US2521663A - Electron target and means for making the same - Google Patents

Electron target and means for making the same Download PDF

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Publication number
US2521663A
US2521663A US783879A US78387947A US2521663A US 2521663 A US2521663 A US 2521663A US 783879 A US783879 A US 783879A US 78387947 A US78387947 A US 78387947A US 2521663 A US2521663 A US 2521663A
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United States
Prior art keywords
target
electron
anode
working
grain structure
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Expired - Lifetime
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US783879A
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English (en)
Inventor
Michael J Zunick
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General Electric X Ray Corp
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General Electric X Ray Corp
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Publication date
Priority to NL666618407A priority Critical patent/NL142818B/xx
Priority to NL90795D priority patent/NL90795C/xx
Application filed by General Electric X Ray Corp filed Critical General Electric X Ray Corp
Priority to US783879A priority patent/US2521663A/en
Priority to GB27159/48A priority patent/GB650237A/en
Priority to FR974403D priority patent/FR974403A/fr
Application granted granted Critical
Publication of US2521663A publication Critical patent/US2521663A/en
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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
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes

Definitions

  • My present invention relates in general to electronics, and has more particular reference to an' improved electron target structure and method of making the same; the invention having specific reference to an electron target structure well suited for use as an anode in an X-ray generator.
  • An X-ray generator comprises an electron emitting cathode and an anode at which X-rays may be generated in response to impingement of electrons, emitted by the cathode, upon a suit able electron target at the anode. Electron impingement on the anode target during operation of the generator tends to disintegrate the target material due to excessive heat liberated at the target as the result of impingement of high speed electrons thereon. Target deterioration may take the form of target deformation, splitting, flaking, and curling, with the result that the target becomes progressively less efiicient as such, more or less rapidly, eventually becoming entirely useless.
  • anode targets such as tungsten, nickel, copper, cobalt, iron, chromium, molybdenum, and other metals, all tend to deteriorate in the manner mentioned when exposed to electronic bombardment; and an important object of the present invention is to minimize deterioration of the character mentioned, particularly in electron targets of tungsten, although the principles of the present invention may have beneficial application in connection with electron targets of other materials than tungsten.
  • Another important object is to minimize electron target deterioration by controlling the grain size of target material, more particularly by controlling grain structure to provide very coarse, elongated grains substantially uniformly distributed throughout the body of the target material.
  • Another important object is to provide material for electron targets, having very coarse, elongated grain structure distributed substan tially uniformly throughout the material, by repeatedly rolling a slab of target material to reduce the sectional dimensions thereof to desired size, and by recrystallizing the material while it is being Worked, whereby to obtain maximum grain growth in the material, as by heating the slab during an interval, or intervals, between successive passes of the slab through the working rollers.
  • Another important object is to provide electron target material, such as worked tungsten, having very coarse, elongated grain structure of the order of about LOGO-2,000 grains per square millimeter, by working the material, as by rolling it, for the reduction of its sectional size, and more or less completely recrystallizing the material during the working thereof, but prior to final working of the material, to obtain maximum grain growth therein, the desired internal grain structure comprising relatively large grains which are substantially elongated, in contrast with the compact or pebbly grain form of so-called equiaxed material, produced by heating the material Without working it, which has poor strength and which tends to crack and disintegrate under the high heat generated in the material when subjected to electronic impingement.
  • electron target material such as worked tungsten
  • Another important object of the invention is to provide electron'target material characterized by relatively large recrystallized grain structure, substantially free of laminations, and worked sufficiently to produce an elongated grain structure, thereby preventing cracking and curling of the material when exposed to electron impact, without, however, carrying the working to the point of producing laminae in the material or breaking up or otherwise reducing the desired coarse and elongated grain structure.
  • Fig. l is a longitudinal section taken through an X-ray generator having an anode providing an electron target;
  • Fig. 2 is a sectional view taken substantially along the line 2-2 in Fig. l to illustrate the electron target end of the anode;
  • Fig. 3 is a representation of a micro picture of tungsten having typical fine grain structure of the sort heretofore commonly employed for electron target purposes in X-ray generators;
  • Fig. 4 is a view similar to Fig. 2, showing the character of deterioration under extended electron bombardment of target material of the fine grain structure shown in Fig. 3;
  • Fig. 5 is a representation of a micro picture of tungsten having relatively fine grain structure partially recrystallized and worked to increase grain size and length;
  • Fig. 6 is a representation of a micro picture of tungsten of relatively coarse, elongated grain structure provided by working the material while substantially recrystallizing the same;
  • Fig. '7 is a representation of a micro picture of tungsten having very coarse, elongated grain structure provided by working the material and more or less completely recrystallizing the same;
  • Fig. 8 is a sectional view comparable to Fig. 2, showing the minimum character of deterioration in an electron target comprising material of the sort illustrated in Fig. '7.
  • an X-ray generator ll comprising a sealed envelope [2 containing an anode l3 and a cathode l4 embodying an electron emitting filament Hi.
  • the cathode and anode may be mounted in co-axial, spaced and facing relationship within the envelope !2.
  • Suitable conductors for energizing the electron emitting filament l5, and for applying suitable operating electrical potential, between the filament and the anode, from an electrical power source disposed outwardly of the envelope, for the operation of the generator may, of course, be provided.
  • the device as shown in Fig. 1, comprises a generator of the sort in which the anode I3 is mounted for rotation within the envelope upon an axle or support stem IS, the anode being caused to rotate by the operation of electrical motor means including the stationary stator ll, mounted on and outwardly of the envelope at the anode containing end thereof.
  • the anode may be provided with an electron target 18, which may comprise an annular ring of suitable target material, such as tungsten, mounted concentrically upon the anode, which may comprise abody or shell of copper forming a mounting base for the target ring, said base in turn being journalled for rotation on the axis stem l3.
  • an electron target 18 may comprise an annular ring of suitable target material, such as tungsten, mounted concentrically upon the anode, which may comprise abody or shell of copper forming a mounting base for the target ring, said base in turn being journalled for rotation on the axis stem l3.
  • the anode is so positioned as to present the target ring i8 continuously in the path of an electron beam l9, emitted by the filament l as the anode rotates.
  • the present invention is not necessarily limited to targets for rotating anodes, but applies equally to stationary targets in which the target may comprise a target member disposed in fixed position in the path of the electron beam.
  • a generator operates to produce X-rays at the surface of the target as the result of the impingement, on the surface of the target, of electrons emitted at the filament l5, when electrically energized, said emitted electrons being impelled toward, and caused to impinge upon, the surface of the target, under the influence of electrical potential applied between the filament and the anode, the higher the anode-cathode potential, the greater the force of electron impingement and the greater the intensity of resulting X-rays.
  • X-rays generated as a result of electron impingement on the target surface pass outwardly of the envelope and may be utilized for various useful purposes.
  • the generator When the generator is in operation, a considerable amount of heat is developed at the target surface as a result of electron impingement thereon, such heat being dissipated through the body of the anode and thence outwardly of the envelope.
  • the temperature at the target surface depends not only on the rate of heat dissipation from the anode, but also upon the intensity of electron bombardment, which,
  • the temperature developed at the target surface may be of the order of the melting temperature of the target material, particularly in high power generators in which high electron driving potential is applied between the anode and the cathode, it being usual, in the interests of operating efficiency, to operate the generator so that its anode, at the target surface, functions at a temperature just short of the softening temperature of the anode material.
  • the excessively high temperature to which the target is subjected tends to cause target deterioration, which is evidenced by bulging, buckling, cracking, curling, and flaking of the target material, and the consequent deformation of the target surface from a desirable fiat condition.
  • Such deformation impairs the eficiency of the generator, and fre-- quently results in rendering the generator completely useless for its intended purpose.
  • target deterioration including bulging, buckling, cracking, curling, and flaking
  • target material of ultra fine grain
  • tungsten having fine grain structure of the order of more than 2,500 grains per square millimeter of surface, such fine grain structure being illustrated in Fig. 3 of the drawings.
  • Targets of fine grain material give satisfactory performance if not overloaded; but the present trend of development toward ever higher powered generators demands target loadings which rapidly deteriorate fine grain targets comprising material of the sort shot-m in Fig. 3; and when so overloaded, a target of such material is found rapidly to disintegrate by cracking, flaking, and curling, in the manner illustrated in Fig. 4, which shows a fine grain target H3 in deteriorated condition such that the target is useless for practical purposes, the same having its surface portions flaked and curled up from the body of the target to form. separated shreds or flakes 20.
  • the present invention contemplates the use of target material having relatively coarse granular structure of the order of substantially less than 2,500 grains per square millimeter, in which the constituent grains are elongated to an appreciable extent.
  • This type of grain structure may be obtained by recrystallizing the target material during the working of a slab of the material, such working consisting of successive slab rolling operations, whereby to reduce the sectional area of the work piece to desired dimensions.
  • the working of the material tends to reduce the size ofconstituent grains by breaking them down as a result of the rolling operations.
  • Recrystallization of the material may be accomplished by heating the Work piece at controlled temperatures in order to accomplish recrystallization and resultant grain growth, such recrystallization being accomplished by heating the work piece during the period between successive rollings; and recrystallization preferably is accomplished as fully as possible by heating the work piece at a temperature, and for a period of time, sufficient to produce grain growth to maximum size, although favorable results are obtained if recrystallization is allowed to proceed to a degree of partial recrystallization short of the maximum possible recrystallizing efiect.
  • Desirable results may be obtained by heating the work piece for either complete or partial recrystallization, several times during the working process, or recrystallization may be accomplished during the rest interval immediately prior to the final rolling step of the working operation.
  • the resultant target material may be obtained substantially free of laminae with a grain structure of the order of 2,000 grains per square millimeter, accomplished by partially recrystallizing the target material, such partially recrystallized material having appreciably elongated grains being illustrated in Fig. 5 of the drawings.
  • FIG. 6 A somewhat coarser grain structure, accom plished by more completely recrystallizing the target material and having a grain structure of the order of 1,500 grains per square millimeter, is illustrated in Fig. 6, while Fig. '7 pictures a grain structure of maximum coarseness of the order of 1,000 grains per square millimeter, accomplished by working the material during and after substantially complete recrystallization of the same.
  • Material of the character depicted in Fig. 7, and also as shown in Figs. 5 and 6, are all characterized by the presence of relatively large and substantially elongated grain structure, as compared with the typical fine grain structure depicted in Fig. 3, which is obtained by working the material without recrystallizing the same, and which has heretofore been considered essential for satisfactory electron targets.
  • the present invention in teaching the recrystallization of target material in conjunction with. the working of the same, also distinguishes from so-called equiaxed material, which is produced by recrystallization without working and which is of coarse grain pebbly structure in which the grains are rounded and not elongated.
  • Targets of material which has been worked while being recrystallized accordingly, may be employed without deterioration under loads which have heretofore been considered destructively high; and even where overloaded and deleteriously afiected as by cracking, in the manner shown in Fig. 8, electron targets of recrystallized material do not materially lose utility.
  • apparatus embodying an electron target of the sort here described does not become useless for further service, even if overloaded sufiiciently to crack the target element in the manner indicated in Fig. 8, although overloads of such character would completely destroy the utility of targets of the best quality and character heretofore provided.
  • An electron target for an X-ray tube comprising mechanically worked tungsten having recrystallized grain structure of the order of 2000 grains per square millimeter or less, wherein the constituent grains are substantially elongated as a result of working the tungsten, whereby the same under heavy electron impact load is highly resistant to cracking, splitting, flaking, and curling at the electron receiving surface of the target.
  • An Y-ray generator embodying an anode having an electron target comprising tungsten having at least partially recrystallized grain structure in the range of 1000-2000 grains per square millimeter, in which the grains are substantially elongated.

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  • X-Ray Techniques (AREA)
  • Physical Vapour Deposition (AREA)
US783879A 1947-11-04 1947-11-04 Electron target and means for making the same Expired - Lifetime US2521663A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL666618407A NL142818B (nl) 1947-11-04 Elektrode voor een elektrische ontladingsbuis, alsmede ontladingsbuis voorzien van deze elektrode.
NL90795D NL90795C (fr) 1947-11-04
US783879A US2521663A (en) 1947-11-04 1947-11-04 Electron target and means for making the same
GB27159/48A GB650237A (en) 1947-11-04 1948-10-19 Improvements in and relating to electron target structures
FR974403D FR974403A (fr) 1947-11-04 1948-10-28 Structure et mode de fabrication perfectionnés d'anticathodes pour tubes électroniques

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Application Number Priority Date Filing Date Title
US783879A US2521663A (en) 1947-11-04 1947-11-04 Electron target and means for making the same

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US2521663A true US2521663A (en) 1950-09-05

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US (1) US2521663A (fr)
FR (1) FR974403A (fr)
GB (1) GB650237A (fr)
NL (2) NL142818B (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2819991A (en) * 1952-08-30 1958-01-14 Rca Corp Carburized thoriated tungsten electrode and method of enhancing its emissivity
US3158513A (en) * 1959-02-26 1964-11-24 Philips Corp Method of manufacturing disc-shaped anodes for rotary-anode X-ray tubes
US3160779A (en) * 1962-04-30 1964-12-08 Gen Electric Single crystal X-ray tube target
US3622824A (en) * 1969-06-30 1971-11-23 Picker Corp Composite x-ray tube target
EP0756308A4 (fr) * 1994-03-28 1996-12-13 Hitachi Ltd Tube a rayons x et sa cible anodique
US5745546A (en) * 1995-03-20 1998-04-28 Siemens Aktiengesellschaft Anode for an x-ray tube
US20070169854A1 (en) * 2004-08-10 2007-07-26 Sanbo Shindo Kogyo Kabushiki Kaisha Copper-based alloy casting in which grains are refined
US9303300B2 (en) 2005-09-30 2016-04-05 Mitsubishi Shindoh Co., Ltd. Melt-solidified substance, copper alloy for melt-solidification and method of manufacturing the same
US11043352B1 (en) * 2019-12-20 2021-06-22 Varex Imaging Corporation Aligned grain structure targets, systems, and methods of forming

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL236552A (fr) * 1959-02-26

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1826514A (en) * 1926-11-26 1931-10-06 Westinghouse Lamp Co Tungsten and method of manufacturing the same
US2332044A (en) * 1942-06-24 1943-10-19 Westinghouse Electric & Mfg Co Brake for rotary anode x-ray tubes
US2430800A (en) * 1943-10-02 1947-11-11 Gen Electric X Ray Corp Rotating anode construction

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1826514A (en) * 1926-11-26 1931-10-06 Westinghouse Lamp Co Tungsten and method of manufacturing the same
US2332044A (en) * 1942-06-24 1943-10-19 Westinghouse Electric & Mfg Co Brake for rotary anode x-ray tubes
US2430800A (en) * 1943-10-02 1947-11-11 Gen Electric X Ray Corp Rotating anode construction

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2819991A (en) * 1952-08-30 1958-01-14 Rca Corp Carburized thoriated tungsten electrode and method of enhancing its emissivity
US3158513A (en) * 1959-02-26 1964-11-24 Philips Corp Method of manufacturing disc-shaped anodes for rotary-anode X-ray tubes
US3160779A (en) * 1962-04-30 1964-12-08 Gen Electric Single crystal X-ray tube target
US3622824A (en) * 1969-06-30 1971-11-23 Picker Corp Composite x-ray tube target
US6487275B1 (en) 1994-03-28 2002-11-26 Hitachi, Ltd. Anode target for X-ray tube and X-ray tube therewith
EP0756308A4 (fr) * 1994-03-28 1996-12-13 Hitachi Ltd Tube a rayons x et sa cible anodique
EP0756308A1 (fr) * 1994-03-28 1997-01-29 Hitachi, Ltd. Tube a rayons x et sa cible anodique
US5745546A (en) * 1995-03-20 1998-04-28 Siemens Aktiengesellschaft Anode for an x-ray tube
US20070169854A1 (en) * 2004-08-10 2007-07-26 Sanbo Shindo Kogyo Kabushiki Kaisha Copper-based alloy casting in which grains are refined
US9328401B2 (en) 2004-08-10 2016-05-03 Mitsubishi Shindoh Co., Ltd. Copper alloy casting having excellent machinability, strength, wear resistance and corrosion resistance and method of casting the same
US10017841B2 (en) 2004-08-10 2018-07-10 Mitsubishi Shindoh Co., Ltd. Copper alloy casting and method of casting the same
US10570483B2 (en) 2004-08-10 2020-02-25 Mitsubishi Shindoh Co., Ltd. Copper-based alloy casting in which grains are refined
US9303300B2 (en) 2005-09-30 2016-04-05 Mitsubishi Shindoh Co., Ltd. Melt-solidified substance, copper alloy for melt-solidification and method of manufacturing the same
US11043352B1 (en) * 2019-12-20 2021-06-22 Varex Imaging Corporation Aligned grain structure targets, systems, and methods of forming
US20210193426A1 (en) * 2019-12-20 2021-06-24 Varex Imaging Corporation Aligned grain structure targets, systems, and methods of forming

Also Published As

Publication number Publication date
FR974403A (fr) 1951-02-22
NL142818B (nl)
GB650237A (en) 1951-02-21
NL90795C (fr)

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