US2679017A - X-ray tube - Google Patents

X-ray tube Download PDF

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Publication number
US2679017A
US2679017A US202776A US20277650A US2679017A US 2679017 A US2679017 A US 2679017A US 202776 A US202776 A US 202776A US 20277650 A US20277650 A US 20277650A US 2679017 A US2679017 A US 2679017A
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US
United States
Prior art keywords
ray
filament
tube
window
anode
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
US202776A
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English (en)
Inventor
Thomas H Rogers
Joseph W Skehan
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.)
Machlett Laboratories Inc
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Machlett Laboratories Inc
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Filing date
Publication date
Priority to NL92553D priority Critical patent/NL92553C/xx
Application filed by Machlett Laboratories Inc filed Critical Machlett Laboratories Inc
Priority to US202776A priority patent/US2679017A/en
Priority to GB29629/51A priority patent/GB698450A/en
Application granted granted Critical
Publication of US2679017A publication Critical patent/US2679017A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details

Definitions

  • This invention relates to an X-ray tube capable of producing a beam of X-raysof highly uniform intensity.
  • the ability of this tube to produce a high intensity beam of soft X-rays is of particular advantage.
  • New to the X-ray art is the position of the X-ray permeable window in the tubes end parallel to itstarget, thus permitting complete axial symmetry of the tube which, in turn, affords convenient and secure mounting of the tube.
  • This invention is an improvement upon the invention of C. B. l-Iorsley described in U. S. Patent No. 2,482,275. Horsley has taught the use of an X-ray target perpendicular to the tubes axis surrounded by a circular filament. Our invention is essentially a modification of the Horsley type construction presenting advances over his invention which make it particularly valuable for specialized uses, some of which are herein described.
  • X-ray applications require great uniformity of intensity across the X-ray beam.
  • uniform intensity X-ray beams are beneficial in general for radiography in that they permit uniformity of exposures over the entire picture area.
  • An extremely uniform beam over a relatively small cross section is required for some specialized uses, of which miororadiography is typical.
  • the most uniform possible beam at relatively low voltages is that one which includes those rays perpendi lar to the target at its center.
  • Such uniformity of the X-ray beam is obtained by locating the X-ray permeable window in such a position that it permits the passage of those rays of greatest possible uniformity for any given cross section of beam.
  • the location of the target on and perpendicular to the tubes axis of rotation makes possible the use of the most highly uniform beam available at relatively low voltages by the simple expedient of placing the X-ray permeable window on the tubes axis parallel to the target.
  • the angular width of the X-ray beam is determined by the spacing between the target and the window and the diameter of the window.
  • the large cathode area as taught by Horsiey is of great advantage here because it enables production of an extremely large electron current between cathode and anode. Since X-ray intensity increases directly as the electron current, as well as directly as the square of the applied voltage, high intensity X radiation is made possible even at relatively low voltages by the large cathode. Another factor important to intensity is the distance between the X-ray source and the irradiated area. Intensity is effectively decreased per unit of the irradiated area the further this area is placed from the source because of the tendency for the X-rays to spread out.
  • Another object of this invention is the production of a high intensity, uniform soft (long wave length) X-ray beam. It has been difficult to remove the easily attenuated soft X-rays from the vacuum envelope once produced, but, since the recent development of thin beryllium windows has alleviated this problem to a large ex.- tent, the importance of soft X-radiation in such fields as superficial therapy and radiography has grown. However, it is a difficult problem to generate soft iii-rays in the first place because for production of long wave lengths, without a larger amount of accompanying hard radiation, relatively small voltages are required. Using prior art tube constructions, such low voltages would produce a very low intensity X-ray beam.
  • X-rays require monochromatic radiation.
  • microradiography is aided by the use of X-rays having but one wave length.
  • work of this sort often requires several different wave lengths of X-rays which may be most easily obtained by employing several target materials. Since there is no Way at present to replace the targets in a sealed-off vacuum tube, it is necessary to have as many tubes as there are target materials. Furthermore, tubes have been awkward to replace so that, when used, much time has been consumed in changing from one target material to another. Thus, the great expense involved and the replacement difficulties have prevented wide spread development of special .monochromatic X ray techniques.
  • the smallness and lightness of our tube make it practical for use in compact apparatus.
  • the concentric filament terminals of our tube make possible a socket arrangement which makes for case in changing tubes and which insures secure and accurate mounting of'the tube withinthe housing.
  • This type of socket also lends itself to leakproof construction, thus preventing the escape of insulation oil where used. Insulation oil itself reduces the requirements of tube insulation in that it inhibits spark over.
  • This socket also permits the tube window to be placed close to the irradiated object where necessary and at the same time insures the operator a maximum of visibility.
  • the tube window is normally kept at ground potential for safetys sake, and, since it is mounted within a filament ring terminal, the filament must also be at ground. potential. Having the filament at ground potential is a major advantage in that it reduces the insulation necessary for the filament transformer, thereby substantially reducing its size and permitting its easy enclosure within the tube housing.
  • Fig. 1 shows an axial section of a preferred construction of our invention.
  • Fig. 2 illustrates an elevational view from above the tube pictured in Fig. 1 looking down toward the X-ray permeable window.
  • Fig. 3 illustrates partly in section and partlyin elevation a socket arrangement for mounting our tube in an X-ray shockproof housing with a tube shown in place therein.
  • FIG. 1 anode block it is of a gen! erally cylindrical shape having one end H re.- quizzed in diameter and terminating in planar target surface, i2-
  • Various kinds of target-ma-v terial. may be used to produce-X-rays of differ-.- ence specific wave length.
  • heavy annular terminal i3 is aifiXed-to the base of block l0.
  • Tubular insulator M which; may be advantageously made of ceramic, is afiixedto terminal is by annular bracket 15.
  • a similar annular bracket l6 joins its opposite end, toring filament terminal.
  • member l1 Concentric with ring terminal I!
  • ring terminal H3 is smaller ring terminal H3, the two terminals being separated by dielectric washer 19 which may beadvantageously made of ceramic.
  • which is preferably constructed of beryllium. For a narrower beam of X-rays a smaller window in a non-permeable annular collar may be used or the window may be further removed from the target. In general, however, the minimum spacing between the target [2 and the window 2
  • the filament 22 which is circular in shape and which is mounted coaxial with the target 12 but, in a preferred form, a little closer to the X-ray window 25 than is the target in order to simplify focusing of the electron beam.
  • the spacing between the filament and the window is preferably somewhat smaller than the radius of the filament circle.
  • the filament may be joined to terminal members by support and conductor posts 23, which are in turn connected alternately to terminal extension members 24 and 25.
  • Filament 22 advantageously lies within or at the mouth of an annular channel having side walls 26 and 21.
  • the cathode potential on the inner side wall 25 prevents electrons from being drawn from the filament directly to proximate points on the anode.
  • the outer wall 21 extends beyond wall 2% and is flared inwardly above the filament. When at cathodepotential, wall 27 causes the electrons to be deflected into a funnel shaped path toward the focal spot on the target surface 12.
  • the channel members since they are all at oathode potential, are advantageously connected as shown to the respective terminal members. It will be noted that the base of the annular channel formed by member 25 is also connected to one of the terminals as shown. It is necessary to terminate this base member 25 just short of inner side wall 25 in order to prevent shorting of the filament. Dielectric members it permit the insulated passage of alternate support posts '24 through the channel base 25 to member 24.
  • Exhaust of the tube may be conveniently accomplished by means of duct 29 through the anode block terminating in seal off means 30.
  • the seal off means may be protected by cap 3
  • an annular collar 32 is often mounted around terminal I! atop bracket 16.
  • Fig. 2 illustrates the same tube from the window end without collar 32. Visible are annular bracket l6 and adjoining terminal H. The
  • Ceramic washer is separating terminals l! and I8 may be seen, but terminal is itself is hidden by bracket 29.
  • is clearly visible.
  • the target surface l2 and the surrounding filament 22 are indicated to show the relative positions of these elements. Also indicated are the insulation bushings 28.
  • Fig. 3 illustrates the tube in elevation within a possible housing mounting.
  • spring fingers 35 affixed to conical socket mem ber 36 contact filament terminal l8. Since conical member 36 engages tubular member 31 which is in turn aflixed to housing 38, this terminal of the filament and consequently the beryllium window will be maintained at ground potential, as is the housing.
  • Members 38 and 31 may have opposing shoulders which approach one another when the members 36 and 31 are advanced in threaded engagement. Upon one of these shoulders may be placed a dielectric block 39 which itself has a shoulder advantageously engaging collar 32. Between collar 32 and the shoulder of member 31 may be placed a de formable O-ring 40 which forms an oil-tight joint between tube and socket.
  • Spring fingers M may be mounted such that contact is made with annular bracket l6 which will serve in this instance as the other filament terminal. These fingers are insulated from the rest of the socket and from the housing by dielectric washers 42 and 53 and held in place atop tubular socket member 31 by some means such as a series of screws 44 parallel to the tubes axis whose heads rest atop dielectric washer 42. When used in general applications there may be employed conical shield 45 which is conveniently afiixed in threaded engagement with socket 36. When soft radiation is employed however, it may be desirable to minimize the extension of 36 such that the X-ray window may be placed immediately adjacent the irradiated area.
  • the size and shape of the housing 38 is left to the individual application. but in every case the tube housing may be made extremely small because of the small tube size and the smallness of the enclosed auxiliary equipment, such as the filament transformer.
  • An X-ray tube comprising a vacuum envelope including a planar window permeable to. X-rays and a ring type cathode terminal coaxial with and surrounding said window and within the vacuum envelope an emitting cathode and an anode, said anode including an X-ray producing target surface parallel to said X-ray permeable window and coaxial with the ring type cathode terminal.
  • An X-ray tube comprising a vacuum envelope including a planar window permeable to X-rays and surrounding said window a ring type cathode terminal to which the window is sealed and within the vacuum envelope an emitting cathode and an anode, said anode including an X-ray producing target parallel to said X-ray permeable window and coaxial with the ring type cathode terminal.
  • An X-ray tube comprising a vacuum envelope including a pair of coaxial ring type filament terminals and within the vacuum envelope an emitting filament and an anode, said anode being coaxial with the ring filament terminals and including an X-ray producing target.
  • An X-ray tube comprising a vacuum envelope including a pair of coaxial ring type filament terminals and a planar X-ray permeable window and within the vacuum envelope an emitting filament and an anode, said anode being coaxial with the filament terminals and including an X-ray producing target parallel to said X-ray permeable window.
  • An X-ray tube comprising a vacuum envelope including a pair of coaxial ring type filament terminals an a planar X-ray permeable ing target parallel to said X-ray permeable win -v dow.
  • An X-ray tube comprising a vacuum envelope including a pair of coaxial ring type filivr.
  • ment terminals a coaxial anode terminal, and a planar X-ray permeable window sealed to one of said terminals and within the vacuum envelope.
  • An X-ray tube comprising a vacuum ene velope including a pair of coaxial ring type filament terminals, a coaxial anode terminal, and a planar X-ray permeable window sealed to one of said terminals and within the vacuum envelope a coaxial circular filament affixed to said filament terminals and a block type anode afiixed to the: anode terminal, said anode being coaxial with the filament and its terminals, and including an X-ray producing target parallel to said X-ray permeable window.
  • An X-ray tube comprising a vacuum envelope including a pair of coaxial ring type filament terminals, a coaxial anode terminal, and a planar X-ray permeable window sealed to one of said terminals and within the vacuum envelope a coaxial circular filament lying wholly within the 180 solid angle subtended by the target face on the window side and affixed to the filament terminals, said anode being coaxial with the filament and its terminals, and including an X-ray producing target parallel to said X-ray permeable window.
  • An X-ray tube comprising a vacuum envelope including a pair of coaxial ring type filament terminals, a coaxial anode terminal and a planar X-ray permeable window sealed to one of said terminals and within the vacuum envelope a coaxial circular filament affixed to said filament terminals, electron defiection means affixed to ment terminals, a coaxial anode terminal and a planar X-ray permeable window sealed to one of said terminals and Within the vacuum envelope a coaxial circular filament affixed to said filament terminals, an annular cathode-potential trough below said filament having parts aifixed to the terminals, that wall of the trough between the filament and the anode preventing direct flow of electrons from filament to anode and the other wall of the trough surrounding the filament and curving inward and above said filament to cause deflection of the electrons into a funnel-shaped path toward the X-ray target, and a block type anode afiixed
  • An X-ray tube comprising a vacuum envelope consisting of a pair of coaxial ring type terminals, a coaxial anode terminal, a planar X-ray permeable window sealed to one of said filament terminals, a ceramic ring sealed between the filament terminals and a ceramic tube sealed between the outer filament ring and the anode terminal and within the vacuum envelope an emitting filament afiixed to the filament terminals and a block type anode ailixed to the anode terminal, said anode including an X-ray producing target parallel to said X-ray permeable window.
  • An X-ray tube comprising a vacuum envelope consisting of a pair of coaxial ring type filament terminals, a coaxial anode terminal, a planar X-ray permeable window sealed to one of said filament terminals, a ceramic ring sealed between the filament terminals and a ceramic tube sealed between the outer filament ring and the anode terminal and within the vacuum envelope a coaxial circular filament affixed to the filament terminals, an annular cathode potential trough below said filament having parts aiiixed to the terminals, that wall of the trough between the filament and the anode preventing direct fiow of electrons from filament to anode and the other wall of the trough surrounding the filament and curving inward and above said filament to cause deflection of the electrons into a funnel-shaped path toward the X-ray target and a block type anode affixed to the anode terminal, said anode being coaxial with the filament and its terminals and including an X-ray producing target parallel to said

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  • X-Ray Techniques (AREA)
US202776A 1950-12-26 1950-12-26 X-ray tube Expired - Lifetime US2679017A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL92553D NL92553C (enrdf_load_stackoverflow) 1950-12-26
US202776A US2679017A (en) 1950-12-26 1950-12-26 X-ray tube
GB29629/51A GB698450A (en) 1950-12-26 1951-12-18 Improvements in x-ray tubes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US202776A US2679017A (en) 1950-12-26 1950-12-26 X-ray tube

Publications (1)

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US2679017A true US2679017A (en) 1954-05-18

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US202776A Expired - Lifetime US2679017A (en) 1950-12-26 1950-12-26 X-ray tube

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US (1) US2679017A (enrdf_load_stackoverflow)
GB (1) GB698450A (enrdf_load_stackoverflow)
NL (1) NL92553C (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3358168A (en) * 1965-01-06 1967-12-12 Morris Associates X-ray tube with cooling jacket for target
US4969173A (en) * 1986-12-23 1990-11-06 U.S. Philips Corporation X-ray tube comprising an annular focus
US5345493A (en) * 1992-01-27 1994-09-06 U.S. Philips Corporation X-ray tube with a reduced working distance
US5367553A (en) * 1990-01-29 1994-11-22 U.S. Philips Corporation X-ray tube comprising an exit window
US5987096A (en) * 1996-12-06 1999-11-16 U.S. Philips Corporation X-ray tube having an internal window shield
US20070230663A1 (en) * 2005-08-29 2007-10-04 Kabushiki Kaisha Toshiba X-ray tube

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124710A (en) * 1960-03-17 1964-03-10 X-ray tubes

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1183871A (en) * 1913-11-19 1916-05-23 Eli Grimes X-ray tube.
US1626465A (en) * 1922-12-06 1927-04-26 Philips Nv X-ray tube
US2472745A (en) * 1946-09-19 1949-06-07 Dow Chemical Co Apparatus for producing a convergent x-ray beam
US2482275A (en) * 1945-11-26 1949-09-20 Machlett Lab Inc Electrical discharge device
US2496003A (en) * 1948-01-02 1950-01-31 Eitel Mccullough Inc Electron tube having annular electrodes
US2517334A (en) * 1947-12-26 1950-08-01 Eitel Mccullough Inc Electron tube having annular envelope
US2569872A (en) * 1949-12-24 1951-10-02 Machlett Lab Inc Electron discharge tube

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1183871A (en) * 1913-11-19 1916-05-23 Eli Grimes X-ray tube.
US1626465A (en) * 1922-12-06 1927-04-26 Philips Nv X-ray tube
US2482275A (en) * 1945-11-26 1949-09-20 Machlett Lab Inc Electrical discharge device
US2472745A (en) * 1946-09-19 1949-06-07 Dow Chemical Co Apparatus for producing a convergent x-ray beam
US2517334A (en) * 1947-12-26 1950-08-01 Eitel Mccullough Inc Electron tube having annular envelope
US2496003A (en) * 1948-01-02 1950-01-31 Eitel Mccullough Inc Electron tube having annular electrodes
US2569872A (en) * 1949-12-24 1951-10-02 Machlett Lab Inc Electron discharge tube

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3358168A (en) * 1965-01-06 1967-12-12 Morris Associates X-ray tube with cooling jacket for target
US4969173A (en) * 1986-12-23 1990-11-06 U.S. Philips Corporation X-ray tube comprising an annular focus
US5367553A (en) * 1990-01-29 1994-11-22 U.S. Philips Corporation X-ray tube comprising an exit window
US5345493A (en) * 1992-01-27 1994-09-06 U.S. Philips Corporation X-ray tube with a reduced working distance
US5987096A (en) * 1996-12-06 1999-11-16 U.S. Philips Corporation X-ray tube having an internal window shield
US20070230663A1 (en) * 2005-08-29 2007-10-04 Kabushiki Kaisha Toshiba X-ray tube
US7460645B2 (en) * 2005-08-29 2008-12-02 Toshiba Electron Tubes & Devices Co., Ltd. X-ray tube

Also Published As

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NL92553C (enrdf_load_stackoverflow)
GB698450A (en) 1953-10-14

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