US3299311A - Velocity modulated electron tube with integrated focusing and getter pump systems, the pump having multiple getter-coated electrodes - Google Patents

Velocity modulated electron tube with integrated focusing and getter pump systems, the pump having multiple getter-coated electrodes Download PDF

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Publication number
US3299311A
US3299311A US279354A US27935463A US3299311A US 3299311 A US3299311 A US 3299311A US 279354 A US279354 A US 279354A US 27935463 A US27935463 A US 27935463A US 3299311 A US3299311 A US 3299311A
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United States
Prior art keywords
getter
electrode
helix
pump
ions
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Expired - Lifetime
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US279354A
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English (en)
Inventor
Veith Werner
Meyerer Paul
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Siemens and Halske AG
Siemens Corp
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Siemens Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • 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
    • H01J29/94—Selection of substances for gas fillings; Means for obtaining or maintaining the desired pressure within the tube, e.g. by gettering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/14—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of thermionic cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/14—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of thermionic cathodes
    • H01J41/16—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of thermionic cathodes using gettering substances
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/18—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes
    • H01J41/20—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes using gettering substances

Definitions

  • Ion getter pumps as separate units as well as in direct connection with electron discharge systems are known.
  • the operation thereof is based upon ionization of residual gases and transfer thereof to an electrode with a well absorbing surface at which they are bound.
  • Such a getter mirror is continuously or periodically renewed or supplemented in order to maintain and to increase the getter action thereof.
  • the invention has in view of this situation particular significance for all kinds of travelling wave. tubes, and especially for traveling field tubes, rearward wave oscillators and klystrons, that is, for tubes operating with a I magnetically focused axially extending electron beamof high density.
  • the object underlying the invention resides in utilizing the electrodes provided for the operation of the respective tube, with the potentials placed thereon and the magnetic fields'thereof, for the functional mechanism of the ion pump.
  • this object is realized in connection with a tube of the previously noted kind, especially a travelling field tube, wherein parts of the electrode system with the potentials thereon and the magnetic focusing field, cooperate in effecting the functions of the ion getter pump, employing as an ion collector, arranged symmetrically in the beam path, near the cathode, at least two electrodes having parts, especially on the surface thereof, which are adapted to operate as getter at least during the operation of the respective tube.
  • accelerated electrons emitted from an electron gun are, with the cooperation of a strong magnetic focusing field guided in a beam of high density along an extended spiral path, usually within a helix, thereby effecting an impact ionization with the residual gases.
  • the ions thereby produced, preponderantly positive ions, are moved, more or less focused, to the cathode, owing to their polarity and the action of the focusing means for the electron beam, and would cause considerable destruction of the cathode by the impact effect.
  • the emitting plane of the cathode is for this reason provided with a central opening formed therein, for the passage of positive ions, which are bound at an absorption plane formed in back of the cathode.
  • this expedient is in its action imperfect and produces conditions which are in part unfavorable for the discharge operation of the tube.
  • the focusing devices customarily used for the electron discharge operation generally prevent ions from leaving the cross sectional discharge area which is filled with electrons.
  • the electrodes forming, in the tube described herein, the ion collector are for this reason so arranged with respect to the electron beam path, that the ions reach such electrodesfby the action of electron optical means, along substantially radially directed paths.
  • the electron optical means required therefor, especially the electrodes forming the ion collector are of particular configuration, and the corresponding potentials are particularly selected, so that the potential distribution produces upon the axis either a saddle or a strong collector lens for the electron beam, from which the electrical field strength is so oriented that the ions are radially outwardly deflected and accelerated.
  • the ions diffusing respectively from the collector space and the cathode space are ripped from the electron beam, owing to the peculiarity of the field. Accordingly, there is produced, within the operation of the ion getter pump mechanism, the action of an ion trap, so that the discharge path proper is continuously liberated of ions.
  • the required ion collector may be formed, in the simplest case, by an electrode which either consists substantially of a getter material such as titanium or which is in operation continuously or periodically provided with a new titanium coating (mirror) or supplemented with such coating.
  • an ion collector comprising two separate electrodes. One of these electrodes may be provided with a potential such that the ions reach such electrode with considerable impact velocity, the kinetic energy causing thereby a vaporization of the getter material on such electrode, such vaporized material being deposited on the adjacent second electrode to form the absorbing mirror surface.
  • the potential of the second electrode which is in operation continuously provided with a new getter mirror, is so selected that it is impacted by the ions with reduced velocity which is however sufiicient for effecting heating thereof to obtain a good getter action for the absorption and binding of the ions.
  • the first electrode of the ion collector is for this purpose particularly advantageously. formed of perforated material, for example, in the form of a mesh cylinder or helix, so that it is impacted only by part of the ions, while the ions passing therethrough impact with reduced velocity the second electrode disposed in back of the first electrode.
  • the dimensioning of the permeable part of the perforated electrode in conjunction with the respective potential makes it possible to adjust the ratio of the parts of the passing and impacting ions so as to obtain a sufficient but not excessive vaporization of the getter material at one of the electrodes and at the other electrode a heating which is sufiicient for an approximately optimum getter action.
  • FIGS. 1 and 2 show embodiments, for use in connection with travelling wave tubes, in which the ion collector, which is respectively disposed at the beginning and at the end of the helix, is formed by electrodes forming part of the electron discharge system; and
  • FIGS, 3 to 6 indicate embodiments in which the electrodes which are part of the ion collector form, jointly with the adjacent electrodes of the discharge system, a kind of toroid, whereby a perforated hollow inner cylinder serves, for example, as one electrode of the ion collector while an outer hollow cylinder serves as the second electrode therefor, one of the cylinders being always on cathode potential.
  • FIG. 1 represents the essential part of an electrode system of a travelling wave tube, for example, a high perveance gun.
  • the high density electron beam 1 which is focused by a not illustrated magnetic field, moves from the cathode 2 which is surrounded by the Wehnelt electrode 3, through the helix 4, tothe right, to a not illustrated collector, thereby causing, along its path, by impact ionization, the formation of ions of positive polarity.
  • the beginning of the helix 4' is by means of a cylinder 5 connected with the acceleration anode 6 which is formed as an apertured diaphragm, thus producing for the ions a strong collector lens, by the action of customary potentials applied, as indicated by the potential lines.
  • the field is in the neighborhood of the axis so oriented for the positive ions 16, iii, moving in the electron beam toward the cathode, that the ions are deflected and accelerated along approximately radial paths, i.e., transverse to the electron beam direction, for example, to the Wehnelt electrode 3 which is at cathode potential.
  • the Wehnelt electrode is for this purpose made of getter material, for example, titanium.
  • the ions impact the Wehnelt electrode with considerable velocity, effecting vaporization of the titanium which travels to the neighboring anode on which the greater part of the ions is then absorbed and bound.
  • This arrangement as well as the arrangements illustrated in FIGS. 3 to 6 may be analogously applied, as shown in FIG. 2, to the space helix collector, in a case in which the collector is on a lower potential than the helix.
  • the helix is terminated by a part 11 which is extended by a hollow somewhat wider cylindrical portion 12 into which projects a perforated cylindrical part 13 forming an extension of the collector 14, a gap being left between the parts 11 and 13.
  • a strong collector lens in the gap plane, which deflects ions 10, in the electron beam approximately radially outwardly.
  • the perforated hollow cylinder 13 which consists substantially of titanium, is effected a vaporization of the titanium, owing to the high impact velocity of the ions, the vaporized material being deposited on the adjacent widened extended end 12 of the helix and acting as a getter mirror for the ions.
  • FIG. 3 shows in schematic manner parts of a travelling field tube in which the ion collector 8, 9 is arranged near the cathode, between the beginning of the helix 4 and the acceleration anode 7.
  • the electrodes, forming the ion collector are constructed and arranged so that they form approximately a toroid of rectangular cross section with circularly shaped end surfaces, the inner hollow cylinder 8 which consists substantially of titanium, through which the electron beam passes axially, being perforated and serving as one electrode and the outer cylinder 9 serving as the other electrode.
  • the inner hollow cylinder 8 extends close to but separated by a small gap from the end walls of the other electrode 9.
  • the helix 4 is at the beginning thereof connected with an apertured diaphragm 6, by way of a cylinder 5, the toroidal ion collector 8, 9 being thus disposed approximately symmetrically between the diaphragm 6 and the acceleration anode 7.
  • the perforated inner cylinder 8, which forms one electrode of the ion collector is at cathode potential
  • the outer hollow cylinder 9, which forms the other electrode of the ion collector is at a potential which is at least a few hundred volts lower than the helix potential
  • the ions 10, 10, formed by impact ionization in the electron beam therefore encounter, at such field distribution, a field direction causing deflection thereof initially approximately radially toward the inner hollow cylinder 8, some of the ions impacting the inner cylinder and effecting, owing to their impact velocity, vaporization of part of the titanium, and others passing through perforations and reaching the outer hollow cylinder which is coated with vaporized titanium.
  • a very effective ion trap is formed owing to the particular field distribution described and especially owing to the formation of a saddle upon the axis, so that ions coming from both directions are ripped from the electron beam, thus effecting a very good getter pump action.
  • FIG. 4 shows a simplified modification of the arrangement just described with reference to FIG. 3.
  • the modification resides in that the outer electrode 9 of the ion collector is by way of the end plate 6 directly connected with the start of the helix 4.
  • the potential of the acceleration anode 7 is by a few hundred volts higher than that of the helix 4, so that the ions cannot move against the resulting field (thus preventing ions from reaching the cathode).
  • the inner hollow cylinder 8 is connected with the end plates such as 6, which supplement the ion collector to form a toroid, and by way of a cylinder 5 also with the helix- 4.
  • the outer hollow cylinder 9 is by narrow gaps separated from the end plates 6 and lies at cathode potential.
  • the potential distribution which is thereby effected produces a field direction which causes the ions 10, appearing in the electron beam 1, to move in part through openings in the perforated inner cylinder 8, with considerable velocity to the outer cylinder 9.
  • the getter material on the outer cylinder 9 is in part vaporized, due to the considerable impact velocity of the ions, and reaches the inner perforated cylinder 8 where the directly impacting ions are bound.
  • the acceleration anode 7 is at a potential lying between that of the cathode and the helix, for example, midway thereof.
  • a considerable improvement of the pump action is obtained by making the potential at the acceleration anode 7 by a few hundred volts higher than that of the helix, thus forming a kind of auxiliary ion trap which assures that no ions can pass through the resulting field and reach the cathode.
  • a system according to claim 2 for a traveling wave tube comprising a high perveance gun, a Wehnelt electrode disposed ahead of the emission face of the cathode and formed as a fiat frustum of a cone with the widened part thereof facing in a direction of the helix extending along the electron beam axis, and an acceleration anode formed as an apertured diaphragm and connected with the helix, said Wehnelt electrode and said acceleration anode serving as parts of the ion collector.
  • a system according to claim 2 for a traveling wave tube comprising a helix extending along the electron beam axis, a tubular extension connected with the helix and forming one electrode for the ion collector, an electron collector provided with a perforated hollow cylinder extending therefrom and forming the other electrode of the ion collector, said perforated cylinder projecting into said tubular extension and forming a narrow gap therewith, the potential on said cylinder being lower than that on the helix.
  • said ion collector comprises two' tubular concentrically disposed cylindrical electrodes and radially extending circular end plates forming therewith approximately a toroid with rectangular cross section, the inner electrode which is axially transversed by the electron beam being substantially formed of titanium and being perforated.
  • a system according to claim 6, for a traveling Wave tube comprising a helix extending along the electron beam axis, an acceleration anode, an apertured diaphragm connected with the helix, said ion collector being disposed approximately symmetrically between said acceleration anode and said apertured diaphragm, the ends of the inner cylindrical electrode of said toroidal ion collector being spaced from the respective circular end plates by narrow gaps.
  • a system according to claim 11, comprising means for mechanically and electrically connecting said inner cylindrical electrode with the helix, the potential on the acceleration anode being by a few hundred volts lower than that of the helix.
  • a system according to claim 12, comprising means for mechanically and electrically connecting said inner cylindrical electrode with the helix, the potential of the acceleration anode being by a few hundred volts higher than that of the helix.
  • acceleration electrode is at a potential which is lower than that of the outer cylindrical electrode of the ion collector and the potential of the outer cylindrical electrode is lower than the potential of the helix.

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  • Electron Sources, Ion Sources (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
  • Microwave Tubes (AREA)
  • Electron Tubes For Measurement (AREA)
US279354A 1962-05-09 1963-05-07 Velocity modulated electron tube with integrated focusing and getter pump systems, the pump having multiple getter-coated electrodes Expired - Lifetime US3299311A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES79366A DE1298648B (de) 1962-05-09 1962-05-09 Laufzeitroehre mit koaxial um den Elektronenstrahl angeordneten Ionenfaengern

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US3299311A true US3299311A (en) 1967-01-17

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US (1) US3299311A (enrdf_load_stackoverflow)
CH (1) CH409156A (enrdf_load_stackoverflow)
DE (1) DE1298648B (enrdf_load_stackoverflow)
GB (1) GB1039884A (enrdf_load_stackoverflow)
NL (1) NL292484A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3476967A (en) * 1965-11-03 1969-11-04 Emi Ltd Electron discharge device with a gettering and collecting electrode
US3495116A (en) * 1965-06-30 1970-02-10 Siemens Ag Pump arrangement with auxiliary cathode for electrical discharge vessels
US3500097A (en) * 1967-03-06 1970-03-10 Dunlee Corp X-ray generator
US4397611A (en) * 1981-07-06 1983-08-09 The Perkin-Elmer Corp. Particle beam instrumentation ion pump
US20160233062A1 (en) * 2015-02-10 2016-08-11 Hamilton Sunstrand Corporation System and Method for Enhanced Ion Pump Lifespan
US10262845B2 (en) 2015-02-10 2019-04-16 Hamilton Sundstrand Corporation System and method for enhanced ion pump lifespan
CN113130277A (zh) * 2021-04-21 2021-07-16 中国科学院空天信息创新研究院 一种收集极组件、速调管永磁聚焦系统
US20220344143A1 (en) * 2019-10-25 2022-10-27 Spacetek Technology Ag Compact Time-of-Flight Mass Analyzer

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2767344A (en) * 1949-12-30 1956-10-16 Bell Telephone Labor Inc Electronic amplifier
US3073987A (en) * 1959-12-17 1963-01-15 Raytheon Co Electron discharge device with getter

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE462688A (enrdf_load_stackoverflow) * 1944-03-11
US2692351A (en) * 1949-12-31 1954-10-19 Bell Telephone Labor Inc Electron beam amplifier
DE1026006B (de) * 1957-04-11 1958-03-13 Siemens Ag Strahlerzeugungssystem fuer elektrische Entladungsgefaesse, insbesondere Laufzeitroehren
GB888577A (en) * 1958-04-24 1962-01-31 Emi Ltd Improvements in or relating to electron discharge devices

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2767344A (en) * 1949-12-30 1956-10-16 Bell Telephone Labor Inc Electronic amplifier
US3073987A (en) * 1959-12-17 1963-01-15 Raytheon Co Electron discharge device with getter

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3495116A (en) * 1965-06-30 1970-02-10 Siemens Ag Pump arrangement with auxiliary cathode for electrical discharge vessels
US3476967A (en) * 1965-11-03 1969-11-04 Emi Ltd Electron discharge device with a gettering and collecting electrode
US3500097A (en) * 1967-03-06 1970-03-10 Dunlee Corp X-ray generator
US4397611A (en) * 1981-07-06 1983-08-09 The Perkin-Elmer Corp. Particle beam instrumentation ion pump
US10665437B2 (en) * 2015-02-10 2020-05-26 Hamilton Sundstrand Corporation System and method for enhanced ion pump lifespan
US10262845B2 (en) 2015-02-10 2019-04-16 Hamilton Sundstrand Corporation System and method for enhanced ion pump lifespan
US20160233062A1 (en) * 2015-02-10 2016-08-11 Hamilton Sunstrand Corporation System and Method for Enhanced Ion Pump Lifespan
US11081327B2 (en) 2015-02-10 2021-08-03 Hamilton Sundstrand Corporation System and method for enhanced ion pump lifespan
US20210327695A1 (en) * 2015-02-10 2021-10-21 Hamilton Sundstrand Corporation System and method for enhanced ion pump lifespan
US11742191B2 (en) * 2015-02-10 2023-08-29 Hamilton Sundstrand Corporation System and method for enhanced ion pump lifespan
US20220344143A1 (en) * 2019-10-25 2022-10-27 Spacetek Technology Ag Compact Time-of-Flight Mass Analyzer
US12191134B2 (en) * 2019-10-25 2025-01-07 Spacetek Technology Ag Compact time-of-flight mass analyzer
CN113130277A (zh) * 2021-04-21 2021-07-16 中国科学院空天信息创新研究院 一种收集极组件、速调管永磁聚焦系统
CN113130277B (zh) * 2021-04-21 2024-02-13 中国科学院空天信息创新研究院 一种收集极组件、速调管永磁聚焦系统

Also Published As

Publication number Publication date
NL292484A (enrdf_load_stackoverflow)
CH409156A (de) 1966-03-15
GB1039884A (en) 1966-08-24
DE1298648B (de) 1969-07-03

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