EP0553914A1 - Tube à rayons X ä foyer variable - Google Patents

Tube à rayons X ä foyer variable Download PDF

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Publication number
EP0553914A1
EP0553914A1 EP93200136A EP93200136A EP0553914A1 EP 0553914 A1 EP0553914 A1 EP 0553914A1 EP 93200136 A EP93200136 A EP 93200136A EP 93200136 A EP93200136 A EP 93200136A EP 0553914 A1 EP0553914 A1 EP 0553914A1
Authority
EP
European Patent Office
Prior art keywords
ray tube
approximately
cathode
focus
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Withdrawn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
EP93200136A
Other languages
German (de)
English (en)
Inventor
Theodorus Jan Jeanette Maria Jenneskens
Lourens Valkonet
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0553914A1 publication Critical patent/EP0553914A1/fr
Withdrawn legal-status Critical Current

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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
    • H01J35/066—Details of electron optical components, e.g. cathode cups

Definitions

  • the invention relates to an X-ray tube, comprising a cathode for generating an electron beam and an anode for generating a X-ray beam in response to impingement of the electron beam.
  • An X-ray tube of this kind is known from EP 389 326.
  • An X-ray tube described therein comprises a cathode with a cathode sleeve which is provided, at a side facing the anode, with two focusing electrodes which are symmetrically arranged around an electron beam path.
  • the electrodes are electrically insulated from the cathode sleeve and can be connected to mutually different potentials, so that the electron beam is deflected.
  • the position of the electron target spot on the anode can thus be changed. Displacement of the electron target spot across the anode may be of importance in order to optimize the position of the electron spot and hence the focal point of an X-ray beam emanating from the tube.
  • the geometry notably a width dimension of the electron spot or the focus, is variable so that, for example measurement can take place with different resolutions.
  • an X-ray tube of the kind set forth in accordance with the invention is characterized in that the cathode comprises an electron emitter and a cathode cap which is arranged so as to be electrically insulated therefrom and which has a geometry and a relative position such that a difference voltage variation between the emitter and the cap of at the most approximately 2000 V enables adjustment of a target spot within a width variation range of up to approximately 2 mm.
  • the focal width on the anode can be varied by way of a potential variation which can be readily realised and which does not give rise to high-voltage problems.
  • a variation of, for example approximately 0.1 mm for realising a focus for high-resolution analysis and, for example approximately 2.0 mm for a focus with a comparatively high energy the use of a single tube suffices for many analysis methods.
  • the focus width variation is notably reduced to extreme values of approximately 0.4 mm and 2 mm or 0.1 mm and 0.5 mm, so that, for example a potential difference variation can be used which is approximately twice as small, benefiting the controllability of the tube.
  • a maximum width value can be adapted.
  • a variation between, for example approximately 0.4 mm and 1.0 mm can be realised by means of a difference voltage variation of approximately 500 V.
  • the electron emitter in a preferred embodiment is line-shaped, so that an elongate focus can be comparatively simply realised, notably the width of said focus being variable by way of an adapted voltage variation.
  • the electron emitter in a further preferred embodiment is formed by a flat cathode, for example a post-delivery cathode.
  • An emissive surface of such a cathode can be varied by variation of the difference voltage, so that an additional means for varying the electron target spot is obtained.
  • the cathode cap in a further preferred embodiment is not constructed to be rotationally symmetrical.
  • the cathode cap is notably constructed to be elliptical, enabling a change-over from, for example a substantially round target spot having a diameter of, for example from 1 to 2 mm, to an elongate target spot having a dimension of, for example 0.4 x 2.0 mm2.
  • Such non-rotational symmetry in the electron-optical system can be supplemented by an elongate electron emitter again.
  • the cathode cap comprises two successive tapered portions in the direction opposing the direction of the electron beam, the electron emitter being arranged approximately at the area of the last tapered portion.
  • an axis of an emitter which is substantially round in the direction transversely of the emission direction is situated in the plane of the last tapered portion.
  • the last tapered portion notably has a diameter ratio or axis ratio, of approximately 1 to 4 to 1 to 6 in the case of an elliptical cathode cap.
  • the cathode cap is subdivided into several, notably two, mutually electrically insulated portions, so that focus displacement can be realised by deflection of the electron beam.
  • a power supply system for the cathode cap voltage can be controlled in steps, the potential of each step adjusting a focus desired for a given analysis mode.
  • An X-ray tube as shown in Fig. 1 comprises an envelope 1 with a conical, ceramic base 2, a cathode 4 with an emissive element in the form of a filament 6, and a cathode sleeve 5, a cylindrical wall 8 and an exit window 10.
  • an anode 12 is deposited as a layer of anode material on an inner side of the exit window.
  • the anode is made of, for example chromium, rhodium, scandium or another anode material.
  • the thickness of the layer is adapted to the desired radiation, to the radiation absorption properties of the material, but notably to the electron absorption thereof, and to the desired high voltage for the tube.
  • a chromium layer and a scandium layer have a thickness of, for example approximately 2.5 ⁇ m and a rhodium layer has a thickness of 1 ⁇ m.
  • the anode preferably operates substantially at ground potential, so that no problems are encountered in respect of the electrical insulation of the comparatively thin beryllium window.
  • a cooling duct 14 having an inlet 16, an outlet 18 and a flow duct 20 which surrounds the exit window, is provided in the envelope.
  • a high-voltage connector which is preferably made of rubber can be inserted into the base 2.
  • Such a high-voltage connector is connected to a high-voltage cable, to supply leads for the filament and to supply leads for any further electrodes to be arranged in a cathode-anode space 22.
  • a mounting sleeve 24 which comprises a mounting flange 26 and an additional radiation shield 28 which also bounds the flow duct 20.
  • a thin-walled mounting sleeve 30 which accommodates the cooling ducts and which also has a temperature-equalizing effect.
  • a cathode sleeve as shown in Fig. 2 comprises an end sleeve 40, a second tapered portion 41, an intermediate sleeve 42, a first tapered portion 43, and a first sleeve 44. Electron-optical properties of the sleeve in respect of electrons to be emitted by the emitter 6 are determined mainly by: the diameter E of the first sleeve 44, the diameter C of the intermediate sleeve 42, the length B of the intermediate sleeve 42, the length A of the end sleeve 40, the diameter D of the emitter 6, and the position of the emitter in the cathode sleeve, expressed as its distance F from the tapered portion 43.
  • the term "diameter" is used in the foregoing, but the geometry of the sleeves is not necessarily rotationally symmetrical. This also holds for the emitter 6. An electron beam 50 emanating from the emitter 6 is focused more or less on the anode 12 by variation of the potential across the sleeve. In a model for the geometry, subject to secondary conditions such as reasonable possibility of mounting in the X-ray tube and possibility of performing comparatively simply potential variations, for example up to approximately 2000 V, an optimum configuration can be calculated for a desired focus width.
  • the drawing shows, by way of solid lines and dashed lines, two focus conditions, for example for 500 V and 1500 V, respectively.

Landscapes

  • X-Ray Techniques (AREA)
EP93200136A 1992-01-27 1993-01-20 Tube à rayons X ä foyer variable Withdrawn EP0553914A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP92200206 1992-01-27
EP92200206 1992-01-27

Publications (1)

Publication Number Publication Date
EP0553914A1 true EP0553914A1 (fr) 1993-08-04

Family

ID=8210381

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93200136A Withdrawn EP0553914A1 (fr) 1992-01-27 1993-01-20 Tube à rayons X ä foyer variable

Country Status (2)

Country Link
EP (1) EP0553914A1 (fr)
JP (1) JPH05275037A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010012403A2 (fr) * 2008-07-29 2010-02-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Cible radiographique et procédé de production de rayons x

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4344011A (en) * 1978-11-17 1982-08-10 Hitachi, Ltd. X-ray tubes
JPS5994348A (ja) * 1983-10-28 1984-05-31 Hitachi Ltd 可変焦点ｘ線管
EP0283039A2 (fr) * 1987-03-19 1988-09-21 Siemens Aktiengesellschaft Tube à rayons X
EP0349388A1 (fr) * 1988-07-01 1990-01-03 General Electric Cgr S.A. Tube radiogène à auto-limitation du flux électronique par saturation
EP0389326A1 (fr) * 1989-03-24 1990-09-26 General Electric Cgr S.A. Tube à rayons x à balayage avec plaques de déflexion

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4344011A (en) * 1978-11-17 1982-08-10 Hitachi, Ltd. X-ray tubes
JPS5994348A (ja) * 1983-10-28 1984-05-31 Hitachi Ltd 可変焦点ｘ線管
EP0283039A2 (fr) * 1987-03-19 1988-09-21 Siemens Aktiengesellschaft Tube à rayons X
EP0349388A1 (fr) * 1988-07-01 1990-01-03 General Electric Cgr S.A. Tube radiogène à auto-limitation du flux électronique par saturation
EP0389326A1 (fr) * 1989-03-24 1990-09-26 General Electric Cgr S.A. Tube à rayons x à balayage avec plaques de déflexion

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 8, no. 209 (E-268)22 September 1984 & JP-A-59 094 348 ( HITACHI ) 31 May 1984 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010012403A2 (fr) * 2008-07-29 2010-02-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Cible radiographique et procédé de production de rayons x
WO2010012403A3 (fr) * 2008-07-29 2010-03-25 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Cible radiographique et procédé de production de rayons x

Also Published As

Publication number Publication date
JPH05275037A (ja) 1993-10-22

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