EP1145271A1 - Tube a rayons x haute energie - Google Patents

Tube a rayons x haute energie

Info

Publication number
EP1145271A1
EP1145271A1 EP00901416A EP00901416A EP1145271A1 EP 1145271 A1 EP1145271 A1 EP 1145271A1 EP 00901416 A EP00901416 A EP 00901416A EP 00901416 A EP00901416 A EP 00901416A EP 1145271 A1 EP1145271 A1 EP 1145271A1
Authority
EP
European Patent Office
Prior art keywords
ray tube
cathode
tube according
anode
electron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00901416A
Other languages
German (de)
English (en)
Inventor
John William Hunt
Peter Thebock
Daniel Damjanovic
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.)
Wahoo Trust
Original Assignee
Wahoo Trust
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 Wahoo Trust filed Critical Wahoo Trust
Publication of EP1145271A1 publication Critical patent/EP1145271A1/fr
Withdrawn legal-status Critical Current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
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/06—Cathodes
    • H01J35/065—Field emission, photo emission or secondary emission cathodes
    • 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
    • H01J35/147—Spot size control

Definitions

  • This invention relates to a high energy x-ray tube.
  • the conventional x-ray tube includes a target which is at an angle to the electrons emitted from the cathode and the characteristic spectrum of a sample is detected by a detector located in the path of the reflected energy.
  • a high energy x-ray tube includes a cold cathode and an anode located in opposed relationship thereto so that electron emission X-rays formed by the electron beam travel directly to the cathode to produce further electron emission.
  • the electron beam is preferably collimated so that it is concentrated in a predetermined pattern, for example in a particular spotsize of the produced X-ray beam on the anode; the resulting x-rays being thereby emitted at 180° to the direction in wliich the electrons are emitted.
  • the collimation is achieved by means of a Pierce-type electron gun design.
  • Pierce's theory of electron beam design comprises the insertion of a unipotential electrode, called the beam forming or focusing electrode which causes fields outside the electron beam to be formed to satisfy the proper boundary conditions in other words the electrons still behave as though they were flowing in a complete diode - that is, they pursue rectilinear trajectories.
  • the cathode includes a window for transmission of the x-rays produced.
  • the geometry of the tube is arranged to prevent arcing across the vacuum or across the material of the tube and the electrodes, and at the same time to achieve optimum focusing of the emitted electrons so that they can strike the anode surface at a right angle and hence produce x-rays whose maximum intensity is orientated at 180° to the electron beam.
  • the cathode may be a cold photocathode made from earth alkali oxides on a metallic base, for example Ni- based MgO due to the fact that a self-sustained electron emission from cold magnesium oxide films applied to a metal sleeve or mesh can be achieved by applying a minimum of 300V to the anode.
  • a positive charge is developed on the magnesium oxide layer producing a high electrical field of the order of 54 kV/cm inside the layer. Electrons which are liberated in the magnesium oxide coating are multiplied by an avalanche effect to gain sufficient energy to leave the surface.
  • This emission current can be controlled by varying the voltage of the anode and/or of the ring electrode so that currents of several tens of milliamperes can be achieved over a period of several thousand hours without any decrease in emission.
  • the cathode may comprise a thin and porous magnesium oxide layer which is applied to the nickel mesh.
  • the tube may be of joined ceramic and metal or glass and metal.
  • Figure 1 is a sectional side view of an X-ray tube according to the invention
  • i Q Figure 2 is a diagrammatic representation of a Pierce-type planar electron gun adapted for use for the X-ray tube of the invention
  • Figure 3 is a graph of the equipotential lines external to the planar space charge limited electron beam at differing distances from the edge of the beam and from the 15 cathode.
  • a ceramic sleeve 10 encloses an anode 12 and a cathode indicated by reference 14.
  • a focusing lens 16 for the X-rays emitted by the anode is located above the cathode.
  • An X-ray window 20 and a cathode and X-ray window structure 22 are also 20 provided at the base of the tube.
  • the cathode is made from an alkaline earth oxide on a metallic base, such as magnesium oxide on a nickel base.
  • the anode may be W-Cu and is parallel with the cathode.
  • the operation of the tube relies on the establishment of an electron path which strike the anode at right angles. Some of the X-rays pass through the window 20 for 2 analyses while those that do not pass through the window strike the cathode and cause further electrons to be emitted therefrom.
  • a Pierce-type electron gun arrangement is provided and this is illustrated in Figure 2 where the cathode 30 is surrounded by a focusing electrode 32 which diverts random electrons back to the desired electron path between cathode and anode 34.

Landscapes

  • X-Ray Techniques (AREA)
  • Luminescent Compositions (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)

Abstract

L'invention se rapporte à un tube à rayons X haute énergie qui possède une cathode froide et une anode disposée en opposition de sorte les rayons X d'émission électronique formés par le faisceau électronique puissent se propager directement en direction de la cathode de manière à produire une autre émission d'électrons. Le faisceau électronique est collimaté de manière à être concentré sur une zone ponctuelle de l'anode, les rayons X résultants étant de ce fait émis à 180° par rapport à la direction dans laquelle les électrons sont émis. Un canon électronique de type Pierce est mis en oeuvre pour la collimation.
EP00901416A 1999-01-18 2000-01-18 Tube a rayons x haute energie Withdrawn EP1145271A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ZA99329 1999-01-18
ZA9900329 1999-01-18
PCT/ZA2000/000010 WO2000042631A1 (fr) 1999-01-18 2000-01-18 Tube a rayons x haute energie

Publications (1)

Publication Number Publication Date
EP1145271A1 true EP1145271A1 (fr) 2001-10-17

Family

ID=25587522

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00901416A Withdrawn EP1145271A1 (fr) 1999-01-18 2000-01-18 Tube a rayons x haute energie

Country Status (4)

Country Link
EP (1) EP1145271A1 (fr)
AU (1) AU763548B2 (fr)
CA (1) CA2360409A1 (fr)
WO (1) WO2000042631A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1303637C (zh) * 2003-04-29 2007-03-07 中国科学院长春光学精密机械与物理研究所 一种新型场致发射的医用微型x射线管
RU2487433C1 (ru) * 2011-12-29 2013-07-10 Открытое акционерное общество "Центральный научно-исследовательский институт "Электрон" Катодный узел электровакуумного прибора для работы при высоких напряжениях
US10624195B2 (en) * 2017-10-26 2020-04-14 Moxtek, Inc. Tri-axis x-ray tube

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714486A (en) * 1970-10-07 1973-01-30 Crary J Mc Field emission x-ray tube
US4359660A (en) * 1980-12-15 1982-11-16 Physics International Company Series diode X-ray source
JPS6047355A (ja) * 1983-08-23 1985-03-14 Hamamatsu Photonics Kk Ｘ線発生管
US5090043A (en) * 1990-11-21 1992-02-18 Parker Micro-Tubes, Inc. X-ray micro-tube and method of use in radiation oncology
JP2710914B2 (ja) * 1993-06-18 1998-02-10 浜松ホトニクス株式会社 Ｘ線発生管
DE4425683C2 (de) * 1994-07-20 1998-01-22 Siemens Ag Elektronenerzeugungsvorrichtung einer Röntgenröhre mit einer Kathode und mit einem Elektrodensystem zum Beschleunigen der von der Kathode ausgehenden Elektronen
US5768337A (en) * 1996-07-30 1998-06-16 Varian Associates, Inc. Photoelectric X-ray tube with gain

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0042631A1 *

Also Published As

Publication number Publication date
AU2226500A (en) 2000-08-01
CA2360409A1 (fr) 2000-07-20
WO2000042631A1 (fr) 2000-07-20
AU763548B2 (en) 2003-07-24

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