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EP0063840A1 - High tension vacuum tube, particularly X ray tube - Google Patents

High tension vacuum tube, particularly X ray tube Download PDF

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Publication number
EP0063840A1
EP0063840A1 EP82200452A EP82200452A EP0063840A1 EP 0063840 A1 EP0063840 A1 EP 0063840A1 EP 82200452 A EP82200452 A EP 82200452A EP 82200452 A EP82200452 A EP 82200452A EP 0063840 A1 EP0063840 A1 EP 0063840A1
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EP
European Patent Office
Prior art keywords
insulator
shielding electrode
conductive part
vacuum tube
voltage vacuum
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.)
Granted
Application number
EP82200452A
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German (de)
French (fr)
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EP0063840B1 (en
Inventor
Horst Dr. Brettschneider
Walter Dr. Hartl
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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Publication of EP0063840A1 publication Critical patent/EP0063840A1/en
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Publication of EP0063840B1 publication Critical patent/EP0063840B1/en
Expired legal-status Critical Current

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    • 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
    • H01J1/52—Screens for shielding; Guides for influencing the discharge; Masks interposed in the electron stream
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details

Definitions

  • the invention relates to a high-voltage vacuum tube, in particular an X-ray tube, with an electrode located in its vacuum space which, in the operating state, carries positive high voltage with respect to an electrically conductive part which at least partially surrounds it, the electrode or a part connected to it having the conductive one Part is connected via an insulator.
  • the electrode is generally the anode of the high-voltage vacuum tube.
  • the electrode can also be the shaft carrying the same potential as the anode disk, which carries the anode disk.
  • the electrically conductive part is usually the metal tube bulb of such a tube or a part thereof.
  • it can also be - in the case of rotating anode x-ray tubes - a metal cylinder which rotates together with an insulator and the shaft of the rotating anode disk and is connected to the housing of the x-ray tube via a bearing, as is known from DE-PS 24 55 974.
  • the insulator is usually shaped so that its truncated cone-shaped inner jacket widens in the axial direction from the connection area with the electrode.
  • the Shaping of the insulator ensures that discharge processes on the insulator surface are prevented, which could reduce the operational safety of the tube.
  • the binding energy of gas layers adsorbed on the surface is reduced by the increased temperature of the insulator, so that desorption stimulated by electrons can take place to an increased extent and discharge processes can thereby be initiated (RA Anderson, JP Brainard: Machanism of pulsed surface flashover involving electron-stimulated desorption, J. Appl. Phys. 51, 1414, (1980)).
  • the object of the present invention is to design a high-voltage vacuum tube of the type mentioned at the outset in such a way that the described discharge processes are largely prevented even when subjected to high thermal loads.
  • This object is achieved in that in the area of the connection between the insulator and the conductive part a shielding electrode carrying the potential of the conductive part is provided at a short distance from the insulator, which is shaped so that the electric field strength is reduced in the connection area.
  • the inventors have recognized that the described discharge processes in the operating state under high thermal stress have their origin in the area of the connection between the insulator and the conductive part, which is exposed to the electric field between the conductive part and the electrode, especially if in this area the insulator is brazed to the electrically conductive part. Because the shielding electrode lowers the electric field in this area, the described discharge processes are largely prevented.
  • the shielding electrode Even when carefully processed (electropolishing), the shielding electrode itself can have the smallest inhomogeneities which form emission centers in the operating state can. If the electrons emitted from these emission centers run towards the electrode (anode) on the insulator surface, this can in turn result in discharge processes.
  • the shielding electrode is arranged opposite the insulator in such a way that most of the electrons emitted on the surface of the shielding electrode facing away from the conductive part cannot strike the inner surface of the insulator, in particular that Shielding electrode is arranged set back from the outer surface given by the inner surface of the insulator, so that it is not cut by the continuation of the conical outer surface of the insulator.
  • the insulator is shaped in such a way that a cavity open to the shielding electrode is enclosed between it and the conductive part.
  • the area of the connection point between the insulator and the conductive part is largely protected against discharge carriers which run through the space between the shielding electrode and the insulator in the direction of the electrically conductive part, so that the discharge processes can be prevented particularly effectively .
  • FIG. 1 shows an X-ray tube
  • the piston 1 is made entirely of metal.
  • the piston 1 is essentially rotationally symmetrical.
  • the anode disk 2 has a flattened focal spot path, which is arranged opposite the cathode 3, which is connected via an insulator 4 to a metal cylinder 5, which in turn is connected to the piston having an opening in this area.
  • the anode is held in two places.
  • a pin 6 is provided which is concentric with the axis of rotation and which carries a bearing 7 which is connected to the cylindrical rotor 9 via a ring 8.
  • the pin 6, the bearing 7 and the ring 8 establish a conductive connection between the piston 1 and the rotor 9, so that the rotor is also grounded to the metal piston.
  • the ring 8 and with it the rotor 9 is connected via a further ring 15 to an insulator 11 which is fastened on a shaft 12 carrying the anode disk 2.
  • the high voltage is supplied to the anode via a further bearing 13 which is mounted in an insulator connected to the tube bulb 1, which has a conical opening 16 for receiving a high-voltage plug.
  • the ball bearing 13 serves to support the shaft 12. The high voltage is thus supplied to the anode disk 2 via the bearing 13 and the shaft 12.
  • the critical area is the area 17 in which the piston 1, the insulator 14 and the vacuum in the tube adjoin one another. This area, which, as the drawing suggests, is not limited to one point, but concentrically surrounds the shaft 12, is exposed to the electric field between the piston 1 and the shaft 12. If the thermal load is excessive, it can reach temperatures of well over 100 ° C.
  • FIG. 2 shows a part of the metal piston with the insulator 14 in a partially broken-away representation on an enlarged scale compared to FIG. 1 with the shielding electrode according to the invention.
  • the ring-shaped shielding electrode 18 is located in the immediate vicinity of the end of the insulator, in which the critical region 17 is located, in which the piston 1, the insulator and the vacuum adjoin one another.
  • the shielding electrode is preferably made of pure iron or another metal, e.g. CrNi steel, and is welded concentrically to the shaft 12 on the inside of the metal piston 1.
  • Both the shielding electrode and the insulator are shaped so that they each form a groove-shaped cavity with the piston 1, which is open to the insulator or to the shielding electrode.
  • This design on the one hand reduces the field strength in the critical area and, on the other hand, the charge carriers passing through the gap between the shielding electrode 18 and the insulator 14 cannot hit this critical area directly.
  • the gap between the mutually facing ends of the insulator 14 and the shielding electrode 18 is approximately 1 mm. However, it should not exceed 3 mm. However, if it is significantly smaller than 0.5 mm, then very high field strengths result in this gap, which can lead to field emission on the surface of the shielding electrode 18. Furthermore the shielding electrode can then be poorly conditioned. If it is significantly larger than 3 mm, then the electric field in the critical area between metal piston 1, insulator 14 and vacuum is hardly reduced by the shielding electrode 18.
  • the shielding electrode is expediently e.g. treated by electropolishing so that there are emission centers on its surface.
  • the electrode 18 should be arranged so that electrons emitted from it run directly to the shaft 12 and cannot reach the insulator.
  • the shielding electrode is expediently arranged in a reset manner, i.e. their inside diameter is like this. dimension that the frusto-conical inner jacket surface of the insulator 14, which extends towards the shielding electrode or its extension indicated by lines 19, does not intersect the shielding electrode 18.
  • FIG. 3 shows a section of an X-ray tube according to the invention.
  • the mutually facing end faces of the insulator 14 and the shielding electrode 18 are approximately planar and run approximately perpendicular to the wall of the metal piston 1.
  • the shielding electrode 18 is shaped similarly to that in Fig. 2, i.e. it encloses with the wall of the piston 1 a groove-shaped, circumferential cavity which is open towards the insulator 14 and into which a comparatively thin end of the insulator 14 projects.
  • the invention was explained above in connection with a fixed insulator, it can in principle also be used with a rotating insulator. If, for example in FIG. 1, the grounded metal ring 15 were so long that there would be an area or a zone in which the vacuum space, the metal ring 15 and the insulator 11 adjoin one another and into which that between the metal ring 15 and the shaft 12 would intervene effective electrical field, the invention could also be applied accordingly.
  • the insulator is shaped in such a way that the electrons striking in the operating state find an electrical field at least on a substantial part of its surface, which moves it away from the surface of the insulator, because the truncated cone-shaped inner jacket of the insulator extends in the axial direction from the connection area with the Electrode extended.
  • the invention is also applicable to an insulator arrangement which is provided with a concentric trough and has an insulator part which is enclosed by the trough and carries the electrode and an outer insulator part which surrounds the trough and with the conductive part (the tube bulb or the rotor) is connected.
  • the invention is also not limited to rotating anode X-ray tubes. Rather, it can also be used with other X-ray tubes as well as with other high-voltage vacuum tubes (e.g. neutron tubes).

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  • X-Ray Techniques (AREA)

Abstract

Bei Hochspannung-Vakuumröhren, insbesondere Röntgenröhren, mit einer positives Hochspannungspotential führenden Elektrode (Anode), die über einen Isolator mit einem leitfähigen Teil (z.B. Metall-Röhrenkolben) verbunden ist, können sich bei sehr hohen Temperaturen Entladungsvorgänge ergeben. Zur Vermeidung dieser Entladungsvorgänge sieht die Erfindung eine Abschirmelektrode (18) in geringem Abstand vom Isolator (14) vor, die so geformt ist, dass die elektrische Feldstärke im Verbindungsbereich (17) zwischen dem Isolator (14) und dem leitfähigen Teil (1) herabgesetzt wird.In the case of high-voltage vacuum tubes, especially X-ray tubes, with a positive high-voltage potential-carrying electrode (anode), which is connected to a conductive part (e.g. metal tube bulb) via an insulator, discharge processes can occur at very high temperatures. To avoid these discharge processes, the invention provides a shielding electrode (18) at a short distance from the insulator (14), which is shaped in such a way that the electric field strength in the connection area (17) between the insulator (14) and the conductive part (1) is reduced becomes.

Description

Die Erfindung bezieht sich auf eine Hochspannungs-Vakuumröhre, insbesondere eine Röntgenröhre, mit einer in ihrem Vakuumraum befindlichen Elektrode, die im Betriebszustand gegenüber einem sie wenigstens teilweise umschliessenden elektrisch leitenden Teil positive Hochspannung führt, wobei die Elektrode oder ein mit ihr verbundener Teil mit dem leitfähigen Teil über einen Isolator verbunden ist.The invention relates to a high-voltage vacuum tube, in particular an X-ray tube, with an electrode located in its vacuum space which, in the operating state, carries positive high voltage with respect to an electrically conductive part which at least partially surrounds it, the electrode or a part connected to it having the conductive one Part is connected via an insulator.

Eine solche Hochspannungs-Vakuumröhre ist aus der DE-OS 25 06 841 bekannt. Die Elektrode ist dabei im allgemeinen die Anode der Hochspannungs-Vakuumröhre. Bei Drehanoden-Röntgenröhren kann die Elektrode aber auch die das gleiche Potential wie die Anodenscheibe führende die Anodenscheibe tragende Welle sein. Der elektrisch leitende Teil ist in der Regel der aus Metall bestehende Röhrenkolben einer solchen Röhre bzw. ein Teil davon. Es kann jedoch auch - bei Drehanoden-Röntgenröhren - ein Metallzylinder sein, der zusammen mit einem Isolator und der Welle der Drehanodenscheibe rotiert und über ein Lager mit dem Gehäuse der Röntgenröhre verbunden ist, wie aus der DE-PS 24 55 974 bekannt. Der Isolator ist in der Regel so geformt, daß sein kegelstumpfförmiger Innenmantel sich in Achsrichtung von dem Verbindungsbereich mit der Elektrode aus erweitert.Such a high-voltage vacuum tube is known from DE-OS 25 06 841. The electrode is generally the anode of the high-voltage vacuum tube. In the case of rotating anode X-ray tubes, however, the electrode can also be the shaft carrying the same potential as the anode disk, which carries the anode disk. The electrically conductive part is usually the metal tube bulb of such a tube or a part thereof. However, it can also be - in the case of rotating anode x-ray tubes - a metal cylinder which rotates together with an insulator and the shaft of the rotating anode disk and is connected to the housing of the x-ray tube via a bearing, as is known from DE-PS 24 55 974. The insulator is usually shaped so that its truncated cone-shaped inner jacket widens in the axial direction from the connection area with the electrode.

Bei der bekannten Hochspannungs-Vakuumröhre wird durch die Formgebung des Isolators erreicht, daß Entladungsvorgänge auf der Isolatoroberfläche unterbunden werden, die die Betriebssicherheit der Röhre herabsetzen könnten. Bei thermisch stark belasteten Röhren wird jedoch durch die erhöhte Temperatur des Isolators die Bindungsenergie von auf der Oberfläche adsorbierten Gasschichten herabgesetzt, so daß durch Elektronen stimulierte Desorption in erhöhtem Maße stattfinden kann und dadurch Entladungsvorgänge eingeleitet werden (R.A. Anderson, J.P. Brainard: Machanism of pulsed surface flashover involving electron-stimulated desorption, J. Appl. Phys. 51, 1414, (1980)).In the known high-voltage vacuum tube, the Shaping of the insulator ensures that discharge processes on the insulator surface are prevented, which could reduce the operational safety of the tube. In the case of thermally highly stressed tubes, however, the binding energy of gas layers adsorbed on the surface is reduced by the increased temperature of the insulator, so that desorption stimulated by electrons can take place to an increased extent and discharge processes can thereby be initiated (RA Anderson, JP Brainard: Machanism of pulsed surface flashover involving electron-stimulated desorption, J. Appl. Phys. 51, 1414, (1980)).

Aufgabe der vorliegenden Erfindung ist es, eine Hochspannungs-Vakuumröhre der eingangs genannten Art so auszugestalten, daß auch bei starker thermischer Belastung die beschriebenen Entladungsvorgänge weitgehend unterbunden werden. Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß im Bereich der Verbindung zwischen dem Isolator und dem leitenden Teil eine das Potential des leitenden Teils führende Abschirmelektrode in geringem Abstand vom Isolator vorgesehen ist, die so geformt ist, daß die elektrische Feldstärke im Verbindungsbereich herabgesetzt wird. Die Erfinder haben erkannt, daß die geschilderten Entladungsvorgänge im Betriebszustand bei starker thermischer Belastung ihren Ursprung in dem Bereich der Verbindung zwischen dem Isolator und dem leitenden Teil haben, der dem elektrischen Feld zwischen dem leitenden Teil und der Elektrode ausgesetzt ist, insbesondere wenn in diesem Bereich der Isolator-durch eine Hartlötung an den elektrisch leitenden Teil angelötet ist. Dadurch,daß die Abschirmelektrode das elektrische Feld in diesem Bereich herabsetzt, werden die geschilderten Entladungsvorgänge weitgehend unterbunden.The object of the present invention is to design a high-voltage vacuum tube of the type mentioned at the outset in such a way that the described discharge processes are largely prevented even when subjected to high thermal loads. This object is achieved in that in the area of the connection between the insulator and the conductive part a shielding electrode carrying the potential of the conductive part is provided at a short distance from the insulator, which is shaped so that the electric field strength is reduced in the connection area. The inventors have recognized that the described discharge processes in the operating state under high thermal stress have their origin in the area of the connection between the insulator and the conductive part, which is exposed to the electric field between the conductive part and the electrode, especially if in this area the insulator is brazed to the electrically conductive part. Because the shielding electrode lowers the electric field in this area, the described discharge processes are largely prevented.

Die Abschirmelektrode selbst kann auch bei sorgfältiger Bearbeitung (elektropolieren) noch kleinste Inhomogenitäten aufweisen, die im Betriebszustand Emissionszentren bilden können. Wenn die aus diesen Emissionszentren emittierten Elektronen auf der Isolatoroberfläche zur Elektrode (Anode) hin laufen, können sich hieraus wiederum Entladungsvorgänge ergeben. Um auch diese Möglichkeit zu verringern, sieht eine Weiterbildung der Erfindung vor, daß die Abschirmelektrode gegenüber dem Isolator so angeordnet ist, daß auf der von dem leitenden Teil abgewandten Oberfläche der Abschirmelektrode emittierte Elektronen größtenteils nicht auf die Innenfläche des Isolators treffen können, insbesondere daß die Abschirmelektrode gegenüber der durch die Innenfläche des Isolators gegebenen Mantelfläche zurückgesetzt angeordnet ist, derart daß sie von der Fortsetzung der kegelmantelförmigen Innenfläche des Isolators nicht geschnitten wird.Even when carefully processed (electropolishing), the shielding electrode itself can have the smallest inhomogeneities which form emission centers in the operating state can. If the electrons emitted from these emission centers run towards the electrode (anode) on the insulator surface, this can in turn result in discharge processes. In order to reduce this possibility, a further development of the invention provides that the shielding electrode is arranged opposite the insulator in such a way that most of the electrons emitted on the surface of the shielding electrode facing away from the conductive part cannot strike the inner surface of the insulator, in particular that Shielding electrode is arranged set back from the outer surface given by the inner surface of the insulator, so that it is not cut by the continuation of the conical outer surface of the insulator.

Eine andere Weiterbildung der Erfindung sieht vor, daß der Isolator so geformt ist, daß zwischen ihn und dem leitenden Teil ein zur Abschirmelektrode offener Hohlraum eingeschlossen wird. Hierbei ist der Bereich der Verbindungsstelle zwischen dem Isolator und dem leitenden Teil gegen Entladungsträger, die durch den Zwinhenraum zwischen der Abschirmelektrode und dem Isolator hindurch in Richtung auf den elektrisch leitenden Teil laufen,.. weitgehend geschützt, so daß die Entladungsvorgänge besonders wirksam unterbunden werden können.Another development of the invention provides that the insulator is shaped in such a way that a cavity open to the shielding electrode is enclosed between it and the conductive part. Here, the area of the connection point between the insulator and the conductive part is largely protected against discharge carriers which run through the space between the shielding electrode and the insulator in the direction of the electrically conductive part, so that the discharge processes can be prevented particularly effectively .

Die Erfindung wird nachstehend anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert. Es zeigen

  • Fig. 1 eine bekannte Röntgenröhre,
  • Fig. 2 einen Teil einer solchen Röntgenröhre mit der erfindungsgemäßen Ausgestaltung,
  • Fig. 3 und 4 andere Ausgestaltungen der Erfindung.
The invention is explained below with reference to an embodiment shown in the drawing. Show it
  • 1 shows a known X-ray tube,
  • 2 shows a part of such an X-ray tube with the configuration according to the invention,
  • 3 and 4 other embodiments of the invention.

Anhand der in Fig. 1 dargestellten bekannten Röntgenröhre sollen zunächst nochmals die der Erfindung zugrunde liegenden Probleme erläutert werden. Fig. 1 zeigt eine Röntgenröhre, deren Koleben 1 vollständig aus Metall besteht.. Der Kolben 1 ist im wesentlichen rotationssymmetrisch aufgebaut. Die Anodenscheibe 2 weist eine abgeflachte Brennfleckbahn auf, der gegenüber die Kathode 3 angeordnet ist, die über einen Isolator 4 mit einem Metallzylinder 5 verbunden ist, der seinerseits mit dem in diesem Bereich eine Öffnung aufweisenden Kolben verbunden ist. Die Anode ist an zwei Stellen gehaltert. Am unteren Ende des Metallkolbens ist ein zur Rotationsachse konzentrischer Zapfen 6 vorgesehen, der ein Lager 7 trägt, das über einen Ring 8 mit dem zylinderförmigen Rotor 9 verbunden ist. Der Zapfen 6, das Lager 7 und der Ring 8 stellen eine leitende Verbindung zwischen dem Kolben 1 und dem Rotor 9 her, so daß mit dem Metallkolben auch der Rotor geerdet ist. Der Ring 8 und mit ihm der Rotor 9 ist über einen weiteren Ring 15 mit einem Isolator 11 verbunden, der auf einer die Anodenscheibe 2 tragenden Welle 12 befestigt ist.On the basis of the known x-ray tube shown in FIG. 1, the problems on which the invention is based will first be explained again. 1 shows an X-ray tube, the piston 1 is made entirely of metal. The piston 1 is essentially rotationally symmetrical. The anode disk 2 has a flattened focal spot path, which is arranged opposite the cathode 3, which is connected via an insulator 4 to a metal cylinder 5, which in turn is connected to the piston having an opening in this area. The anode is held in two places. At the lower end of the metal piston, a pin 6 is provided which is concentric with the axis of rotation and which carries a bearing 7 which is connected to the cylindrical rotor 9 via a ring 8. The pin 6, the bearing 7 and the ring 8 establish a conductive connection between the piston 1 and the rotor 9, so that the rotor is also grounded to the metal piston. The ring 8 and with it the rotor 9 is connected via a further ring 15 to an insulator 11 which is fastened on a shaft 12 carrying the anode disk 2.

Die Zufuhr der Hochspannung an die Anode erfolgt über ein weiteres Lager 13, das in einem mit dem Röhrenkolben 1 verbundenen Isolator angebracht ist, der eine konusförmige Öffnung 16 zur Aufnahme eines Hochspannungssteckers aufweist. Das Kugellager 13 dient zur Lagerung der Welle 12. Die Hochspannung wird der Anodenscheibe 2 also über das Lager 13 und die Welle 12 zugeführt.The high voltage is supplied to the anode via a further bearing 13 which is mounted in an insulator connected to the tube bulb 1, which has a conical opening 16 for receiving a high-voltage plug. The ball bearing 13 serves to support the shaft 12. The high voltage is thus supplied to the anode disk 2 via the bearing 13 and the shaft 12.

Solange die Röntgenröhre thermisch normal belastet wird, finden aufgrund der Form des Isolators 14 keine Entladungsvorgänge statt. Bei sehr starker thermischer Belastung jedoch können auch bei einer derartigen Röntgenröhre Entladungsvorgänge auftreten, insbesondere wenn der Isolator 14 und der Kolben 1 durch eine Hartlötverbindung miteinander verbunden sind. Der kritische Bereich ist dabei der Bereich 17, in dem der Kolben 1, der Isolator 14 und das Vakuum in der Röhre aneinander angrenzen. Dieser Bereich, der sich nicht, wie die Zeichnung vermuten läßt, auf einen Punkt beschränkt, sondern die Welle 12 konzentrisch umschließt, ist dem elektrischen Feld zwischen dem Kolben 1 und der welle 12 ausgesetzt. Er kann bei übermäßiger thermischer Belastung Temperaturen von weit über 100°C annehmen.As long as the X-ray tube is subjected to normal thermal loads, no discharge processes take place due to the shape of the insulator 14. With very strong thermal stress, however, discharge processes can also occur with such an X-ray tube, in particular if the insulator 14 and the piston 1 are connected to one another by a brazed connection. The critical area is the area 17 in which the piston 1, the insulator 14 and the vacuum in the tube adjoin one another. This area, which, as the drawing suggests, is not limited to one point, but concentrically surrounds the shaft 12, is exposed to the electric field between the piston 1 and the shaft 12. If the thermal load is excessive, it can reach temperatures of well over 100 ° C.

Fig. 2 zeigt einen Teil des Metallkolbens mit dem Isolator 14 in teilweise aufgebrochener Darstellung in einem im Vergleich zu Fig. 1 vergrößerten Maßstab mit der erfindungsgemäßen Abschirmelektrode. Die ringförmige Abschirmelektrode 18 befindet sich in unmittelbarer Nähe des Endes des Isolators, in dem sich der kritische Bereich 17 befindet, in dem der Kolben 1, der Isolator und das Vakuum aneinandergrenzen. Die Abschirmelektrode besteht vorzugsweise aus Reineisen oder einem anderen Metall, z.B. CrNi-Stahl, und ist konzentrisch zur Welle 12 auf der Innenseite des Metallkolbens 1 angeschweißt.FIG. 2 shows a part of the metal piston with the insulator 14 in a partially broken-away representation on an enlarged scale compared to FIG. 1 with the shielding electrode according to the invention. The ring-shaped shielding electrode 18 is located in the immediate vicinity of the end of the insulator, in which the critical region 17 is located, in which the piston 1, the insulator and the vacuum adjoin one another. The shielding electrode is preferably made of pure iron or another metal, e.g. CrNi steel, and is welded concentrically to the shaft 12 on the inside of the metal piston 1.

Sowohl die Abschirmelektrode als auch der Isolator sind so geformt, daß sie mit dem Kolben 1 jeweils einen nutenförmigen Hohlraum bilden, der zum Isolator bzw. zur Abschirmelektrode hin offen ist. Durch diese Gestaltung wird einerseits die Feldstärke in dem kritischen Bereich herabgesetzt und andererseits können die durch den Spalt zwischen der Abschirmelektrode 18 und dem Isolator 14 hindurchtretenden Ladungsträger nicht unmittelbar diesen kritischen Bereich treffen.Both the shielding electrode and the insulator are shaped so that they each form a groove-shaped cavity with the piston 1, which is open to the insulator or to the shielding electrode. This design on the one hand reduces the field strength in the critical area and, on the other hand, the charge carriers passing through the gap between the shielding electrode 18 and the insulator 14 cannot hit this critical area directly.

Der Spalt zwischen den einander zugewandten Enden des Isolators 14 und der Abschirmelektrode 18 beträgt etwa 1 mm. Er sdlte aber 3 mm nicht überschreiten. Ist er jedoch wesentlich kleiner als 0,5 mm, dann ergeben sich in diesem Spalt sehr hohe Feldstärken, die zur Feldemission auf der Oberfläche der Abschirmelektrode 18 führen können. Außerdem läßt sich die Abschirmelektrode dann schlecht konditionieren. Ist er wesentlich größer als 3 mm, dann wird das elektrische Feld in dem kritischen Bereich zwischen Metallkolben 1, Isolator 14 und Vakuum kaum durch die Abschirmelektrode 18 herabgesetzt.The gap between the mutually facing ends of the insulator 14 and the shielding electrode 18 is approximately 1 mm. However, it should not exceed 3 mm. However, if it is significantly smaller than 0.5 mm, then very high field strengths result in this gap, which can lead to field emission on the surface of the shielding electrode 18. Furthermore the shielding electrode can then be poorly conditioned. If it is significantly larger than 3 mm, then the electric field in the critical area between metal piston 1, insulator 14 and vacuum is hardly reduced by the shielding electrode 18.

Zweckmäßigerweise wird die Abschirmelektrode z.B. durch Elektropolieren so behandelt, daß sich auf ihrer Oberflächelaum Emissionszentren befinden. Um zu verhindern, daß gleichwohl noch aus ihrer Oberfläche austretende Elektronen auf die der Welle 12 zugewandten Fläche des Isolators treffen können und auf dieser zur Welle 12 bzw. dem damit verbundenen Kugellager 13 (Fig. 1) laufen können, wodurch Entladungsvorgänge ausgelöst werden könnten, sollte die Elektrode 18 so angeordnet sein, daß aus ihr emittierte Elektronen direkt zur Welle 12 laufen und den Isolator nicht erreichen können. Zu diesem Zweck ist die Abschirmelektrode zweckmäßigerweise zurückgesetzt angeordnet, d.h. ihr Innendurchmesser ist so. bemessen, daß-die kegelstumpfförmige, sich zur Abschirmelektrode hin erweiternde Innenmantelfläche des Isolators.14 bzw. deren durch Linien 19 angedeutete Verlängerung die Abschirmelektrode 18 nicht schneiden.The shielding electrode is expediently e.g. treated by electropolishing so that there are emission centers on its surface. In order to prevent electrons that still emerge from their surface from striking the surface of the insulator facing the shaft 12 and from running to the shaft 12 or the associated ball bearing 13 (FIG. 1), which could trigger discharge processes, the electrode 18 should be arranged so that electrons emitted from it run directly to the shaft 12 and cannot reach the insulator. For this purpose, the shielding electrode is expediently arranged in a reset manner, i.e. their inside diameter is like this. dimension that the frusto-conical inner jacket surface of the insulator 14, which extends towards the shielding electrode or its extension indicated by lines 19, does not intersect the shielding electrode 18.

Eine andere Ausführungsform der Erfindung ist in Fig. 3 dargestellt, die einen Ausschnitt aus einer erfindungsgemäßen Röntgenröhre zeigt. Die einander zugewandten Stirnflächen des Isolators 14 und der Abschirmelektrode 18 sind dabei näherungsweise eben und verlaufen ungefähr senkrecht zur Wand des Metallkolbens 1. Dadurch wird zwar die Feldstärke in der kritischen Zone zwischen dem Kolben, dem Isolator 14 und dem Vakuum herabgesetzt, doch können durch den Spalt hindurchtretende Ladungsträger diese Zone unmittelbar erreichen. Diese Ausführungsform ist daher nicht ganz so wirksam wie die in Fig. 2 dargestellte.Another embodiment of the invention is shown in FIG. 3, which shows a section of an X-ray tube according to the invention. The mutually facing end faces of the insulator 14 and the shielding electrode 18 are approximately planar and run approximately perpendicular to the wall of the metal piston 1. Although the field strength in the critical zone between the piston, the insulator 14 and the vacuum is reduced, the Charge carriers passing through the gap reach this zone immediately. This embodiment is therefore not quite as effective as that shown in FIG. 2.

Eine weitere Ausführungsform ist schließlich in Fig. 4 dargestellt. Die Abschirmelektrode 18 ist dabei ähnlich geformt wie in Fig. 2, d.h. sie schließt mit der Wand des Kolbens 1 einen nutenförmigen, umlaufenden und zum Isolator 14 hin offenen Hohlraum ein, in den ein vergleichsweise dünnes Ende des Isolators 14 hineinragt.Another embodiment is finally shown in FIG. 4. The shielding electrode 18 is shaped similarly to that in Fig. 2, i.e. it encloses with the wall of the piston 1 a groove-shaped, circumferential cavity which is open towards the insulator 14 and into which a comparatively thin end of the insulator 14 projects.

Obwohl die Erfindung vorstehend in Verbindung mit einem feststehenden Isolator erläutert wurde, ist sie grundsätzlich auch bei einem rotierenden Isolator anwendbar. Wenn beispielsweise in Fig. 1 der geerdete Metallring 15 so lang wäre, daß sich ein Bereich bzw. eine Zone ergäbe, in der der Vakuumrau, der Metallring 15 und der Isolator 11 aneinander angerenzen und in die das zwischen dem Metallring 15 und der Welle 12 wirksame elektrische Feld eingreifen würde, könnte die Erfindung auch dabei entsprechend angewandt werden.Although the invention was explained above in connection with a fixed insulator, it can in principle also be used with a rotating insulator. If, for example in FIG. 1, the grounded metal ring 15 were so long that there would be an area or a zone in which the vacuum space, the metal ring 15 and the insulator 11 adjoin one another and into which that between the metal ring 15 and the shaft 12 would intervene effective electrical field, the invention could also be applied accordingly.

In der Zeichnung ist der Isolator so geformt, daß die im Betriebszustand auftreffenden Elektronen zumindest auf einem wesentlichen Teil seiner Oberfläche ein elektrisches Feld vorfinden, das sie von der Isolatoroberfläche weg bewegt, weil der kegelstumpfförmige Innenmantel des Isolators sich in Achsrichtung gesehen von dem Verbindungsbereich mit der Elektrode aus erweitert. Anstelle dieser Isolatorform ist die Erfindung jedoch auch bei einer Isolatoranordnung anwendbar, die mit einer konzentrischen Mulde versehen ist und einen von der Mulde umschlossenen, die Elektrode tragenden Isolatorteil aufweist sowie einen äußeren Isolatorteil, der die Mulde umschließt und mit dem leitenden Teil (dem Röhrenkolben oder dem Rotor) verbunden ist.In the drawing, the insulator is shaped in such a way that the electrons striking in the operating state find an electrical field at least on a substantial part of its surface, which moves it away from the surface of the insulator, because the truncated cone-shaped inner jacket of the insulator extends in the axial direction from the connection area with the Electrode extended. Instead of this form of insulator, however, the invention is also applicable to an insulator arrangement which is provided with a concentric trough and has an insulator part which is enclosed by the trough and carries the electrode and an outer insulator part which surrounds the trough and with the conductive part (the tube bulb or the rotor) is connected.

Die Erfindung beschränkt sich auch nicht auf Drehanoden-Röntgenröhren. Sie kann vielmehr auch bei anderen Röntgenröhren sowie bei anderen Hochspannungs-Vakuumröhren (z.B. Neutronenröhren) angewandt werden.The invention is also not limited to rotating anode X-ray tubes. Rather, it can also be used with other X-ray tubes as well as with other high-voltage vacuum tubes (e.g. neutron tubes).

Claims (7)

1. Hochspannungs-Vakuumröhre, insbesondere Röntgenröhre, mit einer in ihrem Vakuumraum befindlichen Elektrode, die im Betriebszustand gegenüber einem sie wenigstens teilweise umschliessenden elektrisch leitenden Teil positive Hochspannung führt, wobei die Elektrode oder ein mit ihr verbundener Teil mit dem leitfähigen Teil über einen Isolator verbunden ist,
dadurch gekennzeichnet, daß im Bereich (17) der Verbindung zwischen dem Isolator (14) und dem leitenden Teil (1) eine das Potential des leitenden Teils (1) führende Abschirmelektrode (18) in geringem Abstand vom Isolator (14) vorgesehen ist, die so geformt ist, daß die elektrische Feldstärke in dem Verbindungsbereich (17) herabgesetzt wird.1. High-voltage vacuum tube, in particular an X-ray tube, with an electrode located in its vacuum space, which in the operating state carries positive high voltage with respect to an electrically conductive part that at least partially surrounds it, the electrode or a part connected to it being connected to the conductive part via an insulator is
characterized in that in the area (17) of the connection between the insulator (14) and the conductive part (1) a shielding electrode (18) carrying the potential of the conductive part (1) is provided at a short distance from the insulator (14) is shaped so that the electric field strength is reduced in the connection region (17). 2. Hochspannungs-Vakuumröhre nach Anspruch 1,
dadurch gekennzeichnet, daß die Abschirmelektrode (18) gegenüber dem Isolator (14) so angeordnet ist, daß von der von dem leitenden Teil (1) abgewandten Oberfläche der Abschirmelektrode emittierte Elektronen größtenteils nicht auf die Innenfläche des Isolators (14) treffen können.2. High-voltage vacuum tube according to claim 1,
characterized in that the shielding electrode (18) is arranged opposite the insulator (14) in such a way that most of the electrons emitted from the surface of the shielding electrode facing away from the conductive part (1) cannot strike the inner surface of the insulator (14). 3. Hochspannungs-Vakuumröhre nach Anspruch 2,
dadurch gekennzeichnet, daß die Abschirmelektrode (18) gegenüber der durch die Innenfläche des Isolators (14) gegebenen Mantelfläche (19) zurückgesetzt angeordnet ist, derart, daß sie von der Fortsetzung (19) der kegelmantelförmigen Innenfläche des Isolators (14) nicht geschnitten wird.3. High-voltage vacuum tube according to claim 2,
characterized in that the shielding electrode (18) is set back from the lateral surface (19) given by the inner surface of the insulator (14), such that it is not cut by the continuation (19) of the conical outer surface of the insulator (14). 4. Hochspannungs-Vakuumröhre nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Abschirmelektrode (18) so geformt ist, daß zwischen ihr und dem leitenden Teil (1) ein zum Isolator hin offener Hohlraum eingeschlossen wird (Fig. 2).4. High-voltage vacuum tube according to one of the preceding claims, characterized in that the shielding electrode (18) is shaped so that between it and the conductive part (1) an open to the insulator cavity is enclosed (Fig. 2). 5. Hochspannungs-Vakuumröhre nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Isolator so geformt ist, daß zwischen ihn und dem leitenden Teil ein zur Abschirmelektrode offener Hohlraum eingeschlossen wird (Fig. 2).5. High-voltage vacuum tube according to one of the preceding claims, characterized in that the insulator is shaped so that an open to the shielding electrode cavity is enclosed between him and the conductive part (Fig. 2). 6. Hochspannungs-Vakuumröhre nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die der Abschirmelektrode zugewandte Stirnfläche des Isolators eben ist und ungefähr senkrecht zur Wand verläuft (Fig. 3).6. High-voltage vacuum tube according to one of the preceding claims, characterized in that the end face of the insulator facing the shielding electrode is flat and extends approximately perpendicular to the wall (Fig. 3). 7. Hochspannungs-Vakuumröhre nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die dem Isolator zugewandte Stirnfläche der Abschirmelektrode eben ist und ungefähr senkrecht zur Oberfläche des leitenden Teils verläuft (Fig. 3).7. High-voltage vacuum tube according to one of the preceding claims, characterized in that the end face of the shielding electrode facing the insulator is flat and extends approximately perpendicular to the surface of the conductive part (Fig. 3).
EP82200452A 1981-04-23 1982-04-14 High tension vacuum tube, particularly x ray tube Expired EP0063840B1 (en)

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DE3116169 1981-04-23
DE19813116169 DE3116169A1 (en) 1981-04-23 1981-04-23 HIGH VOLTAGE VACUUM TUBES, ESPECIALLY X-RAY TUBES

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EP0063840B1 EP0063840B1 (en) 1985-10-16

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EP (1) EP0063840B1 (en)
JP (1) JPS57182952A (en)
CA (1) CA1184231A (en)
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WO1986005921A1 (en) * 1985-03-28 1986-10-09 Gesellschaft Für Elektronische Röhren Comet Bern X-ray tube with a cylindrical metal component enclosing the anode and cathode
DE4241572A1 (en) * 1992-10-02 1994-04-28 Licentia Gmbh High voltage tube
US5402464A (en) * 1992-10-02 1995-03-28 Licentia Patent-Verwaltungs-Gmbh High-voltage electronic tube
DE102009025841B4 (en) * 2008-05-19 2015-09-17 General Electric Company Apparatus for a compact high voltage insulator for an X-ray and vacuum tube and method of assembling same
WO2019011993A1 (en) * 2017-07-11 2019-01-17 Thales Compact source for generating ionizing rays

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JPS60163355A (en) * 1984-02-03 1985-08-26 Toshiba Corp X-ray tube
US6901136B1 (en) * 2003-12-02 2005-05-31 Ge Medical Systems Global Technology Co., Llc X-ray tube system and apparatus with conductive proximity between cathode and electromagnetic shield
JP5278895B2 (en) * 2008-04-25 2013-09-04 株式会社日立メディコ Anode grounded X-ray tube equipment
US7783012B2 (en) * 2008-09-15 2010-08-24 General Electric Company Apparatus for a surface graded x-ray tube insulator and method of assembling same
US9384932B2 (en) 2010-10-27 2016-07-05 Schlumberger Technology Corporation Thick-film resistorized ceramic insulators for sealed high voltage tube electrodes
DE102014018449B3 (en) 2014-12-12 2016-06-09 Audi Ag Electric machine
CN112216584B (en) * 2020-10-09 2024-05-14 西门子爱克斯射线真空技术(无锡)有限公司 X-ray generator with shielding member
DE102022209314B3 (en) * 2022-09-07 2024-02-29 Siemens Healthcare Gmbh X-ray tube with at least one electrically conductive housing section
CN117596759B (en) * 2024-01-19 2024-04-05 上海超群检测科技股份有限公司 X-ray apparatus

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
WO1986005921A1 (en) * 1985-03-28 1986-10-09 Gesellschaft Für Elektronische Röhren Comet Bern X-ray tube with a cylindrical metal component enclosing the anode and cathode
DE4241572A1 (en) * 1992-10-02 1994-04-28 Licentia Gmbh High voltage tube
US5402464A (en) * 1992-10-02 1995-03-28 Licentia Patent-Verwaltungs-Gmbh High-voltage electronic tube
DE102009025841B4 (en) * 2008-05-19 2015-09-17 General Electric Company Apparatus for a compact high voltage insulator for an X-ray and vacuum tube and method of assembling same
WO2019011993A1 (en) * 2017-07-11 2019-01-17 Thales Compact source for generating ionizing rays
FR3069100A1 (en) * 2017-07-11 2019-01-18 Thales COMPACT IONIZING RAY GENERATING SOURCE, MULTIPLE SOURCE ASSEMBLY AND SOURCE REALIZATION METHOD
US11101097B2 (en) 2017-07-11 2021-08-24 Thales Compact source for generating ionizing radiation, assembly comprising a plurality of sources and process for producing the source

Also Published As

Publication number Publication date
DE3116169A1 (en) 1982-11-11
IL65554A (en) 1985-04-30
EP0063840B1 (en) 1985-10-16
JPH0355933B2 (en) 1991-08-26
DE3266898D1 (en) 1985-11-21
US4499592A (en) 1985-02-12
JPS57182952A (en) 1982-11-11
CA1184231A (en) 1985-03-19
IL65554A0 (en) 1982-07-30

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