EP0482986A1 - Kollektor für eine Mikrowellenröhre und Mikrowellenröhre mit einem solchen Kollektor - Google Patents

Kollektor für eine Mikrowellenröhre und Mikrowellenröhre mit einem solchen Kollektor Download PDF

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Publication number
EP0482986A1
EP0482986A1 EP91402784A EP91402784A EP0482986A1 EP 0482986 A1 EP0482986 A1 EP 0482986A1 EP 91402784 A EP91402784 A EP 91402784A EP 91402784 A EP91402784 A EP 91402784A EP 0482986 A1 EP0482986 A1 EP 0482986A1
Authority
EP
European Patent Office
Prior art keywords
interaction space
collector
diameter
orifice
enclosure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91402784A
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English (en)
French (fr)
Inventor
Bernard Epsztein
Alain Durand
Eric Lemaire
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 Electron Devices SA
Original Assignee
Thomson Tubes Electroniques
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson Tubes Electroniques filed Critical Thomson Tubes Electroniques
Publication of EP0482986A1 publication Critical patent/EP0482986A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01J23/027—Collectors
    • H01J23/0275—Multistage collectors

Definitions

  • the present invention relates to manifolds for microwave tubes. It also relates to microwave tubes comprising such collectors and in particular tubes with longitudinal interaction.
  • Klystrons and traveling wave tubes belong to this category of microwave turbines. Their operation is based on an energy exchange between a linear electron beam and a microwave electromagnetic wave.
  • the electron beam is emitted in a cannon, through a cathode.
  • the barrel is placed at the entrance of a tubular interaction space.
  • the electron beam is long and thin, it traverses the interaction space.
  • a focusing device surrounds the interaction space and confines the beam electrons on desired trajectories.
  • the electron beam interacts with a microwave electromagnetic wave.
  • the amplified microwave electromagnetic wave is extracted by an appropriate device at the output of the interaction space.
  • the electron beam ends up in a collector placed at the exit of the interaction space.
  • the interaction space includes a microwave circuit which is generally either a helical delay line in the case of a traveling wave tube, or a succession of resonant cavities in the case of a klystron.
  • the interaction space is brought to a potential which is generally a mass.
  • the electron beam After having given up part of its energy to the microwave electromagnetic wave, the electron beam still has significant kinetic energy when entering the collector.
  • the collector dissipates this energy in the form of heat. We are trying to recover some of this energy by braking the electrons in the beam.
  • a depressed collector is used which is brought to a potential intermediate between the potential of the cathode and that of the interaction space.
  • the collector may include one or more successive electrodes; when there are several, they are brought to decreasing potentials the further one moves away from the interaction space.
  • the collector then has several stages. The use of a depressed collector helps to increase the efficiency of the microwave tube and to reduce the difficulties encountered in removing heat.
  • the electron beam due to its interaction with the microwave electromagnetic wave, is far from being monocinetic. Fast electrons have more energy than slow electrons.
  • the slowest electrons are intercepted by the first electrode, the other electrons continue their course. Their speed is reduced by the braking field which exists between the successive electrodes. They are gradually intercepted by the different electrodes.
  • the potential is lower than that which corresponds to the energy of the slowest electrons, these electrons are reflected and are returned to the interaction space. Some can even reach the electron gun where they are reflected again.
  • the additional modulated current which corresponds to them causes a parasitic coupling between the input and the output of the interaction space. This causes a phase and amplitude distortion, as a function of the frequency, of the microwave electromagnetic wave recovered at the output of the interaction space.
  • the noise at the outlet of the tube is increased and the tube can even start to oscillate. This drawback is particularly troublesome in certain telecommunications which then present crosstalk.
  • the reflected electrons which do not reach the barrel are intercepted by the microwave circuit. They cause it to heat up and even melt, which is fatal for the life of the tube.
  • microwave tubes with strong beam modulation such as klystrons and power traveling wave tubes
  • depression is reduced to a few things and we then find the difficulties in removing heat.
  • the performance of the microwave tube is affected.
  • the present invention aims to remedy these drawbacks. It offers a depressed collector collecting the electrons of a beam, almost all of the slowest electrons being projected in an area where they do not cause damage, instead of being reflected towards the interaction space.
  • the present invention provides a collector for collecting the electrons of a beam, arranged downstream of an interaction space, comprising a depressed enclosure, limited upstream by an inlet wall provided with an orifice and a chamber expansion interposed between the interaction space and the depressed enclosure and brought to the same potential as the interaction space.
  • the expansion chamber is limited upstream by an inlet wall provided with an orifice.
  • the entry port in the depressed enclosure has a diameter D.
  • the inlet to the expansion chamber has a diameter d .
  • the diameter D is greater than twice the diameter d .
  • the interior surface of the chamber entrance wall expansion and the outer surface of the entry wall of the depressed enclosure can be sensiblememt in the form of truncated cones, oriented in the same direction, flared downstream.
  • the cones can have approximately the same angle at the top.
  • the interaction space may have a circular cross section whose diameter is substantially equal to that at the orifice of the inlet wall of the expansion chamber.
  • the distance L between the orifice of the inlet wall of the expansion chamber and the orifice of the inlet wall of the depressed enclosure is greater than or equal to the diameter d of the orifice the inlet wall of the expansion chamber.
  • the exterior surface of the inlet wall of the expansion chamber can be cooled by circulation of a fluid.
  • the potential of the interaction space can be a mass.
  • FIG. 1 represents, in longitudinal section, a depressed collector 10, of known type, for microwave tube with linear electron beam 1.
  • This beam is produced by a cathode of an electron gun, not shown.
  • the electrons of the beam 1 then travel through an interaction space 2 of tubular shape.
  • the collector 10 collects a large part of the electrons.
  • the collector 10 is built around an axis XX ′ of revolution which coincides with the axis of the electron beam 1.
  • This interaction space 2 includes a microwave circuit which can be, for example, a delay line in the case of traveling wave tubes or a succession of resonant cavities in the case of klystrons.
  • the microwave circuit is not shown.
  • the interaction space 2 is brought to a potential which is generally a mass.
  • the interaction space 2 is surrounded by a focusing device 6 which prevents the electron beam from diverging. It confines the electrons on desired substantially parallel trajectories.
  • An annular conductive part 3 is disposed downstream of the interaction space 2. It is brought to the same potential as the latter.
  • the collector 10 shown is depressed with a single stage or a single electrode. It could have been multistage with a succession of electrodes brought to decreasing potentials the further one moves away from the interaction space.
  • the enclosure 4 is formed by an enclosure 4 provided with an orifice 7 to let the electrons penetrate.
  • This enclosure 4 forms the electrode.
  • the enclosure 4 is mechanically connected, in leaktight manner, by means of an insulating spacer 5 to the annular part 3. This connection is made near the orifice 7.
  • the enclosure 4 is brought to a lower potential to the potential of the interaction space 2.
  • the insulating spacer 5 of cylindrical shape, electrically isolates the interaction space 2 and the collector 10.
  • the wall of the enclosure 4 is represented by two frustoconical tubes assembled by their large end.
  • the small end of one of the tubes is closed, which forms a bottom at the collector.
  • the small end of the other frustoconical tube is open and the opening forms the orifice 7 of the enclosure 4.
  • a suitable fluid can circulate around the enclosure 4 to cool its wall. This is not shown.
  • the electron beam In the interaction space 2, the electron beam is focused by an axial magnetic field. At the exit of the interaction space, this magnetic field suddenly decreases. Leaving the interaction space 2, the electron beam 1 begins to diverge rapidly, under the influence of space charge forces.
  • the electron beam 1, due to its passage in the interaction space where it interacted with an electromagnetic wave is far from being monocimetic. Some electrons are slower than others. If the potential of the enclosure 4 is lower than that which corresponds to the energy of the slower electrons, these will not be able to penetrate into the enclosure 4. They will be reflected in the interaction space 2. Some electrons will strike the microwave circuit causing it to heat up, others may even reach the electron gun.
  • FIG. 2 represents in longitudinal section a collector 20, according to the invention, for microwave tube with linear electron beam 21.
  • This collector 20 like that shown in FIG. 1, is built around an axis of revolution XX ′. This axis is also the axis of the electron beam 21.
  • the collector 20 according to the invention differs mainly from the collector shown in FIG. 1 in that it includes an expansion chamber 22 placed upstream of a depressed enclosure 23.
  • the electron beam 21 is formed by a cathode of an electron gun, not shown.
  • the electron beam 21 traverses an interaction space 24 of tubular shape.
  • the interaction space 24 is surrounded by a focusing device 25 which prevents the electron beam 21 from diverging.
  • the electron beam 21 enters the collector 20.
  • the depressed chamber 23 has a single stage. One could envisage that it includes several.
  • the depressed enclosure 23 is limited by a wall 26.
  • This wall is provided, upstream, with an orifice 27 to allow the electrons to penetrate.
  • This orifice 27 is preferably circular, of diameter D , centered on the axis XX ′.
  • the wall portion 26 surrounding the orifice 27 forms an inlet wall 30 to the depressed enclosure 23.
  • the wall 26 is made of a metal which is a good conductor of heat such as copper.
  • the depressed chamber 23 is brought to a potential lower than the potential of the interaction space 24. This potential is however greater than the potential of the cathode producing the electron beam.
  • the wall 26 of the depressed enclosure 23 is shown by two frustoconical tubes assembled by their large ends.
  • the small end of one of the frustoconical tubes is closed and forms a bottom at the depressed enclosure 23.
  • the small end of the other frustoconical tube has an opening which corresponds to the orifice 27 of the depressed enclosure 23.
  • This last frustoconical tube forms the inlet wall 30 of the depressed enclosure 23.
  • the expansion chamber 22 is placed between the outlet of the interaction space 24 and the depressed enclosure 23. It is limited upstream by an inlet wall 28, conductive, tightly connected to the space d 'interaction 24.
  • This inlet wall 28 is provided with an orifice 29, preferably circular, of diameter d , centered on the axis XX ′. The diameter d is sufficient to let the electrons pass through the beam.
  • This orifice 29 has substantially the same diameter as that of the interior of the interaction space 24.
  • the inlet wall 28 of the expansion chamber 22 is brought to the potential of the interaction space 24. It is made of a metal that dissipates heat well, such as copper, for example. Downstream, the expansion chamber 22 is limited by the inlet wall 30 of the depressed precinct 23.
  • the inlet wall 28 of the expansion chamber 22 and the inlet wall 30 of the depressed enclosure 23 are connected to each other, in leaktight manner, by an electrically insulating spacer 31.
  • the spacer 31 shown is tubular.
  • the inlet wall 28 of the expansion chamber 22 and the inlet wall 30 of the depressed enclosure 23 are brought to different potentials; they create an electrostatic lens.
  • the electrons in the beam 21 diverge rapidly. This divergence is due to the magnetic field which decreases rapidly at the exit from the interaction space 24, to the influence of the space charge forces and also to the effect of electrostatic lens.
  • the inner surface of the inlet wall 28 of the expansion chamber 22 and the outer surface of the inlet wall 30 of the depressed chamber 23 are shaped so that almost all of the electrons are too slow to penetrate in the depressed enclosure 23 strike the interior surface of the inlet wall 28 of the expansion chamber 22.
  • the equipotential surfaces are oriented so that the electrons having an almost zero speed are deflected towards the inlet wall 28 of the expansion chamber 22.
  • the trajectory of an electron is substantially normal to an equipotential surface.
  • the inner surface of the inlet wall 20 of the expansion chamber 22 and the outer surface of the inlet wall 30 of the depressed enclosure 23 are substantially in the form of truncated straight cones.
  • the cones are oriented in the same direction and are flared downstream. They can have substantially the same angle at the top.
  • the path traveled by the electrons between the exit from the interaction space 24 and the entry to the depressed chamber 23 is much longer than in the collectors of the known art.
  • the electrons Upon entering the expansion chamber 22 the electrons disperse rapidly. The fast electrons penetrate into the depressed enclosure 23. Almost all of the slow electrons strike the inlet wall 28 of the expansion chamber 22, a negligible fraction of the slow electrons are returned to the interaction space 24.
  • the diameter D of the orifice 27 of the inlet wall 30 of the depressed enclosure 23 is greater than twice the diameter d of the orifice 29 of the inlet wall 28 of the expansion chamber 22.
  • the distance L between the orifice 29 of the inlet wall 28 of the expansion chamber 22 and the orifice 27 of the inlet wall 30 of the depressed enclosure 23, is greater than diameter d .
  • the inlet wall 28 of the expansion chamber 22 will be bombarded by a large number of electrons. It will heat up, it is possible to cool it by circulating a fluid 32 around its outer surface.

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  • Microwave Tubes (AREA)
EP91402784A 1990-10-23 1991-10-18 Kollektor für eine Mikrowellenröhre und Mikrowellenröhre mit einem solchen Kollektor Withdrawn EP0482986A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9013092A FR2668297A1 (fr) 1990-10-23 1990-10-23 Collecteur pour tube hyperfrequence et tube hyperfrequence comportant un tel collecteur.
FR9013092 1990-10-23

Publications (1)

Publication Number Publication Date
EP0482986A1 true EP0482986A1 (de) 1992-04-29

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Family Applications (1)

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EP91402784A Withdrawn EP0482986A1 (de) 1990-10-23 1991-10-18 Kollektor für eine Mikrowellenröhre und Mikrowellenröhre mit einem solchen Kollektor

Country Status (3)

Country Link
EP (1) EP0482986A1 (de)
JP (1) JPH04282535A (de)
FR (1) FR2668297A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2694129A1 (fr) * 1992-07-21 1994-01-28 Litton Systems Inc Expulseur d'ions pour collecteur.

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3368102A (en) * 1965-06-09 1968-02-06 Sperry Rand Corp Collector structure operating at a depressed potential for collecting a hollow electron beam

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62222543A (ja) * 1986-03-20 1987-09-30 Nec Corp 進行波管

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3368102A (en) * 1965-06-09 1968-02-06 Sperry Rand Corp Collector structure operating at a depressed potential for collecting a hollow electron beam

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
INTERNATIONAL ELECTRON DEVICES MEETING, Techni- cal Digest, Los Angeles, CA, December 7-10, 1986 E.W. McCUNE: "A UHF-TV klystron using multistage depressed collector technology", pages 160-163 *
PATENT ABSTRACTS OF JAPAN vol. 12, no. 85 (E-591)(2932) 17 Mars 1988 & JP-A-62 222 543 ( NEC CORP. ) 30 Septembre 1987 *
PATENT ABSTRACTS OF JAPAN vol. 14, no. 324 (E-951)(4267) 11 Juillet 1990 & JP-A-2 109 234 ( TOSHIBA CORP. ) 20 Avril 1990 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2694129A1 (fr) * 1992-07-21 1994-01-28 Litton Systems Inc Expulseur d'ions pour collecteur.

Also Published As

Publication number Publication date
JPH04282535A (ja) 1992-10-07
FR2668297A1 (fr) 1992-04-24

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