EP0122834B1 - Mikrowellen-Wellentypwandler - Google Patents

Mikrowellen-Wellentypwandler Download PDF

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Publication number
EP0122834B1
EP0122834B1 EP84400542A EP84400542A EP0122834B1 EP 0122834 B1 EP0122834 B1 EP 0122834B1 EP 84400542 A EP84400542 A EP 84400542A EP 84400542 A EP84400542 A EP 84400542A EP 0122834 B1 EP0122834 B1 EP 0122834B1
Authority
EP
European Patent Office
Prior art keywords
transformer
axis
section
mode
gyrotron
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
Application number
EP84400542A
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English (en)
French (fr)
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EP0122834A1 (de
Inventor
Georges Mourier
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
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Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0122834A1 publication Critical patent/EP0122834A1/de
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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
    • H01J23/027—Collectors
    • 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
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • 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

Definitions

  • the present invention relates to a microwave propagation mode transformer for gyrotron type power millimetric oscillators which operate on high modes.
  • Gyrotrons are now used to heat plasmas in order to bring them to a thermonuclear temperature.
  • the problem which arises is that, to obtain a significant radiation, it is necessary to pass from a complex mode, the circular mode TE one for example, which is produced in the cavity of revolution of the gyrotrons, to a mode where the electric field is linearly polarized, and is therefore substantially parallel to a given direction, and even where it is preferable to pass to a plane wave.
  • the present invention makes it possible to solve the problem of passing from a complex mode, of the TE on type, to a mode in which the electric field is substantially parallel to a given direction, and even to a plane wave.
  • the present invention relates to a transformer of microwave propagation modes, constituted by a waveguide, of substantially elliptical section, and of increasing eccentricity along the axis of the transformer, this transformer ensuring the transition to a mode where the field electric is substantially parallel to a given direction, characterized in that:
  • This patent application in fact relates to an antenna which receives a hybrid mode, such as the HE 11 mode - see page 3, line 7 of this application - which allows the antenna to radiate.
  • This antenna transforms this mode into another mode which improves the radiation of the antenna.
  • the mode transformer is connected to the cavity of revolution of a gyrotron, which provides it with a complex mode, such as for example the TE 12 mode of FIG. 1, which does not allow the radiation.
  • the mode transformer ensures the transition from a TE type mode on which does not allow radiation to a mode which allows to obtain a high radiation, that is to say a mode where the electric field is substantially parallel to a given direction. It does not seem obvious to us at all given the antenna function of the waveguide of increasing ellipticity of the cited European patent application to use this device, in association with a gyrotron, and with a different function.
  • FIG 1 there is shown the electric field lines in the circular cross section of the cavity 1 of a gyrotron, in the case where a TE o2 mode is established in this cavity.
  • the solid circles indicate the areas where the electric field is maximum and the dotted circles indicate the areas where the electric field is zero.
  • This circular and symmetrical TE 02 mode does not allow radiation.
  • Figure 2 shows the distribution of electric field lines in the cross section of a guide wave 2 of elliptical section placed following the cavity of a gyrotron where a TE o2 mode is established as in Figure 1.
  • a and b the major axis and the minor axis of the ellipse.
  • the minor axis b twice equals the interior radius R of the gyrotron cavity.
  • Figure 3 shows the distribution of the electric field lines in the cross section of a system consisting of two parallel conductive plates, bearing the reference 3.
  • the distance d between the plates is taken equal to twice the radius R of the cavity of the gyrotron. It can be seen that the electric field lines are parallel to the x direction.
  • the mode transformer according to the invention makes it possible to pass from the TE o2 mode established in the circular section cavity of a gyrotron and which does not allow radiation to a mode where the electric field is substantially parallel to the direction x by using a waveguide, of substantially elliptical section, and of increasing eccentricity, and which allows a significant radiation.
  • the eccentricity is zero when a equals b, i.e. when the ellipse becomes a circle.
  • the mode transformer according to the invention consists of a waveguide of substantially elliptical section, and of increasing eccentricity, that is to say that the cross section of this transformer has the shape of an ellipse whose the major axis a increases and tends towards the cross section of FIG. 3 which is that of a system made up of two parallel plates which can be assimilated to the cross section of an ellipse with eccentricity equal to 1.
  • the field lines have the distribution indicated in Figure 2 and then tend towards the distribution of Figure 3, that is to say that when the eccentricity of the ellipse increases, the field lines become more and more parallel to the x direction.
  • the frequency f and the radius R of the cavity are linked by the following relation: where c is the speed of light. This relation expresses that the frequency is very close to the cutoff frequency.
  • the transformer according to the invention can be produced by carrying out a metallic deposit on a matrix by electrolysis, as is done to produce waveguides.
  • FIG. 4 illustrates another method making it possible to obtain a transformer of modes of elliptical section, of increasing eccentricity.
  • FIG. 5 represents a mode transformer 9 which is obtained in this way.
  • Figure 6 is a projection of sections made perpendicular to the Oz axis on the horn shown in Figure 5.
  • the small axis b of the ellipse, directed along the axis Oy slightly increases along the Oz axis.
  • the horn shown in Figure 5 is a good embodiment of the mode transformer because it is shown that as the eccentricity of an ellipse increases, the energy electromagnetic is concentrated between two hyperbolas H, and H z having F, and F z for foci.
  • FIG. 7 shows an ellipse with its two foci F, and F 2 and the two hyperbolas H 1 and H Z. If the dimensions of the guide are large compared to the wavelength, the distribution of the electrical energy density E 2 is close to a Gaussian function as shown in FIG. 8.
  • FIGS. 7 and 8 shows that it is possible without disturbance to modify the walls of the guide and even the hatched spaces limited by the hyperbolas H, and H 2 of FIG. 7.
  • the transformer according to the invention it is possible to consider to give the order of magnitude of the ellipticity that in the final section of the transformer, there are some wavelengths between the two foci F, and F Z.
  • a mode transformer consisting of a guide of elliptical section, of increasing eccentricity, can therefore be produced by the horn of FIG. 5, consisting of two parts of cone of revolution.
  • the two half-horns 7 can come from two different truncated cones. It is necessary to obtain a horn comprising two parts of decreasing curvature and whose distance to the axis z increases less quickly than the radius of curvature, which will play the role of ellipses of increasing eccentricity.
  • the transformer according to the invention may comprise on the parts close to the ends of the long axis of the cavities in which there is an absorbent material which absorbs any mode other than the desired mode.
  • FIG. 9 represents the cross section of a mode transformer obtained by brazing two parts of truncated cone. The parts close to the ends of the major axis were dug to obtain the elongated volumes V 1 and V z which contain an absorbent material 10. Since there is only very little energy stored near the ends of the major axis, the volumes V, and V 2 do not disturb the operation of the mode transformer.
  • FIG. 9 the field lines obtained from a TR 02 mode are shown in the circular cavity of the gyrotron. It can be seen that the electric field lines are substantially parallel to the x axis, and therefore to the major axis of the ellipse a.
  • FIG. 10 shows an embodiment of the transformer according to the invention.
  • FIG. 10 is a perspective view where we see, on the left side a gyrotron 11, which is symbolically represented by a cylinder, followed by the mode transformer according to the invention 9 which is made up of two mirrors M, and M Z. These two mirrors are concave, They are arranged on either side of the Oz axis, perpendicular to the y axis, and face each other. These two mirrors are contained in a vacuum enclosure which is not shown in FIG. 10.
  • the outline of the window 12 is shown in dotted lines which ensures the vacuum tightness of the enclosure containing the mirrors M, and M 2 .
  • the transformer according to the invention can be found, as is the case in FIG. 10, in the same vacuum enclosure as the gyrotron. It can also be placed at the exit of a gyrotron of usual structure.
  • the shape of the mirrors M 1 and M 2 is chosen so that the sections perpendicular to the z axis of the transformer according to the invention thus produced are substantially elliptical and of increasing eccentricity along the oz axis, provided that not take into account the ends of the major axis of these ellipses where we have seen that the electric field is very weak.
  • the transformer according to the invention can ensure the passage, modes other than the TE modes is in a mode where the electric field is substantially parallel to a given direction.
  • Figures 11 and 13 show the electric field lines in the cross section of cavity 1 of the gyrotron when a TE mode 12 and a TE mode 22 is established in this cavity.
  • Figures 12 and 14 show the electric field lines in the cross section of the transformer according to the invention consisting of the two mirrors M, and M 2 which is placed following the cavity of a gyrotron where the TE mode is established respectively. 12 of FIG. 11 and the TE mode 22 of FIG. 13. A TE c mode and a TE d mode of open guide are obtained in the transformer according to the invention. It can be seen that the electric field lines are directed substantially along the x axis and have 3 and 4 successive alternations between M 1 and M 2 .
  • the continuous magnetic field created by a focusing solenoid 21 placed around the gyrotron, decreases, the electron beam diverges and strikes the walls of the transformer 9.
  • focusing means are arranged around the transformer which direct the electron beam onto collector plates Ci and C 2 .
  • These plates are arranged on either side of the Oz axis, perpendicular to the x axis, and face each other. They are therefore located on the parts close to the ends of the long axis of the ellipses constituting the section of the transformer. They are contained in the vacuum enclosure containing the mirrors M 1 and M 2 .
  • the focusing means which are not shown in FIG. 10, can consist for example of two elongated windings pressed along the transformer 9 in the manner of the deflection coils of the television tubes, and connected to a DC voltage source . These windings are traversed by currents rotating in opposite directions around the x axis.
  • Collector zones can be provided in the other embodiments of the transformer according to the invention when the transformer is placed inside the vacuum enclosure.
  • the volumes V I and V2 can be used to collect the electron beam.
  • the configurations of the electric field represented in FIGS. 2, 3, 9, 12 and 14 have in common the following characteristics. There is propagation in the z direction. In the y direction there is a standing wave and in the x direction there is a slow variation in amplitude, with no phase variation.
  • This wave system can be represented by two crossed plane waves O 1 and O2, the paths of which have been shown in FIG. 15, in the plane yOz, in a section of waveguide 13 following the transformer according to the invention and having two walls parallel to the Oz axis.
  • This waveguide section has the same section as the final section of the transformer and has a constant section along the axis Oz. It has been shown on the right-hand side of FIG. 15 that when the guide is interrupted, the geometric optics indicate that two beams of plane waves 14 and 15 of different directions are obtained.
  • the two beams 14 and 15 remain parallel before diverging by diffraction after a distance L R , called Rayleigh distance, which is equal to:
  • the transformer according to the invention is followed by a section of waveguides having the same section as the final section of the transformer and having a constant section along the axis. Oz.
  • This part 18 comprises two mirrors M 3 and M 4 .
  • the inclination of these two mirrors is chosen so that the mirror M 3 receives the plane wave 14 and reflects it vertically in FIG. 16 and so that the mirror M 4 receives the plane wave 15 and also reflects it vertically.
  • the waves reflected by the two mirrors must also not be disturbed.
  • the mirror M 3 is parallel to the wave 15.
  • Part 18 ends with a window 20 which is vacuum tight and transparent to radiation.
  • Mirrors M 3 and M 4 can be given a spherical or cylindrical curvature so as to compensate over a certain length for the diffraction of the beam coming from the tube through the window.
  • Part 18 can also allow a single parallel beam to be obtained while using only a single curved mirror, more bulky than the two mirrors M, and M 2 .
  • the embodiment of Figure 16 makes the main axis of the Oz tube vertical, which. is preferable for its mechanical strength, while the parallel beam obtained is horizontal, which is practical for users.

Landscapes

  • Microwave Tubes (AREA)
  • Waveguide Switches, Polarizers, And Phase Shifters (AREA)

Claims (3)

1. Wandler für Höchstfrequenz-Ausbreitungsmoden, der aus einem Wellenleiter von im wesentlichen elliptischen Querschnitt (2) und einer entlang der Achse (z) des Wandlers (9) wachsenden Excentrizität (e) besteht, wobei dieser Wandler den Übergang zu einer Welle sicherstellt, wo das elektrische Feld im wesentlichen parallel zu einer gegebenen Richtung (Oz) ist, dadurch gekennzeichnet, daß:
- dieser Wandler mit einem Hohlraum eines Gyrotrons verbunden ist, das ihm eine komplexe Welle vom Typ TRon liefert, wobei der Wandler in der gleichen Vakuumzelle wie das Gyrotron angeordnet ist;
- dieser Wandler aus zwei konkaven Spiegeln (M1, MZ) besteht, die sich gegenüberstehen, wobei die Form der Spiegel so ist, daß die zur Achse (z) des Wandlers (9) senkrechten Querschnitte im wesentlichen elliptisch und von wachsender Exzentrizität (e) entlang dieser Achse (Oz) unter der Bedingung sind, nicht die Enden der großen Achse dieser Ellipsen zu berücksichtigen;
- dieser Wandler Fokussierungsmittel enthält, die den Elektronenstrahl zu Sammlerplatten (C,, C2) leiten, die sich auf den den Enden der großen Achse (a) der Ellipse benachbarten Teilen befinden, die den Querschnitt des Wandlers (9) bildet.
2. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß die kleine Achse (b) der Ellipse konstant ist.
3. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß die kleine Achse (b) der Ellipse entlang der Achse (Oz) des Wandlers wächst.
EP84400542A 1983-03-18 1984-03-16 Mikrowellen-Wellentypwandler Expired EP0122834B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8304484A FR2542928B1 (fr) 1983-03-18 1983-03-18 Transformateur de modes de propagation hyperfrequence
FR8304484 1983-03-18

Publications (2)

Publication Number Publication Date
EP0122834A1 EP0122834A1 (de) 1984-10-24
EP0122834B1 true EP0122834B1 (de) 1989-11-29

Family

ID=9287014

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84400542A Expired EP0122834B1 (de) 1983-03-18 1984-03-16 Mikrowellen-Wellentypwandler

Country Status (5)

Country Link
US (1) US4636689A (de)
EP (1) EP0122834B1 (de)
JP (1) JPS59196601A (de)
DE (1) DE3480626D1 (de)
FR (1) FR2542928B1 (de)

Families Citing this family (16)

* 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
US4849761A (en) * 1988-05-23 1989-07-18 Datron Systems Inc. Multi-mode feed system for a monopulse antenna
SU1665432A1 (ru) * 1989-01-05 1991-07-23 Институт прикладной физики АН СССР Преобразователь волны высшего типа круглого волновода в волну зеркального лучевода
US5030929A (en) * 1990-01-09 1991-07-09 General Atomics Compact waveguide converter apparatus
JPH03274802A (ja) * 1990-03-26 1991-12-05 Toshiba Corp 導波路およびこれを用いたジャイロトロン装置
FR2661559A1 (fr) * 1990-04-27 1991-10-31 Thomson Tubes Electroniques Convertisseur de mode de propagation guidee des ondes electromagnetiques et tube electronique comportant un tel convertisseur.
US5180944A (en) * 1991-01-25 1993-01-19 Varian Associates, Inc. Gyrotron with a mode convertor which reduces em wave leakage
FR2672730B1 (fr) * 1991-02-12 1993-04-23 Thomson Tubes Electroniques Dispositif convertisseur de modes et diviseur de puissance pour tube hyperfrequence et tube hyperfrequence comprenant un tel dispositif.
US5734303A (en) * 1994-03-11 1998-03-31 The United States Of America As Represented By The Secretary Of The Air Force Microwave waveguide mode converter having a bevel output end
US5777572A (en) * 1994-07-19 1998-07-07 Northrop Grumman Corporation Device for damaging electronic equipment using unfocussed high power millimeter wave beams
ES2112771B1 (es) * 1995-09-25 1998-12-16 Univ Navarra Publica Antenas de bocina conversoras de modos en guia de onda a estructuras gaussianas.
US5942956A (en) * 1996-01-18 1999-08-24 Purdue Research Foundation Design method for compact waveguide mode control and converter devices
FR2756970B1 (fr) * 1996-12-10 2003-03-07 Thomson Tubes Electroniques Tube hyperfrequence a interaction longitudinale a cavite a sortie au dela du collecteur
US7893789B2 (en) * 2006-12-12 2011-02-22 Andrew Llc Waveguide transitions and method of forming components
CN106450595B (zh) * 2016-11-21 2021-08-17 山东省科学院海洋仪器仪表研究所 一种双束输出的准光模式变换装置
CN114927399B (zh) * 2022-05-27 2023-04-11 电子科技大学 一种具有分裂式轴向能量提取结构的相对论磁控管

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1137378A (fr) * 1954-07-01 1957-05-28 Thomson Houston Comp Francaise Perfectionnements à la fabrication des jonctions de guide d'ondes
US2923903A (en) * 1955-04-14 1960-02-02 Nonreciprocal electromagnetic wave medium
GB964458A (en) * 1961-08-23 1964-07-22 Telefunken Patent Improvements in or relating to directional acrials
DE1541050A1 (de) * 1966-08-09 1969-08-28 Siemens Ag Auskoppelsystem fuer eine Ablenkverstaerkerroehre
US3710258A (en) * 1971-02-22 1973-01-09 Sperry Rand Corp Impulse radiator system
US3818383A (en) * 1973-02-27 1974-06-18 Andrew Corp Elliptical-to-rectangular waveguide transition
DE2748956A1 (de) * 1977-11-02 1979-05-03 Licentia Gmbh Hohlleitertwist
US4200820A (en) * 1978-06-30 1980-04-29 Varian Associates, Inc. High power electron beam gyro device
FR2445611A1 (fr) * 1978-12-29 1980-07-25 Thomson Csf Generateur d'ondes radioelectriques pour hyperfrequence
US4356430A (en) * 1980-09-05 1982-10-26 Varian Associates, Inc. Gyrotron cavity resonator with an improved value of Q
US4398121A (en) * 1981-02-05 1983-08-09 Varian Associates, Inc. Mode suppression means for gyrotron cavities
DE3109667A1 (de) * 1981-03-13 1982-09-23 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt "breitbandiger rillenhornstrahler"

Also Published As

Publication number Publication date
FR2542928B1 (fr) 1985-10-04
FR2542928A1 (fr) 1984-09-21
DE3480626D1 (de) 1990-01-04
US4636689A (en) 1987-01-13
JPS59196601A (ja) 1984-11-08
EP0122834A1 (de) 1984-10-24

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