US2436833A - High density beam tube - Google Patents

High density beam tube Download PDF

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Publication number
US2436833A
US2436833A US447194A US44719442A US2436833A US 2436833 A US2436833 A US 2436833A US 447194 A US447194 A US 447194A US 44719442 A US44719442 A US 44719442A US 2436833 A US2436833 A US 2436833A
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US
United States
Prior art keywords
tube
spread
ions
potential
electron
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
US447194A
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English (en)
Inventor
Spangenberg Karl
Lester M Field
Helm Robert
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
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
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Priority to US447194A priority Critical patent/US2436833A/en
Priority to GB9486/43A priority patent/GB579371A/en
Priority to ES0172514A priority patent/ES172514A1/es
Priority to FR939121D priority patent/FR939121A/fr
Priority to CH270142D priority patent/CH270142A/fr
Application granted granted Critical
Publication of US2436833A publication Critical patent/US2436833A/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
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • H01J29/62—Electrostatic lenses
    • H01J29/622—Electrostatic lenses producing fields exhibiting symmetry of revolution
    • H01J29/624—Electrostatic lenses producing fields exhibiting symmetry of revolution co-operating with or closely associated to an electron gun

Definitions

  • This invention relates to electron beam tubes, more particularly'to tubes such as the velocity modulation type wherein the electron beam traverses a field-free space for a comparatively great distance;
  • tubes of these types it is'desirable to produce an electron beam of high density, that is a beam' haVing as little spread as possible, somewhat analogously to the production of a high concentrated beam of light for projection over a distance.
  • Such tubes are of great use in the electronic art, examples being velocity modulation tube beampower transmitting and receiving tubes, television projecting tubes, high-intensity X-ray tubes,- and:
  • the art has depended to a; large extent upon the ionization of molecules of residual gas within the tube, the positive ions formed bythe impactof electrons from the beam.
  • Our invention is designed to overcome, solel by electrostatic means, the beam-spread difiiculty" 35'- above described and the modus operandi thereof is hereinafter set forth.
  • Ourinvention' has for one object the productlon of an electron beam of low impedance and the propagation of such beam over a relatively great distance through afield-free space enclosed by a conducting shield;
  • Another object of our invention is the provision of an electrical circuit and determination of the constants thereof, which'may be applied to an electron beam tube in order substantiall to reduce or practically wholly to prevent undesired electron beam spread within such tube.
  • Yet another object of'this invention is to pro vide a method andmeans for trapping and confining within a predetermined region positive gas ions produced in an electron beam tube.
  • Yet another purpose of our invention is to provide quantitative data from which the design
  • construction and operating constants of an eleotron beam tube may be predicatedin such fashion
  • Another object is to providemeans and a method for limiting the cross section of an electron beam to any desired degree commensurate with the current carried thereby, by the employment of purely electrostatic means.
  • Still another object is to provide means for maintaining a dense electronxbeam'in extremely good vacua, such as 10-? mm./Hg.
  • Fig. 1 is a diagrammatic representation showing one form of cathode raytube, embodying our invention and also showing the axial potential distribution thereof when connected according to our invention.
  • Fig. 2 shows a family of curves illustrating the beam-spread effects observed-with a tube constructed and operated according to the prior art.
  • Fig. 3 shows the beam-spread effect due to mutual electron repulsion, in the absence of positive ion effect, of. an initially parallel electron beam.
  • Fig. 4 is a nomograph showing the beamspread effect corresponding .to'a given potential, total current and beam length in the absence of positive ion effect, of an initially parallel electron beam.
  • Fig. 5 shows graphically beam-spread effects as observed and as calculated according to the theory of operation of our invention.
  • the firstpoint to beconsidered is at what pressure enough gas molecules will be found present so as to furnish a sufficient quantity of positive ions completely to neutralize the electron charges of such beam.
  • Formulae well known in the electronic art give the number of electrons existing molecules to supply a quantity: of-positive ions.
  • E. S. U. V is the potentialexpressed in E. S. U.
  • e i the electroniccharge, also expressed in E. S. U.
  • Fig. 3 in which Z is the axial length of the beam there is shown a graph illustrating the theoretical beam-spread effect in the absence of positive ionization. Theory shows that spreading beams are reducible to the shape illustrated by the graph by a suitable change of vertical and horizontal scale factors. Further in any given structure if the potential be changed by a given factor the current, if from a space charge limited source will in turn change in such a way that the shape of the beam is not in any way altered. We have experimentally verified this rather astonishing conclusion.
  • the graph of Fig. 3 can likewise be used for initially convergent beams, provided that the beam electrons are initially so directed that in the absence of electrostaticrepulsion they would converge to a point, since such beams become parallel at some point and thereafter diverge.
  • Fig. 4 there is shown a diagram which allows the beam-spread efiect to be computed for a given potential, total current and beam length.
  • the laws illustrated in Figs. 3 and 4 serve to explain some of the beam-spread effects shown by the graph of Fig. 2, but still leave unexplained the occurrence of very appreciable beam-spread at pressures lying between 10- mm./Hg and l-' mm./I-Ig, since considerations previously discussed indicate that over this range of pressures there exists a sufllcient quantity of positive ions confined within-the drift tube, to neutralize com-- pletely the negative ..charges. of the electrons in the. beam.
  • an ,explanation of the removal of positive ions from the interior ofthe field-:freespaceconstituted by the drift tube may be found by considering that there exists adjacent the beam opening atone end of the drift tube an external field which extends.
  • An electron beam tube including means for generating electrons, means for producing a beam of said electrons, means for accelerating said beam, means for defining a substantially field-free space through which said beam passes,
  • the method of substantially preventing beam-spread of an electron stream within a field-free space which includes directing a beam of electrons within said space, establishing and maintaining a reverse potential gradient at least at one end of said field-free space, so as to trap positive ions therewithin.
  • a cathode ray tube system including means for generating and for collecting an electron stream in an atmosphere of not more than 10"- mm./Hg, a field-free drift tube through which said stream passes, and means for maintaining the direct current potential of said drift tube tive with respect to said accelerating electrode so as to prevent leakage of positive ion from said 10 drift tube. and means for collecting the electrons.
  • the method of pro- .iecting a beam over a distance without substantial spread thereof which includes the steps of establishing a substantially'field-free space, passing through the space said beam, and establishing at each end said field-free space of a relatively slight potential gradient in the reverse direction to the normal potential gradient along the course of said beam, whereby positive gas ions are held within said field-free space so as substantially to neutralize the space-charge efiects tending to cause spread o'f'said beam.
  • a vacuum tube system including an accelerating electrode, a field-free drift tube insulated from other electrodes and means for keeping said drift tube slightly negative with respect to said accelerating electrode so as to prevent leakage of positive ions from said drift tube.
  • a system for reducing the spread of an electron stream due to space charge effects including a source of positive ions, a fieldfree chamber within which the ions are produced and through which said stream passes, and means for retaining said ions within said chamber, said last means comprising electrostatic means so connected as to establish at least at oneend of said chamber a slight di'rectcurrent potential gradient along said stream in a direction reverse to the gradient prevailing along said stream before the entrance thereof into said chamber.
  • a system for projecting a low impedance electron beam including conductive means defining a field-free chamber through which said beam is projected, gaseous means within said chamber producing positive ions under the impactof said beam, and electrostatic means maintaining at one end of said chamber a direct current potential gradient along said stream in a reverse direction to the potential gradient used in establishing said stream, whereby said ions are restrained within said chamber and act to neutralize the spacecharge effect tending to spread said beam and increase the impedance thereof.
  • An electron beam tube for the production and projection of a beam of high density including an electron source, an accelerating electrode establishing the beam, a drift tube through which said beam passes, means for keeping said drift tube at a slightly negative fixed direct current potential with respect to said accelerating electrode and means for collecting the electrons of said beam after passage thereof through said drift tube, whereby said negatively charged drift tube tends to retain therewithin positive ions formed from the residual gas within the beam tube.
  • a cathode ray tube system including means for generating an electron beam, means for accelerating said beam, means for projecting said beam through a tubular electrode and means for main taining said tubular electrode at a direct current potential negative with respect to the potential of said accelerating means adjacent said tubular electrode by an amount which is less than one 121 half. of one percent of thepotentialwof said lastmentioned: accelerating; -means- 'so. -as toprevent leakage ofv positive ions:- from :said 1 tubnlan electtrode.
  • a mztlmde ray/tube system wherein the voltage diflerence between the voltage of the said tubular electrode and said acceleratingjmeans is .p 6:94X10" where p is the number of unneutralized electrons per centimeter length in the beam at the section where itkpassesthrough ithe tubular electrode.

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  • Particle Accelerators (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Electron Sources, Ion Sources (AREA)
US447194A 1942-06-15 1942-06-15 High density beam tube Expired - Lifetime US2436833A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US447194A US2436833A (en) 1942-06-15 1942-06-15 High density beam tube
GB9486/43A GB579371A (en) 1942-06-15 1943-06-11 Means for preventing the spreading of high density electron beams
ES0172514A ES172514A1 (es) 1942-06-15 1946-02-09 MEJORAS EN HAZ ELECTRoNICO DE ALTA DENSIDAD
FR939121D FR939121A (fr) 1942-06-15 1946-04-03 Tubes à faisceaux électroniques dirigés
CH270142D CH270142A (fr) 1942-06-15 1946-11-19 Dispositif comprenant un tube à faisceau électronique.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US447194A US2436833A (en) 1942-06-15 1942-06-15 High density beam tube

Publications (1)

Publication Number Publication Date
US2436833A true US2436833A (en) 1948-03-02

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ID=23775370

Family Applications (1)

Application Number Title Priority Date Filing Date
US447194A Expired - Lifetime US2436833A (en) 1942-06-15 1942-06-15 High density beam tube

Country Status (5)

Country Link
US (1) US2436833A (fr)
CH (1) CH270142A (fr)
ES (1) ES172514A1 (fr)
FR (1) FR939121A (fr)
GB (1) GB579371A (fr)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2152825A (en) * 1933-07-08 1939-04-04 Loewe Opta Gmbh Braun tube
US2160021A (en) * 1937-06-29 1939-05-30 Rca Corp Electrode arrangement for cathode ray tubes
US2174580A (en) * 1937-07-08 1939-10-03 Hazeltine Corp Cathode-ray tube system
US2206666A (en) * 1937-10-22 1940-07-02 Rca Corp Cathode ray tube
US2220839A (en) * 1937-07-14 1940-11-05 Gen Electric Electrical discharge device
US2226107A (en) * 1933-12-09 1940-12-24 Loewe Radio Inc Braun tube, more particularly for television purposes
US2245627A (en) * 1938-06-24 1941-06-17 Univ Leland Stanford Junior Stabilization of frequency
US2278210A (en) * 1940-07-05 1942-03-31 Bell Telephone Labor Inc Electron discharge device

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2152825A (en) * 1933-07-08 1939-04-04 Loewe Opta Gmbh Braun tube
US2226107A (en) * 1933-12-09 1940-12-24 Loewe Radio Inc Braun tube, more particularly for television purposes
US2160021A (en) * 1937-06-29 1939-05-30 Rca Corp Electrode arrangement for cathode ray tubes
US2174580A (en) * 1937-07-08 1939-10-03 Hazeltine Corp Cathode-ray tube system
US2220839A (en) * 1937-07-14 1940-11-05 Gen Electric Electrical discharge device
US2206666A (en) * 1937-10-22 1940-07-02 Rca Corp Cathode ray tube
US2245627A (en) * 1938-06-24 1941-06-17 Univ Leland Stanford Junior Stabilization of frequency
US2278210A (en) * 1940-07-05 1942-03-31 Bell Telephone Labor Inc Electron discharge device

Also Published As

Publication number Publication date
CH270142A (fr) 1950-08-15
FR939121A (fr) 1948-11-04
ES172514A1 (es) 1946-03-16
GB579371A (en) 1946-08-01

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