US1920601A - Electron discharge device - Google Patents

Electron discharge device Download PDF

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Publication number
US1920601A
US1920601A US296489A US29648928A US1920601A US 1920601 A US1920601 A US 1920601A US 296489 A US296489 A US 296489A US 29648928 A US29648928 A US 29648928A US 1920601 A US1920601 A US 1920601A
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US
United States
Prior art keywords
cathode
electrons
velocity
rays
radiations
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
US296489A
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English (en)
Inventor
Slack Charles Morse
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.)
Westinghouse Lamp Co
Original Assignee
Westinghouse Lamp Co
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 to NL28272D priority Critical patent/NL28272C/xx
Application filed by Westinghouse Lamp Co filed Critical Westinghouse Lamp Co
Priority to US296489A priority patent/US1920601A/en
Priority to GB22306/29A priority patent/GB316579A/en
Priority to FR679583D priority patent/FR679583A/fr
Priority to DEW83325D priority patent/DE581356C/de
Application granted granted Critical
Publication of US1920601A publication Critical patent/US1920601A/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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J33/00—Discharge tubes with provision for emergence of electrons or ions from the vessel; Lenard tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
    • H01J5/02—Vessels; Containers; Shields associated therewith; Vacuum locks
    • H01J5/18—Windows permeable to X-rays, gamma-rays, or particles

Definitions

  • This invention relates to an electron discharge device for and method of producing high electron velocities and to the application or such high speed electrons for the production of X-radiations of high frequency and, consequently,-high penetrating power, or for producing a stream of high velocity cathode or Lenard rays for germicidal and other purposes.
  • the penetrating power of the rays depends upon the frequency of the X-radiation, which in turn depends upon the velocity of the electrons by which they are produced. It .is necessa in many instances, in
  • Cathode ray, tubes of this type have'been constructed for operation with a potential drop therethrough of several hundred 5 thousand vol
  • the frequency of the X-rays and the electron velocity available for the cathode ray tubes, are restricted by the available voltages which may be impressed upon the electrodes.
  • the voltages 3 which are now available for use in the operation of such devices are limited by practical considerations and cannot be readily increased due to increased insulating difliculties in the tubes.
  • a further object is to provide a method of and a tube for producing X-radiation of higher frequency than those obtainable directly by the voltage applied between the electrodes.
  • My invention is based upon the phenomenon hundred thousand volts
  • Figure 1 is a sectional view of an X-ray tube embodying my invention
  • Figure 2 is a sectional view of a modified form of tube; and t Figure 3 is a sectional view of a cathode ray tube embodying the principle of my'invention.
  • the device shown in Figure 1 comprises a glass envelope 1 containing a filamentary cathode 2 and an anti-cathode or target 3.
  • the cathode end 4 of the tube has a reentrant glass stem 5 terminating in a press 6 through which the leading-in conductors '7 for the cathode are sealed.
  • the cathode 2 may be of any suitable electron emit ting material, but I prefer to construct it of tungsten or tantalum in the form of a coil mounted within a focusing cup 8, as is usual in X-ray construction.
  • An electrostatic shield 9 surrounds the cathode and protects the seal from puncturing. It also prevents sharp point sparking'from the cathode.
  • This shield may take the form of a split metal tube of nickel, monel metal chrome-iron or other metal, held in place on friction. Obviously, other convenient methods of support maybe employed.
  • the anti-cathode or target 3 may consist of a solid cylindrical metal block 10, preferably-of copper, with an inclined face 11 containing a rei'ractory metal insert or disc 12 of a metal of high atomic weight, such as tungsten.
  • the anti-cathode is supported on a metal tube 13 carried by the reentrant stem 14 and current is conducted thereto by a leading-in conductor 15 sealed through the press.
  • a second cathode 16 is positioned adjacent the cathode 2 and is electrically connected thereto. This cathode is made the electrons generated therein upon a secondary target 17 which may form a part of the anticathode 3.
  • the secondary target is provided'with' the, reentrant stem 5 by concave in order to focus.
  • a high potential such as ordinarily employed in x-ray tube operation, may be impressed between the cathodes 2 and 16 and the anti-cathodes 3 and 17 and a heating current may be passed through the cathode 2 to heat the same to an electron emitting temperature.
  • a heating current may be passed through the cathode 2 to heat the same to an electron emitting temperature.
  • the final velocity of the electrons, at point of impact with the target 12 may be determined by the equation.
  • the X-rays developed at the target 12,arepondered in all directions from the face thereof and 40 consist largely 'of rays near the limiting frequency, as determined by the velocity of the impinging electron. Some of these X-rays are directed against the concave face of the secondary cathode 16 and give rise to secondary electrons. The initial velocity of these secondary,
  • the initial velocity of the secondary electrons may be expressed bythe same equation, which expresses the relationship between the velocity of the primary electron and the frequency of the resultant X-ray,namely trons from the cathode 2.
  • the maximum or limiting velocity which any of these secondary electrons can have at point of impact upon the target 18, will be twice that attained by the highest velocity primary electrons at point of impact with '75 the anti-cathode 11"br. twice thflt obtainable diat potentials of 100,000 volts applied directly berectly by the potential difierence between the electrodes.
  • the secondary electrons upon impact with the 7 target 18 generate X-rays of a frequency very much higher than the rays generated by the primary electrons and, consequently, higher than can be obtained directly by the voltage difference between the electrodes. These X-rays of higher frequency have greater penetrating power.
  • the reference characters A, B, C and D indicate, respectively, the possible path of a primary electron, the resultant X-radiation, the secondary electron generated thereby, and the final X-radiation.
  • Figure 2 is shown a modification which is designed to give greater eliiciency due to increased area of the secondary cathode upon which the original X-rays may strike.
  • the secondary cathode 20 is disposed about the primary cathode, and a single o anti-cathode 21 is provided for both the primary and secondary electrons.
  • the X-rays generated by the secondary electrons which for convenience may be termed the secondary X-rays, may produce tertiary electrons which in turn may produce tertiary X-rays and this may be repeated a number of times, each cycle producing electrons of increased initial velocity, but in very much smallernumbers.
  • FIG. 3 I have shown a cathode ray tube comprising the envelope 22 having a cathode 23 similar to that shown in Figure 1, a second and a third cathode 24 and 25, and a target or anticathode 26. 5
  • the electrons emitted at high velocity from the cathode 25 are focused through a tubular anode 27 mounted in a tubular extension 28 of the envelope.
  • the anode 27 is provided with a terminal 29 which may be connected to the same source of potential as the anti-cathode 26.
  • the anode 2'1 serves to project the electron stream at high velocity through a thin glass window 30 blown in the end of the tubular extension 28. The construction of this window and the arrangement of the anode relative thereto is more fully described in my copending application Serial No. 272,194, filed April 23, 1928, and entitled Cathode ray tube.
  • the window 30 may have a dome thickness of from .0001 to .005 inches and is permeable to high velocity electrons with only a small loss of energy.
  • a window having a thickness of .001 inches the energy absorption in the glass tween the anode and an incandescent cathode, without the intervention of the intermediate electrodes 24, 25 and 26, corresponds to a decrease in inter-electrode potential of only about 16,000 volts, and at 200,000 volts there is a loss .of energy corresponding only to .a decrease of about 8,000 volts between the electrodes. Since the energy loss in the glass decreases as the velocity of the electron stream increases.
  • An electron discharge device comprising an emitting cathode, an anode disposed opposite said cathode, means for directing the electrons from said cathode upon said anode to produce X-radiations,
  • a second cathode positioned to intercept a portion of said X-radiations and to produce secondary electron emission therefroin, and means for increasing the velocity. of said secondary electrons.
  • An electron discharge device comprising an enclosing envelope, a source of primary electrons of low initial velocity, means for accelerating said electrons to a high 'X-radiations therefrom, means for generating secondary-electrons of high initial velocity by said x-radiations, and means for increasing the velocity of said secondary electrons.
  • An electron discharge device comprising an a source of initial velocity dependent upon the frequency of said X-radlations, and means for increasing the velocity of said electrons.
  • An electron discharge device comprising an a source of x-radiations, means for generating electrons ,with said xradiations having an initial velocity dependent on the frequency of said x-radiations, and an electrode serving as an anode for said cathode for increasing the velocity of said electrons.
  • An-clectron discharge device comprising an enclosing envelope, a'source of x-radiations, a cathode positioned to intercept said X-radiations and to generate electrons having a high initial velocity, and means for increasing the velocity of said electrons.
  • An electron discharge device comprising an enclosing-envelope, a source of X-radiations, a cathode positioned to intercept said X-radiations and to generate electrons having a high initial velocity, and means for increasing the velocity of said electrons and producing X-radiations of higher limiting frequency than the limiting frequency of said source of X-radiations.
  • An electron discharge device comprising an enclosing envelope, a thermionically active cathmeans for directing a stream of electrons from said cathode upon said anticathode for producing X-radiations, a second cathode electrically connected to said thermionically active cathode and positioned to intercept a portion of said X-radiations and to produce secondary electrons, and means for generating other X-radiations with said secondary electrons.
  • An X-ray tube for producing X-radiations of high frequency comprising an enclosing envelope, a cathode, an anti-cathode cooperating therewith to produce X-radiations under the infiuence of an impressed potential, a second cathode disposed adjacent said first mentioned cathode to intercept said X-radiations and to produce secondary electrons having a high initial velocity, said second cathode forming means for directing said secondary electrons upon said anti-cathode to generate additional X-radiations.
  • the method of producing X-rays of high frequency comprising generating X-rays of lower frequency, utilizing said cathode rays having a maximum. initial velocity dependent on the limiting frequency of said X-rays, increasing the velocity of said cathode rays and utilizing said high velocity electrons to produce X-rays of high frequency.
  • An electron discharge device comprising an enclosing envelo a source of electrons, an anode, means for focusing said electrons upon X-rays to produce said anode and producing x-radiations at said anode under the influence of a potential difference between the electrodes, a second cathode positioned so as to intercept a portion of said X- generate secondary electrons tube comprising an enclosing a cathode, an anti-cathode cooperating for producing X-radiations under the of an impressed potential, a second v concave shape disposed adjacent said first mentioned cathode and electrically connected thereto for intercepting said X-radiations, producing secondary electrons having an initial velocity dependent upon the frequency of said x radiations and directing said secondary electrons onto said anti-cathode to generate addi- 11.

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  • X-Ray Techniques (AREA)
US296489A 1928-07-31 1928-07-31 Electron discharge device Expired - Lifetime US1920601A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL28272D NL28272C (enrdf_load_stackoverflow) 1928-07-31
US296489A US1920601A (en) 1928-07-31 1928-07-31 Electron discharge device
GB22306/29A GB316579A (en) 1928-07-31 1929-07-19 Improvements relating to electron discharge devices
FR679583D FR679583A (fr) 1928-07-31 1929-07-30 Perfectionnements aux dispositifs émetteurs d'électrons
DEW83325D DE581356C (de) 1928-07-31 1929-08-01 Vakuumentladungsgefaess zur Erzeugung sehr harter Roentgenstrahlen oder sehr schnell bewegter Elektronen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US296489A US1920601A (en) 1928-07-31 1928-07-31 Electron discharge device

Publications (1)

Publication Number Publication Date
US1920601A true US1920601A (en) 1933-08-01

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Family Applications (1)

Application Number Title Priority Date Filing Date
US296489A Expired - Lifetime US1920601A (en) 1928-07-31 1928-07-31 Electron discharge device

Country Status (5)

Country Link
US (1) US1920601A (enrdf_load_stackoverflow)
DE (1) DE581356C (enrdf_load_stackoverflow)
FR (1) FR679583A (enrdf_load_stackoverflow)
GB (1) GB316579A (enrdf_load_stackoverflow)
NL (1) NL28272C (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2764706A (en) * 1952-12-26 1956-09-25 Dunlee Corp Hooded anode x-ray tube with tilted target
US2767341A (en) * 1952-08-12 1956-10-16 Dunlee Corp Anode structure for double filament x-ray tube
US2853618A (en) * 1954-10-27 1958-09-23 Marco John J De Method and apparatus for the use of fluorescent x-rays in powder diffraction
US3033984A (en) * 1959-02-17 1962-05-08 United States Steel Corp Apparatus for increasing the energy of x-rays
US4359660A (en) * 1980-12-15 1982-11-16 Physics International Company Series diode X-ray source

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1002896B (de) * 1954-03-10 1957-02-21 Dr Bernhard Hess Photoelektrische Roentgenroehre
DE1053681B (de) * 1954-10-19 1959-03-26 Dr Bernhard Hess Einrichtung zur Erzeugung von Ladungstraegern mit einer Vervielfachung der von einer primaeren Strahlung erzeugten Ladungstraeger
DE1131332B (de) * 1955-03-11 1962-06-14 Dr Bernhard Hess Roentgenroehre

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2767341A (en) * 1952-08-12 1956-10-16 Dunlee Corp Anode structure for double filament x-ray tube
US2764706A (en) * 1952-12-26 1956-09-25 Dunlee Corp Hooded anode x-ray tube with tilted target
US2853618A (en) * 1954-10-27 1958-09-23 Marco John J De Method and apparatus for the use of fluorescent x-rays in powder diffraction
US3033984A (en) * 1959-02-17 1962-05-08 United States Steel Corp Apparatus for increasing the energy of x-rays
US4359660A (en) * 1980-12-15 1982-11-16 Physics International Company Series diode X-ray source

Also Published As

Publication number Publication date
FR679583A (fr) 1930-04-15
GB316579A (en) 1930-02-13
DE581356C (de) 1933-07-26
NL28272C (enrdf_load_stackoverflow)

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