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EP0003937B1 - Cathode for an electron gun - Google Patents

Cathode for an electron gun Download PDF

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Publication number
EP0003937B1
EP0003937B1 EP79400126A EP79400126A EP0003937B1 EP 0003937 B1 EP0003937 B1 EP 0003937B1 EP 79400126 A EP79400126 A EP 79400126A EP 79400126 A EP79400126 A EP 79400126A EP 0003937 B1 EP0003937 B1 EP 0003937B1
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EP
European Patent Office
Prior art keywords
resistance
platelet
cathode according
cathode
support
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
EP79400126A
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German (de)
French (fr)
Other versions
EP0003937A2 (en
EP0003937A3 (en
Inventor
Gérard Marhic
Philippe Martin
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.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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Publication of EP0003937A2 publication Critical patent/EP0003937A2/en
Publication of EP0003937A3 publication Critical patent/EP0003937A3/en
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Publication of EP0003937B1 publication Critical patent/EP0003937B1/en
Expired 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
    • H01J3/027—Construction of the gun or parts thereof
    • 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
    • H01J1/13—Solid thermionic cathodes
    • H01J1/15—Cathodes heated directly by an electric current
    • H01J1/16—Cathodes heated directly by an electric current characterised by the shape

Definitions

  • the present invention relates to a cathode for an electronic gun comprising at least one pellet made of a material capable of emitting, at high temperature, electrons, for example lanthanum hexaboride (LaB6) and at least one heating resistor made of a material with high electrical resistivity, for example pyrolitic graphite, said pellet and said resistance being traversed, in series, by an electric heating current.
  • a cathode for an electronic gun comprising at least one pellet made of a material capable of emitting, at high temperature, electrons, for example lanthanum hexaboride (LaB6) and at least one heating resistor made of a material with high electrical resistivity, for example pyrolitic graphite, said pellet and said resistance being traversed, in series, by an electric heating current.
  • LaB6 lanthanum hexaboride
  • a heating resistor made of a material with high electrical resistivity, for example pyrolitic graphite
  • the cathode constitutes the electron generator of cannons mounted on various devices using electron beams.
  • the emitted electrons are subjected to the action of the Wehnelt which regulates the power of the beam, accelerated by a voltage established between the cathode and an anode and finally focused by a magnetic lens which makes them converge on a practically point surface.
  • Cathodes of the aforementioned type consist essentially of a LaB6 emitting pellet having, at least in part, the shape of a rectangular parallelepiped and by two blocks of pyrolitic graphite, cubic in shape, placed on either side. other of the emitting tablet.
  • the whole is mounted on a fixed support comprising two metal arms connected to a source of electrical energy, these two arms being in direct contact with the graphite blocks and pressing them against the emitting pad which is interposed between them.
  • the invention aims to overcome these drawbacks and for this purpose provides a cathode whose i d pellet is in the form of a hollow part mounted on a support integral with the barrel, in which is engaged and against a wall of which is applied the resistance of pyrolitic graphite.
  • Heat transmission therefore takes place not only by conduction between the surfaces in contact but also by radiation since most of the radiation emitted by the resistor meets the pellet. This results in a better efficiency of the cathode.
  • the pad and the resistor are in the form of a part of revolution, the axes of these parts being in coincidence when the resistor is engaged in the pellet.
  • the pellet is in the form of a cup provided with a flat bottom wall and a side wall flaring from said bottom wall and the resistance is in the form of a truncated cone whose small base is applied against the bottom of the cup.
  • the cathode comprises a sheath made of an electrically conductive and chemically inert material with respect to LaB6, for example in graphite and inside which said pellet is inserted.
  • This sheath is mounted directly on the aforementioned support.
  • the sheath makes it possible to maintain the pellet without it being necessary to weld it to the support, thus eliminating any chemical reaction between LaB6 and the material of said support.
  • the sheath also ensures the conduction of the heating current.
  • the resistance is applied against the bottom wall of the pellet by elastic means.
  • the cathode according to the invention is housed inside a cylindrical barrel shown schematically in 2 and fixed to a support plate integral with the latter and shown schematically in 3.
  • the barrel 2 comprises, in a manner known per se, a certain number of other elements, in particular one or more magnetic lenses, an anode and a Wehnelt, only the latter being represented in 4.
  • the barrel 2 as well as all the elements which it comprises admit the axis XX 'as the axis of revolution.
  • the cathode 1 essentially consists of an emitting patch 10 made of LaB6, housed in a sheath 11 mounted on a support 12 fixed itself on the support plate 3 of the barrel 2 and of a heating resistor 14.
  • the patch and the sheath are housed in the central opening 4a of Wehnelt 4.
  • the emitting pad 10 is constituted by a hollow part of revolution and has the shape of a bowl provided with a flat bottom wall 10a and a side wall 10b flared outwards.
  • the sheath 11 in which the pellet 10 is housed is made of graphite and has the shape of a tubular cylinder of revolution, It is provided, at its upper end, with a lip or the like 11a, projecting inwards, against which the outside face 10c of the pad 10 is supported and at its lower part, a flange 11 b projecting outwards which bears on the support 12.
  • the support 12 is constituted by two front and rear frustoconical capsules 12a and 12b respectively, these capsules being joined by their large bases and fixed by the latter to the support plate 3.
  • the resistor 14 made of pyrolitic graphite, has the general shape of a truncated cone whose small and large bases are designated respectively by 14a and 14b and is further provided with an axial recess 14c.
  • the resistor 14 is in abutment, by its small base 14a in the form of a crown, against the flat bottom 1a of the pellet.
  • the bottom of 1 Oa and the small base 14a are given substantially equal diameters and the conical resistor 14 an angle at the top substantially less than that from the flared edge 10b of the patch.
  • the resistance 14 is applied against the pellet by a rod or pusher 15 provided, at its upper end, with a head 15a resting on its large base 14b.
  • the pusher 15 is secured, by means of a first metal ring 16, to a first tubular element 17 of axis XX ′ inside which it is housed, this first tubular element 17 being itself secured by through an insulating ring 18, a second tubular element 19 of axis XX 'in which it is housed.
  • the tubular element 19 is itself mounted on a support rod 20.
  • the plunger 15 and the tubular elements 17 and 19 constitute a rigid assembly which has the function of transmitting to the resistor 14 the thrust of elastic means.
  • These elastic means consist of a corrugated sheath or bellows 23 of axis XX ′ and surrounding the annular element 19.
  • the sheath 23 is fixed, at its upper part 23 a, to the capsule 12 b of the support 12 and is provided, at its lower end 23b of an annular stop 24 which bears, by means of an insulating ring 25, for example made of alumina against the end of the element 19.
  • the assembly constituted by the pusher 15 and the tubular elements 17 and 19 also has the function of creating, between the heating resistor 14, the temperature of which is of the order of 1700 ° and the corrugated sheath 23, a significant decrease in temperature by so that said corrugated sheath as well as the support rod 20 reach a temperature of the order of 200 to 300 ° C.
  • the cathode is also provided with frustoconical screens 26 and 27 located respectively inside and outside the capsule 12.
  • the elastic support provided by the corrugated sheath 23 protects the pellet and the resistance from mechanical stresses encountered with rigid systems, which makes it possible to significantly increase the service life of the cathode. .
  • the invention applies to all devices using electron beam generators, in particular to electron bombardment welding devices and electron microscopes.

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  • Electron Sources, Ion Sources (AREA)
  • Solid Thermionic Cathode (AREA)
  • Thermistors And Varistors (AREA)

Description

La présente invention concerne une cathode pour canon électronique comportant au moins une pastille faite en un matériau susceptible d'émettre, à haute température, des électrons, par exemple de l'hexaborure de lanthane (LaB6) et au moins une résistance chauffante faite en un matériau à haute résistivité électrique, par exemple du graphite pyrolitique, ladite pastille et ladite résistance étant parcourues, en série, par un courant électrique de chauffage.The present invention relates to a cathode for an electronic gun comprising at least one pellet made of a material capable of emitting, at high temperature, electrons, for example lanthanum hexaboride (LaB6) and at least one heating resistor made of a material with high electrical resistivity, for example pyrolitic graphite, said pellet and said resistance being traversed, in series, by an electric heating current.

On sait que la cathode constitue le générateur d'électrons des canons montés sur divers appareils utilisant des faisceaux électroniques. Les électrons émis sont soumis à l'action du Wehnelt qui règle la puissance du faisceau, accélérés par une tension établie entre la cathode et une anode et enfin focalisés par une lentille magnétique qui les fait converger sur une surface pratiquement ponctuelle.It is known that the cathode constitutes the electron generator of cannons mounted on various devices using electron beams. The emitted electrons are subjected to the action of the Wehnelt which regulates the power of the beam, accelerated by a voltage established between the cathode and an anode and finally focused by a magnetic lens which makes them converge on a practically point surface.

On connaît déjà des cathodes du type susmentionné qui sont constituées essentiellement par une pastille émettrice en LaB6 ayant, en partie au moins, la forme d'un parallélépipède rectangle et par deux blocs en graphite pyrolitique, de forme cubique, placés de part et d'autre de la pastille émettrice. Le tout est monté sur un support fixe comportant deux bras métalliques reliés à une source d'énergie électrique, ces deux bras étant en contact direct avec les blocs de graphite et les pressant contre la pastille émettrice qui est intercalée entre eux.Cathodes of the aforementioned type are already known which consist essentially of a LaB6 emitting pellet having, at least in part, the shape of a rectangular parallelepiped and by two blocks of pyrolitic graphite, cubic in shape, placed on either side. other of the emitting tablet. The whole is mounted on a fixed support comprising two metal arms connected to a source of electrical energy, these two arms being in direct contact with the graphite blocks and pressing them against the emitting pad which is interposed between them.

Ces cathodes connues présentent certains inconvénients:

  • - la transmission de la chaleur engendrée par effet Joule dans le graphite pyrolitique vers la pastille en LaB6, ne peut se faire pratiquement que par les surfaces en contact, puisque, en raison de la géométrie de l'ensemble, la plus grande partie du rayonnement émis par les blocs en graphite ne peut atteindre la pastille. Il en résulte que ces cathodes ont un rendement thermique défectueux.
  • - le montage de la pastille et des blocs entre deux bras rigides peut entraîner, en raison des dilatations thermiques, des contraintes mécaniques excessives; il est difficile, avec une telle configuration de non révolution de la cathode, d'obtenir u bon positionnement de la pastille émettrice, ceci en raison des variations thermiques et des dilatations.
These known cathodes have certain drawbacks:
  • - the transmission of the heat generated by the Joule effect in pyrolitic graphite towards the LaB6 pellet, can practically only be done by the surfaces in contact, since, due to the geometry of the assembly, most of the radiation emitted by the graphite blocks cannot reach the pellet. As a result, these cathodes have a defective thermal efficiency.
  • - the mounting of the pad and the blocks between two rigid arms can cause, due to thermal expansions, excessive mechanical stresses; it is difficult, with such a configuration of non-revolution of the cathode, to obtain a good positioning of the emitting pad, this due to thermal variations and expansions.

L'invention a pour but de pallier ces inconvénients et propose à cet effet une cathode dont id pastille se présente sous forme d'une pièce creuse montée sur un support solidaire du canon, dans laquelle est engagée et contre une paroi de laquelle est appliquée la résistance de graphite pyrolitique.The invention aims to overcome these drawbacks and for this purpose provides a cathode whose i d pellet is in the form of a hollow part mounted on a support integral with the barrel, in which is engaged and against a wall of which is applied the resistance of pyrolitic graphite.

La transmission de chaleur se fait donc non seulement par conduction entre les surfaces en contact mais également par rayonnement puisque la plus grande partie du rayonnement émis par la résistance rencontre la pastille. Il en résulte un meilleur rendement de la cathode.Heat transmission therefore takes place not only by conduction between the surfaces in contact but also by radiation since most of the radiation emitted by the resistor meets the pellet. This results in a better efficiency of the cathode.

Dans un mode de réalisation de l'invention, la pastille et la résistance se présentent sous forme d'une pièce de révolution, les axes de ces pièces étant en coïncidence lorsque la résistance est engagée dans la pastille.In one embodiment of the invention, the pad and the resistor are in the form of a part of revolution, the axes of these parts being in coincidence when the resistor is engaged in the pellet.

La symétrie de révolution permet d'obtenir une répartition plus homogène de la chaleur rayonnée par la résistance donc une température homogène de la pastille, elle simplifie en outre la fabrication.The symmetry of revolution makes it possible to obtain a more homogeneous distribution of the heat radiated by the resistance, therefore a homogeneous temperature of the pellet, it also simplifies the manufacture.

La pastille se présente sous forme d'une coupelle munie d'une paroi de fond plane et d'une paroi latérale s'évasant à partir de ladite paroi de fond et la résistance se présente sous la forme d'un tronc de cône dont la petite base est appliquée contre le fond de la coupelle.The pellet is in the form of a cup provided with a flat bottom wall and a side wall flaring from said bottom wall and the resistance is in the form of a truncated cone whose small base is applied against the bottom of the cup.

Cette forme donnée à la pastille et à la résistance facilite leur montage ainsi que leur centrage relatif.This shape given to the pad and to the resistance facilitates their mounting as well as their relative centering.

Dans un autre mode de réalisation de l'invention, la cathode comporte un fourreau fait en un matériau électriquement conducteur et chimiquement inerte vis à vis du LaB6, par exemple en graphite et à l'intérieur duquel est insérée ladite pastille. Ce fourreau est monté directement sur le support précité.In another embodiment of the invention, the cathode comprises a sheath made of an electrically conductive and chemically inert material with respect to LaB6, for example in graphite and inside which said pellet is inserted. This sheath is mounted directly on the aforementioned support.

Le fourreau permet de maintenir la pastille sans qu'il soit nécessaire de la souder au support, supprimant ainsi toute réaction chimique entre le LaB6 et le matériau dudit support. Le fourreau assure en outre la conduction du courant de chauffage.The sheath makes it possible to maintain the pellet without it being necessary to weld it to the support, thus eliminating any chemical reaction between LaB6 and the material of said support. The sheath also ensures the conduction of the heating current.

Toujours selon l'invention, la résistance est appliquée contre la paroi de fond de la pastille par des moyens élastiques.Still according to the invention, the resistance is applied against the bottom wall of the pellet by elastic means.

L'utilisation de moyens élastiques pour maintenir en place la résistance et la pastille permet d'éviter la formation de contraintes mécaniques sous l'effet des dilatations thermiques.The use of elastic means to hold the resistance and the pad in place makes it possible to avoid the formation of mechanical stresses under the effect of thermal expansions.

D'autres aspects et avantages de l'invention apparaîtront au cours de la description qui va suivre.Other aspects and advantages of the invention will emerge during the description which follows.

Le dessin annexé, donné uniquement à titre d'exemple non limitatif, représente schématiquement et en coupe une cathode selon un mode de réalisation de l'invention.The appended drawing, given solely by way of nonlimiting example, shows schematically and in section a cathode according to an embodiment of the invention.

Selon le mode de réalisation représenté, la cathode selon l'invention, désignée d'une façon générale par la référence 1, est logée à l'intérieur d'un canon cylindrique représenté schématiquement en 2 et fixée à une platine porteuse solidaire de ce dernier et représentée schématiquement en 3. Outre la cathode 1, le canon 2 comporte, de façon connue en soi, un certain nombre d'autres éléments, en particulier une ou plusieurs lentilles magnétiques, une anode et un Wehnelt, seul ce dernier étant représenté en 4. Le canon 2 ainsi que l'ensemble des éléments qu'il comporte admettent l'axe XX' comme axe de révolution.According to the embodiment shown, the cathode according to the invention, generally designated by the reference 1, is housed inside a cylindrical barrel shown schematically in 2 and fixed to a support plate integral with the latter and shown schematically in 3. In addition to the cathode 1, the barrel 2 comprises, in a manner known per se, a certain number of other elements, in particular one or more magnetic lenses, an anode and a Wehnelt, only the latter being represented in 4. The barrel 2 as well as all the elements which it comprises admit the axis XX 'as the axis of revolution.

La cathode 1 se compose essentiellement d'une pastille émettrice 10 en LaB6, logée dans un fourreau 11 monté sur un support 12 fixé lui-même sur la platine porteuse 3 du canon 2 et d'une résistance chauffante 14. La pastille et le fourreau sont logés dans l'orifice central 4a du Wehnelt 4.The cathode 1 essentially consists of an emitting patch 10 made of LaB6, housed in a sheath 11 mounted on a support 12 fixed itself on the support plate 3 of the barrel 2 and of a heating resistor 14. The patch and the sheath are housed in the central opening 4a of Wehnelt 4.

La pastille émettrice 10 est constituée par une pièce creuse de révolution et présente la forme d'une cuvette munie d'une paroi de fond 10a plane et d'une paroi latérale 10b évasée vers l'extérieur.The emitting pad 10 is constituted by a hollow part of revolution and has the shape of a bowl provided with a flat bottom wall 10a and a side wall 10b flared outwards.

Le fourreau 11 dans lequel est logée la pastille 10, est en graphite et présente la forme d'un cylindre tubulaire de révolution, Il est muni, à son extrémité supérieure, d'une lèvre ou analogue 11a, en saillie vers l'intérieur, contre lequel prend appui la face extérieure 10c de la pastille 10 et à sa partie inférieure, d'un rebord 11 b en saillie vers l'extérieur qui prend appui sur le support 12.The sheath 11 in which the pellet 10 is housed, is made of graphite and has the shape of a tubular cylinder of revolution, It is provided, at its upper end, with a lip or the like 11a, projecting inwards, against which the outside face 10c of the pad 10 is supported and at its lower part, a flange 11 b projecting outwards which bears on the support 12.

Le support 12 est constitué par deux capsules tronconiques avant et arrière 12a et 12b respectivement, ces capsules étant réunies par leurs grandes bases et fixées par ces dernières à la platine porteuse 3.The support 12 is constituted by two front and rear frustoconical capsules 12a and 12b respectively, these capsules being joined by their large bases and fixed by the latter to the support plate 3.

La résistance 14, en graphite pyrolitique, présente la forme générale d'un tronc de cône dont la petite et la grande base sont désignées respectivement par 14a et 14b et est munie en outre d'un évidement axial 14c. La résistance 14 est en appui, par sa petite base 14a en forme de couronne, contre le fond plat 1 Oa de la pastille. Afin de faciliter la mise en place et le centrage de la résistance 14 dans la pastille 10, on donne au fond de 1 Oa et à la petite base 14a des diamètres sensiblement égaux et à la résistance conique 14 un angle au sommet sensiblement inférieur à celui du bord évasé 10b de la pastille.The resistor 14, made of pyrolitic graphite, has the general shape of a truncated cone whose small and large bases are designated respectively by 14a and 14b and is further provided with an axial recess 14c. The resistor 14 is in abutment, by its small base 14a in the form of a crown, against the flat bottom 1a of the pellet. In order to facilitate the positioning and centering of the resistor 14 in the pellet 10, the bottom of 1 Oa and the small base 14a are given substantially equal diameters and the conical resistor 14 an angle at the top substantially less than that from the flared edge 10b of the patch.

La résistance 14 est appliquée contre la pastille par une tige ou poussoir 15 muni, à son extrémité supérieure, d'une tête 15a en appui sur sa grande base 14b. Le poussoir 15 est solidaire, par l'intermédiaire d'une première bague métallique 16, d'un premier élément tubulaire 17 d'axe XX' à l'intérieur duquel il est logé, ce premier élément tubulaire 17 étant solidaire lui-même par l'intermédiaire d'une bague isolante 18, d'un second élément tubulaire 19 d'axe XX' dans lequel il est logé. L'élément tubulaire 19 est monté lui-même sur une tige de supportage 20.The resistance 14 is applied against the pellet by a rod or pusher 15 provided, at its upper end, with a head 15a resting on its large base 14b. The pusher 15 is secured, by means of a first metal ring 16, to a first tubular element 17 of axis XX ′ inside which it is housed, this first tubular element 17 being itself secured by through an insulating ring 18, a second tubular element 19 of axis XX 'in which it is housed. The tubular element 19 is itself mounted on a support rod 20.

Le poussoir 15 et les éléments tubulaires 17 et 19 constituent un ensemble rigide qui a pour ionction de transmettre à la résistance 14 la poussée de moyens élastiques. Ces moyens élastiques sont constitués par une gaine annelée ou soufflet 23 d'axe XX' et entourant l'élément annulaire 19. La gaine 23 est fixée, à sa partie supérieure 23 a, à la capsule 12 b du support 12 et est munie, à son extrémité inférieure 23b d'une butée annulaire 24 qui prend appui, par l'intermédiaire d'une bague isolante 25, par exemple en alumine contre l'extrémité de l'élément 19.The plunger 15 and the tubular elements 17 and 19 constitute a rigid assembly which has the function of transmitting to the resistor 14 the thrust of elastic means. These elastic means consist of a corrugated sheath or bellows 23 of axis XX ′ and surrounding the annular element 19. The sheath 23 is fixed, at its upper part 23 a, to the capsule 12 b of the support 12 and is provided, at its lower end 23b of an annular stop 24 which bears, by means of an insulating ring 25, for example made of alumina against the end of the element 19.

L'ensemble constitué par le poussoir 15 et les éléments tubulaires 17 et 19 a également pour fonction de créer, entre la résistance chauffante 14 dont la température est de l'ordre de 1700° et la gaine annelée 23, une diminution sensible de température de façon que ladite gaine annelée ainsi que la tige de supportage 20 atteignent une température de l'ordre de 200 à 300°C.The assembly constituted by the pusher 15 and the tubular elements 17 and 19 also has the function of creating, between the heating resistor 14, the temperature of which is of the order of 1700 ° and the corrugated sheath 23, a significant decrease in temperature by so that said corrugated sheath as well as the support rod 20 reach a temperature of the order of 200 to 300 ° C.

Pour limiter la transmission de chaleur par rayonnement de la résistance 14 vers le canon, la cathode est munie en outre d'écrans 26 et 27 tronconiques situés respectivement à l'intérieur et à l'extérieur de la capsule 12.To limit the transmission of heat by radiation from the resistor 14 to the barrel, the cathode is also provided with frustoconical screens 26 and 27 located respectively inside and outside the capsule 12.

On voit que, grâce au positionnement relatif de la pastille 10 et de la résistance 14 et grâce à la forme de révolution donnée à ces deux pièces, pratiquement toute l'énergie rayonnée par la résistance, en particulier par sa face conique, est absorbée par la pastille 10, en particulier par sa paroi évasée 10b, réduisant ainsi au maximum les pertes d'énergie thermique.We see that, thanks to the relative positioning of the patch 10 and of the resistor 14 and thanks to the shape of revolution given to these two parts, practically all the energy radiated by the resistor, in particular by its conical face, is absorbed by the patch 10, in particular by its flared wall 10b, thus reducing to the maximum the losses of thermal energy.

Par ailleurs, l'appui élastique assuré par la gaine annelée 23 met la pastille et la résistance à l'abri des contraintes mécaniques que l'on rencontre avec les systèmes rigides, ce qui permet d'augmenter sensiblement la durée de vie de la cathode.Furthermore, the elastic support provided by the corrugated sheath 23 protects the pellet and the resistance from mechanical stresses encountered with rigid systems, which makes it possible to significantly increase the service life of the cathode. .

L'invention s'applique à tous les appareils utilisant des générateurs de faisceaux électroniques en particulier aux appareils de soudage par bombardement d'électrons et aux microscopes électroniques.The invention applies to all devices using electron beam generators, in particular to electron bombardment welding devices and electron microscopes.

De nombreuses variantes pourraient être apportées au mode de réalisation décrit et représenté, sans pour autant sortir du cadre de l'invention.Many variants could be made to the embodiment described and shown, without going beyond the ambit of the invention.

Claims (10)

1. Cathode for an electron gun having at least one platelet consisting of a material which is susceptible to emit electrons at a high temperature, such as lanthanum hexaboride, and at least one heating resistance consisting of a material having high electrical resistivity, such as pyrolytic graphite, the said platelet and the said resistance being passed serially by an electric heating current, characterized in that the platelet is a hollowed member mounted on a support (12) connected in a form-locking manner with the electron gun (2), in which member the said resistance (14) engages and against a wall (10a) of which member the resistance is forced.
2. Cathode according to claim 1, characterized in that the platelet (10) and the resistance (14) are rotating members, whereby the axis of these members coincide, if the resistance engages in the platelet.
3. Cathode according to claim 2, characterized in that the platelet (10) has the shape of a capsule having a plane bottom wall (10a) and a side wall (10b) widening from the said bottom wall, and that the resistance (14) has the shape of a truncated cone, the smallest base (14a) of which is forced against the bottom wall (10a) of the capsule.
4. Cathode according to claim 3, characterized in that the resistance (14) having the shape of a truncated cone is penetrated by an axial recess (14c), its small base (14) forced against the bottom (10a) of the platelet having the shape of a ring.
5. Cathode according to claim 1, characterized in that it comprises a casing (11) consisting of an electrically conductive material, such as graphite, in the interior of which the platelet (10) is inserted, the casing being directly mounted on the support (12).
6. Cathode according to the claims 3 and 5, characterized in that the casing (11) has the shape of a tubular rotating cylinder mounted on the support (12) and being provided with an inner lip (11 a) at one of its extremities, on which the platelet (10) is supported.
7. Cathode according to claim 1, characterized in that the resistance (14) is forced against the bottom wall of the platelet (10) by elastic means.
8. Cathode according to claim 7, characterized in that the said elastic means consist of a annularly arranged tubular element (23), the extremities of which are connected with the support (12) of the cathode and a shank (15) in contact with the resistance (14) in a form-locking manner.
9. Cathode according to claim 8, characterized in that the extremities of the annularly arranged tubular element (23) and the shank (15) are connected together in a form-locking manner by means of an intermediate member of tubular rigid coaxial elements (17, 19), in which the shank (17) is provided and which are in turn in the annular element (23).
10. Cathode according to the claims 8 and 9, characterized in that they are provided with shields (26, 27) to interrupt the thermal radiation, the shields being mounted on the support (12) and on the tubular rigid elements (17) in neighborhood to the resistance (14).
EP79400126A 1978-03-01 1979-02-28 Cathode for an electron gun Expired EP0003937B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7805813 1978-03-01
FR7805813A FR2418964A1 (en) 1978-03-01 1978-03-01 CATHODE FOR ELECTRONIC CANNON

Publications (3)

Publication Number Publication Date
EP0003937A2 EP0003937A2 (en) 1979-09-05
EP0003937A3 EP0003937A3 (en) 1979-09-19
EP0003937B1 true EP0003937B1 (en) 1980-10-15

Family

ID=9205196

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79400126A Expired EP0003937B1 (en) 1978-03-01 1979-02-28 Cathode for an electron gun

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US (1) US4220889A (en)
EP (1) EP0003937B1 (en)
JP (1) JPS54125959A (en)
DE (1) DE2960025D1 (en)
FR (1) FR2418964A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2520553A1 (en) * 1982-01-22 1983-07-29 Cameca ELECTRONIC OPTICAL APPARATUS COMPRISING PYROLYTIC GRAPHITE ELEMENTS
US4673842A (en) * 1985-09-03 1987-06-16 General Electric Company Graphite cathode cup for gridded x-ray tubes
US5015908A (en) * 1989-01-23 1991-05-14 Varian Associates, Inc. Fast warm-up cathode for high power vacuum tubes
US5480527A (en) * 1994-04-25 1996-01-02 Vapor Technologies, Inc. Rectangular vacuum-arc plasma source
CN103094019A (en) * 2013-01-21 2013-05-08 江苏达胜加速器制造有限公司 Filament used for microcurrent electronic gun

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2498775A (en) * 1948-01-16 1950-02-28 Westinghouse Electric Corp Cathode construction
FR1514813A (en) * 1967-03-17 1968-02-23 Lokomotivbau Elektrotech Large area massive cathode cathode cathode device in lanthanum hexaboride for electron ray generator
US3440475A (en) * 1967-04-11 1969-04-22 Lokomotivbau Elektrotech Lanthanum hexaboride cathode system for an electron beam generator
US3532923A (en) * 1969-03-17 1970-10-06 Ibm Pyrolytic graphite support for lanthanum hexaboride cathode emitter
DE2008176A1 (en) * 1970-02-21 1971-09-09 Fernseh Gmbh Holder for the indirectly heated cathode of a cathode ray system
FR2106968A5 (en) * 1970-09-30 1972-05-05 Cit Alcatel
US3958146A (en) * 1974-02-08 1976-05-18 Gte Sylvania Incorporated Fast warm up picture tube cathode cap having high heat emissivity surface on the interior thereof
JPS5277661A (en) * 1975-12-24 1977-06-30 Jeol Ltd Electron gun

Also Published As

Publication number Publication date
EP0003937A2 (en) 1979-09-05
FR2418964B1 (en) 1980-09-05
DE2960025D1 (en) 1981-01-22
US4220889A (en) 1980-09-02
JPS54125959A (en) 1979-09-29
FR2418964A1 (en) 1979-09-28
EP0003937A3 (en) 1979-09-19

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