EP0251830A1 - Mehrfachstrahl-Lasertron - Google Patents

Mehrfachstrahl-Lasertron Download PDF

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Publication number
EP0251830A1
EP0251830A1 EP87401020A EP87401020A EP0251830A1 EP 0251830 A1 EP0251830 A1 EP 0251830A1 EP 87401020 A EP87401020 A EP 87401020A EP 87401020 A EP87401020 A EP 87401020A EP 0251830 A1 EP0251830 A1 EP 0251830A1
Authority
EP
European Patent Office
Prior art keywords
lasertron
photocathodes
laser beam
beams
optical system
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.)
Granted
Application number
EP87401020A
Other languages
English (en)
French (fr)
Other versions
EP0251830B1 (de
Inventor
Duc Tien Tran
Georges Faillon
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
Original Assignee
Thomson CSF SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0251830A1 publication Critical patent/EP0251830A1/de
Application granted granted Critical
Publication of EP0251830B1 publication Critical patent/EP0251830B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01J23/04—Cathodes
    • 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
    • H01J25/04—Tubes having one or more resonators, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly density modulation, e.g. Heaff tube
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements or of ion traps common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/021—Electron guns using a field emission, photo emission, or secondary emission electron source
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/34—Photoemissive electrodes
    • H01J2201/342—Cathodes

Definitions

  • the present invention relates to multiple beam lasertrons.
  • a photocathode is illuminated by a laser beam, the wavelength of which is chosen as a function of the output work of the material from which the photocathode is made.
  • a pulsed laser beam at frequency F tears out of the photocathode, at this same frequency F, packets of electrons. These electron packets are then accelerated in an electrostatic electric field and thus gain kinetic energy. They then cross a cavity resonating at frequency F and their kinetic energy is transformed into electromagnetic energy at frequency F. We take the energy from the cavity by coupling it to an external use circuit.
  • FIGS. 1 and 2 two embodiments of lasertrons according to the prior art have been represented schematically and seen in longitudinal section.
  • references 1, 2 and 3 respectively designate the photocathode, the laser beam and the electron beam.
  • the photocathode 1 is illuminated obliquely by the laser fascia 2 and the electron beam 3 propagates along the longitudinal axis XX ⁇ of the tube.
  • the laser beam 2 and the electron beam 3 propagate along the longitudinal axis XX ⁇ of the tube, but in the opposite direction.
  • the laser beam 2 is therefore normal to the emissive surface of the photocathode.
  • the electron beam 3 is accelerated by the electrostatic electric field created by an anode 4, then enters a cavity 5 resonating at frequency F.
  • a collector 6 then receives the electron beam.
  • the electromagnetic energy is taken at the frequency F from the cavity 5 by coupling it to an external use circuit, by a waveguide 7, associated with a window 8, as in FIG. 1 or by a loop 9, as in figure 2.
  • lasertrons are very compact tubes. In lasertrons, electron packets are torn from the photocathode at frequency F. Whereas in tubes such as klystrons, it is necessary to use several cavities to distribute the electrons of an initially continuous beam into packets.
  • the embodiments of lasertrons which are represented in FIGS. 1 and 2 have the following drawbacks: - In the embodiment of Figure 1, the photocathode is lit obliquely. This results on the one hand, a poor light output of the photocathode and on the other hand, a laser beam lighting device which must be made as compact as possible to accommodate it near high voltage parts; - In the embodiment of Figure 2, the laser beam and the electron beam take the same path. Consequently, the surface of the photocathode which receives the laser beam is limited by the diameter D of the sliding tube of the cavity 5 which allows the passage of these beams. Furthermore, the laser beam lighting device is subjected to bombardment of the electron beam.
  • the present invention provides a new structure of lasertrons which makes it possible to avoid the drawbacks of known lasertrons.
  • the present invention relates to a lasertron, characterized in that it comprises: n (n: whole number greater than 1) photocathodes, receiving by operating a laser beam, pulsed at a frequency F, and emitting n electron beams; m (m: whole number greater than 0) resonant cavities which resonate at frequency F; n sliding tubes allowing the passage of n electron beams; a collector; and directing means located near the photocathodes, ensuring, in operation, an oblique lighting of the photocathodes by the laser beam.
  • the invention provides a new structure of lasertrons, called multiple beam lasertrons. Two embodiments of these lasertrons are shown seen in longitudinal section in FIGS. 3 and 4.
  • Multibeam klystrons are known in the prior art articles, as well as French Patent No. 992,853. These klystron were also described in French patent application No. 86 03949 and 86 03950, filed March 19, 1986, on behalf of the Applicant and not yet published. A great advantage of these klystrons is that they are particularly suitable for operation at very high power. Indeed, we demonstrate that for the same high frequency power, the acceleration voltage applied between the anode and a cathode of the klystron is much lower in a klystron with multiple beams than in klystrons with a single beam.
  • Multi-beam klystrons generally operate in the TM01 mode.
  • Multiple beam lasertrons are obtained by making modifications to the same beam lasertrons of the same type as those made to single beam klystrons to obtain multiple beam klystrons.
  • n photocathodes lit by a laser beam are used.
  • Each photocathode produces an electron beam which crosses at least one resonance cavity with n sliding tubes, before arriving at a collector.
  • Multi-beam lasertrons therefore make it possible to obtain high high-frequency powers and, when operating in TM02 mode, large powers and high frequencies.
  • FIG. 3 shows by way of example the modifications made to the lasertron of FIG. 1 to obtain a lasertron with multiple beams.
  • n photocathodes marked with the reference 1, are used; they are illuminated by the laser beam 2.
  • n photocathodes 1 produce n electron beams 3 which are accelerated by n anodes 4 positively polarized with respect to the cathodes.
  • n beams 3 pass through a cavity 5 to n sliding tubes 16 and give up their kinetic energy therein in the form of electromagnetic energy before being collected in the collector 6.
  • the multiple beam lasertron of FIG. 3 always has the drawbacks indicated in the introduction to the description with regard to the single beam lasertron of FIG. 1.
  • FIG. 4 is a cross-sectional view of a lasertron with multiple beams of entirely new structure and which does not have the drawbacks of the lasertrons of FIGS. 1, 2, and 3.
  • This lasertron has n photocathodes 1 which are regularly distributed around the longitudinal axis XX ⁇ of the tube.
  • An incident laser beam 2 arrives on an optical system 10, which can be constituted by a lens, made of quartz, for example.
  • the incident laser beam is annular.
  • This optical system 10 is centered on the axis XX ⁇ . It is placed before the collector, in the direction of propagation of the laser beam, as it appears in Figure 4.
  • the optical system produces a laser beam which moves parallel to the longitudinal axis XX ⁇ of the tube.
  • the lasertron of FIG. 4 comprises a single resonance cavity 5, the walls 12 and 13 of which, perpendicular to the axis XX ⁇ , are pierced with n orifices 14. These orifices make it possible to obtain in operation n laser beams.
  • a cooling device is arranged on the wall 12 of the cavity 5 which receives the impact of the laser beam and which transforms it into n laser beams. Part of the laser power is thus collected.
  • the diameter of the orifices 14 allowing the passage of the n laser beams is chosen, as well as the thickness of the walls 12 and 13 from the cavity, so as to limit the leakage of electromagnetic energy from the cavity.
  • another optical system 11 is arranged, which may be constituted by a lens; this optical system 11 ensures the deflection of the n laser beams so that they illuminate the n photocathodes at an angle as little inclined as possible.
  • the optical system 11 comprises a plate 15 ensuring its protection against various deposits, which can result from the evaporation of various constituents of the photocathodes.
  • n photocathodes being lit by n laser beams, each emit an electron beam 3, focused by anodes 4, and which pass through the cavity 5 by n sliding tubes 16 before falling on the collector 6.
  • the electromagnetic power is taken by a waveguide 7, through a dielectric window 8.
  • Coils 9 ensure the focusing of the n electron beams.
  • the lasertron of Figure 4 in addition to the inherent advantages of multiple beam lasertrons, has many advantages.
  • the optical system which produces the laser beam and which focuses it does not receive an electron beam which risks damaging it and making it opaque.
  • the two optical systems 10 and 11 are also protected from electron beams.
  • the plate 15 protects the lens 11 from products which may come from the photocathodes.
  • the laser beams illuminate the photocathodes with an almost normal incidence which improves the light output of the photocathodes.
  • lasertrons comprising several successive cavities, generally two, are known.
  • the invention therefore relates to laserers with multiple beams, having one or more successive cavities.

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  • Lasers (AREA)
EP87401020A 1986-05-30 1987-05-04 Mehrfachstrahl-Lasertron Expired - Lifetime EP0251830B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8607826 1986-05-30
FR8607826A FR2599565B1 (fr) 1986-05-30 1986-05-30 Lasertron a faisceaux multiples.

Publications (2)

Publication Number Publication Date
EP0251830A1 true EP0251830A1 (de) 1988-01-07
EP0251830B1 EP0251830B1 (de) 1990-07-11

Family

ID=9335849

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87401020A Expired - Lifetime EP0251830B1 (de) 1986-05-30 1987-05-04 Mehrfachstrahl-Lasertron

Country Status (4)

Country Link
US (1) US4749906A (de)
EP (1) EP0251830B1 (de)
DE (1) DE3763628D1 (de)
FR (1) FR2599565B1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0485266A1 (de) * 1990-11-09 1992-05-13 Thomson Tubes Electroniques Durch optoelektronische Umschaltung modulierte Elektronenkanone
EP0895266A1 (de) * 1997-07-29 1999-02-03 Sumitomo Heavy Industries, Ltd. Elektronenkanone mit photokathode

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2625836B1 (fr) * 1988-01-13 1996-01-26 Thomson Csf Collecteur d'electrons pour tube electronique
FR2643507A1 (fr) * 1989-02-21 1990-08-24 Thomson Tubes Electroniques Canon a electrons a faisceau electronique module par un dispositif optique
FR2737340B1 (fr) * 1995-07-28 1997-08-22 Thomson Tubes Electroniques Tube electronique multifaisceau a couplage cavite/faisceau ameliore
FR2756970B1 (fr) * 1996-12-10 2003-03-07 Thomson Tubes Electroniques Tube hyperfrequence a interaction longitudinale a cavite a sortie au dela du collecteur
FR2764730B1 (fr) * 1997-06-13 1999-09-17 Thomson Tubes Electroniques Canon electronique pour tube electronique multifaisceau et tube electronique multifaisceau equipe de ce canon
FR2780809B1 (fr) 1998-07-03 2003-11-07 Thomson Tubes Electroniques Tube electronique multifaisceau avec champ magnetique de correction de trajectoire des faisceaux
FR2803454B1 (fr) * 1999-12-30 2003-05-16 Thomson Tubes Electroniques Generateur d'impulsions hyperfrequences integrant un compresseur d'impulsions
US6828574B1 (en) * 2000-08-08 2004-12-07 Applied Materials, Inc. Modulator driven photocathode electron beam generator
US7116051B2 (en) * 2003-07-16 2006-10-03 Vancil Bernard K Multibeam klystron

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3107313A (en) * 1959-10-30 1963-10-15 Johann R Hechtel Velocity modulated electron tube with cathode means providing plural electron streams
US3403257A (en) * 1963-04-02 1968-09-24 Mc Donnell Douglas Corp Light beam demodulator
DE3038405A1 (de) * 1979-10-10 1981-04-23 United States Department of Energy, 20545 Washington, D.C. Hf-emitter

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3356851A (en) * 1963-10-22 1967-12-05 Picker X Ray Corp Division Inc Image intensifier tube with separable optical coupler

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3107313A (en) * 1959-10-30 1963-10-15 Johann R Hechtel Velocity modulated electron tube with cathode means providing plural electron streams
US3403257A (en) * 1963-04-02 1968-09-24 Mc Donnell Douglas Corp Light beam demodulator
DE3038405A1 (de) * 1979-10-10 1981-04-23 United States Department of Energy, 20545 Washington, D.C. Hf-emitter

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0485266A1 (de) * 1990-11-09 1992-05-13 Thomson Tubes Electroniques Durch optoelektronische Umschaltung modulierte Elektronenkanone
FR2669145A1 (fr) * 1990-11-09 1992-05-15 Thomson Tubes Electroniques Canon a electrons module par commutation optoelectronique.
US5313138A (en) * 1990-11-09 1994-05-17 Thomson Tubes Electroniques Electron gun modulated by optoelectronic switching
EP0895266A1 (de) * 1997-07-29 1999-02-03 Sumitomo Heavy Industries, Ltd. Elektronenkanone mit photokathode
US6094010A (en) * 1997-07-29 2000-07-25 Sumitomo Heavy Industries, Ltd. Electron gun with photocathode and folded coolant path

Also Published As

Publication number Publication date
DE3763628D1 (de) 1990-08-16
FR2599565A1 (fr) 1987-12-04
FR2599565B1 (fr) 1989-01-13
EP0251830B1 (de) 1990-07-11
US4749906A (en) 1988-06-07

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