current beyond which there is virtual cathode formation.
  • the modulation circuit 7 By the modulation circuit 7 is brought an alternating electric field.
  • the voltage between parts 25 and 45 resulting from this field must be of sufficient amplitude so that, for one of the alternations, the electron beam 8 is stopped by a mechanism of the virtual cathode type and no longer reaches the circuit.
  • outlet 4 the electrons then being absorbed by the walls delimiting the injection zone 3; at the next alternation, the voltage applied between the same elements 25 and 45 restores the beam; the beam current is thus modulated in intensity at the frequency of the modulation signal.
  • the output circuit 4 is then excited by the preceding modulated current and thus ensures the transformation into microwave energy of at least part of the energy of the electrons of the beam.
  • Screens 21 and 41 conventionally have the function of absorbing divergent electrons. It should be noted that the modulation (7) and output (4) microwave circuits make it possible, by the choice of their dimensions, to precisely define the frequency of the modulation signal and, which is the aim sought, the frequency of the signal. output, thus obtaining
  • the maximum period of the alternating modulation field may be only a fraction of the beam switching time between the on state and the virtual cathode; in practice it can be of the order of the transit time of the electrons in the structure.
  • the generator described here is, like a vircator, particularly compact; the length of the injection region 3, limited by the screens 21 and 41 happens to be in fact, in practice, of the order of the operating wavelength.
  • V o can pose technological problems due to the order of magnitude of the voltages (MV) and currents (kA) used. It is then possible to use voltage pulses, of a duration for example of the order of a hundred nanoseconds, transmitted to the cathode by the coaxial structure 12-20, for example. The duration of these pulses remains long compared to the period of the pulses produced, typically of the order of a hundred picoseconds.
  • the reinjection means can be produced by any known means, such as a coupling loop produced in an opening in the wall 40 or a circuit outside the generator shown.
  • FIG. 2 represents a second embodiment of the device used according to the invention, in which means are provided for post-acceleration of the beam after modulation, in order to improve the efficiency of the assembly.
  • the output circuit 4 is also formed as in FIG. 1 by the cylindrical inner conductor 5 surrounded by the conductor 40, the shoulder 43 and the screen 41.
  • the injection zone is no longer closed by the screen 21 and the shoulder 43 but by a conductive element 61 similar to the screen 41 and an external conductor 60, arranged in the extension of the armature 20 and providing with the latter the slot 71 to which the modulation circuit is connected; the element 60 also houses an annular slot 62 with the screen 61 to allow the passage of the electron beam 8.
  • the elements 60 and 61 are therefore electrically isolated both from the barrel 1 and from the output circuit 4.
  • a voltage -V o is applied to the cathode with respect to the anode, the modulation signal via circuit 7 and, in addition, a post-acceleration voltage + Vération at the output circuit. relative to the wall 60, which is for example at the potential of the anode. In this way, the electrons are accelerated out of the injection zone 3.
  • FIG. 3 represents a third embodiment of the device used according to the invention, in which the electron beam is a solid cylinder.
  • the emissive surface of the cathode, now marked 12, of the barrel 1 is in the form of a disc so as to emit a solid cylindrical electron beam 80.
  • the internal conductor of the output circuit 4, now marked 51 is constituted by a flat surface in the form of a disc.
  • the screens 21 and 41 of FIG. 1 have been replaced here by the elements marked 26 and 46, constituted by grids or metallic sheets sufficiently thin for their absorption of electrons to be very low.
  • the diameter of the cathode 12 must be substantially less than the wavelength of the energy. microwave obtained at the output, for example of the order of half the wavelength.

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  • Particle Accelerators (AREA)
  • Microwave Tubes (AREA)

Claims (9)

  1. Verwendung einer Verstärkervorrichtung für Mikrowellen, die nacheinander aufweist:
    - eine Elektronenkanone, die einen Elektronenstrahl (8) in einer Injektionszone (3) erzeugen kann,
    - eine Mikrowellen-Modulationsschaltung (7), die eine Wechselspannung an die Injektionszone anlegen kann,
    - eine Mikrowellen-Ausgangsschaltung (4), die zumindest einen Teil der Energie der Elektronen des Strahls in Mikrowellenenergie umwandeln kann,
    dadurch gekennzeichnet, daß während des Betriebs der Vorrichtung der vom Elektronenstrahl transportierter Strom geringer als der Maximalwert des Stroms ist, der in der Injektionszone transportiert werden kann, und daß die Wechselspannung eine ausreichend große Amplitude hat, um während einer ihrer Halbwellen die Bildung einer virtuellen Kathode auszulösen, die den Durchlaß der Elektronen verbietet, so daß der so vom Strahl transportierte Strom mit der Modulationsfrequenz der Wechselspannung moduliert wird, wobei die Ausgangsschaltung durch den erwähnten modulierten Strom angeregt wird.
  2. Verwendung nach Anspruch 1, dadurch gekennzeichnet, daß die Ausgangsschaltung eine koaxiale Schaltung ist.
  3. Verwendung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Modulationsschaltung eine koaxiale Schaltung ist.
  4. Verwendung nach den Ansprüchen 2 und 3, dadurch gekennzeichnet, daß der zentrale Leiter (40) der Modulationsschaltung vom Außenleiter der Ausgangsschaltung gebildet wird.
  5. Verwendung nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß die Ausgangsschaltung elektrisch gegenüber der Injektionszone isoliert ist und daß eine Elektronen-Beschleunigungsspannung zwischen die Injektionszone und die Ausgangsschaltung gelegt wird.
  6. Verwendung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Elektronenstrahl ein Hohlzylinder ist.
  7. Verwendung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Elektronenstrahl ein Vollzylinder ist.
  8. Verwendung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß weiter Mittel zur erneuten Injektion eines Teils des von der Ausgangsschaltung gelieferten Signal in die Modulationsschaltung vorgesehen sind, so daß sich ein Oszillator ergibt.
  9. Verwendung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß außerdem Mittel zum Anlegen eines magnetischen Fokussierfeldes an den Elektronenstrahl vorgesehen sind.
EP90902637A 1989-01-27 1990-01-26 Mikrowellen-verstärker oder oszillator-anordnung Expired - Lifetime EP0407558B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR8901007 1989-01-27
FR8901007A FR2642584B1 (fr) 1989-01-27 1989-01-27 Dispositif amplificateur ou oscillateur fonctionnant en hyperfrequence
PCT/FR1990/000059 WO1990009029A1 (fr) 1989-01-27 1990-01-26 Dispositif amplificateur ou oscillateur fonctionnant en hyperfrequence

Publications (2)

Publication Number Publication Date
EP0407558A1 EP0407558A1 (de) 1991-01-16
EP0407558B1 true EP0407558B1 (de) 1995-08-02

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EP90902637A Expired - Lifetime EP0407558B1 (de) 1989-01-27 1990-01-26 Mikrowellen-verstärker oder oszillator-anordnung

Country Status (7)

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US (1) US5164634A (de)
EP (1) EP0407558B1 (de)
JP (1) JPH03503818A (de)
CA (1) CA2026111C (de)
DE (1) DE69021290T2 (de)
FR (1) FR2642584B1 (de)
WO (1) WO1990009029A1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2830371B1 (fr) * 2001-09-28 2005-08-26 Thales Sa Generateur d'ondes hyperfrequences a cathode virtuelle
SE532955C2 (sv) * 2006-06-01 2010-05-18 Bae Systems Bofors Ab Anordning för generering av mikrovågor
RU2444082C2 (ru) * 2010-05-24 2012-02-27 Государственное образовательное учреждение высшего профессионального образования "Саратовский государственный университет им. Н.Г. Чернышевского" Генератор свч сигналов на виртуальном катоде
RU2671915C2 (ru) * 2017-12-14 2018-11-07 Александр Петрович Ишков Авторезонансный СВЧ-генератор
CN113936982B (zh) * 2021-08-23 2023-07-21 西北核技术研究所 一种束流调控的高效率低磁场相对论返波管

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2252565A (en) * 1940-03-09 1941-08-12 Rca Corp Electron discharge device
US2428622A (en) * 1942-11-12 1947-10-07 Gen Electric Tuning and coupling means for highfrequency systems
DE975093C (de) * 1944-03-30 1961-08-10 Karl Dr Hausser Anordnung mit einer Bremsfeldroehre zur Erzeugung sehr kurzer elektrischer Wellen
GB852421A (en) * 1956-02-21 1960-10-26 Vickers Electrical Co Ltd Improvements relating to velocity modulated electron discharge devices
FR2070322A5 (de) * 1969-12-01 1971-09-10 Thomson Csf
US4345220A (en) * 1980-02-12 1982-08-17 The United States Of America As Represented By The Secretary Of The Air Force High power microwave generator using relativistic electron beam in waveguide drift tube
US4422045A (en) * 1981-03-20 1983-12-20 Barnett Larry R Barnetron microwave amplifiers and oscillators
US4751429A (en) * 1986-05-15 1988-06-14 The United States Of America As Represented By The United States Department Of Energy High power microwave generator
US4745336A (en) * 1986-05-27 1988-05-17 Ga Technologies Inc. Microwave generation by virtual cathode with phase velocity matching
US4730170A (en) * 1987-03-31 1988-03-08 The United States Of America As Represented By The Department Of Energy Virtual cathode microwave generator having annular anode slit

Also Published As

Publication number Publication date
DE69021290T2 (de) 1995-12-21
US5164634A (en) 1992-11-17
FR2642584B1 (fr) 1994-05-06
JPH03503818A (ja) 1991-08-22
DE69021290D1 (de) 1995-09-07
WO1990009029A1 (fr) 1990-08-09
CA2026111C (fr) 2000-05-30
CA2026111A1 (fr) 1990-07-28
EP0407558A1 (de) 1991-01-16
FR2642584A1 (fr) 1990-08-03

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