EP0350357A1 - Supraleitende Vorrichtung zur Elektroninjektion in einer Elektronenröhre - Google Patents

Supraleitende Vorrichtung zur Elektroninjektion in einer Elektronenröhre Download PDF

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Publication number
EP0350357A1
EP0350357A1 EP89401739A EP89401739A EP0350357A1 EP 0350357 A1 EP0350357 A1 EP 0350357A1 EP 89401739 A EP89401739 A EP 89401739A EP 89401739 A EP89401739 A EP 89401739A EP 0350357 A1 EP0350357 A1 EP 0350357A1
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EP
European Patent Office
Prior art keywords
rod
bar
tube
electrons
sheath
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Withdrawn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
EP89401739A
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English (en)
French (fr)
Inventor
Pierre Blanchard
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 EP0350357A1 publication Critical patent/EP0350357A1/de
Withdrawn legal-status Critical Current

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    • 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
    • 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
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode

Definitions

  • the subject of the present invention is a device for injecting electrons into an electron tube which takes advantage of the high speed that electrons accelerated by an electric field can acquire in a superconductive material.
  • These electrons are in fact capable of acquiring kinetic energy at least equal to the energy, called extraction energy in the following, which is necessary for them to cross the potential barrier initially confining them in the material.
  • any electron tube is based on the existence inside the tube of an electron beam. Any electron tube must therefore be fitted with an electron injection device.
  • the characteristics of the electron beam supplied such as its intensity and directivity, are variable depending on the type of tube considered, however it is necessary in most cases to have an electron beam substantially parallel, narrow, and intense . These constraints are for example essential to equip a microwave tube, such as a traveling wave tube or a klystron, or a Crookes tube (X-ray emitter), or a cathode ray tube.
  • thermoelectronic emission that is to say the emission of electrons by certain metals (referred to as thermoemissives in the following) when they are heated, the intensity of this emission being the higher the hotter these metals are.
  • This known device generally comprises a heat conducting plate, one face of which is covered with a layer of a thermoemissive metal and is oriented towards the zone of the tube where the electrons must be injected.
  • This plate constitutes a cathode and is heated by means of a filament in which an electric current flows.
  • An anode is arranged in the tube.
  • the current created by the electrons emitted by the heated cathode increases, at a given temperature and for a given emissive surface, with the potential difference applied between the cathode and the anode then reaches a saturation value which is all the greater as the temperature is high. This current is therefore limited by the very principle of operation of the known device.
  • Another known device operates on the same principle but has a different geometry: the plate is replaced by a hollow cylinder whose external surface is covered with a thermoemissive metal, and the filament is located in the hollow of the cylinder.
  • thermoemissive metal the directions of emission of the electrons ejected out of the thermoemissive metal are distributed in a cone of solid angle substantially equal to 2 ⁇ steradian
  • these known devices have a duration of use limited by a degradation of the layer of thermoemissive metal (the latter, brought to high temperature, tends to sublimate, that is to say to pass from solid state in gaseous state).
  • the device according to the invention is based on a principle different from that set out in the above; in fact, this device takes advantage of one of the properties of a superconductive material, namely the high mobility of the electrons in a superconductor.
  • the device which is the subject of the invention in fact comprises a bar of a material superconductor of predetermined length, a first end of which opens into the tube and the second end of which is connected to electrical supply means so that the bar acts as a cathode.
  • An anode, called main in the following, is located in the tube, the cathode and the main anode preferably being located at a first and at the second end of the tube, respectively.
  • Electrons are accelerated along the bar and reach the first end of it with a kinetic energy greater than or substantially equal to the energy of extraction of the superconductive material. These electrons are then ejected from the first end of the bar and injected into the tube, in a direction substantially parallel to the axis of the bar.
  • the treatment to which the electrons are then subjected depends on the type of electron tube considered.
  • An anode, called secondary in the following, is placed in the part of the tube where the electrons are injected and is brought to a so-called secondary voltage. To initiate the injection phenomenon, the secondary voltage is brought to a starting value, high and independent of the main voltage. Then, it is brought to an operating value, lower and lower than the voltage at which the main anode is brought.
  • a more specific subject of the invention is a device for injecting electrons into an electronic tube, characterized in that it comprises: - a bar of predetermined length, made of a superconductive material, a first end of which opens into the injection part of the tube; - Power supply means, ensuring the application of a main voltage between the second end of the bar, the latter playing the role of a cathode, and a main anode located in the receiving part of the tube; - means for initiating the electron injection phenomenon; electrons being accelerated by the electric field applied between the cathode and the anode along the rod, thereby acquiring a kinetic energy at least equal to the energy of extraction of the material constituting the bar, and thus being ejected out of the bar, by the first end of the latter and injected into said part of the tube.
  • the intensity of the electron beam generated is not limited in any way by the principle of creation of this beam; the directions of emission of the electrons are all substantially parallel to the axis of the bar; the temperature of the cathode being lower than the critical temperature of the superconductive material, and this cathode comprising no thin surface deposit, the device does not wear out like the known devices.
  • a device equips an electronic tube 1 abstractly separated into three parts: - A part 11, where the electrons are injected, called injection in what follows; a part 12, where the electrons are treated, known as the treatment in the following (such treatment of the electrons depending on the type of tube considered); - A part 13, where the electrons are collected after treatment, called reception in the following.
  • the processing part 12 having a very precise geometry which depends on the type of tube considered, is very schematically represented by a rectangle.
  • the injection 11 and receiving 13 parts are delimited by walls 2 of the tube 1, which are for example made of ceramic.
  • FIG. 1 illustrates a first embodiment of the device according to the invention which comprises: a thin bar 3, also called a rod in the following, made of a first material which is superconductive, playing the role of a cathode, and of which a first end 31 opens into the injection part 11 of the tube 1; -an anode (called main) 6, located in the receiving part 13 of the tube 1; - An anode (called secondary) 7, located in the injection part 11 of the tube 1; electrical supply means 4, ensuring the application of two independent voltages, qualified respectively as main and secondary, applied respectively between the main anode and the secondary anode on the one hand, and the cathode constituted by the rod 3 on the other hand.
  • a thin bar 3 also called a rod in the following, made of a first material which is superconductive, playing the role of a cathode, and of which a first end 31 opens into the injection part 11 of the tube 1
  • main an anode
  • secondary An anode
  • electrical supply means 4 ensuring the
  • the rod 3 is electrically connected to the supply means 4 via a part 8, so as not to deteriorate the superconductivity of the rod 3 by heating during the passage of an intense electric current; this piece 8 further provides a mechanical rigidity function of the rod 3.
  • this part 8 is made of a second material, which is electrically conductive (such as copper) and has the shape of a bar , whose transverse dimensions are greater than those of the rod 3; the rod 3 is embedded over substantially its entire length, and on the side of its second end 32 in this part 8, so that only the first end 31 of this rod 3 protrudes from the part 8.
  • the device of Figure 1 further comprises cooling means ensuring the maintenance of the material constituting the rod 3 in a superconductive state.
  • This material is cooled by means of part 8, the material constituting this part 8 also being a heat conductor.
  • This part 8 is in fact immersed in a tank 5, filled with liquid nitrogen 24, and enclosing in a sealed manner for example by means of a solder the two ends of the part 8 at two orifices 20 and 21 (respectively qualified as second and third in the following), the rod 3 projecting as little as possible out of the tank 5 through the third orifice 21: the tank 5 is in fact rigidly and tightly fixed to the walls 2 of the tube 1 so that the third orifice 21 opens into the injection part 11 of the tube 1.
  • the walls 2 of the tube 1 are made of ceramic and the tank 5 is made of Kovar, which allows such fixing to be carried out by soldering.
  • the tank 5 is also connected to a liquid nitrogen tank by means of a pipe 23 and open to the open air at the level of an orifice 9 (described first in the following): in a manner known by l '' skilled in the art, liquid nitrogen 24 permanently feeds the tank 5 and evaporates continuously through the first orifice 9.
  • the part 8 is long enough for the rod 3 to remain at low temperature although the part 8 is in contact with the outside of the tank.
  • the electrons supplied by the supply means 4, and having reached the part 8, are accelerated towards the injection part 11 of the tube 1. They pass into the superconductive rod 3 at its second end 32 , and therefore are accelerated over the entire length of the rod 3.
  • This length is predetermined so that electrons having been accelerated by the electric field corresponding to the voltages created by the electrical supply means 4, have acquired a kinetic energy at least equal to the energy of extraction of the material constituting the rod 3.
  • the electron beam obtained is therefore intense . It is also substantially parallel and directed in the direction of the rod 3. Finally, its transverse dimensions are substantially delimited by those of the rod 3.
  • the electrons injected into the injection part 11, of the tube 1 remain grouped thanks to a shape suitable, known per se to those skilled in the art, for the secondary anode. They are then guided to the main anode 6 (the secondary voltage being smaller than the main voltage after initiation of the injection phenomenon) and pass through the processing part 12 of the tube 1, before being collected in the receiving part 13 of the tube.
  • the secondary voltage is therefore brought to a so-called start-up value in what follows, sufficient to initiate the phenomenon of ejection of electrons from the rod 3 by tearing off the electrons accumulated at its first end 31 which obstruct the ejection of electrons from the supply means 4.
  • the secondary voltage is reduced to a value, called operating in what follows, lower than the starting value.
  • the start-up value of the secondary voltage is independent of the value of the main voltage (which is the same during the initiation of the injection phenomenon and during operation).
  • the operating value of the secondary voltage is lower than the value of the main voltage, so that electrons injected into the injection part 11 of the tube 1 are guided to the treatment part 12, then collected in the part receiving 13 of this tube, as has been explained in the foregoing.
  • the second embodiment of the device which is the subject of the invention, illustrated by FIG. 2 differs from the first, illustrated by FIG. 1, in that the rod 3 is only embedded in the part 8 over part of its length ; in other words, the part 8 of FIG. 2 is shorter than that of FIG. 1; this part 8 is partially replaced by a sheath 40, made of an electrically insulating material, such as for example ceramic, surrounding the part of the rod 3 not embedded in the part 8, and rigidly fixed to the part 8.
  • the part 8 is made of copper
  • the sheath 40 is made of ceramic, which allows such fixing by brazing.
  • the sheath which is electrically insulating, forces the electrons to pass through the superconductive rod 3 at the level of the attachment of the part 8 to the sheath 40 so that these are accelerated over a distance at least equal to the length (called minimum distance in the following) of the part of the rod 3 not embedded in the part 8.
  • minimum distance the length of the part of the rod 3 not embedded in the part 8.
  • the transverse dimensions of the sleeve 40 are for example substantially identical to those of the part 8, but they could as well be smaller than that of this part 8.
  • the rest of the description of FIG. 2 is similar to that of FIG. 1, except that the tank 5 encloses the sheath 40 instead of the part 8 at the third orifice 21.
  • the device illustrated in FIG. 3 differs from that illustrated in FIG. 1 in that the part 8 has a shoulder 41, the part of this part 8 located on the side of the injection part 11 of the tube 1 having transverse dimensions smaller than those of the rest of the part 8.
  • the existence of such a shoulder 41 modifies the lines of the electric field in the part 8, in a manner known to man from art, which forces part of the residual electrons to pass through the rod 3 at this shoulder 41: by choosing the position of the shoulder 41, it is therefore possible to reduce the drawback of FIG. 1, cited in the above.
  • the device of Figure 4 differs from that of Figure 1 in that the rod 3 is surrounded by a sheath 42 made of an insulating material over substantially its entire length with the exception of its two ends 31 and 32; the rod 3 surrounded by this sheath 42 being embedded substantially over the entire length of the sheath 42 on the side of the second end 32 of the rod 3, so as to leave free the first end 31 of the rod 3.
  • the tank 5 encloses a part of the part 8 at the third orifice 21 (while in the configuration of FIG. 3, the tank 5 encloses the sheath 40), which advantageously allows soldering between metals ( indeed, the part 8 is for example of copper and the tank for example of Kovar).
  • the device of FIG. 4 operates in a similar fashion to that of FIG. 2, except that the electrons are accelerated over substantially the entire length of the rod 3.
  • FIG. 5 illustrates a fifth embodiment of the invention which differs from the first in that the rod 3 embedded in the part 8 is replaced by a bar 3 (of a superconductive material) whose transverse dimensions are only slightly smaller to those of the part 8, the bar being rigidly fixed to the part 8, by means known per se, such as for example by embedding its second end 32 (located on the side of the supply means 4).
  • the tank directly encloses the superconducting bar 3 at the level of the third orifice 21.
  • the device of FIG. 5 operates in the same way as that of FIG.

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  • Particle Accelerators (AREA)
  • Electron Sources, Ion Sources (AREA)
EP89401739A 1988-07-05 1989-06-20 Supraleitende Vorrichtung zur Elektroninjektion in einer Elektronenröhre Withdrawn EP0350357A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8809063A FR2634055A1 (fr) 1988-07-05 1988-07-05 Dispositif a supraconducteur d'injection d'electrons dans un tube electronique
FR8809063 1988-07-05

Publications (1)

Publication Number Publication Date
EP0350357A1 true EP0350357A1 (de) 1990-01-10

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EP89401739A Withdrawn EP0350357A1 (de) 1988-07-05 1989-06-20 Supraleitende Vorrichtung zur Elektroninjektion in einer Elektronenröhre

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US (1) US5015920A (de)
EP (1) EP0350357A1 (de)
JP (1) JPH02112139A (de)
FR (1) FR2634055A1 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03266346A (ja) * 1990-03-14 1991-11-27 Toshiba Corp イオン生成装置
US5348934A (en) * 1991-09-09 1994-09-20 Raytheon Company Secondary emission cathode having supeconductive oxide material
US20060019833A1 (en) * 2004-07-21 2006-01-26 Lewis Arthur J Superconductor electromagnetic transmitter device

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4414487A (en) * 1980-12-29 1983-11-08 Technological University Of Nagaoka Superconducting electron beam generator

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2484643A (en) * 1945-03-06 1949-10-11 Bell Telephone Labor Inc High-frequency electronic device
US2853646A (en) * 1954-06-07 1958-09-23 Jr Wilson S Geisler Electron discharge device
US2917653A (en) * 1957-02-13 1959-12-15 Westinghouse Electric Corp Electron discharge device
AT312121B (de) * 1972-10-09 1973-12-27 Boris Grigorievich Sokolov Elektronenstrahlanlage zur Warmbehandlung von Objekten durch Elektronenbeschuß
US4527091A (en) * 1983-06-09 1985-07-02 Varian Associates, Inc. Density modulated electron beam tube with enhanced gain
JPS607046A (ja) * 1983-06-23 1985-01-14 Shuichi Iida 電子ビ−ム装置
KR900003310B1 (ko) * 1986-05-27 1990-05-14 리가가구 겡큐소 이온 발생 장치

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4414487A (en) * 1980-12-29 1983-11-08 Technological University Of Nagaoka Superconducting electron beam generator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 9, no. 118 (E-316)[1841], 23 mars 1985, page 23 E 316; & JP-A-60 007 046 (SHIYUUICHI IIDA) 14-01-1985 *

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US5015920A (en) 1991-05-14
JPH02112139A (ja) 1990-04-24
FR2634055A1 (fr) 1990-01-12

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