EP0481052B1 - Verstärkerröhre mit einem gitter aus stegenvariabler breite - Google Patents

Verstärkerröhre mit einem gitter aus stegenvariabler breite Download PDF

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Publication number
EP0481052B1
EP0481052B1 EP91908979A EP91908979A EP0481052B1 EP 0481052 B1 EP0481052 B1 EP 0481052B1 EP 91908979 A EP91908979 A EP 91908979A EP 91908979 A EP91908979 A EP 91908979A EP 0481052 B1 EP0481052 B1 EP 0481052B1
Authority
EP
European Patent Office
Prior art keywords
grid
bars
width
rods
valve according
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
EP91908979A
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English (en)
French (fr)
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EP0481052A1 (de
Inventor
Michel Pierre Tardy
Jean-Pierre Buge
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
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Filing date
Publication date
Application filed by Thomson Tubes Electroniques filed Critical Thomson Tubes Electroniques
Publication of EP0481052A1 publication Critical patent/EP0481052A1/de
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/28—Non-electron-emitting electrodes; Screens
    • H01J19/38—Control electrodes, e.g. grid
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/46—Control electrodes, e.g. grid; Auxiliary electrodes

Definitions

  • the invention relates to power amplification tubes such as for example tetrodes.
  • the grid is then subjected to a very significant heating.
  • the normal gate current is a current consumption in one direction, it is found that an increase in the operating power of the tube leads to the reversal of the direction of current flow in the connection of wire rack. It has been observed, for example, that when starting a tetrode, the gate current very quickly passes from a positive normal value of a few amperes to a negative value of a few amperes (in a few seconds).
  • This high temperature of the grid can be the cause of tube malfunctions: the grid radiates a very large amount of heat towards the colder parts of the tube and causes abnormal degassing thereof.
  • the ions released in the tube are then sources of electrical breakdowns, disjunctions, etc.
  • Grid insulation ceramics can deteriorate (cracks) under the action of heat. In any case, this results in a reduction in the reliability and the service life of the tubes.
  • the object of the invention is to reduce the risks of malfunction which appear to be due to an abnormal increase in the temperature of the grid, in tubes whose grid is placed in a high frequency resonant circuit and is traversed by high frequency currents generated. by this resonance.
  • the width varies along a bar between one side where the bar is subjected to weaker currents and another side where the bar is subjected to higher currents.
  • the width of the bars is greater at the bottom of the grid (that is to say on the side of the connection towards the outside of the tube) than at the top .
  • the invention turns out to be particularly advantageous.
  • the top of the grid is most often placed with a current node and a high frequency voltage belly, but the bottom is much closer to a current belly.
  • the bars have a regularly increasing width as one approaches the bottom of the grid. Growth can be continuous or discontinuous.
  • the invention is applicable to grids with vertical bars or grids with oblique bars. Grids with oblique bars are often built to improve the mechanical strength of these grids.
  • the application of the invention is intended especially for grids produced by machining or cutting, such as grids of pyrolytic graphite machined by sandblasting or molybdenum grids cut by laser by electroerosion or by stamping.
  • triode grid or high power tetrode having a cylindrical cathode, a grid (triode) or two cylindrical grids (tetrode) of mesh structure, surrounding the cathode, and an anode surrounding the grids.
  • the invention is applicable to other tube structures where the same problems are encountered (anode surrounded by the grids and the cathode for example).
  • the grid whether it is a modulation grid (G1) or a screen grid (G2), is very often made up (and it is this case which interests us especially here) of a sheet of refractory material in the shape of a machined cylinder. in a mesh structure.
  • the function of these grids is to establish a determined potential distribution in the vicinity of the cathode while letting pass the major part of the flow of electrons emitted by the cathode towards the anode.
  • the bars of the mesh structure are close enough to each other to allow the establishment of potentials as well distributed as possible, and yet they are sufficiently separated from each other by the free space of the meshes to let pass such a large proportion. as possible electrons.
  • the bars are either vertical bars (to allow an optimal evacuation of the high frequency currents because these propagate from top to bottom taking into account the distribution of the high frequency potentials along the height of the cylindrical grid), or bars crossed obliques (to improve the mechanical strength of the structure).
  • the bars are very thin compared to the intervals between bars.
  • the vertical direction conventionally chosen here is the axis of the cylinder constituting the grid.
  • FIG. 1 represents a conventional grid of high power amplification tube. This is a pyrolytic graphite grid, but it could also be a metal.
  • the grid 10 essentially consists of a network of vertical bars 12 extending between the top 14 of the grid and the bottom 16. The grid is electrically connected to the outside of the tube by a contact made at the bottom of the grid and not shown.
  • horizontal circular bars 18 make it possible to mechanically connect the vertical bars to one another in order to increase the rigidity of the structure.
  • the horizontal bars do not or hardly participate in the evacuation of the currents in the grid. Very few high frequency currents develop in the horizontal bars. On the contrary, the vertical bars are the seat of high frequency currents which, in this type of structure, are all the higher the closer you get to the bottom of the grid.
  • the grid is most often placed in a high frequency resonant circuit in which the top of the grid is at a belly of current and a node of tension, while the bottom of the grid approaches a current belly.
  • FIG. 2 represents another conventional grid structure in pyrolytic graphite.
  • the bars are oblique and there are two networks of crossed oblique bars 20 and 22.
  • the whole forms a diamond mesh network.
  • the bars have constant widths from top to bottom of the grid.
  • the vertical or oblique bars variable widths according to the distribution of high frequency current densities in the grid for the desired operation of the tube (that is to say in particular for a frequency and a desired power). Where the current density tends to be higher, wider bars will be used.
  • the increase in the width of the bar makes it possible to increase the cross section through which the currents flow, therefore to reduce the power dissipated by the Joule effect.
  • this increase in width makes it possible to increase the radiating surface of the bar.
  • the temperature of the bar will be reduced.
  • the currents at different points on the grid can be calculated from Maxwell's equations; currents and potentials indeed follow well-known physical and mathematical laws; we can therefore determine which are the places (for a given operation) where the current density will be the highest, and we give the bars a wider section in these places.
  • the current density in the bars of the grid is often very high at the bottom of the grid, on the connection side, for a cylindrical grid conventionally having a connection on only one side of the cylinder.
  • the width of the bars increases from the top of the grid downwards, at least in the lower part of the grid.
  • the vertical bars have a continuously variable width from top to bottom of the grid. But the variation can also be in stages.
  • the vertical bars have a constant width over part of the height of the grid, then, downwards, the width increases regularly or in stages.
  • the solutions are the same: continuous growth or in stages, from the top of the grid or only in the lower part of the grid.
  • the horizontal bars themselves may be wider at the bottom of the grid than at the top, if only for convenience of manufacture.
  • FIG. 3 illustrates an example of the constitution of a grid, for vertical bars: the width (L1, L2) of the bars goes downwards.
  • This figure represents a detail of the grid; the proportions are not respected, for reasons of convenience of representation, so that the increase in width of the bars can be clearly seen; in practice, in fact, the bars can be very thin compared to the interval between consecutive bars; on the other hand the interval between horizontal bars can be much wider than the interval between vertical bars.
  • the invention is applicable in the same way to grids whose bars are not vertical but oblique, such as for example a grid such as that of FIG. 2 comprising a series of oblique bars all parallel crossed with another series of oblique bars all parallel.
  • FIG. 4 An exemplary embodiment of the invention with a grid of oblique bars reinforced by horizontal bars (triangular mesh) is shown in Figure 4.
  • the two networks of oblique bars 20 and 22 have widths increasing from top to low.
  • the horizontal bars 24 also have increasing widths from top to bottom, but only for reasons of manufacturing convenience; they could all have the same width because the heating due to the flow of current in these horizontal bars is low.
  • the grids can be made of pyrolytic graphite; they are then generally cut by sandblasting by means of sand projection nozzles.
  • the grids are made of metal (preferably molybdenum). They are then produced by laser cutting or by mechanical cutting or by electroerosion.

Landscapes

  • Solid Thermionic Cathode (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Microwave Tubes (AREA)
  • Carbon And Carbon Compounds (AREA)

Claims (8)

  1. Elektronische Hochfrequenz-Verstärkerröhre mit einem Gitter, das in einem Ausgangs-Resonanzkreis der Röhre angeordnet ist, dadurch gekennzeichnet, daß das Gitter Stege hat, deren Breite veränderlich und an den Stellen größer ist, an denen die durch die Resonanz erzeugten Hochfrequenzströme höher sein können.
  2. Elektronische Hochfrequenz-Verstärkerröhre nach Anspruch 1, dadurch gekennzeichnet, daß das Gitter langestreckte Stege hat, deren Breite sich entlang dem Steg ändert.
  3. Elektronenröhre nach einem der Ansprüche 1 und 2, dadurch gekennzeichnet, daß das Gitter die Form eines vertikalen Zylinders hat und daß die Stege, deren Breite veränderlich ist, vertikale oder bezüglich der Vertikalen schräge Stege sind.
  4. Elektronenröhre nach Anspruch 3, dadurch gekennzeichnet, daß die Breite der Stege zum unteren Ende des Gitters hin, auf der Seite eines elektrischen Anschlusses des Gitters, größer als nach oben hin ist.
  5. Elektronenröhre nach Anspruch 4, dadurch gekennzeichnet, daß die Breite der Stege in dem Maße, wie man sich dem unteren Ende des Gitters nähert, gleichmäßig zunimmt.
  6. Elektronenröhre nach Anspruch 4, dadurch gekennzeichnet, daß die Stege eine stetig zunehmende Breite haben.
  7. Elektronenröhre nach Anspruch 4, dadurch gekennzeichnet, daß dadurch gekennzeichnet, daß die Stege über einen Teil der Höhe des Gitters eine konstante Breite und im unteren Teil des Gitters eine veränderliche Breite haben.
  8. Elektronenröhre nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß das Gitter aus pyrolytischem Graphit oder aus Metall besteht.
EP91908979A 1990-05-04 1991-04-23 Verstärkerröhre mit einem gitter aus stegenvariabler breite Expired - Lifetime EP0481052B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9005640A FR2661778A1 (fr) 1990-05-04 1990-05-04 Tube d'amplification a grille avec barreaux de largeur variable.
FR9005640 1990-05-04
PCT/FR1991/000334 WO1991017559A1 (fr) 1990-05-04 1991-04-23 Tube d'amplification a grille avec barreaux de largeur variable

Publications (2)

Publication Number Publication Date
EP0481052A1 EP0481052A1 (de) 1992-04-22
EP0481052B1 true EP0481052B1 (de) 1995-04-05

Family

ID=9396335

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91908979A Expired - Lifetime EP0481052B1 (de) 1990-05-04 1991-04-23 Verstärkerröhre mit einem gitter aus stegenvariabler breite

Country Status (6)

Country Link
US (1) US5317230A (de)
EP (1) EP0481052B1 (de)
JP (1) JPH05501635A (de)
DE (1) DE69108666T2 (de)
FR (1) FR2661778A1 (de)
WO (1) WO1991017559A1 (de)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1948122A (en) * 1931-12-29 1934-02-20 Frederick S Mccullough Thermionic tube
DE1134167B (de) * 1960-12-14 1962-08-02 Standard Elektrik Lorenz Ag Gitter fuer die gebuendelte Elektronenstroemung von Kathodenstrahl- oder Laufzeitroehren und Verfahren zu seiner Herstellung
FR1408119A (fr) * 1964-09-18 1965-08-06 Siemens Ag Tube électronique à grille-écran
FR2432215A1 (fr) * 1978-07-27 1980-02-22 Thomson Csf Tube electronique a grille cylindrique en graphite pyrolytique
FR2561820A1 (fr) * 1984-03-23 1985-09-27 Thomson Csf Tube a grilles avec ecran metallique

Also Published As

Publication number Publication date
FR2661778A1 (fr) 1991-11-08
DE69108666T2 (de) 1995-08-17
US5317230A (en) 1994-05-31
JPH05501635A (ja) 1993-03-25
EP0481052A1 (de) 1992-04-22
DE69108666D1 (de) 1995-05-11
WO1991017559A1 (fr) 1991-11-14

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