EP1028449A1 - X-ray tube - Google Patents

X-ray tube Download PDF

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Publication number
EP1028449A1
EP1028449A1 EP00200428A EP00200428A EP1028449A1 EP 1028449 A1 EP1028449 A1 EP 1028449A1 EP 00200428 A EP00200428 A EP 00200428A EP 00200428 A EP00200428 A EP 00200428A EP 1028449 A1 EP1028449 A1 EP 1028449A1
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EP
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Prior art keywords
ray tube
tube according
electron beam
anode
ray
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Granted
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EP00200428A
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German (de)
French (fr)
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EP1028449B1 (en
Inventor
Geoffrey Harding
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Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
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Philips Corporate Intellectual Property GmbH
Koninklijke Philips Electronics NV
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/112—Non-rotating anodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/14—Arrangements for concentrating, focusing, or directing the cathode ray
    • H01J35/153—Spot position control
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/08—Targets (anodes) and X-ray converters
    • H01J2235/081—Target material
    • H01J2235/082—Fluids, e.g. liquids, gases

Definitions

  • the invention relates to an X-ray tube with a device for generating and Focusing an electron beam on a target.
  • An X-ray tube of this type is known for example from DE 195 44 203.
  • An electron source cathode
  • An electron source cathode
  • the electron beam is through this Arrangement with a very small focus and a relatively high electron density the target is directed so that X-rays are generated with high efficiency.
  • the thermal conductivity of the anode decreases with increasing temperature. This in turn causes heat conduction from the electron focus in and through the anode material becomes lower and the temperature at the focal point continues increases so that the melting temperature of the anode material reaches even faster and can be exceeded. Destruction of the anode surface is then the immediate one Episode. For these reasons, it must be ensured that the focus temperature in X-ray tubes of this type does not exceed about 1500 ° C, so that in essence Dimensions without the possible further increase in the x-ray density must become.
  • This measure can raise the focus temperature to approximately 2200 ° C without damaging the anode. Because the one emitted by thermal emission Energy is proportional to the fourth power of the anode surface temperature such rotating anode tubes operate essentially with radiation cooling. However, the measures mentioned are either relatively complex or only of limited effect.
  • the invention is therefore based on the object of an X-ray tube of the type mentioned To create a way that produces a much higher X-ray density can be.
  • This object is achieved according to claim 1 in such an X-ray tube by that the target is gaseous or vaporous at least in the operating state of the X-ray tube Contains material that is under pressure in one for electron and x-rays at least partially permeable chamber is included.
  • the electron density at the focal point of the electron beam can be increased significantly, so that a much higher X-ray density can be achieved without the anode temperature takes impermissibly high values.
  • a noble gas with a sufficiently high atomic number could be used as the material in the chamber be present, e.g. Xenon, both in the operating state and in the Breaks are gaseous.
  • claim 2 describes the use of a Heavy metal that solidifies during the breaks (i.e. at around room temperature) can be liquid, and that in the operating state (i.e. at comparatively high temperatures) is in a vapor-like physical state.
  • An advantageous embodiment is specified in claim 3.
  • the entry window according to claim 4 and in particular according to its dimensioning Claim 5 has the advantage that on the one hand the passing electrons lose energy suffer from only about five percent, and that, on the other hand, the window pressure differences can withstand up to 100 bar.
  • a coating of the entrance window according to claim 6 or 7 has the advantage that it even in the event of an unintentional increase in the operating pressure within the Chamber is not attacked and clouded by the high temperature plasma.
  • an X-ray tube 1 has a cathode 2 and an anode 3.
  • the cathode essentially comprises a cathode head 20 with a filament 21 (FIG. 2), by a power supply device (not shown) with a corresponding one Heating current is applied.
  • the anode 3 opposite the cathode 2 is essentially semicircular, so that between the cathode 2 and the anode 3 a radial electric field is generated.
  • a channel 4 with an inlet opening 41 for the electrons runs through the anode 3, which is opposite the cathode 2.
  • the channel 4 is on with its outlet opening 42 Diamond window 7 directed a chamber 6, which contains the target.
  • the inlet opening 41 of the channel 4 is larger than the outlet opening 42.
  • the channel narrows in the direction of the outlet opening (conical course) and is preferred arranged and designed such that the electrons entering the channel below meet a surface of the channel at an angle of maximum 1 °. In this case the electrons are reflected elastically towards the exit opening 42 without that X-rays are already generated by this impact and significant energy losses occur. This also helps to increase the efficiency of the X-ray tube increase as well as those electrons that are tangential to the filament of the cathode Have speed component in the focus 51 are scattered.
  • the cathode 2 In the operating state, the cathode 2 emits electrons in a known manner radial electrical field of the anode are accelerated towards and through this the inlet opening 41 enter the channel 4.
  • Channel 4 acts as a collimator and concentrates the electrons in the form of an electron beam 5 into a focal point 51.
  • This focal point lies within the chamber 6, so that the target material located there (for example mercury) evaporates and the pressure in the chamber at the Operating temperature of the X-ray tube is essentially that of a high-pressure gas relief lamp (about 50 bar).
  • the path length of the electrons in a mercury vapor is at a pressure of 50 bar several millimeters. This creates a line-like pattern directly behind the diamond window Focal point with a length of about 5 mm in the direction of propagation of the electrons and a width of about 2 mm perpendicular to it.
  • the operating pressure within the chamber 6 should be optimized taking into account the following boundary values: if the pressure is too low, the electrons diffuse too far out of the focal point area, so that the focal point becomes relatively large. On the other hand, if the pressure is too high, the inside of the diamond window is too close to the high temperature plasma so that it may be attacked and conversion to carbon occurs. The operating pressure should therefore be between these two values.
  • the diamond window can also be coated with one or more thin metal layers, for example made of titanium and / or platinum, in order in this way to provide protection against the plasma.
  • Figure 2 shows a plan view of the cathode 2 according to arrow "A" in Figure 1 and leaves the recognize actual filament 21.
  • Figure 3 is finally a plan view of the Anode 3 shown according to arrow ⁇ B '', in the center of which the inlet opening 41 of channel 4 lies.
  • a significantly higher X-ray density can be achieved can be achieved without the anode being heated to impermissibly high values.
  • the heat generated in the chamber 6 is dissipated exclusively by radiation cooling.

Abstract

The X-ray tube includes an arrangement for producing and focusing an electron ray (5) on a target material. The target comprises a gaseous or steam material, at least during the operation of the tube, which is enclosed under pressure in a chamber (6), at least partially transparent for electron ray and X-ray radiation. The target comprises preferably a heavy metal, such as quicksilver.

Description

Die Erfindung betrifft eine Röntgenröhre mir einer Einrichtung zur Erzeugung und Fokussierung eines Elektronenstrahls auf ein Target.The invention relates to an X-ray tube with a device for generating and Focusing an electron beam on a target.

Eine Röntgenröhre dieser Art ist zum Beispiel aus der DE 195 44 203 bekannt. Die mit einer Elektronenquelle (Kathode) erzeugten Elektronen werden in Richtung auf eine Anode beschleunigt und treten dort in einen sich konisch verengenden Durchtrittskanal ein, an dessen Ausgang sich das Target befindet. Der Elektronenstrahl wird durch diese Anordnung mit einem sehr kleinen Fokus und einer relativ hohen Elektronendichte auf das Target gerichtet, so daß Röntgenstrahlen mit hohem Wirkungsgrad erzeugt werden.An X-ray tube of this type is known for example from DE 195 44 203. With An electron source (cathode) generated electrons are directed towards one Anode accelerates and enter a conically narrowing passage there at the exit of which the target is located. The electron beam is through this Arrangement with a very small focus and a relatively high electron density the target is directed so that X-rays are generated with high efficiency.

Eine mit dieser Anordnung an sich mögliche, erhebliche Steigerung der Röntgenstrahldichte (das heißt der Anzahl der pro Flächeneinheit des Targets emittierten Photonen) im Vergleich zu bekannten Röntgenröhren wird jedoch durch die damit verbundene Erhöhung der Anodentemperatur begrenzt. Wenn diese Temperatur nämlich in den Bereich der Schmelztemperatur des Anodenmaterials gelangt, steigt der Dampfdruck an, so daß elektrische Entladungen zwischen Anode und Kathode auftreten können.A considerable increase in the X-ray density possible with this arrangement (ie the number of photons emitted per unit area of the target) in However, compared to known X-ray tubes is due to the associated increase the anode temperature is limited. If this temperature is in the range the melting temperature of the anode material reaches, the vapor pressure rises, so that electrical discharges between anode and cathode can occur.

Weiterhin vermindert sich die thermische Leitfähigkeit der Anode mit steigender Temperatur. Dies führt wiederum dazu, daß die Wärmeleitung von dem Elektronen-Brennpunkt in und durch das Anodenmaterial geringer wird und die Temperatur im Brennpunkt weiter ansteigt, so daß die Schmetztemperatur des Anodenmaterials noch schneller erreicht und überschritten werden kann. Eine Zerstörung der Anodenoberfläche ist dann die unmittelbare Folge. Aus diesen Gründen muß sichergestellt sein, daß die Brennpunkts-Temperatur bei Röntgenröhren dieser Art etwa 1500°C nicht übersteigt, so daß in wesentlichem Maße auf die an sich mögliche weitere Steigerung der Röntgenstrahldichte verzichtet werden muß.Furthermore, the thermal conductivity of the anode decreases with increasing temperature. This in turn causes heat conduction from the electron focus in and through the anode material becomes lower and the temperature at the focal point continues increases so that the melting temperature of the anode material reaches even faster and can be exceeded. Destruction of the anode surface is then the immediate one Episode. For these reasons, it must be ensured that the focus temperature in X-ray tubes of this type does not exceed about 1500 ° C, so that in essence Dimensions without the possible further increase in the x-ray density must become.

Da eine Verminderung der Anodentemperatur durch Strahlungskühlung infolge der elektromagnetischen Emission aus der Anode praktisch keine Rolle spielt, besteht nur die Möglichkeit, entweder die Anode zum Beispiel mit einem Kühlmittel (Wasser o.ä.) zu kühlen, oder diese ständig zu drehen, so daß der betreffende Bereich in dem Elektronen-Brennpunkt nur für eine relativ kurze Zeit erwärmt wird und sich dann wieder abkühlen kann. Because a decrease in anode temperature due to radiation cooling due to electromagnetic Emission from the anode is practically irrelevant, there is only the possibility either cooling the anode with a coolant (water or similar), for example, or to rotate it continuously so that the area in question is in the electron focus is only heated for a relatively short time and can then cool down again.

Durch diese Maßnahme kann die Brennpunkts-Temperatur auf etwa 2200°C gesteigert werden, ohne daß die Anode beschädigt wird. Da die durch thermische Emission abgestrahlte Energie proportional zu der vierten Potenz der Anoden-Oberflächentemperatur ist, arbeiten solche Röhren mit sich drehender Anode im wesentlichen mit einer Strahlungskühlung. Die genannten Maßnahmen sind allerdings entweder relativ aufwendig oder nur von begrenzter Wirkung.This measure can raise the focus temperature to approximately 2200 ° C without damaging the anode. Because the one emitted by thermal emission Energy is proportional to the fourth power of the anode surface temperature such rotating anode tubes operate essentially with radiation cooling. However, the measures mentioned are either relatively complex or only of limited effect.

Der Erfindung liegt deshalb die Aufgabe zugrunde, eine Röntgenröhre der eingangs genannten Art zu schaffen, mit der eine wesentlich höhere Röntgenstrahldichte erzeugt werden kann.The invention is therefore based on the object of an X-ray tube of the type mentioned To create a way that produces a much higher X-ray density can be.

Gelöst wird diese Aufgabe gemäß Anspruch 1 bei einer solchen Röntgenröhre dadurch, daß das Target ein zumindest im Betriebszustand der Röntgenröhre gas- oder dampfförmiges Material enthält, das unter Überdruck in einer für Elektronen- und Röntgenstrahlung zumindest teilweise durchlässigen Kammer eingeschlossen ist.This object is achieved according to claim 1 in such an X-ray tube by that the target is gaseous or vaporous at least in the operating state of the X-ray tube Contains material that is under pressure in one for electron and x-rays at least partially permeable chamber is included.

Indem nun das Target von der Anode getrennt und weitgehend thermisch isoliert ist, kann die Elektronendichte im Brennpunkt des Elektronenstrahls wesentlich erhöht werden, so daß auch eine wesentlich höhere Röntgenstrahldichte erzielbar ist, ohne daß die Anodentemperatur unzulässig hohe Werte annimmt.By now separating the target from the anode and largely thermally isolating it the electron density at the focal point of the electron beam can be increased significantly, so that a much higher X-ray density can be achieved without the anode temperature takes impermissibly high values.

Als Material könnte dabei in der Kammer ein Edelgas mit einer ausreichend hohen Ordnungszahl vorhanden sein, z.B. Xenon, das sowohl im Betriebszustand als auch in den Betriebspausen gasförmig ist. Anspruch 2 beschreibt demgegenüber die Verwendung eines Schwermetalls, das in den Betriebspausen (d.h. bei etwa Zimmertemperatur) fest oder flüssig sein kann, und das sich im Betriebszustand (d.h. bei vergleichsweise hohen Temperaturen) in einenmdampfförmigen Aggregatzustand befindet. Eine vorteilhafte Ausgestaltung ist in Anspruch 3 angegeben.A noble gas with a sufficiently high atomic number could be used as the material in the chamber be present, e.g. Xenon, both in the operating state and in the Breaks are gaseous. In contrast, claim 2 describes the use of a Heavy metal that solidifies during the breaks (i.e. at around room temperature) can be liquid, and that in the operating state (i.e. at comparatively high temperatures) is in a vapor-like physical state. An advantageous embodiment is specified in claim 3.

Das Eintrittsfenster gemäß Anspruch 4 und inbesondere dessen Dimensionierung gemäß Anspruch 5 hat den Vorteil, daß einerseits die hindurchtretenden Elektronen einen Energieverlust von nur etwa fünf Prozent erleiden, und daß andererseits das Fenster Druckdifferenzen von bis zu 100 bar standhalten kann.The entry window according to claim 4 and in particular according to its dimensioning Claim 5 has the advantage that on the one hand the passing electrons lose energy suffer from only about five percent, and that, on the other hand, the window pressure differences can withstand up to 100 bar.

Eine Beschichtung des Eintrittsfensters gemäß Anspruch 6 oder 7 hat den Vorteil, daß es auch bei einer eventuellen unbeabsichtigten Erhöhung des Betriebsdruckes innerhalb der Kammer durch das Hochtemperatur-Plasma nicht angegriffen und eingetrübt wird.A coating of the entrance window according to claim 6 or 7 has the advantage that it even in the event of an unintentional increase in the operating pressure within the Chamber is not attacked and clouded by the high temperature plasma.

Die Verwendung von Quecksilber mit der in Anspruch 8 genannten Menge hat einen besonders guten Wirkungsgrad zur Folge.The use of mercury with the amount mentioned in claim 8 has one particularly good efficiency.

Weitere Einzelheiten, Merkmale und Vorteile der Erfindung ergeben sich aus der folgenden Beschreibung einer bevorzugten Ausführungsform anhand der Zeichnung. Es zeigt:

  • Fig. 1 einen schematischen Querschnitt durch eine solche Ausführungsform;
  • Fig. 2 eine Ansicht gemäß Pfeil A in Figur 1 und
  • Fig. 3 eine Ansicht gemäß Pfeil B in Figur 1.
    • Further details, features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the drawing. It shows:
  • 1 shows a schematic cross section through such an embodiment;
  • Fig. 2 is a view according to arrow A in Figure 1 and
  • 3 shows a view according to arrow B in FIG. 1.

    • Eine Röntgenröhre 1 weist gemäß Figur 1 eine Kathode 2 und eine Anode 3 auf. Die Kathode umfaßt im wesentlichen Katodenkopf 20 mit einem einen Heizfaden 21 (Fig.2), der durch eine Stromversorgungseinrichtung (nicht dargestellt) mit einem entsprechenden Heizstrom beaufschlagt wird. Die der Kathode 2 gegenüberliegende Anode 3 ist im wesentlichen halbkreisförmig, so daß zwischen der Kathode 2 und der Anode 3 ein radiales elektrisches Feld erzeugt wird.According to FIG. 1, an X-ray tube 1 has a cathode 2 and an anode 3. The The cathode essentially comprises a cathode head 20 with a filament 21 (FIG. 2), by a power supply device (not shown) with a corresponding one Heating current is applied. The anode 3 opposite the cathode 2 is essentially semicircular, so that between the cathode 2 and the anode 3 a radial electric field is generated.

    Durch die Anode 3 verläuft ein Kanal 4 mit einer Eintrittsöffnung 41 für die Elektronen, die der Kathode 2 gegenüberliegt. Der Kanal 4 ist mit seiner Austrittsöffnung 42 auf ein Diamantfenster 7 einer Kammer 6 gerichtet, die das Target enthält.A channel 4 with an inlet opening 41 for the electrons runs through the anode 3, which is opposite the cathode 2. The channel 4 is on with its outlet opening 42 Diamond window 7 directed a chamber 6, which contains the target.

    Die Eintrittsöffnung 41 des Kanals 4 ist größer, als die Austrittsöffnung 42. Der Kanal verengt sich in Richtung auf die Austrittsöffnung (konischer Verlauf) und ist vorzugsweise derart angeordnet und ausgebildet, daß die in den Kanal eintretenden Elektronen unter einem Winkel von maximal 1° auf eine Oberfläche des Kanals treffen. In diesem Fall werden die Elektronen elastisch in Richtung auf die Austrittsöffnung 42 reflektiert, ohne daß durch diesen Aufprall bereits Röntgenstrahlung erzeugt wird und wesentliche Energieverluste auftreten. Auch dies trägt dazu bei, den Wirkungsgrad der Röntgenröhre zu erhöhen, da auch diejenigen Elektronen, die eine zu dem Heizfaden der Kathode tangentiale Geschwindigkeitskomponente aufweisen, in den Brennpunkt 51 gestreut werden.The inlet opening 41 of the channel 4 is larger than the outlet opening 42. The channel narrows in the direction of the outlet opening (conical course) and is preferred arranged and designed such that the electrons entering the channel below meet a surface of the channel at an angle of maximum 1 °. In this case the electrons are reflected elastically towards the exit opening 42 without that X-rays are already generated by this impact and significant energy losses occur. This also helps to increase the efficiency of the X-ray tube increase as well as those electrons that are tangential to the filament of the cathode Have speed component in the focus 51 are scattered.

    Das Diamantfenster 7 der Kammer 6 hat vorzugsweise einen freien Durchmesser von 1 mm und eine Dicke von etwa 10 µm. Es ist bekannt (siehe Tabellen des Energieverlustes und der Reichweiten von Elektronen und Positionen in M.J. Berger und S.M. Seltzer, NBS/NSS Report 39, 1964), daß Elektronen mit einer Energie von etwa 200 keV beim Hindurchtreten durch ein solches Fenster einen Energieverlust von nur etwa 5% erleiden. Da ferner das Diamantmaterial eine niedrige Ordnungszahl (Z = 6) hat, werden die Elektronen beim Hindurchtreten durch das Fenster nur mit sehr kleinen Winkeln gestreut so daß der Elektronenstrahl 5 im wesentlichen unbeeinflußt in die Kammer 6 eintritt.The diamond window 7 of the chamber 6 preferably has a free diameter of 1 mm and a thickness of about 10 µm. It is known (see tables of energy loss and the ranges of electrons and positions in M.J. Berger and S.M. Seltzer, NBS / NSS Report 39, 1964) that electrons with an energy of about 200 keV at Passing through such a window will suffer an energy loss of only about 5%. Furthermore, since the diamond material has a low atomic number (Z = 6), the electrons become when passing through the window only scattered with very small angles that the electron beam 5 enters the chamber 6 essentially unaffected.

    Im Bereich der Austrittsöffnung 42 des Kanals 4 befindet sich schließlich eine Kühleinrichtung 8.Finally, there is a cooling device in the area of the outlet opening 42 of the channel 4 8th.

    Im Betriebszustand emittiert die Kathode 2 in bekannter Weise Elektronen, die in dem radialen elektrischen Feld der Anode in Richtung auf diese beschleunigt werden und durch die Eintrittsöffnung 41 in den Kanal 4 eintreten. Der Kanal 4 wirkt als Kollimator und konzentriert die Elektronen in Form eines Elektronenstrahl 5 in einen Brennpunkt 51. Dieser Brennpunkt liegt innerhalb der Kammer 6, so daß das dort befindliche Targetmaterial (zum Beispiel Quecksilber) verdampft und der Druck in der Kammer bei der Betriebstemperatur der Röntgenröhre im wesentlichen dem in einer Hochdruck-Gasentlastungslampe (etwa 50 bar) entspricht.In the operating state, the cathode 2 emits electrons in a known manner radial electrical field of the anode are accelerated towards and through this the inlet opening 41 enter the channel 4. Channel 4 acts as a collimator and concentrates the electrons in the form of an electron beam 5 into a focal point 51. This focal point lies within the chamber 6, so that the target material located there (for example mercury) evaporates and the pressure in the chamber at the Operating temperature of the X-ray tube is essentially that of a high-pressure gas relief lamp (about 50 bar).

    Die Weglänge der Elektronen beträgt in einem Quecksilberdampf mit einem Druck von 50 bar mehrere Millimeter. Somit entsteht direkt hinter dem Diamantfenster ein linienartiger Brennpunkt mit einer Länge von etwa 5 mm in Ausbreitungsrichtung der Elektronen und einer Breite von etwa 2 mm senkrecht dazu.The path length of the electrons in a mercury vapor is at a pressure of 50 bar several millimeters. This creates a line-like pattern directly behind the diamond window Focal point with a length of about 5 mm in the direction of propagation of the electrons and a width of about 2 mm perpendicular to it.

    Der Betriebsdruck innerhalb der Kammer 6 sollte unter Berücksichtigung folgender Randwerte optimiert werden: wenn der Druck zu niedrig ist, diffundieren die Elektronen zu weit aus dem Brennpunktsbereich heraus, so daß der Brennpunkt relativ groß wird. Wenn der Druck andererseits zu hoch ist, liegt die Innenseite des Diamantfensters zu nahe an dem Hochtemperatur-Plasma, so daß sie möglicherweise davon angegriffen wird und eine Umwandlung in Kohlenstoff auftritt. Der Betriebsdruck sollte also zwischen diesen beiden Werten liegen.
    Als zusätzliche Maßnahme kann das Diamantfenster auch mir einer oder mehreren dünnen Metallschichten zum Beispiel aus Titan und/oder Platin beschichtet werden, um auf diese Weise einen Schutz vor dem Plasma zu schaffen.     The operating pressure within the chamber 6 should be optimized taking into account the following boundary values: if the pressure is too low, the electrons diffuse too far out of the focal point area, so that the focal point becomes relatively large. On the other hand, if the pressure is too high, the inside of the diamond window is too close to the high temperature plasma so that it may be attacked and conversion to carbon occurs. The operating pressure should therefore be between these two values.
    As an additional measure, the diamond window can also be coated with one or more thin metal layers, for example made of titanium and / or platinum, in order in this way to provide protection against the plasma.

    Figur 2 zeigt eine Draufsicht auf die Kathode 2 gemäß Pfeil "A" in Figur 1 und läßt den eigentlichen Heizfaden 21 erkennen. In Figur 3 ist schließlich eine Draufsicht auf die Anode 3 gemäß Pfeil ''B'' gezeigt, in deren Zentrum die Eintrittsöffnung 41 des Kanals 4 liegt.Figure 2 shows a plan view of the cathode 2 according to arrow "A" in Figure 1 and leaves the recognize actual filament 21. In Figure 3 is finally a plan view of the Anode 3 shown according to arrow `` B '', in the center of which the inlet opening 41 of channel 4 lies.

    Mit der erfindungsgemäßen Röntgenröhre kann eine wesentlich höhere Röntgenstrahldichte erzielt werden, ohne daß die Anode auf unzulässig hohe Werte erhitzt wird. Die in der Kammer 6 entstehende Wärme wird ausschließlich durch Strahlungskühlung abgeführt.With the X-ray tube according to the invention, a significantly higher X-ray density can be achieved can be achieved without the anode being heated to impermissibly high values. In the the heat generated in the chamber 6 is dissipated exclusively by radiation cooling.

    Claims (8)

    Röntgenröhre mir einer Einrichtung zur Erzeugung und Fokussierung eines Elektronenstrahls auf ein Target,
    dadurch gekennzeichnet, daß das Target ein zumindest im Betriebszustand der Röntgenröhre gas- oder dampfförmiges Material enthält, das unter Überdruck in einer für Elektronen- und Röntgenstrahlung zumindest teilweise durchlässigen Kammer (6) eingeschlossen ist.    X-ray tube with a device for generating and focusing an electron beam onto a target,
    characterized in that the target contains a gaseous or vaporous material, at least in the operating state of the x-ray tube, which is enclosed under overpressure in a chamber (6) which is at least partially permeable to electron and x-ray radiation.         Röntgenröhre nach Anspruch 1,
    dadurch gekennzeichnet, daß das Target ein Schwermetall enthält.    X-ray tube according to claim 1,
    characterized in that the target contains a heavy metal.         Röntgenröhre nach Anspruch 2,
    dadurch gekennzeichnet, daß das Schwermetall Quecksilber ist, dessen Menge so gewählt ist, daß es unter Einwirkung des Elektronenstrahls (5) verdampft und ein Gas mit einem Druck von etwa 50 bar bildet.    X-ray tube according to claim 2,
    characterized in that the heavy metal is mercury, the amount of which is selected such that it evaporates under the action of the electron beam (5) and forms a gas at a pressure of approximately 50 bar.         Röntgenröhre nach Anspruch 1,
    dadurch gekennzeichnet, daß die Kammer (6) aus Quarzglas ist und ein Eintrittsfenster (7) für den Elektronenstrahl (5) aus Diamant aufweist.    X-ray tube according to claim 1,
    characterized in that the chamber (6) is made of quartz glass and has an entry window (7) for the electron beam (5) made of diamond.         Röntgenröhre nach Anspruch 4,
    dadurch gekennzeichnet, daß das Eintrittsfenster (7) eine Dicke von etwa 10 µm und einen Durchmesser von etwa 10 mm aufweist.    X-ray tube according to claim 4,
    characterized in that the entrance window (7) has a thickness of approximately 10 µm and a diameter of approximately 10 mm.         Röntgenröhre nach Anspruch 4,
    dadurch gekennzeichnet, daß das Eintrittsfenster (7) mit mindestens einer Metallschicht beschichtet ist.     X-ray tube according to claim 4,
    characterized in that the entrance window (7) is coated with at least one metal layer.         Röntgenröhre nach Anspruch 6,
    dadurch gekennzeichnet, daß die Metallschicht Titan oder Platin enthält.    X-ray tube according to claim 6,
    characterized in that the metal layer contains titanium or platinum.         Röntgenröhre nach Anspruch 1,
    dadurch gekennzeichnet, daß die Einrichtung zur Erzeugung und Fokussierung eines Elektronenstrahls eine Kathode (2) und eine Anode (3) mit einem konischen Durchtrittskanal (4) aufweist, dessen der Kathode zugewandte Eintrittsöffnung (41) größer ist als seine Austrittsöffnung (42), und der so angeordnet und ausgebildet ist, daß die Elektronen unter einem Winkel von maximal etwa 1 Grad auf eine Oberfläche des Durchtrittskanals (4) treffen.    X-ray tube according to claim 1,
    characterized in that the device for generating and focusing an electron beam has a cathode (2) and an anode (3) with a conical passage channel (4) whose inlet opening (41) facing the cathode is larger than its outlet opening (42), and which is arranged and designed such that the electrons strike a surface of the passage (4) at an angle of at most about 1 degree.
    EP00200428A 1999-02-12 2000-02-03 X-ray tube Expired - Lifetime EP1028449B1 (en)

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    DE19905802 1999-02-12
    DE19905802A DE19905802A1 (en) 1999-02-12 1999-02-12 X-ray tube

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    EP1028449B1 EP1028449B1 (en) 2005-01-26

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    DE10129463A1 (en) * 2001-06-19 2003-01-02 Philips Corp Intellectual Pty X-ray tube with a liquid metal target
    SE530094C2 (en) * 2006-05-11 2008-02-26 Jettec Ab Method for generating X-rays by electron irradiation of a liquid substance
    DE102013209447A1 (en) * 2013-05-22 2014-11-27 Siemens Aktiengesellschaft X-ray source and method for generating X-ray radiation

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    EP1028449B1 (en) 2005-01-26
    DE50009314D1 (en) 2005-03-03
    US6359968B1 (en) 2002-03-19
    DE19905802A1 (en) 2000-08-17
    JP2000243332A (en) 2000-09-08

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