US2727167A - Ion pump - Google Patents

Ion pump Download PDF

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US2727167A
US2727167A US282992A US28299252A US2727167A US 2727167 A US2727167 A US 2727167A US 282992 A US282992 A US 282992A US 28299252 A US28299252 A US 28299252A US 2727167 A US2727167 A US 2727167A
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container
walls
cathode
anode
vacuum
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US282992A
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Alpert Daniel
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CBS Corp
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Westinghouse Electric Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/38—Exhausting, degassing, filling, or cleaning vessels

Definitions

  • My invention relates to high-vacuum pumping devices and in particular comprises an electrical discharge tube in which electrons emitted from a thermionic cathode produce very high vacuums by capturing molecules of gas and afiixing them to the walls of a vacuum system, which fixation is later made permanent by burying them under a coating of sublimed metal.
  • An object of my invention is accordingly to provide a high-vacuum pumping device of a novel type.
  • Another object is to provide a gas-evacuating system capable of exhausting vacuum apparatus to an extremely low residual pressure.
  • Still another object is to provide an evacuating system which is extremely simple and of low cost.
  • a vacuum-tight container preferably in the form of a glass cylinder with a rounded lower end, and having at its upper end a press of conventional type through which in-leads 2, 3, 4, 5 and 6 are sealed vacuum-tight.
  • a pipe 7 which may be sealed or otherwise attached vacuum-tight to a vacuum-system embodying a vessel which is to be evacuated.
  • the vacuum-system also embodies a suitable preliminary or roughpumping device capable of reducing the pressure in the vacuum-system to a residual of the order of 0.001 mm. of mercury or less.
  • the press of the tube 1 supports two metal rods 8 and 9 extending into tube 1, and these together with an extension 11 of the in-lead 4 are so shaped as to extend parallel to the axis of tube 1, equidistant therefrom and from each other, for the greater part of their length.
  • the parallel portions of the members 8, 9 and 11 support a helical conductor 12 which acts as anode to attract electrons.
  • a filament 13 capable of being heated to a temperature at which it emits electrons freely is supported within the helix 12 parallel to the axis thereof on extensions of the in-leads 2 and 3.
  • a second filament 14 of metal which can be heated to a temperature at which it evaporates copiously is similarly supported upon extensions of the in-leads 5 and 6.
  • the filament 13 may be of tungsten and the filament 14 of nickel or of one of the known metallic getters employed in tube-evacuation practice.
  • the filaments 13 and 14 extend well down into the rounded lower end of the tube 1, and the arrangement is such that that portion of the tube may dip into a reservoir of liquid air or the like (not shown). Such immersion has been found to facilitate the evacuation process.
  • the duct 7 is attached to the vacuum-system, and the latter pumped out to the best vacuum practicable with the preliminary pump.
  • the preliminary pump may even be heated to a temperature safely below the melting point of its walls.
  • the filaments 13 and 14 are heated by current flow sufliciently to effectively outgas them.
  • the pump is preferably shut off from the remainder of the system, heating of filament 14 is stopped, and filament 13 maintained at its thermionically-emissive operating temperature.
  • the tube 1 is immersed in liquid air, and a voltage impressed between in-leads 4 and 3 making the helix 12 positive by around volts relative to filament 13.
  • the pumping arrangement is suitably effective for many purposes even where the evaporation of metal from the surface of filament 14 is not carried out at all.
  • a vacuum-pumping device comprising a vacuumtight container in the form of an elongated cylinder having its walls coated with a getter and having an olftake duct joined to its walls near one end, a thermionicallyemissive filament supported within said container, an anode cooperating with said filament within said container, said anode comprising a conductor with spaced turns positioned between said filament and the walls of said container, a body comprising said getter to be heated electrically within said container, and in-leads for conveying current to said filament, said anode, and said body sealed through the walls of said container.
  • a vacuum-pumping device comprising a vacuumtight container in the form of an elongated cylinder having its walls coated with a getter and having an ofttake duct joined to its walls near one end, a thermionicallyemissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode within said container, said anode comprising a conductor with spaced turns positioned between said walls and said cathode a body comprising said getter to be heated electrically within said container, and in-leads for said cathode, said body and said anode sealed through the walls of said container near said ofitake duct.
  • a pumping device comprising a vacuum-tight container in the form of an elongated cylinder having its walls coated with-a getter and having an ofitake duet near one end leading tosaid vessel, a thermionically-emissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode within said container, said anode comprising a conductor with spaced turnspositioned between said cathode and the walls of said container, a body comprising said getter to be heated electrically in said container, and in leads for said cathode, said body and anode sealed through the walls of said containernear said oiitake duct.
  • a pumping device cornprising a vacuum-tight container in the form of an elongated cylinder having its walls coated with a getter and having an ofitake duct near one end leading to said vessel, 21 thermionically-emissive cathode supported withinsaid container to'be heated by electric current, an
  • a body cooperating with said cathode within said container, a body comprising said getter to be heated electrically within said container, and in-leads for said cathode, said body and anode sealed through the walls of said container near said ofitake duct.
  • a pumping device comprising a vacuum-tight container having its walls coated with a getter and havingan ofitake duct near one end. leading to said vessel, a thermionicallyemissive cathode supported within said container to be heated; by electric current, an anode cooperating with said cathode within said container, said anode comprising a helical conductor positioned between said cathode and the walls of said container, a body of said getter to be heated electrically in said container and in-leads for said cathode body and anode sealed through the walls of said container.
  • thermionically-emissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode within said container, a body comprising said getter to be heated electrically within said container, and in-leads for said cathode, said body and anode sealed through the walls of said container near said oiitake duct.
  • a vacuum-pumping device comprising a vacuumtight container having its walls coated with a getter and having ofi'take duct near one end, a thermionicallyemissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode Within said container, said anode comprising a helical conductor positioned between said cathode and the walls of said container a body comprising said getter to be heated electrically within said container, and in-leads for said cathode body and anode sealed through the walls of: said container.
  • a pumping device comprising a vacuum-tight enclosure having its walls coated with a getter and having an offtake dnct leading to said vessel, an electron-emissive cathode supported within said enclosure, an anode cooperating with said cathode within said enclosure, said anode comprising a conductor with spaced turns positioned between said cathode and the wall of said enclosure, a body of said getter to be heated electrically within said enclosure and i-n-leads for said anode, said body and said cathode sealed through the walls of said enclosure.

Description

D. ALPERT Dec. 13, 1955 ION PUMP Filed April 18. 1952 INVENTOR Daniel Alpert ATTORN EY United States Patent fiice 2,727,167 Patented Dec. 13, 1955 1%: PUMP Daniel Alpert, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application April 18, 1952, Serial No. 282392 8 Claims. (Cl. 313-7) My invention relates to high-vacuum pumping devices and in particular comprises an electrical discharge tube in which electrons emitted from a thermionic cathode produce very high vacuums by capturing molecules of gas and afiixing them to the walls of a vacuum system, which fixation is later made permanent by burying them under a coating of sublimed metal. By this means I have found it possible to evacuate to residual pressures of around 5 10 mm. of mercury (i. e. circa 7 l0 atmospheres), which is only about one five-hundredth of the residual pressure ordinarily attainable with the diffusion pumps usually employed for high-vacuum pumpmg.
An object of my invention is accordingly to provide a high-vacuum pumping device of a novel type.
Another object is to provide a gas-evacuating system capable of exhausting vacuum apparatus to an extremely low residual pressure.
Still another object is to provide an evacuating system which is extremely simple and of low cost.
Other objects of my invention will become apparent upon reading the following description taken in connection with the drawings in which the single figure is an elevational view, partly broken away, of an evacuation device embodying the principles of my invention.
Referring in detail to the drawings, a vacuum-tight container 1, preferably in the form of a glass cylinder with a rounded lower end, and having at its upper end a press of conventional type through which in-leads 2, 3, 4, 5 and 6 are sealed vacuum-tight. Issuing also from the upper end is a pipe 7 which may be sealed or otherwise attached vacuum-tight to a vacuum-system embodying a vessel which is to be evacuated. The vacuum-system also embodies a suitable preliminary or roughpumping device capable of reducing the pressure in the vacuum-system to a residual of the order of 0.001 mm. of mercury or less.
The press of the tube 1 supports two metal rods 8 and 9 extending into tube 1, and these together with an extension 11 of the in-lead 4 are so shaped as to extend parallel to the axis of tube 1, equidistant therefrom and from each other, for the greater part of their length. The parallel portions of the members 8, 9 and 11 support a helical conductor 12 which acts as anode to attract electrons. A filament 13 capable of being heated to a temperature at which it emits electrons freely is supported within the helix 12 parallel to the axis thereof on extensions of the in-leads 2 and 3. A second filament 14 of metal which can be heated to a temperature at which it evaporates copiously is similarly supported upon extensions of the in-leads 5 and 6. To give specific examples, the filament 13 may be of tungsten and the filament 14 of nickel or of one of the known metallic getters employed in tube-evacuation practice.
The filaments 13 and 14 extend well down into the rounded lower end of the tube 1, and the arrangement is such that that portion of the tube may dip into a reservoir of liquid air or the like (not shown). Such immersion has been found to facilitate the evacuation process.
In using the above-described arrangement, the duct 7 is attached to the vacuum-system, and the latter pumped out to the best vacuum practicable with the preliminary pump. During this procedure no liquid-air is used with tube 1, but it may even be heated to a temperature safely below the melting point of its walls. The filaments 13 and 14 are heated by current flow sufliciently to effectively outgas them. When the preliminary pumping has reached the limits of its effectiveness in evacuation, the pump is preferably shut off from the remainder of the system, heating of filament 14 is stopped, and filament 13 maintained at its thermionically-emissive operating temperature. The tube 1 is immersed in liquid air, and a voltage impressed between in-leads 4 and 3 making the helix 12 positive by around volts relative to filament 13.
The residual pressure within the entire vacuum system begins to drop, at a rate depending, of course, on the volume of the system being evacuated. While this operation or" my arrangement is in no sense dependent, of CO. rse, on the correctness of this theory, it appears that the electrons accelerated by the electric field due to anode l2. collide with and capture molecules of the gas within container 1 and many of these pass between the turns of helix 12 into incidence with the walls of container 1 to which a large number of them adhere. Their progressive removal from the free space within the vacuum system, of course, lowers the residual gas pressure throughout the latter.
in the course of continued use the walls of tube 1 become saturated with adherent gas molecules and the effectiveness of the evacuation process is lost. However, I have found that its effectiveness may be restored by heating the filament 14 by current flow to the point where its metal evaporates and condenses on the walls of container 1 to form a getter coating 19, thereby apparently burying the adherent gas molecules on the container walls. in this way the pumping action may be carried on indefinitely.
However, the pumping arrangement is suitably effective for many purposes even where the evaporation of metal from the surface of filament 14 is not carried out at all.
I claim as my invention:
1. A vacuum-pumping device comprising a vacuumtight container in the form of an elongated cylinder having its walls coated with a getter and having an olftake duct joined to its walls near one end, a thermionicallyemissive filament supported within said container, an anode cooperating with said filament within said container, said anode comprising a conductor with spaced turns positioned between said filament and the walls of said container, a body comprising said getter to be heated electrically within said container, and in-leads for conveying current to said filament, said anode, and said body sealed through the walls of said container.
2. A vacuum-pumping device comprising a vacuumtight container in the form of an elongated cylinder having its walls coated with a getter and having an ofttake duct joined to its walls near one end, a thermionicallyemissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode within said container, said anode comprising a conductor with spaced turns positioned between said walls and said cathode a body comprising said getter to be heated electrically within said container, and in-leads for said cathode, said body and said anode sealed through the walls of said container near said ofitake duct.
3. In combination with a vessel to be evacuated, a pumping device comprising a vacuum-tight container in the form of an elongated cylinder having its walls coated with-a getter and having an ofitake duet near one end leading tosaid vessel, a thermionically-emissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode within said container, said anode comprising a conductor with spaced turnspositioned between said cathode and the walls of said container, a body comprising said getter to be heated electrically in said container, and in leads for said cathode, said body and anode sealed through the walls of said containernear said oiitake duct.
4. In combination with a vessel to be evacuated to a pressure of the order of 7 l0 atmospheres, a pumping device cornprising a vacuum-tight container in the form of an elongated cylinder having its walls coated with a getter and having an ofitake duct near one end leading to said vessel, 21 thermionically-emissive cathode supported withinsaid container to'be heated by electric current, an
anode. cooperating with said cathode within said container, a body comprising said getter to be heated electrically within said container, and in-leads for said cathode, said body and anode sealed through the walls of said container near said ofitake duct.
5. In combination with a vessel to be evacuated, a pumping device comprising a vacuum-tight container having its walls coated with a getter and havingan ofitake duct near one end. leading to said vessel, a thermionicallyemissive cathode supported within said container to be heated; by electric current, an anode cooperating with said cathode within said container, said anode comprising a helical conductor positioned between said cathode and the walls of said container, a body of said getter to be heated electrically in said container and in-leads for said cathode body and anode sealed through the walls of said container.
6. In combination with a vessel to be evacuated to a tight container having, its walls coated with a getter and having an offtake duct near one end leading to said vessel, 21 thermionically-emissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode within said container, a body comprising said getter to be heated electrically within said container, and in-leads for said cathode, said body and anode sealed through the walls of said container near said oiitake duct.
7. A vacuum-pumping device comprising a vacuumtight container having its walls coated with a getter and having ofi'take duct near one end, a thermionicallyemissive cathode supported within said container to be heated by electric current, an anode cooperating with said cathode Within said container, said anode comprising a helical conductor positioned between said cathode and the walls of said container a body comprising said getter to be heated electrically within said container, and in-leads for said cathode body and anode sealed through the walls of: said container.
8. in combination with a vesselto be evacuated, a pumping device comprising a vacuum-tight enclosure having its walls coated with a getter and having an offtake dnct leading to said vessel, an electron-emissive cathode supported within said enclosure, an anode cooperating with said cathode within said enclosure, said anode comprising a conductor with spaced turns positioned between said cathode and the wall of said enclosure, a body of said getter to be heated electrically within said enclosure and i-n-leads for said anode, said body and said cathode sealed through the walls of said enclosure.
References Cited in the file of. this patent UNITED STATES PATENTS 2,l79,437 Socolofsky Nov. 7, 1939 2,222,005 Sutherlin Nov. 19, 1940 2,393,650 Metcalf "Jan. 29, 1946 2,454,564 Nelson Nov. 23, 1948 2,469,006 Shelby May 3, 1949
US282992A 1952-04-18 1952-04-18 Ion pump Expired - Lifetime US2727167A (en)

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2850225A (en) * 1955-11-10 1958-09-02 Wisconsin Alumni Res Found Pump
US2894679A (en) * 1953-11-23 1959-07-14 Wisconsin Alumni Res Found Pump
US2919380A (en) * 1957-07-23 1959-12-29 Philco Corp Electron discharge devices
US2947465A (en) * 1958-05-20 1960-08-02 Michael A Otavka Means and method for producing a vacuum
US2967012A (en) * 1957-04-15 1961-01-03 High Voltage Engineering Corp Getter-ion pump
US2980317A (en) * 1957-02-27 1961-04-18 Leybolds Nachfolger E Vacuum device
US2984314A (en) * 1957-11-22 1961-05-16 New York Air Brake Co Trapping device
US2988657A (en) * 1958-08-02 1961-06-13 Philips Corp Ion pump
US3036933A (en) * 1959-10-06 1962-05-29 Ibm Vacuum evaporation method
US3042824A (en) * 1960-06-22 1962-07-03 Varian Associates Improved vacuum pumps
US3074621A (en) * 1958-05-30 1963-01-22 Heraeus Gmbh W C Getter-ion pump
US3085913A (en) * 1960-10-03 1963-04-16 Ibm Vacuum evaporation method
US3181775A (en) * 1962-03-20 1965-05-04 Wisconsin Alumni Res Found Pumping apparatus
US3214359A (en) * 1961-12-11 1965-10-26 Gen Electric Hydrogen pumping method and apparatus
US3233577A (en) * 1961-05-29 1966-02-08 Sperry Rand Corp Gettering means in a vacuum deposition device
US3535055A (en) * 1959-05-25 1970-10-20 Bendix Corp Cold-cathode discharge ion pump
US4306515A (en) * 1976-06-08 1981-12-22 Balzers Patent- Und Beteilingungs-Aktiengesellschaft Vacuum-deposition apparatus
US5655886A (en) * 1995-06-06 1997-08-12 Color Planar Displays, Inc. Vacuum maintenance device for high vacuum chambers
US20160090976A1 (en) * 2014-09-30 2016-03-31 Honeywell International Inc. Systems and methods for a dual purpose getter container

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2179437A (en) * 1938-08-10 1939-11-07 Arthur R Socolofsky Incandescent lamp
US2222005A (en) * 1939-10-31 1940-11-19 Westinghouse Electric & Mfg Co Mounting and flashing getter
US2393650A (en) * 1939-06-14 1946-01-29 Cons Eng Corp Apparatus for analyzing hydrocarbons
US2454564A (en) * 1947-04-08 1948-11-23 Gen Electric Ionization-type vacuum gauge
US2469006A (en) * 1944-09-27 1949-05-03 Eugene F Shelby Apparatus for high evacuation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2179437A (en) * 1938-08-10 1939-11-07 Arthur R Socolofsky Incandescent lamp
US2393650A (en) * 1939-06-14 1946-01-29 Cons Eng Corp Apparatus for analyzing hydrocarbons
US2222005A (en) * 1939-10-31 1940-11-19 Westinghouse Electric & Mfg Co Mounting and flashing getter
US2469006A (en) * 1944-09-27 1949-05-03 Eugene F Shelby Apparatus for high evacuation
US2454564A (en) * 1947-04-08 1948-11-23 Gen Electric Ionization-type vacuum gauge

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2894679A (en) * 1953-11-23 1959-07-14 Wisconsin Alumni Res Found Pump
US2850225A (en) * 1955-11-10 1958-09-02 Wisconsin Alumni Res Found Pump
US2980317A (en) * 1957-02-27 1961-04-18 Leybolds Nachfolger E Vacuum device
US2967012A (en) * 1957-04-15 1961-01-03 High Voltage Engineering Corp Getter-ion pump
US2919380A (en) * 1957-07-23 1959-12-29 Philco Corp Electron discharge devices
US2984314A (en) * 1957-11-22 1961-05-16 New York Air Brake Co Trapping device
US2947465A (en) * 1958-05-20 1960-08-02 Michael A Otavka Means and method for producing a vacuum
US3074621A (en) * 1958-05-30 1963-01-22 Heraeus Gmbh W C Getter-ion pump
US2988657A (en) * 1958-08-02 1961-06-13 Philips Corp Ion pump
US3535055A (en) * 1959-05-25 1970-10-20 Bendix Corp Cold-cathode discharge ion pump
US3036933A (en) * 1959-10-06 1962-05-29 Ibm Vacuum evaporation method
US3042824A (en) * 1960-06-22 1962-07-03 Varian Associates Improved vacuum pumps
US3085913A (en) * 1960-10-03 1963-04-16 Ibm Vacuum evaporation method
US3233577A (en) * 1961-05-29 1966-02-08 Sperry Rand Corp Gettering means in a vacuum deposition device
US3214359A (en) * 1961-12-11 1965-10-26 Gen Electric Hydrogen pumping method and apparatus
US3181775A (en) * 1962-03-20 1965-05-04 Wisconsin Alumni Res Found Pumping apparatus
US4306515A (en) * 1976-06-08 1981-12-22 Balzers Patent- Und Beteilingungs-Aktiengesellschaft Vacuum-deposition apparatus
US5655886A (en) * 1995-06-06 1997-08-12 Color Planar Displays, Inc. Vacuum maintenance device for high vacuum chambers
US20160090976A1 (en) * 2014-09-30 2016-03-31 Honeywell International Inc. Systems and methods for a dual purpose getter container

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