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WO2008147289A1 - Vircator - Google Patents

Vircator Download PDF

Info

Publication number
WO2008147289A1
WO2008147289A1 PCT/SE2008/000365 SE2008000365W WO2008147289A1 WO 2008147289 A1 WO2008147289 A1 WO 2008147289A1 SE 2008000365 W SE2008000365 W SE 2008000365W WO 2008147289 A1 WO2008147289 A1 WO 2008147289A1
Authority
WO
WIPO (PCT)
Prior art keywords
anode
vircator
conductors
cathode
parallel
Prior art date
Application number
PCT/SE2008/000365
Other languages
English (en)
Inventor
Sten E Nyholm
Tomas Hurtig
Original Assignee
Totalförsvarets Forskningsinstitut
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 Totalförsvarets Forskningsinstitut filed Critical Totalförsvarets Forskningsinstitut
Publication of WO2008147289A1 publication Critical patent/WO2008147289A1/fr

Links

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
    • 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 an improvement of an existing type of a micro-wave generator. More specifically it relates to a generator of a vircator type that is given such a configuration that it is possible to achieve an electromagnetical field coupling between the different resonance areas of the vircator.
  • a vircator is a type of radiation generator that comprises a vacuum pumped cavity and, usually, two electrodes, a cathode and an anode.
  • vircator types wherein the differences resides in, among other things, the geometrical configuration of the cathode and the anode.
  • a vircator type with two planar electrodes placed on a symmetry axis a so called axial vircator, but there are also other types for example the co-axial vircator wherein the anode and the cathode are provided in the form of two concentric cylinders.
  • reflextriode and the reditrone can also mention the reflextriode and the reditrone.
  • the functionality of the vircator is based on the fact that electrons accelerated from the cathode in the direction of the anode are allowed to pass through the anode through small apertures in the same. Those electrons that pass the anode through these small apertures will form an electron cloud in the area beyond the anode (in the direction taken from the cathode).
  • the electron cloud formed in this way will constitute a virtual cathode, a fact that has given the device its name vircator (in English, Virtual cathode oscillator).
  • the virtual cathode will reflect the incoming electrons and this will lead to an oscillation of electrons between the real and the virtual cathode.
  • the electrons oscillate will oscillate with a given frequency to and fro in the direction of the radiation.
  • the charge density of the electron cloud will also vary which will lead to a change of the self-oscillation frequency for the electron plasma in the cloud.
  • the two electron oscillations depending on variations of position and density, will couple to the surrounding cavity and will often lead to different radiation modes and different radiation frequencies.
  • the diode that is, the area between the anode and the virtual cathode.
  • the present invention has as a purpose to provide a vircator with improved radiation characteristics regarding both frequency and mode. This object is achieved by means of a vircator according to claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.
  • the fundamental idea behind the present invention is to provide the anode in the vircator arrangement with apertures or slots that makes it possible for electromagnetic radiation to at least partially pass the anode.
  • Such an arrangement would yield the advantage that the two oscillation areas in the vircator were coupled through their electromagnetic fields. Each of these resonance areas would therefore resonate with the generated electromagnetic field and as a result one obtains a controllable coupling between the two areas.
  • partial passage through the anode is hereby meant that only certain polarizations of the electromagnetic radiation are allowed to pass. It is also possible to connect the anode to an externally placed regulation mechanism that can direct the anode so that one can manipulate the polarization direction from a position outside of the vircator cavity.
  • Fig. 1 is a schematic disclosure of the configuration of a known axial vircator.
  • Fig. 2 discloses, in cross-section, the configuration of a known axial vircator.
  • Fig. 3 discloses a possible geometric configuration for an anode used in the present invention.
  • a number of parallel metal rods that are attached to a circular frame is provided parallel with the frame holder.
  • Fig.4 discloses another possible geometric configuration for an anode used in the present invention.
  • a number of parallel metal threads that are attached to a circular frame and are arranged in angle relative the frame holder.
  • Fig. 5 discloses a possible geometric configuration for an anode that can be used in the present invention.
  • a piece with a number of cut-out slots the metal piece is attached to a circular frame and the slots are orthogonal to the holder.
  • Fig. 6 discloses schematically a cylindrical anode with axis-parallel conductors. The anode is intended to be provided within a cylindrical cathode. Only parts of the conductors are shown.
  • the cathode is constructed from, or lined with, a material or structure that can easily emit electrons. If a voltage is applied between the cathode 1 and anode 2 an electromagnetic field is generated that will rip electrons from the cathode 1 and accelerate these towards anode 2.
  • the anode 2 is made from a thin foil or a fine-meshed net that partly let the accelerated electrons pass. The electrons that pass the anode will be collected in the area between the anode 2 and the window 3 and they will build up an electron cloud 5. As has been mentioned earlier this cloud could be construed as a virtual cathode.
  • the anode 2 is provided with slots or elongated apertures that make it possible for electromagnetic radiation to pass the anode.
  • the apertures or slots cannot be to large. The reason behind this is the fact that the acceleration field will bend towards the direction of the conductors provided in the anode.
  • the apertures can not be too small either since this would make the electrons collide with the conductors in the anode.
  • the measure that is suited to regulate the choice of dimensions is the transparency of the anode which is defined to be the ratio between open area and anode area. The main purpose of having a well balanced transparency is to make it possible to quickly build up the electron cloud that defines the virtual cathode.
  • the anode is constructed out of an arrangement of parallel extending metal rods attached to a circular frame.
  • the anode in place of the fine-meshed net or the foil, is given the shape depicted in figure 3 the electromagnetic radiation from the two radiation generating areas will get coupled through the electromagnetic field that is polarized orthogonal to the direction in which the conductors of the anode runs, this arrangement will give a higher degree of coupling between the different electron oscillations then is the case with the use of known anode configurations.
  • Figure 4 discloses another geometrically preferred shape wherein the anode comprises a number of metal threads oriented in an ambiguous angle relative the holder.
  • Figure 5 gives yet another possible embodiment of the invention wherein the anode is constructed from a metal plate cast in one piece but where parallel slots have been cut out in a direction parallel to the holder.
  • One of the advantages of the above given anode configuration is that it is easy to control the geometric transparency of the anode, that is the total projected surface of the space between the threads/rods/slots as part of the total surface of the anode. It will be easy to adjust this transparency by means of changing the width of the slots or the space between the slots or, in the corresponding case, changing the dimensions or the mutual distance between threads/rods.
  • Another advantage that comes with the use of metal rods is that one can give their cross-section area such dimensions that they are capable of conducting the currents that can be necessary in case of large power output.
  • anode is well suited for use in a co-axial vircator.
  • the present invention which provides a partial transparency for micro-wave radiation, a coupling of oscillations of the electron plasma is obtained in the virtual cathode and in the volume between the cathode and the anode which provides the user with the possibility to control the generated modes.
  • the externally arranged regulation mechanism could be a squeeze mechanism that either squeezes the conductors together so that their mutual distance is reduced or release the conductors so that their mutual distance is increased.
  • the cylinder surface that is spanned by these conductors would in these cases increase and decrease, respectively.

Landscapes

  • Compositions Of Oxide Ceramics (AREA)
  • Microwave Tubes (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

La présente invention concerne un Vircator qui assure un couplage de champ électromagnétique entre les deux zones de résonance dans le Vircator. Cela est effectué en concevant l'anode du Vircator afin que des rayonnements électromagnétiques ayant certaines directions de polarisation puissent passer à travers l'anode.
PCT/SE2008/000365 2007-05-29 2008-05-29 Vircator WO2008147289A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0701286-7 2007-05-29
SE0701286A SE531183C2 (sv) 2007-05-29 2007-05-29 Virkator

Publications (1)

Publication Number Publication Date
WO2008147289A1 true WO2008147289A1 (fr) 2008-12-04

Family

ID=40075357

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2008/000365 WO2008147289A1 (fr) 2007-05-29 2008-05-29 Vircator

Country Status (2)

Country Link
SE (1) SE531183C2 (fr)
WO (1) WO2008147289A1 (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003030204A2 (fr) * 2001-09-28 2003-04-10 Thales Generateur d'ondes hyperfrequences a cathode virtuelle

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003030204A2 (fr) * 2001-09-28 2003-04-10 Thales Generateur d'ondes hyperfrequences a cathode virtuelle

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SINGH G. ET AL.: "PIC simulation of effect of energy-dependent foil transparency in an axially-extracted vircator", PLASMA SCIENCE, IEEE TRANSACTIONS, vol. 32, no. 6, December 2004 (2004-12-01), pages 2210 - 2216, XP011123332 *

Also Published As

Publication number Publication date
SE531183C2 (sv) 2009-01-13
SE0701286L (sv) 2008-11-30

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