US3567983A - X-ray tube with magnetic focusing means - Google Patents

X-ray tube with magnetic focusing means Download PDF

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Publication number
US3567983A
US3567983A US733020A US3567983DA US3567983A US 3567983 A US3567983 A US 3567983A US 733020 A US733020 A US 733020A US 3567983D A US3567983D A US 3567983DA US 3567983 A US3567983 A US 3567983A
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United States
Prior art keywords
window
tube
anode
ray tube
electrons
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Expired - Lifetime
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US733020A
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English (en)
Inventor
Gerhard Heinrich Friedri Vries
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith
    • H01J35/18—Windows
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/16—Vessels
    • H01J2235/165—Shielding arrangements
    • H01J2235/168—Shielding arrangements against charged particles

Definitions

  • X-RAY TUBE WITH MAGNETIC FOCUSING MEIAS 4D ABSTRACT An X-ray tube having a beryllium window in a 4 C metal wall portion of the tube which is integral with the anode, [52] U.S. Cl 313/57, the beam channel extending in the axial direction of the tube 313/55, 250/90 at the window being surrounded by a strong magnetic field the [51] Int. Cl ..H0lj 35/14, lines of force of which extend substantially parallel to the axis H01 j 35/18 of the tube, the region of substantially constant field strength [50] Field of Search 313/55, 57, on the side of the tube cross section closed by the window having a maximum width.
  • This invention relates to an X-ray tube provided with an X ray exit window which is made of beryllium and satisfactorily transmits soft X-rays having a wave length of not less than A.
  • the window is arranged in the metal wall of the tube. It is known to provide such a tube with means to prevent the window from being struck by electrons.
  • the window is screened electrostatically, which is achieved when the window is at cathode potential or when a gauzelike electrode held at cathode potential is arranged between the window and the electron target on the anode of the X-ray tube.
  • Electrons striking the anode with a high velocity and then terminating on the window due to elastic reflection are particularly harmful in an X-ray tube having a window transmitting soft rays, because for wavelengths exceeding 15 A.
  • the thickness of the beryllium window is preferably not larger than 0.05 mm. so that this window has such a low heat capacity and such a low thermal conductivity that excessive heating owing to the energy of the rapid electrons is inevitable, as a result of which such a tube cannot be used for anode voltages exceeding those at which X-rays of the said wavelength are produced.
  • the beam channel extending in the axial direction of the tube is surrounded at the X-ray exit window and on its inner side by a strong magnetic field, the lines of force of which extend substantially parallel to the axis of the tube, while the region of substantially constant field strength at least on the side of the tube cross section closed by the window has a maximum width.
  • this field serves to promote the concentration of the electrons and the compression of the electron beams to a minimum cross section.
  • the conventional electrostatic focusing which is obtained by suitably shaping the support of the thermionic cathode, is sometimes insufficient and is especially unsatisfactory if the electrons are accelerated towards the anode over a comparatively large distance.
  • a magnetic focusing field is used which preferably has a small focal distance.
  • pole pieces in the immediate proximity of the electron target in a manner such that a lateral passage for the X-rays is left free between the opposite poles.
  • Such a lens considerably contributes to the focusing with a maximum magnetic induction along the axis of the lens.
  • the magnetic field strength required is obtained only under the influence of the saturation of the iron of the pole pieces.
  • Such a magnetic focusing field acts on the elastically reflected electrons released in the target on the anode as a stray field because the area at which the electrons are produced is located inside the operative range and in the proximity of the maximum strength of the lens field.
  • the paths of these electrons which have a high initial velocity, are not or substantially not influenced by the magnetic field in the proximity of the target. This accounts for the fact that with a sufficient strength of the field surrounding the electron paths, a minimum lens effect is advantageous to cause the electrons reflected from the anode to terminate under the influence of the said magnetic field on areas other than the tube window and even to conduct such electrons back to the anode.
  • FIG. 1 is a sectional view of the X-ray tube according to the invention.
  • FIGS. 2, 3 and 4 are a few cross sections of the anode part of the tube at the level of the window.
  • a glass sheath 1 encloses a space which is exhausted to a vacuum and in which a thermionic cathode 2 is arranged, the support 3 of which is fused to the glass wall.
  • a hollow metal tube 4 projecting beyond a seal 5 on the wall 1 terminates opposite the cathode 2.
  • the metal tube 4 consists of a ferromagnetic material, for example, iron and supports at its end a copper anode 6 by means of which the tube 4 is closed in a vacuum-tight manner. The conventional materials for cooling the anode are not shown in the drawing.
  • the wall of the metal tube 4 is provided with an aperture or passage 7 for the X- rays, which aperture is closed by a thin-walled beryllium window 8 which has a thickness of, for example, about 0.05 mm.
  • the window 8 Due to the mechanical and electrical connection between the window 8 and the anode tube 4, the window is at the same potential as the anode 6.
  • the cathode 2 and the anode 6 have applied to them the operating voltage, electrons elastically reflected from the anode surface 9 will be deflected towards the window 8 which is a target for such electrons, which are accelerated by the operating voltage applied and the velocity of which is hardly reduced by the deflection, is exposed to strong heating.
  • the electrons are conducted away from the window by a magnetic field which along the beam channel constituted by the inner wall of the anode tube 4 at the level of the window annularly encloses the electron paths terminating on the anode.
  • Such a strong magnetic field enclosing the electron paths is capable of varying sufficiently the direction of the penetrating electronstravelling towards the window so that such electrons pass the window, and strike other areas of the anode tube or return to the anode.
  • the desired screening of the window is obtained by a magnetic field of not more than 5,000 Gauss.
  • a thick-walled anode tube 4 which has an annular interruption at the level of the window 8.
  • the bore of the tube 4 is, so to say, magnetically screened so that the field in this space is suppressed.
  • the field is produced by a magnetic yoke 10 which joins the anode tube 4 and is provided with an energizing magnet coil 11.
  • the required field may be produced by a permanent magnet.
  • the interruption 12 provided in the anode tube 4 for forming the magnet poles is suitably bridged by a nonmagnetic material.
  • FIGS. 2 and 3 are shaped so that, while retaining a sufficiently strong field at the window, the anode tube may have a smaller weight.
  • the shape of the cross section of FIG. 4 is preferred when two or more windows 8 transmitting Xrays in various directions are arranged, as is the case, for example, in multiple X-ray diffraction apparatus.
  • the dimensions of the tube may be substantially equal to those of the construction without the window screening described.
  • An X-ray tube comprising an evacuated envelope having a metal wall portion provided with a window therein for the transmission of X-rays having a wavelength of not less than 15 A., a cathode and an anode within said envelope defining a given axis within said envelope, said anode being integral with said wall portion having said window, and means in proximity to said anode for generating a magnetic field the lines of force of which extend substantially parallel to the axis of said tube, said window being positioned parallel to said axis whereby said window, in the absence of the magnetic field, is struck by scattered electrons from said anode, said magnetic field having a region of substantially constant field strength of maximum width in proximity to said window whereby scattered electrons from said anode are prevented from striking said window.

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  • X-Ray Techniques (AREA)
US733020A 1967-06-17 1968-05-29 X-ray tube with magnetic focusing means Expired - Lifetime US3567983A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6708463A NL6708463A (xx) 1967-06-17 1967-06-17

Publications (1)

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US3567983A true US3567983A (en) 1971-03-02

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Application Number Title Priority Date Filing Date
US733020A Expired - Lifetime US3567983A (en) 1967-06-17 1968-05-29 X-ray tube with magnetic focusing means

Country Status (9)

Country Link
US (1) US3567983A (xx)
AT (1) AT285755B (xx)
BE (1) BE716713A (xx)
CH (1) CH484510A (xx)
DE (1) DE1764179A1 (xx)
FR (1) FR1570861A (xx)
GB (1) GB1163509A (xx)
NL (1) NL6708463A (xx)
SE (1) SE353814B (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4713833A (en) * 1982-06-17 1987-12-15 Kevex Corporation X-ray source apparatus
EP1944789A1 (en) * 2005-10-07 2008-07-16 Hamamatsu Photonics K.K. X-ray tube and x-ray source including same
US10825640B2 (en) 2018-04-12 2020-11-03 Hamamatsu Photonics K.K. X-ray tube

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1217270B (de) * 1958-10-08 1966-05-18 Friedrich Stuebbe Bandfoerderer
JPS585502B2 (ja) * 1976-05-26 1983-01-31 株式会社東芝 Ｘ線管
GB2178225B (en) * 1985-07-16 1990-01-24 English Electric Valve Co Ltd Improvements in or relating to ignitron devices
US9644847B2 (en) 2015-05-05 2017-05-09 June Life, Inc. Connected food preparation system and method of use
US10739013B2 (en) 2015-05-05 2020-08-11 June Life, Inc. Tailored food preparation with an oven
US11116050B1 (en) 2018-02-08 2021-09-07 June Life, Inc. High heat in-situ camera systems and operation methods
WO2021102254A1 (en) 2019-11-20 2021-05-27 June Life, Inc. System and method for estimating foodstuff completion time
US11680712B2 (en) 2020-03-13 2023-06-20 June Life, Inc. Method and system for sensor maintenance
WO2021195622A1 (en) 2020-03-27 2021-09-30 June Life, Inc. System and method for classification of ambiguous objects
USD978600S1 (en) 2021-06-11 2023-02-21 June Life, Inc. Cooking vessel
USD1007224S1 (en) 2021-06-11 2023-12-12 June Life, Inc. Cooking vessel

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4713833A (en) * 1982-06-17 1987-12-15 Kevex Corporation X-ray source apparatus
EP1944789A1 (en) * 2005-10-07 2008-07-16 Hamamatsu Photonics K.K. X-ray tube and x-ray source including same
EP1944789A4 (en) * 2005-10-07 2011-09-07 Hamamatsu Photonics Kk X-RAYS AND X-RAY SOURCE WITH IT
US10825640B2 (en) 2018-04-12 2020-11-03 Hamamatsu Photonics K.K. X-ray tube

Also Published As

Publication number Publication date
AT285755B (de) 1970-11-10
NL6708463A (xx) 1968-12-18
SE353814B (xx) 1973-02-12
GB1163509A (en) 1969-09-10
DE1764179A1 (de) 1971-05-27
CH484510A (de) 1970-01-15
BE716713A (xx) 1968-12-17
FR1570861A (xx) 1969-06-13

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