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EP0215034A1 - X-ray tube with a cylindrical metal component enclosing the anode and cathode. - Google Patents

X-ray tube with a cylindrical metal component enclosing the anode and cathode.

Info

Publication number
EP0215034A1
EP0215034A1 EP86901329A EP86901329A EP0215034A1 EP 0215034 A1 EP0215034 A1 EP 0215034A1 EP 86901329 A EP86901329 A EP 86901329A EP 86901329 A EP86901329 A EP 86901329A EP 0215034 A1 EP0215034 A1 EP 0215034A1
Authority
EP
European Patent Office
Prior art keywords
ceramic insulator
ray tube
ceramic
cathode
anode
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
EP86901329A
Other languages
German (de)
French (fr)
Other versions
EP0215034B1 (en
Inventor
Engelbert Berger
Dieter-W Zickert
Peter Gutknecht
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.)
GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN
Original Assignee
GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN
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 GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN filed Critical GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN
Priority to AT86901329T priority Critical patent/ATE40767T1/en
Publication of EP0215034A1 publication Critical patent/EP0215034A1/en
Application granted granted Critical
Publication of EP0215034B1 publication Critical patent/EP0215034B1/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith

Definitions

  • the present invention relates to an X-ray tube with a cylindrical metal part surrounding the anode and the cathode, of which at least one of the electrodes anode and cathode is electrically insulated by means of a disk-shaped ceramic insulator which is attached to an axial end of the metal is partially arranged.
  • Known x-ray tubes of this type have shields in the interior of the cylindrical metal part, which are shaped and arranged in such a way that the electrical field resulting on the inner surfaces of the ceramic insulators points in its direction away from the insulator surface against the interior of the x-ray tube. This largely prevents the inside surfaces of the ceramic insulators, which are hit by unavoidable field emission electrons, from becoming electrically charged as a result of secondary electron emission and thereby reducing the dielectric strength of the X-ray tube.
  • the disk-shaped ceramic insulator is designed in a stepped or ramp-shaped manner in radial directions on its axial end surface facing away from the interior of the X-ray tube in order to form an annular axial recess which is filled with an insulating material whose dielectric constant is less than that of the ceramic material and that in the case of a ceramic insulator that insulates the anode from the metal part, the recess is arranged radially on the inside and in the case of a ceramic insulator that insulates the cathode of the metal part, the recess is arranged radially on the outside.
  • This configuration of the X-ray tube ensures, in a surprisingly simple manner, that the direction of the electric field on the inner insulator surface points away from the insulator surface into the interior of the tube.
  • the electrical field strength is reduced at the locations where the field emission primarily occurs, namely at the so-called triple points.
  • the triple point is located on the cathode side in the soldering-technical connection between the ceramic insulator and the high-voltage supply in the center of the insulator.
  • the triple point lies in the soldering connection between the outer circumference of the ceramic insulator and the cylindrical metal part.
  • the insulating material filling the recess of the ceramic insulator can be a part of a rubber-elastic disc which is pressed in the axial direction onto the step-shaped or ramp-shaped end face of the ceramic insulator.
  • FIG. 1 shows an axial longitudinal section through an X-ray tube designed according to the invention with associated connecting parts
  • 4 and 5 are analog sectional views of two further exemplary embodiments of the anode-side ceramic insulator.
  • the X-ray tube shown has a cylindrical metal part 11 which is provided with a window 12 inserted in a vacuum-tight manner for the exit of the X-ray radiation.
  • a window 12 inserted in a vacuum-tight manner for the exit of the X-ray radiation.
  • annular disk-shaped ceramic insulator 13 At the upper axial end of the metal part 11 in FIG. 1 there is an annular disk-shaped ceramic insulator 13, the outer periphery of which is connected to the metal part 11 in a vacuum-tight manner.
  • the axial end face 16 of the ceramic insulator 13 facing away from the interior of the metal part 11 is offset radially outwards by a step 17 running in the circumferential direction, so that an annular axial recess 18 is formed on the ceramic insulator 13 adjacent to its outer circumference.
  • This depression 18 is filled by a part 19 of a rubber-elastic washer 20 which is pressed onto the ceramic insulator 13 in a manner known per se by means of a connecting part 21.
  • the rubber-elastic washer 20 has a smaller dielectric constant than the ceramic insulator 13.
  • there is a layer of insulation grease (not shown in FIG.
  • the interior of the metal part 11 facing axial end surface 26 of the ab ⁇ 'ceramic insulator 23 is deposited by a Windier extending in the circumferential direction stage 27 ein ⁇ radially, so that the ceramic insulator 23 adjacent its inner periphery an annular axial recess
  • This recess 28 is formed. This recess 28 is by a lot
  • the rubber-elastic washer 30 is pressed onto the ceramic insulator 23 in a manner not known per se by means of a connecting part 31.
  • the rubber-elastic washer 30 has a smaller dielectric constant than the ceramic insulator 23.
  • the metal part 11 is connected to earth potential, while a voltage which is negative with respect to the earth potential is applied to the cathode 1 through the connection part 21 and a voltage which is positive with respect to the earth potential is applied through the connection part 31 to the anode 25.
  • Potential lines then appear in the interior of the tube, as indicated, for example, by the dashed lines 32 and 33 in FIG. 1.
  • the potential lines 32 in the region of the ceramic insulator 13 assume a diverging profile that deviates from the axis-parallel direction, in such a way that on the flat inner end face 3 ⁇ of the ceramic insulator 13, the electrical field vectors 35, which are always at right angles to the potential lines 32, have directions pointing away from the ceramic insulator 13 towards the interior of the X-ray tube.
  • the depression 28 of the other ceramic insulator 23, which is filled with insulating material 29 with a lower dielectric constant, has the result that the potential lines 33 in the area of the ceramic insulator 23 assume a converging course and therefore the electric field vectors 36 on the flat inner end surface 37 of the ceramic insulator 23 have directions facing away from the inside of the X-ray tube.
  • the angle between the field vectors 35 and 36 on the one hand and the inner end surface 34 and 37 of the ceramic insulator 13 and 23 on the other hand is due to the difference in the dielectric constant of the ceramic material and the rubber-elastic insulating material due to the radial width and the axial depth of the Indentation 18 and 28 and determined by the dimensions of the ceramic insulator 13 and 23 respectively.
  • the X-ray tube according to FIG. 1 has a noticeably higher joint dielectric strength.
  • the advantages described were checked and confirmed using a test X-ray tube.
  • the experimental X-ray tube with the structure shown in FIG. 1 had ceramic insulators 13 and 23 with an outside diameter of 107 mm and an inside diameter of 45 mm.
  • the axial thickness dimension of the ceramic insulators was 10 mm and was reduced to 7 mm at the location of the recess 18 or 28, so that the steps 17 and 27 had a height of 3 mm.
  • the rubber-elastic washers 20 and 30 consisted of silicone rubber with a dielectric constant of 3.2 and a Shore hardness of 28.
  • each rubber-elastic washer 20 and 30 were flat and parallel, and the outside - The knife was 100 mm, the inside diameter was 45 mm and the axial thickness was 10 mm.
  • the X-ray tube could easily be operated with a voltage of up to 340 kV between the anode and cathode.
  • the ceramic insulator 113 shown in FIG. 2 for the cathode side of the X-ray tube has, on its axial end face 116 to be turned outwards, two steps 117 running in the circumferential direction, by means of which an axial recess 118 adjacent to the outer circumference of the ceramic insulator is formed.
  • the example of a ceramic insulator 213 shown in FIG. 3 for the cathode side of the X-ray tube has a ramp-shaped step 217 on its axial end face 216 to be turned outwards, by means of which an axial depression 218 adjoining the outer circumference of the ceramic insulator is formed.
  • the ceramic insulator 123 shown in FIG. 4 for the anode side of the X-ray tube has on its outward-facing axial end face 126 two steps 117 running in the circumferential direction, by means of which an axial depression 128 adjacent to the inner circumference of the ceramic isolator is formed.
  • the ceramic insulator 223 for the anode side of the X-ray tube can also have a ramp-shaped step 227 on the axial end surface to be turned outwards, so that an axial recess 228 adjacent to the inner circumference of the ceramic insulator is formed .
  • the depressions 118, 218, 128 and 228 of the ceramic insulators 113, 213, 123 and 223 according to FIGS. 2 to 5 are each made with rubber-elastic insulating material when the X-ray tube is assembled or installed, the dielectric constant of which is smaller than that of the ceramic material, completely filled out. '
  • X-ray tubes in which the cathode or the anode is electrically conductively connected to the cylindrical metal part.
  • the cathode or the anode is electrically conductively connected to the cylindrical metal part.
  • only the other anode or cathode is insulated from the cylindrical metal part by a ceramic insulator.
  • the invention can also be used with such X-ray tubes in that the then only existing ceramic insulator in the manner described above is provided on its axial end surface facing away from the inside of the X-ray tube with a depression which is completely filled with an insulating material whose dielectric constant is smaller than that of the ceramic material.

Landscapes

  • X-Ray Techniques (AREA)
  • Microwave Tubes (AREA)

Abstract

In order to increase the dielectrical resistance without resorting to internal shielding, the ring plate shaped ceramic insulators (13, 23) which carry the cathode (15) and the anode (25) at the axial inside end surfaces (16, 26) of the X-ray tube are stepped down in radial directions by a step (17, 27) in order to permit the forming of an axial hollow (18, 28) running in the form of a ring. On the ceramic insulator (13) which carries the cathode (15), the hollow (18) borders on the external periphery of the ceramic insulator. Conversely, the hollow (28) on the ceramic insulator (23) carrying the anode (25) borders on the inside periphery of the ceramic insulator. Each of the hollows is entirely filled with an insulation material (19, 29), the dielectric constant of which is less than that of the ceramic material. This insulation material (19, 29) is functionally part of a rubber-elastic ring plate (20, 30) which is pressed onto the outer axial end surface of the respective ceramic insulator (13, 23).

Description

Röntgenröhre mit einem die Anode und die Kathode umgebenden zylindrischen MetallteilX-ray tube with a cylindrical metal part surrounding the anode and the cathode
Die vorliegende Erfindung betrifft eine Röntgenröhre mit ei¬ nem die Anode und die Kathode umgebenden zylindrischen Metall¬ teil, von welchem zumindest eine der Elektroden Anode und Ka¬ thode mittels eines scheibenförmigen Keramikisolators elek¬ trisch isoliert ist, der an einem achsialen Ende des Metall¬ teils angeordnet ist.The present invention relates to an X-ray tube with a cylindrical metal part surrounding the anode and the cathode, of which at least one of the electrodes anode and cathode is electrically insulated by means of a disk-shaped ceramic insulator which is attached to an axial end of the metal is partially arranged.
Bekannte Röntgenröhren dieser Art weisen im Innenraum des zylindrischen Metallteils Abschirmungen auf, die derart ge¬ formt und angeordnet sind, dass das sich auf den inneriliegen- den Flächen der Keramikisolatoren ergebende elektrische Feld seiner Richtung nach von der Isolatorfläche weg gegen den Innenraum der Röntgenröhre weist. Hierdurch lässt sich weit¬ gehend verhüten, dass die von unvermeidbaren Feldemissions- Ξlektronen getroffenen Innenflächen der Keramikisolatoren sich infolge von Sekundärelektronen-Emission elektrisch aufladen und dadurch die Spannungsfestigkeit der Röntgenröhre herabge¬ setzt wird.Known x-ray tubes of this type have shields in the interior of the cylindrical metal part, which are shaped and arranged in such a way that the electrical field resulting on the inner surfaces of the ceramic insulators points in its direction away from the insulator surface against the interior of the x-ray tube. This largely prevents the inside surfaces of the ceramic insulators, which are hit by unavoidable field emission electrons, from becoming electrically charged as a result of secondary electron emission and thereby reducing the dielectric strength of the X-ray tube.
Aufgabe der vorliegenden Erfindung ist es, eine Röntgenröhre der eingangs genannten Art zu schaffen, bei welcher die er¬ wähnten Abschirmungen entbehrlich sind und dennoch an der Innenfläche des oder jedes Keramikisolators das elektrische Feld seiner Richtung nach von der Isolatorfläche weg gegen das Röhreninnere weist.It is an object of the present invention to provide an X-ray tube of the type mentioned at the outset, in which the shields mentioned are dispensable and yet the electrical field on the inner surface of the or each ceramic insulator points in the direction away from the insulator surface against the interior of the tube.
Diese Aufgabe ist erfindungsgemäss dadurch gelöst, dass der scheibenförmige Keramikisolator an seiner vom Innenraum der Röntgenröhre abgewandten achsialen Endfläche in radialen Richtungen stufen- oder rampenförmig ausgebildet ist zur Bildung einer ringförmig verlaufenden achsialen Vertiefung, die mit einem Isoliermaterial ausgefüllt ist, dessen Dielek¬ trizitätskonstante kleiner als diejenige des Keramikmaterials ist, und dass im Falle eines die Anode vom Metallteil iso¬ lierenden Keramikisolators die Vertiefung radial innen und im Fall eines die Kathode vom Metallteil isolierenden Kera¬ mikisolators die Vertiefung radial aussen angeordnet ist.This object is achieved according to the invention in that the disk-shaped ceramic insulator is designed in a stepped or ramp-shaped manner in radial directions on its axial end surface facing away from the interior of the X-ray tube in order to form an annular axial recess which is filled with an insulating material whose dielectric constant is less than that of the ceramic material and that in the case of a ceramic insulator that insulates the anode from the metal part, the recess is arranged radially on the inside and in the case of a ceramic insulator that insulates the cathode of the metal part, the recess is arranged radially on the outside.
Durch diese Ausbildung der Röntgenröhre wird auf überraschend einfache Weise erreicht, dass an der innenliegenden Isola¬ torfläche das elektrische Feld seiner Richtung nach von der Isolatorfläche weg in das Röhreninnere weist. Zusätzlich er¬ gibt sich die vorteilhafte Wirkung, dass die elektrische Feldstärke an den Orten, an denen die Feldemmission vornehm¬ lich einsetzt, nämlich an den sogenannten Triple-Punkten, reduziert ist. Auf der Kathodenseite befindet sich der Triple- Punkt in der löttechnisehen Verbindung zwischen dem Keramik¬ isolator und der Hochspannungszuführung im Zentrum des Iso¬ lators. Auf der Anodenseite hingegen liegt der Triple-Punkt in der löttechnischen Verbindung zwischen dem Aussenumfang des Keramikisolators und dem zylindrischen Metallteil. Die beiden durch die erfindungsgemässe Ausbildung erzielten Effekte tra¬ gen zu einer-merklichen Erhöhung der Spannungsfestigkeit der Röntgenröhre bei.This configuration of the X-ray tube ensures, in a surprisingly simple manner, that the direction of the electric field on the inner insulator surface points away from the insulator surface into the interior of the tube. In addition, there is the advantageous effect that the electrical field strength is reduced at the locations where the field emission primarily occurs, namely at the so-called triple points. The triple point is located on the cathode side in the soldering-technical connection between the ceramic insulator and the high-voltage supply in the center of the insulator. On the anode side, on the other hand, the triple point lies in the soldering connection between the outer circumference of the ceramic insulator and the cylindrical metal part. The two effects achieved by the design according to the invention contribute to a noticeable increase in the dielectric strength of the X-ray tube.
In zweckmässiger Ausgestaltung der erfindungsgemässen Röntgen¬ röhre kann das die Vertiefung des Keramikisolators ausfüllen¬ de Isoliermaterial eine Partie einer gummielastischen Scheibe sein, die in achsialer Richtung an die stufen- oder rampen- förmig ausgebildete Endfläche des Keramikisolators angepresst ist.In an expedient embodiment of the X-ray tube according to the invention, the insulating material filling the recess of the ceramic insulator can be a part of a rubber-elastic disc which is pressed in the axial direction onto the step-shaped or ramp-shaped end face of the ceramic insulator.
Weitere Einzelheiten und Vorteile ergeben sich aus der nun folgenden Beschreibung von Ausführungsbeispielen der Röntgen¬ röhre gemäss der Erfindung sowie aus der zugehörigen Zeich¬ nung, anhand welcher die Erfindung rein beispielsweise erläu¬ tert wird. Fig. 1 zeigt einen achsialen Längsschnitt durch eine nach der Erfindung ausgebildete Röntgenröhre mit zuge¬ hörigen Anschlussteilen;Further details and advantages result from the following description of exemplary embodiments of the X-ray tube according to the invention and from the associated drawing, on the basis of which the invention is explained purely by way of example. 1 shows an axial longitudinal section through an X-ray tube designed according to the invention with associated connecting parts;
Fig. 2 und 3 zeigen je einen achsialen Schnitt durch zwei andere Ausführungsbeispiele des kathodenseitigen Ke¬ ramikisolators;2 and 3 each show an axial section through two other exemplary embodiments of the cathode-side ceramic insulator;
Fig. 4 und 5 sind analoge Schnittdarstellungen von zwei weiteren Ausführungsbeispielen des anodenseitigen Keramikisolators.4 and 5 are analog sectional views of two further exemplary embodiments of the anode-side ceramic insulator.
Gemäss Fig. 1 weist die dargestellte Röntgenröhre einen zylindrischen Metallteil 11 auf, der mit einem vakuumdicht eingesetzten Fenster 12 für den Austritt der Röntgenstrah¬ lung versehen ist. An dem in Fig. 1 oberen achsialen Ende des Metallteils 11 befindet sich ein ringscheibenförmiger Kera¬ mikisolator 13, dessen äusserer Umfang mit dem Metallteil 11 vakuumdicht verbunden ist. In der zentralen Durchbrechung des Keramikisolators 13 sitzt ebenfalls vakuumdicht eine Hochspannungsdurchführung 1 , welche die Kathode 15 der Röntgenröhre trägt. Die vom Innenraum des Metallteils 11 ab¬ gewandte achsiale Endfläche 16 des Keramikisolators 13 ist durch eine in Umfangsrichtung verlaufende Stufe 17 radial auswärts abgesetzt, so dass am Keramikisolator 13 angrenzend an seinen äusseren Umfang eine ringförmige achsiale Vertie¬ fung 18 gebildet ist. Diese Vertiefung 18 ist durch eine Par¬ tie 19 einer gummielastischen Ringscheibe 20 ausgefüllt, die mittels eines Anschlussteiles 21 auf nicht dargestellte, an sich bekannte Weise an den Keramikisolator 13 angepresst ist. Die gummielastische Ringscheibe 20 weist eine kleinere Di¬ elektrizitätskonstante als der Keramikisolator 13 auf. Zweck- massig befinden sich in den Fugen zwischen dem Keramikisola¬ tor 13 und der gummielastischen Ringscheibe 20 wie auch zwi¬ schen dem Anschlussteil 21 und der gummielastischen Ring¬ scheibe 20 je eine (in Fig. 1 nicht dargestellte) Schicht Isolationsfett. An dem in Fig. 1 unteren achsialen Ende des zylindrischen Metallteils 11 befindet sich ebenfalls ein ringscheibenförmi¬ ger Keramikisolator 23, dessen äusserer Umfang mit dem Metall¬ teil 11 vakuumdicht verbunden ist. In der zentralen Durch¬ brechung des Keramikisolators 23 sitzt ebenfalls vakuumdicht eine Hochspannungsdurchführung 24, welche die Anode 25 der Röntgenröhre trägt. Die vom Innenraum des Metallteils 11 ab¬ gewandte achsiale Endfläche 26 des'Keramikisolators 23 ist durch eine in Umfangsrichtung verlaufende Stufe 27 radial ein¬ wärts abgesetzt, so dass am Keramikisolator 23 angrenzend an seinen inneren Umfang eine ringförmige achsiale Vertiefung1, the X-ray tube shown has a cylindrical metal part 11 which is provided with a window 12 inserted in a vacuum-tight manner for the exit of the X-ray radiation. At the upper axial end of the metal part 11 in FIG. 1 there is an annular disk-shaped ceramic insulator 13, the outer periphery of which is connected to the metal part 11 in a vacuum-tight manner. A high-voltage bushing 1, which carries the cathode 15 of the X-ray tube, also sits in a vacuum-tight manner in the central opening of the ceramic insulator 13. The axial end face 16 of the ceramic insulator 13 facing away from the interior of the metal part 11 is offset radially outwards by a step 17 running in the circumferential direction, so that an annular axial recess 18 is formed on the ceramic insulator 13 adjacent to its outer circumference. This depression 18 is filled by a part 19 of a rubber-elastic washer 20 which is pressed onto the ceramic insulator 13 in a manner known per se by means of a connecting part 21. The rubber-elastic washer 20 has a smaller dielectric constant than the ceramic insulator 13. Appropriately, there is a layer of insulation grease (not shown in FIG. 1) in the joints between the ceramic insulator 13 and the rubber-elastic washer 20 and also between the connecting part 21 and the rubber-elastic washer 20. At the lower axial end of the cylindrical metal part 11 in FIG. 1 there is also an annular disk-shaped ceramic insulator 23, the outer periphery of which is connected to the metal part 11 in a vacuum-tight manner. A high-voltage bushing 24, which carries the anode 25 of the X-ray tube, also sits in a vacuum-tight manner in the central opening of the ceramic insulator 23. The interior of the metal part 11 facing axial end surface 26 of the ab¬ 'ceramic insulator 23 is deposited by a Windwärts extending in the circumferential direction stage 27 ein¬ radially, so that the ceramic insulator 23 adjacent its inner periphery an annular axial recess
28 gebildet ist. Diese Vertiefung 28 ist durch eine Partie28 is formed. This recess 28 is by a lot
29 einer gummielastischen Ringscheibe 30 vollständig ausge¬ füllt. Mittels eines Anschlussteiles 31 ist die gummielasti¬ sche Ringscheibe 30 auf nicht dargestellte, an sich bekannte Weise an den Keramikisolator 23 angepresst. Die gummielasti¬ sche Ringscheibe 30 weist eine kleinere Dielektrizitätskon¬ stante als der Keramikisolator 23 auf. In den Fugen zwischen dem Keramikisolator 23 und der gummielastischen Ringscheibe29 of a rubber-elastic washer 30 completely filled. The rubber-elastic washer 30 is pressed onto the ceramic insulator 23 in a manner not known per se by means of a connecting part 31. The rubber-elastic washer 30 has a smaller dielectric constant than the ceramic insulator 23. In the joints between the ceramic insulator 23 and the rubber-elastic washer
30 wie auch zwischen dem Anschlussteil 31 und der gummielasti¬ schen Ringscheibe 30 befindet sich zweckmässig je eine (nicht dargestellte) Schicht Isolationsfett.30 as well as between the connecting part 31 and the rubber-elastic washer 30 there is expediently one layer (not shown) of insulation grease.
Zum Betrieb der beschriebenen Röntgenröhre wird der Metallteil 11 auf Erdpotential gelegt, während an die Kathode 1 eine gegenüber dem Erdpotential negative Spannung durch den An¬ schlussteil 21 hindurch und an die Anode 25 eine gegenüber dem Erdpotential positive Spannung durch den Anschlussteil 31 hindurch angelegt wird. Im Innenraum der Röhre stellen sich dann Potentiallinien ein, wie sie z.B. durch die gestrichel¬ ten Linien 32 und 33 in Fig. 1 angedeutet sind. Infolge der Vertiefung 18 des Keramikisolators 13, welche mit Isolier¬ material 19 mit niedrigerer Dielektrizitätskonstante ausge¬ füllt ist, nehmen die Potentiallinien 32 im Bereich des Ke¬ ramikisolators 13 einen von der achsparallelen Richtung abweichenden,divergierenden Verlauf an, und zwar derart, dass an der ebenen inneren Endfläche 3^ des Keramikisolators 13 die zu den Potentiallinien 32 stets rechtwinklig stehenden elektrischen Feldvektoren 35 vom Keramikisolator 13 weg gegen den Innenraum der Röntgenröhre weisende Richtungen haben. Aehnlich hat die Vertiefung 28 des andern Keramikisolators 23, welche mit Isoliermaterial 29 mit niedrigerer Dielektrizitäts¬ konstante ausgefüllt ist, zur Folge, dass die Potentiallinien 33 im Bereich des Keramikisolators 23 einen konvergierenden Verlauf annehmen und deshalb die elektrischen Feldvektoren 36 an der ebenen inneren Endfläche 37 des Keramikisolators 23 von diesem weg gegen das Innere der Röntgenröhre weisende Richtungen haben. Der Winkel zwischen den Feldvektoren 35 bzw. 36 einerseits und der inneren Endfläche 34 bzw. 37 des Keramik¬ isolators 13 bzw. 23 anderseits ist durch den Unterschied der Dielektrizitätskonstanten des Keramikmaterials und des gummi- elastischen Isoliermaterials durch die radiale Breite und die achsiale Tiefe der Vertiefung 18 bzw. 28 und durch die Abmes¬ sungen des Keramikisolators 13 bzw. 23 bestimmt. Weil sowohl auf der Kathodenseite als auch der Anodenseite die elektrische Feldstärke ihrer Richtung nach von der dortigen inneren End¬ fläche des Keramikisolators 13 bzw. 23 weg ins Innere der Röntgenröhre weist, sind Aufladungen an den Keramikisolatoren 13 und 23 wie auch damit verbundene Feldstärkenüberhöhungen wirksam vermieden. Im Vergleich zu ähnlichen bekannten Rönt¬ genröhren, bei denen die Keramikisolatoren jeweils ebene äussere Endflächen ohne die Stufen 17 und 27 aufweisen, hat die Röntgenröhre gemäss Fig. 1 eine merklich höhere Fugen- Spannungsfestigkeit.To operate the described X-ray tube, the metal part 11 is connected to earth potential, while a voltage which is negative with respect to the earth potential is applied to the cathode 1 through the connection part 21 and a voltage which is positive with respect to the earth potential is applied through the connection part 31 to the anode 25. Potential lines then appear in the interior of the tube, as indicated, for example, by the dashed lines 32 and 33 in FIG. 1. As a result of the recess 18 in the ceramic insulator 13, which is filled with insulating material 19 with a lower dielectric constant, the potential lines 32 in the region of the ceramic insulator 13 assume a diverging profile that deviates from the axis-parallel direction, in such a way that on the flat inner end face 3 ^ of the ceramic insulator 13, the electrical field vectors 35, which are always at right angles to the potential lines 32, have directions pointing away from the ceramic insulator 13 towards the interior of the X-ray tube. Similarly, the depression 28 of the other ceramic insulator 23, which is filled with insulating material 29 with a lower dielectric constant, has the result that the potential lines 33 in the area of the ceramic insulator 23 assume a converging course and therefore the electric field vectors 36 on the flat inner end surface 37 of the ceramic insulator 23 have directions facing away from the inside of the X-ray tube. The angle between the field vectors 35 and 36 on the one hand and the inner end surface 34 and 37 of the ceramic insulator 13 and 23 on the other hand is due to the difference in the dielectric constant of the ceramic material and the rubber-elastic insulating material due to the radial width and the axial depth of the Indentation 18 and 28 and determined by the dimensions of the ceramic insulator 13 and 23 respectively. Because both on the cathode side and on the anode side the electrical field strength points in their direction away from the inner end face of the ceramic insulator 13 and 23 into the interior of the X-ray tube, charges on the ceramic insulators 13 and 23 as well as the associated field strength increases are effectively avoided . In comparison to similar known X-ray tubes, in which the ceramic insulators each have flat outer end faces without steps 17 and 27, the X-ray tube according to FIG. 1 has a noticeably higher joint dielectric strength.
Die geschilderten Vorteile wurden anhand einer Versuchs- Röntgenröhre überprüft und bestätigt gefunden. Die Versuchs- Röntgenrδhre mit dem in Fig. 1 gezeigten Aufbau wies Keramik¬ isolatoren 13 und 23 mit einem Aussendurchmesser von 107 mm, einem Innendurchmesser von 45 mm auf. Die achsiale Dicken¬ abmessung der Keramikisolatoren betrug 10 mm und war an der Stelle der Vertiefung 18 bzw. 28 auf 7 mm reduziert, so dass die Stufe 17 bzw. 27 eine Höhe von 3 mm hatte. Die gummi- elastischen Ringscheiben 20 und 30 bestanden aus Silikon¬ kautschuk mit einer Dielektrizitätskonstante von 3,2 und einer Shorehärte von 28. In unbelastetem Zustand waren die beiden achsialen Endflächen jeder gummielastischen Ring¬ scheibe 20 bzw. 30 eben und parallel, und der Aussendurch- messer betrug 100 mm, der Innendurchmesser 45 mm und die achsiale Dicke 10 mm. Die Röntgenröhre liess sich problemlos mit einer Spannung bis zu 340 kV zwischen Anode und Kathode betreiben.The advantages described were checked and confirmed using a test X-ray tube. The experimental X-ray tube with the structure shown in FIG. 1 had ceramic insulators 13 and 23 with an outside diameter of 107 mm and an inside diameter of 45 mm. The axial thickness dimension of the ceramic insulators was 10 mm and was reduced to 7 mm at the location of the recess 18 or 28, so that the steps 17 and 27 had a height of 3 mm. The rubber-elastic washers 20 and 30 consisted of silicone rubber with a dielectric constant of 3.2 and a Shore hardness of 28. In the unloaded state, the two axial end faces of each rubber-elastic washer 20 and 30 were flat and parallel, and the outside - The knife was 100 mm, the inside diameter was 45 mm and the axial thickness was 10 mm. The X-ray tube could easily be operated with a voltage of up to 340 kV between the anode and cathode.
Praktisch gleich gute Ergebnisse lassen sich erzielen, wenn die Keramikisolatoren etwa gemäss den in den Fig. 2 bis 5 ge¬ zeigten Ausführungsbeispielen geformt sind.Practically equally good results can be achieved if the ceramic insulators are shaped approximately according to the exemplary embodiments shown in FIGS. 2 to 5.
Der in Fig. 2 dargestellte Keramikisolator 113 für die Ka¬ thodenseite der Röntgenröhre weist an seiner nach aussen zu wendenden achsialen Endfläche 116 zwei in Umfangsrichtung verlaufende Stufen 117 auf, durch welche eine an den Aussen¬ umfang des Keramikisolators angrenzende achsiale Vertiefung 118 gebildet ist.The ceramic insulator 113 shown in FIG. 2 for the cathode side of the X-ray tube has, on its axial end face 116 to be turned outwards, two steps 117 running in the circumferential direction, by means of which an axial recess 118 adjacent to the outer circumference of the ceramic insulator is formed.
Das in Fig. 3 gezeigte Beispiel eines Keramikisolators 213 für die Kathodenseite der Röntgenröhre weist an seiner nach aussen zu wendenden achsialen Endfläche 216 eine rampenförmi- ge Abstufung 217 auf, durch die eine an den Aussenumfang des Keramikisolators angrenzende achsiale Vertiefung 218 gebil¬ det ist.The example of a ceramic insulator 213 shown in FIG. 3 for the cathode side of the X-ray tube has a ramp-shaped step 217 on its axial end face 216 to be turned outwards, by means of which an axial depression 218 adjoining the outer circumference of the ceramic insulator is formed.
Der in Fig. 4 gezeigte Keramikisolator 123 für die Anodensei¬ te der Röntgenröhre weist an seiner nach aussen zu wendenden achsialen Endfläche 126 zwei in Umfangsrichtung verlaufende Stufen 117 auf, durch die eine an den Innenumfang des Kera¬ mikisolators angrenzende achsiale Vertiefung 128 gebildet ist. Gemäss Fig. 5 kann der Keramikisolator 223 für die Anoden¬ seite der Röntgenröhre aber auch eine rampenförmige Abstu¬ fung 227 an der nach aussen zu wendenden achsialen Endfläche aufweisen, so dass eine an den inneren Umfang des Keramik¬ isolators angrenzende achsiale Vertiefung 228 gebildet ist.The ceramic insulator 123 shown in FIG. 4 for the anode side of the X-ray tube has on its outward-facing axial end face 126 two steps 117 running in the circumferential direction, by means of which an axial depression 128 adjacent to the inner circumference of the ceramic isolator is formed. 5, the ceramic insulator 223 for the anode side of the X-ray tube can also have a ramp-shaped step 227 on the axial end surface to be turned outwards, so that an axial recess 228 adjacent to the inner circumference of the ceramic insulator is formed .
Die Vertiefungen 118, 218, 128 und 228 der Keramikisolatoren 113, 213, 123 und 223 gemäss den Fig. 2 bis 5 werden beim Zusammenbau oder Einbau der Röntgenröhre jeweils mit gummi¬ elastischem Isoliermaterial, dessen Dielektrizitätskonstan¬ ten kleiner als diejenige des Keramikmaterials ist, voll¬ ständig ausgefüllt.'The depressions 118, 218, 128 and 228 of the ceramic insulators 113, 213, 123 and 223 according to FIGS. 2 to 5 are each made with rubber-elastic insulating material when the X-ray tube is assembled or installed, the dielectric constant of which is smaller than that of the ceramic material, completely filled out. '
Bekanntlich gibt es Röntgenröhren, bei denen die Kathode oder die Anode mit dem zylindrischen Metallteil elektrisch leitend verbunden ist. In einem solchen Fall ist jeweils nur die an¬ dere Elektrode Anode oder Kathode durch einen Keramikisolator von dem zylindrischen Metallteil isoliert. Die Erfindung ist auch bei solchen Röntgenröhren anwendbar, indem der dann ein¬ zige vorhandene Keramikisolator in der vorstehend beschriebe¬ nen Weise an seiner vom Innern der Röntgenröhre abgewandten achsialen Endfläche mit einer Vertiefung versehen ist, die vollständig ausgefüllt ist mit einem Isoliermaterial, dessen Dielektrizitätskonstante kleiner als diejenige des Keramik¬ materials ist. As is known, there are X-ray tubes in which the cathode or the anode is electrically conductively connected to the cylindrical metal part. In such a case, only the other anode or cathode is insulated from the cylindrical metal part by a ceramic insulator. The invention can also be used with such X-ray tubes in that the then only existing ceramic insulator in the manner described above is provided on its axial end surface facing away from the inside of the X-ray tube with a depression which is completely filled with an insulating material whose dielectric constant is smaller than that of the ceramic material.

Claims

P a t e n t a n s p r ü c h eP a t e n t a n s r u c h e
. Röntgenröhre mit einem die Anode und die Kathode um¬ gebenden zylindrischen Metallteil, von welchem zumindest eine der Elektroden Anode und Kathode mittels eines scheibenförmi¬ gen Keramikisolators elektrische isoliert ist, der an einem achsialen Ende des Metallteils angeordnet ist, dadurch ge¬ kennzeichnet, dass der scheibenförmige Keramikisolator (13; 23; 113; 123; 213; 223) an seiner vom Innenraum der Röntgen¬ röhre abgewandten achsialen Endfläche (16; 26; 116; 126; 216; 226) in radialen Richtungen stufen- oder rampenförmig ausge¬ bildet ist zur Bildung einer ringförmig verlaufenden achsialen Vertiefung (18; 28; 118; 128; 218; 228), die mit einem Iso¬ liermaterial (19; 29) ausgefüllt ist, dessen Dielektrizitäts¬ konstante kleiner als diejenige des Keramikmaterials ist, und dass im Falle eines die Anode (25) vom Metallteil (11 ) isolierenden Keramikisolators (13; 113; 213) die Vertiefung radial innen und im Falle eines die Kathode (15) vom Metall¬ teil (11) isolierenden Keramikisolators (23; 123; 223) die Vertiefung radial aussen angeordnet ist.. X-ray tube with a cylindrical metal part surrounding the anode and the cathode, from which at least one of the electrodes anode and cathode is electrically insulated by means of a disk-shaped ceramic insulator which is arranged at an axial end of the metal part, characterized in that the disc-shaped ceramic insulator (13; 23; 113; 123; 213; 223) on its axial end surface (16; 26; 116; 126; 216; 226) facing away from the interior of the X-ray tube is formed in steps or ramps in radial directions to form an annular axial recess (18; 28; 118; 128; 218; 228) which is filled with an insulating material (19; 29) whose dielectric constant is smaller than that of the ceramic material, and that in the case one of the ceramic insulators (13; 113; 213) insulating the anode (25) from the metal part (11) insulates the recess radially on the inside and, in the case of one, insulates the cathode (15) from the metal part (11) ends ceramic insulator (23; 123; 223) the depression is arranged radially on the outside.
2. Röntgenröhre nach Anspruch 1, dadurch gekennzeich¬ net, dass das die Vertiefung (18; 28; 118; 128; 218; 228) des Keramikisolators (13; 23; 113; 123; 213; 223) ausfüllende Isoliermaterial eine Partie (19; 29) einer gummielastischen Scheibe (20; 30) ist, die in achsialer Richtung an die stu¬ fen- oder rampenförmig ausgebildete Endfläche (16; 26;,116; 126; 216; 226) des Keramikisolators angepresst ist.2. X-ray tube according to claim 1, characterized in that the insulating material filling the recess (18; 28; 118; 128; 218; 228) of the ceramic insulator (13; 23; 113; 123; 213; 223) fills a section (19th ; 29) is a rubber-elastic disc (20; 30) which is pressed in the axial direction on the step-shaped or ramp-shaped end face (16; 26;, 116; 126; 216; 226) of the ceramic insulator.
3. Röntgenröhre nach Anspruch 2, dadurch gekennzeichnet, dass die gummielastische Scheibe (20; 30) in entspanntem Zustand stufenfreie achsiale Endflächen aufweist, die etwa die gleiche Grosse wie jene des Keramikisolators (13; 23; 113; 123; 213; 223) aufweisen.3. X-ray tube according to claim 2, characterized in that the rubber-elastic disc (20; 30) in the relaxed state has stepless axial end faces, which have the same size as that of the ceramic insulator (13; 23; 113; 123; 213; 223).
4. Röntgenröhre nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das die Vertiefung (18; 28; 118; 128; 218; 228) auffüllende Isoliermaterial (19; 29) Silikonkaut¬ schuk mit einer Shore-Härte von vorzugsweise etwa 28 und einer Dielektrizitätskonstante von etwa 3,2 ist.4. X-ray tube according to one of claims 1 to 3, characterized in that the depression (18; 28; 118; 128; 218; 228) filling insulating material (19; 29) silicone rubber with a Shore hardness of preferably about 28 and a dielectric constant of about 3.2.
5. Röntgenröhre nach einem der Ansprüche 1 bis 4, bei welcher die Anode und die Kathode je mittels eines scheiben¬ förmigen Keramikisolators vom zylindrischen Metallteil elek¬ trisch isoliert sind, dadurch gekennzeichnet, dass jeder der scheibenförmigen Keramikisolatoren (13; 23; 113; 123; 213; 223) an seiner vom Innenraum der Röntgenröhre abgewandten achsialen Endfläche (16; 26; 116; 126; 216; 226) in radialer Richtung stufen- oder rampenförmig ausgebildet ist zur Bildung einer ringförmig verlaufenden achsialen Vertiefung (18; 28; 118; 128; 218; 228), die mit einem Isoliermaterial (19, 29) ausgefüllt ist, dessen Dielektrizitätskonstante kleiner als diejenige des Keramikmaterials ist, und dass die Vertiefung (28; 128; 228) des die Anode (25) tragenden Keramikisolators (23; 123; 223) radial innen und die Vertiefung (18; 118; 218) des die Kathode (15) tragenden Keramikisolators (13; 113; 213) radial aussen angeordnet ist. 5. X-ray tube according to one of claims 1 to 4, in which the anode and the cathode are each electrically isolated from the cylindrical metal part by means of a disk-shaped ceramic insulator, characterized in that each of the disk-shaped ceramic insulators (13; 23; 113; 123 ; 213; 223) on its axial end surface (16; 26; 116; 126; 216; 226) facing away from the interior of the x-ray tube is designed in the radial direction step or ramp-shaped to form an annular axial recess (18; 28; 118; 128; 218; 228), which is filled with an insulating material (19, 29), the dielectric constant of which is smaller than that of the ceramic material, and that the recess (28; 128; 228) of the ceramic insulator (23; 123; 223) is arranged radially inside and the recess (18; 118; 218) of the ceramic insulator (13; 113; 213) carrying the cathode (15) is arranged radially outside.
EP86901329A 1985-03-28 1986-03-13 X-ray tube with a cylindrical metal component enclosing the anode and cathode Expired EP0215034B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86901329T ATE40767T1 (en) 1985-03-28 1986-03-13 X-RAY TUBE WITH A CYLINDRICAL METAL PART SURROUNDING THE ANODE AND THE CATHODE.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1363/85 1985-03-28
CH1363/85A CH665920A5 (en) 1985-03-28 1985-03-28 X-ray tube WITH THE ANODE AND CATHODE SURROUNDING CYLINDRICAL METAL PART.

Publications (2)

Publication Number Publication Date
EP0215034A1 true EP0215034A1 (en) 1987-03-25
EP0215034B1 EP0215034B1 (en) 1989-02-08

Family

ID=4208683

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86901329A Expired EP0215034B1 (en) 1985-03-28 1986-03-13 X-ray tube with a cylindrical metal component enclosing the anode and cathode

Country Status (6)

Country Link
EP (1) EP0215034B1 (en)
JP (1) JPS62502796A (en)
AT (1) ATE40767T1 (en)
CH (1) CH665920A5 (en)
DE (1) DE3662079D1 (en)
WO (1) WO1986005921A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4137804A1 (en) * 1991-11-16 1993-05-19 Licentia Gmbh High voltage X=ray tube - has annular grove in insulating annular disc, whose vacuum-side annular strip has annular gap
DE19842467A1 (en) * 1998-09-16 2000-03-23 Siemens Ag Miniature X-ray tube for insertion into narrow objects, especially vessel systems in living tissue
DE50205708D1 (en) * 2002-09-09 2006-04-13 Comet Holding Ag Flamatt HIGH VOLTAGE VACUUM TUBE
AU2003281900A1 (en) 2003-12-02 2005-06-24 Comet Holding Ag Modular x-ray tube and method for the production thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE6946926U (en) * 1969-12-03 1971-07-22 C H P Mueller Gmbh ROENTGE PIPE WITH METAL PISTON.
GB1458027A (en) * 1973-01-08 1976-12-08 Philips Electronic Associated Electric discharge vacuum tube
DE2506841C2 (en) * 1975-02-18 1986-07-03 Philips Patentverwaltung Gmbh, 2000 Hamburg High voltage vacuum tube
DE2747486A1 (en) * 1977-10-22 1979-04-26 Licentia Gmbh Small X=ray tube avoiding insulator charging - has vacuum vessel formed from metal part surrounding cathode and insulating cylinder around anode
DE2855905A1 (en) * 1978-12-23 1980-06-26 Licentia Gmbh DEVICE WITH A X-RAY TUBE
DE3116169A1 (en) * 1981-04-23 1982-11-11 Philips Patentverwaltung Gmbh, 2000 Hamburg HIGH VOLTAGE VACUUM TUBES, ESPECIALLY X-RAY TUBES

Non-Patent Citations (1)

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Title
See references of WO8605921A1 *

Also Published As

Publication number Publication date
EP0215034B1 (en) 1989-02-08
JPH0570897B2 (en) 1993-10-06
ATE40767T1 (en) 1989-02-15
CH665920A5 (en) 1988-06-15
DE3662079D1 (en) 1989-03-16
JPS62502796A (en) 1987-11-12
WO1986005921A1 (en) 1986-10-09

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