US1977541A - X-ray tube - Google Patents

X-ray tube Download PDF

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Publication number
US1977541A
US1977541A US435604A US43560430A US1977541A US 1977541 A US1977541 A US 1977541A US 435604 A US435604 A US 435604A US 43560430 A US43560430 A US 43560430A US 1977541 A US1977541 A US 1977541A
Authority
US
United States
Prior art keywords
anticathode
focal spot
axis
cathode
tube
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.)
Expired - Lifetime
Application number
US435604A
Other languages
English (en)
Inventor
Bouwers Albert
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
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
Priority claimed from NL45957A external-priority patent/NL31411C/xx
Application filed by Philips Gloeilampenfabrieken NV filed Critical Philips Gloeilampenfabrieken NV
Application granted granted Critical
Publication of US1977541A publication Critical patent/US1977541A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • 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
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • H01J35/101—Arrangements for rotating anodes, e.g. supporting means, means for greasing, means for sealing the axle or means for shielding or protecting the driving
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
    • H01J35/26—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof by rotation of the anode or anticathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/10—Drive means for anode (target) substrate
    • H01J2235/1026—Means (motors) for driving the target (anode)
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/12—Cooling
    • H01J2235/1225—Cooling characterised by method
    • H01J2235/1262—Circulating fluids
    • H01J2235/1266—Circulating fluids flow being via moving conduit or shaft

Definitions

  • the invention relates to X-ray tubes in which the anticathode and the electron beam move relatively with respect to one another.
  • Such tubes present the great advantage that, with a given energy supplied to the tube the surface on which the electron beam strikes is loaded much less heavily than when the electron beam continuously strikes the same portion of the anticathode.
  • such tubes may be loaded much 5 more heavily or for a much longer time or again they may be constructed so as to have smaller dimensions for a given load.
  • the heating is not uniform, that is: the heating is not the same at every point of the surface which participates in the forming of the focal spot. In itself this is not disadvantageous, but since the maximum load of the tube is determined by the highest temperature occurring at any point, it is only possible tov work with an energy smaller than that which corresponds to the uniform heating to the highest admissible temperature.
  • such a uniform heating is obtained by giving the focal spot a particular shape.
  • the time interval during which; in each revolution or period of the relative movement of the anticathode with respect to the electron beam, a point'of the anticathode surface is loaded depends on the speed at which .50. a point on the anticathode passes through the electron beam and on the length of the path described in the electron beam by the said point.
  • the various portions of the anticathode move at different speeds with relation to the electron beam, and when the paths described in the latter are of equal length, the material in the points moving with the greatest speed will be loaded during the shortest periods of time and will consequently be heated least. If, With a rotary anticathode the focal spot has a rectangular shape, this is the case with the part farthest remote from the axis of rotation.
  • An X-ray tube has an electron beam which conveniently has an elongated shape and whose longitudinal axis is preferably perpendicular to the direction of the mOvement.
  • the focal spot has everywhere or for a considerable portion such a dimension in the direction of the movement of the anode that it is traversed in substantially 7 equal periods of time.
  • the tube may comprise a rotary anticathode and may have a focal spot whose breadth increases proportionately to the distance from the axis of rotation.
  • the focal spot is preferably limited by two lines which intersect each other in or near the axis of rotation.
  • Figure 1 is a side View, partly in section, of an X-ray tube comprising a rotary anticathode according to the invention.
  • Fig. 2 is a perspective view of part of the anticathode and showing the shape of a focal spot as used heretofore.
  • Fig. 3 is a perspective View of part of the anticathode and showing the shape of a focal spot in accordance with the invention.
  • Figure 1 shows an X-ray tube whose outer wall consists of two'glass parts 1-1 which are surrounded by cylinders 2-2 of a material which is poorly transparent to X-rays. Between glass parts 1-1 is sealed a part 3 of metal preferably of form-chromium, which has a window 4 through which X-rays can emerge from the tube.
  • the tube comprises an incandescent cathode 5 arranged in a metal vessel 6.
  • the ends of this incandescent cathode are connected to contact pins 7, one bymeans of asupply wire (not shown) 100 and the cylinder is ,3; tion and which the other via the metal vessel 6.
  • To these contact pins may be connected the supply wires for the heating current.
  • the beam of electrons emitted by the cathode is concentrated by vessel 6, forming the focussing device, on a small area of the anticathode 8.
  • the shape of the cross-sect 1 of the of cathode rays depends on the of the aperture 9 of the focussing device.
  • the cathode rays impact on a portion of the anticathode which is located on one side of the apex of the conical end-surface.
  • the anticathode is rotatably secured to a spindle 10 in which terminates the metal member 11 which is sealed to the glass wall of the tube and which is connected to the contact member 20.
  • the rotation of the anticathode is obtained due to the fact that it constitutes the rotor of an induction motor.
  • it is constituted by a cylinder of good conducting material, for example copper, wlL'ch encloses another cylinder of a material having a high permeability.
  • the stator 15 of the motor is located entirely outside the tube. Magnet windings 17 on this stator furnish the field ofthe motor and may be connected to a multiphase alternating current network or, in conjunction with devices adapted to bring about a mutual phase-displacement, to an ordinary alternating current supply consequently connected to ground so that there is no possibility of coming into contact with the parts under tension.
  • This cylinder surrounds the metal portion 3 of the Wall. A layer 19 of lead provided between this metallic portion prevents undesirable X-rays from emerging.
  • Figure 2 represents the slightly conical endsurface of the anticathode 8 of Fig. 1, the focal spot produced thereon during operation being indicated by 21. This is the place where the electrons emitted by the incandescent cathode impinge on the end-surface of the body 8 and from which the X-rays emanate. Its shape is determined by that of the aperture 9 of the focusslng device.
  • the focal spot shown in Figure 2 has the shape of a rectangle whose longitudinal axis is located along a generatrix of the conical surface. If the width of this focal spot is called d, the time t during which, in each revolution, 2.
  • the maximum admissible load will be the load which causes the temperature of that portion of the focal spot which is nearest the axis of rotain every revolution is loaded during a time n, to rise to the said value T1 because the temperatures, produced in other portions of the focal spot with a larger 1* and consequently a smaller t, are lower.
  • the focal spot is formed on the conical end-surface of the anticathode, this theoretically ideal focal spot is consequently limited by two straight lines which intersect each other in the axis of rotation, namely by two generatrices of the conical surface.
  • the short sides of the focal spot are portions of circles around the axis, the focus may also be rounded off on one or on both sides. It is essential that the proportionality of the breadth and the distance from the axis exists over a considerable portion of the lengths of the focal spot.
  • the illustrated shape of the focal spot is also favourable in view of the emerging beam of rays.
  • the portion of the conical surface which in each revolution turns through the beam of cathode rays may consist of a tungsten ring having at any point the same thickness.
  • theanticathode mirror be very thin, for example less than 0,3 mm.
  • the load may be such that both the surface of the tungsten and the surface of separation with the material lying under it, which preferably is copper, are thermally loaded at a maximum; the efi'iciency of the tube in this case being as high as possible.
  • An X-ray tube having an envelope, a rotatable anode, a .cathode, and a focussing device for said cathode, and having an aperture therein, the width of the said aperture at any point along its side being directly proportional to the distance of said point from the axis of rotation of the anode.
  • an envelope a rotatable anode having a cylindrical portion and a conical front surface, a cathode adapted to be heated to incandescence and a device cooperating with said cathode for focussing the beam of cathode rays, said cathode facing a conical front surface of the anode and being slightly displaced laterally from the axis of rotation of the anode, the focussing device having an elongated aperture for the passage of the electrons, which is'wider at the side remote from said axis than at the side adjacent said axis.
  • a method of loading a rotatable anode by an electron beam comprising projecting a beam, of electrons thereon, the width of said beam in any point ofa section perpendicular to the cathode rays, increasing linearly at least over a considerable portion of the length of said section, with increase in the distance outwardly from the axis of the rotation of the anode.

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  • X-Ray Techniques (AREA)
US435604A 1929-04-19 1930-03-13 X-ray tube Expired - Lifetime US1977541A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL45957A NL31411C (en, 2012) 1927-01-18 1929-04-19

Publications (1)

Publication Number Publication Date
US1977541A true US1977541A (en) 1934-10-16

Family

ID=41055079

Family Applications (1)

Application Number Title Priority Date Filing Date
US435604A Expired - Lifetime US1977541A (en) 1929-04-19 1930-03-13 X-ray tube

Country Status (9)

Country Link
US (1) US1977541A (en, 2012)
AT (1) AT118763B (en, 2012)
BE (1) BE368820A (en, 2012)
CH (1) CH146975A (en, 2012)
DE (1) DE605180C (en, 2012)
DK (1) DK44241C (en, 2012)
FR (1) FR692620A (en, 2012)
GB (1) GB331052A (en, 2012)
NL (1) NL34152C (en, 2012)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3296476A (en) * 1961-10-31 1967-01-03 Licentia Gmbh X-ray tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE900977C (de) * 1939-02-18 1954-01-04 Dr Rolf Hosemann Roentgenroehre mit Strichbrennfleck und flexibel befestigter Pendelanode
AT346981B (de) * 1976-03-18 1978-12-11 Plansee Metallwerk Roentgendrehanode und verfahren zu deren herstellung

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3296476A (en) * 1961-10-31 1967-01-03 Licentia Gmbh X-ray tube

Also Published As

Publication number Publication date
DE605180C (de) 1934-11-06
GB331052A (en) 1930-06-26
CH146975A (de) 1931-05-15
AT118763B (de) 1930-08-11
FR692620A (fr) 1930-11-07
BE368820A (en, 2012) 1930-04-30
DK44241C (da) 1931-06-22
NL34152C (en, 2012) 1934-11-15

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