US3221197A - Scavenging system - Google Patents

Scavenging system Download PDF

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Publication number
US3221197A
US3221197A US110055A US11005561A US3221197A US 3221197 A US3221197 A US 3221197A US 110055 A US110055 A US 110055A US 11005561 A US11005561 A US 11005561A US 3221197 A US3221197 A US 3221197A
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United States
Prior art keywords
scavenging
dissociator
organic
gases
molecular
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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
US110055A
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English (en)
Inventor
Patrick P Coppola
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General Electric Co
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General Electric Co
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Filing date
Publication date
Priority to NL278453D priority Critical patent/NL278453A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US110055A priority patent/US3221197A/en
Priority to CH577162A priority patent/CH430024A/de
Priority to GB18419/62A priority patent/GB984893A/en
Priority to DE19621464612 priority patent/DE1464612C/de
Priority to FR897596A priority patent/FR1321995A/fr
Application granted granted Critical
Publication of US3221197A publication Critical patent/US3221197A/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
    • 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
    • H01J7/00—Details not provided for in the preceding groups and common to two or more basic types of discharge tubes or lamps
    • H01J7/14—Means for obtaining or maintaining the desired pressure within the vessel
    • H01J7/18—Means for absorbing or adsorbing gas, e.g. by gettering
    • H01J7/186—Getter supports
    • 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

  • This invention relates to improvements in gas scavenging or gettering apparatus for high-vacuum apparatus such as electron discharge devices, and more particularly to scavenging or gettering apparatus for use with electron discharge devices containing organic materials, to scavenge undesired organic gases therefrom.
  • the usual operation of such an ion pump involves the emission of electrons from a cathode, which may be heated or may operate as a cold emitter.
  • the electrons caused to follow paths, which may be made tortuous by the interaction of magnetic fields, through a region containing gases to be scavenged.
  • the resulting bombardment of the gas atoms or molecules by the electrons produces gas ions.
  • the positive ions resulting are drawn to the cathode, which usually consists of a metal which may have a chemical affinity for certain of the ions and which also is readily sputterable by the ion bombardment.
  • Some of the ions are buried in the cathode itself, and the resultant sputtering action buries other ions beneath a blanket of sputtered metal on other surfaces of the ion pump.
  • one object of the invention is to provide an improved gas scavenging system for substantially prolonging the operating life of electron discharge devices of the type having organic materials within the electron discharge environment thereof.
  • Another object is to provide improved apparatus for gettering or scavenging organic molecules in a partially or substantially evacuated system.
  • Another object is to provide such scavenging apparatus which enables an electron discharge device with which it is associated to have a permanently sealed envelope, within which, or in a sealed appendage to which, the scavenging apparatus may be situated.
  • Another object is to provide such apparatus including a vacuum pump of the ionic type, and wherein special provision is made for prevent-ing contamination and reduction of the pumping ability of the ion pump by materials which the ion pump itself cannot adequately dispose of.
  • Another object is to provide improved apparatus for generating hydrogen from a relatively inexpensive hydrocarbon source.
  • Another object is to provide a gas scavenging system of the character described wherein operation of the gas scavenging system generates as a by-product of such operation additional gettering or gas scavenging material.
  • Another object is to provide a gas scavenging system of the character described which is inexpensive, compact. and capable of operating for relatively long periods of the order of several thousands of hours.
  • Another object is to provide apparatus for scavenging organic gases which is particularly suitable for atta-ch ment to or association with an electron discharge device of the type wherein organic gases are generated during operation of the electron discharge device.
  • Another object is to provide such organic gas scavenging apparatus which is particularly suitable for attachment to or association with an electron discharge device of the electron beam type wherein an organic target is subjected to impingement by an electron beam and thereby gives off organic gases.
  • FIGURE 1 is a schematic block diagram of a scavenging system constructed in accordance with the present invention
  • FIGURE 2 is a fragmentary detailed sectional view of one form of a portion of the system of FIGURE 1;
  • FIGURE 3 is a fragmentary sectional view of another form of portions of the system of FIGURE 1;
  • FIGURE 4 is a fragmentary sectional view of another portion of the system of FIGURE 1.
  • the present invention provides a scavenging system wherein organic materials to be scavenged are subjected to a preliminary dissociation by which they are converted or decomposed into lower molecular Weight components as well as their carbon, hydrogen and other constituents. After such dissociation, the various constituents are exposed to a series of scavenging agents by means of which the particular constituents of the organic materials are selectively scavenged, the series of scavenging agents being arranged in such a way that succeeding scavenging agents are protected from exposure to contaminating or saturating, constituents, or from otherwise being rendered ineffectual, by the scavenging action of the preceding scavenging agents.
  • FIGURE 1 shows an exemplary source 2 of organic material to be scavenged.
  • the source 2 is shown as an electron discharge device of the electron beam type wherein the beam is generated by an electron gun 4 in an evacuable envelope 6 and impinges upon a target 8 within the envelope.
  • the target 8 may be an organic material of a type such that under bombardment by the electron beam various organic gases are given ofi by the target, such as methane, ethane, and benzene, as well as high molecular weight hydrocarbons.
  • Such an electron discharge device 2 may be intended to be operated under evacuated conditions wherein the desired ambient pressures are of the order of 10- to 10- millimeters of mercury, or less.
  • the organic gases generated by such electron bombardment would very quickly contaminate the electron emitter as well as destroy the desired degree of evacuation of the discharge device.
  • electron discharge device 2 is connected by a gas flow passage to a dissociator 12 which in turn is connected by a gas flow passage 14 to a scavenger pump 16, as will be more fully described hereinafter.
  • Dissociator 12 consists of means for breaking down or decomposing the organic gases into various molecular, parti-molecular and atomic constituents. According to one form of my invention such dissociation may be accomplished pyrolytically, that is by application of heat.
  • Suitable pyrolytic dissociator means 18 is shown in greater detail in FIGURE 2 and includes a container 20 of any suitable material such as glass, refractory material, or suitable metal, having a gas inlet 22 and an outlet 24. Within the container 20 is a heated body 26 which may be made of any suitable material having an adequately long life at elevated temperatures of the order of 1000-1100 C. The heated body may be for example a filament 27 of refractory metal such as tungsten or rhenium resistance heated by means of a potential source 28 or the like.
  • the heated body 26 may be coated or otherwise protected by a material such as aluminum oxide which is substantially non-reactive chemically with the organic gas input to the pyrolytic station.
  • the heated body 26 may consist of a porous refractory member 30, as shown in FIGURE 3, of a material such as beryllium oxide or aluminum oxide, brought to a suitable operating temperature by a heater 32 and potential source 34.
  • organic molecule dissociation may be employed at dissociator 12 within the contemplation of the invention.
  • a suitable chemical catalyst the presence of which produces or enhances the decomposition of one or more of the organic gases desired to be scavenged.
  • suitable catalysts are activated alumina, activated silica, activated magnesium oxide, activated carbon, and activated aluminum silicate.
  • Catalysts may also be used which comprise suitable noble metals such as platinum or palladium.
  • Dissociator 12 may also employ ionization to produce or enhance the dissociation of the organic materials desired to be scavenged.
  • a suitable source of ions may be provided within or adjacent container 20, as best shown in FIGURE 2, for example by means of a directly heated electron emitter 36 and a spaced anode 38 connected to a suitable potential source 39.
  • the electrons emitted from emitter 36 collide with the molecules of organic gases in the container 20, forming ions which in turn react with enhanced efficiency with the heated body 26 and dissociate into their various constituents, including carbon and hydrogen.
  • ionization alone may be employed as a dissociation mechanism, in the absence of any direct pyrolytic dissociation, where provision of heated dissociating elements is undesired.
  • protection of the ionization source against contamination by organics, or selection of an ion source not deleteriously affected by the presence of the organics may be required.
  • the free carbon thus derived by the decomposition of organic materials in dissociator 12 deposits as shown at 40 on the available adjacent surfaces such as the walls of the container 20.
  • a unique feature of the present invention is that the resulting layer of carbon 40 which is thus gradually built up on the walls of container 20 or other available surfaces of dissociator 12, further enhances the efiiciency of gas scavenging action by the dissociator because the carbon layer 40 itself serves as a scavenging material for some of the other dissociated products which may be present, such as fragments of hydrocarbon or other organic molecules, carbon monoxide, carbon dioxide, and the like.
  • this carbon layer 49 is continually being built up by the dissociating process, its surface is continually being renewed as a sorber for gases to be scavenged.
  • the pyrolytic dissociating means 18 may be so constructed and arranged as to provide therein or adjacent thereto surfaces or areas of reduced temperature. Such surfaces of reduced temperature are useful for preferentially receiving depositions of carbon and their relative coolness inhibits desorption of gases which are scavenged by the deposited carbon. These cool surfaces may be provided by any suitable artificial cooling means if desired, or conveniently by being situated as remotely as possible, consistent with deposition of carbon thereon, from the heated elements of the pyrolytic station.
  • Oxygen bearing compounds of elements such as barium, calcium and stronium having, when reduced, a gas scavenging ability may also be utilized within the pyrolytic station to oxidize various dissociation products of the organic gases, thereby forming, for example, carbon monoxide or carbon dioxide from available carbon. Also after reduction of such compounds, the resulting metals such as barium can scavenge other dissociation products of the organic gases.
  • the dissociator 12 may include, in advance of any pyrolytic, ionization or catalytic dissociating means as heretofore described, a molecular filtration means 41 as best shown in FIGURE 4.
  • the filtration means 41 includes a container 42 in which is situated a charge of organic gas sorbing material 44 such as one or more of the zeolites, activated alumina, activated charcoal or the like. If desired, the composition of the molecular sorbing materials may be particularly suited to particular gas constituents to be scavenged.
  • an absorption material of the Zeolites family such as Molecular Sieve Material Type 13X, available from the Linde Air Products Co., or activated charcoal may effectively be employed.
  • the filtration means 41 may contain suitable commercially available zeolites such as Linde Air Products Co. Molecular Sieve Material Types 4A and 5A.
  • cooling means may be provided for maintaining the charge of sorbing material 44 at or below room temperature.
  • any suitable cooling means may be employed, such as one or more Peltier junctions, shown schematically at 46 in FIGURE 4, and suitably energized from a potential source 48.
  • Gases remaining after treatment by the dissociator 12 are those which have neither been extracted by the molecular filtration means 41 nor scavenged by other portions of dissociator 12, and such residual gases can be expected to consist essentially of hydrogen with perhaps some carbon monoxide, carbon dioxide, water, nitrogen, and perhaps traces of oxygen.
  • Scavenging pump 16 may preferably be an ion pump of conventional design, either of the thermal evaporation or cold cathode type, or pump 16 may if desired be a diffusion pump or other suitable residual gas scavenging pump.
  • pump 16 may consist for example of a suitably heated member of a material, such as titanium, having good hydrogen absorption capability, such as shown at in FIGURE 3.
  • the molecular filter 41 and the other portions of dissociator 12 may conveniently be packaged as an appendage to, or integral portion of the inlet of the scavenging pump 16.
  • apparatus constructed according to my invention has utility beyond that of gettering or gas scavenging apparatus.
  • the hydrogen scavenging stage removed or rendered inoperative, it provides an effective means of removing all constituents except hydrogen from a suitable low cost organic source, and thus can serve as an effective generator of hydrogen gas.
  • Apparatus for scavenging organic gases from a partially evacuated environment comprising dissociator means for converting said organic gases into their molecular, parti-molecular, and atomic constituents, said dissociator means including a material selected from the group consisting of refractory oxides and catalysts, and scavenging pump means coupled to said dissociator means for selectively eliminating said constituents.
  • said dissociator means includes a pyrolytic element and means further associated with said pyrolytic element for subjecting said organic gases to ionization adjacent said pyrolytic element.
  • said dissociator means further includes a pyrolytic element and materials selected from the group consisting of barium, calcium, strontium, and oxygen bearing compounds thereof, titanium, zirconium, and intermetallic compounds thereof.
  • said scavenging pump means includes means for collecting and forming a sorbing surface of carbon produced by said dissociator means.
  • said scavenging pump means includes means providing a surface onto which free carbon produced by said dissociating means from said organic gases can deposit to form additional self-replenishing sorption surfaces for sorbing others of said constituents.
  • a scavenging system for scavenging organic gases from said envelope, said scavenging system comprising dissociator means for converting said organic gases into their molecular, parti-molecular and atomic constituents, said dissociator means including a material selected from the group consisting of refractory oxides and catalysts, and scavenging pump means coupled to said dissociator means for absorbing said constituents.
  • a gas scavenging pump of the ionic type including an ionization chamber for receiving gases to be scavenged, means for emitting electrons into the ionization chamber for collision with gas particles therein to form ions, and a surface of a material sputterable by ion bombardment to bury ions, of a gas flow passage for admitting gases to be scavenged into said ionization chamber, and organic molecule dissociating means arranged in said passage in the path of gases flowing into said ionization chamber.
  • said dissociating means includes pyrolytic means situated between the entrance of said flow passage and said ion pump and molecular filter means situated between the entrance of said flow passage and said pyrolytic means, said molecular filter means including a charge of a material from the group consisting of the zeolites, activated alumina, and activated charcoal.
  • said dissociating means includes a porous ceramic member arranged for flow of entering gases therethrough, and means for heating said ceramic member to a temperature sufiicient to produce thermal dissociation of entering gases upon contact therewith.
  • said dissociating means includes a pyrolytic element, and means for catalyzing dissociation of gases exposed to said pyrolytic element.
  • a gas scavenging system for gettering an electron discharge device including an organic target and an electron beam impinging thereon, said system comprising an ion pump, a gas flow passage connected at one end to the ion pump and adapted to be connected at its other end to the interior of the electron discharge device envelope, and gas dissociating means disposed in said gas flow passage for decomposing gases exposed thereto into molecular, parti-molecular, and atomic constituents, said dissociator means including a material selected from the group consisting of refractory oxides and catalysts.
  • Apparatus for scavenging organic gases from a partially evacuated environment comprising dissociator means including a pyrolytic element for converting said organic gases into their molecular, parti-molecular, and atomic constituents, and scavenging pump means coupled to said dissociator means for selectively eliminating said constituents, said dissociator means being located between said scavenging pump means and the source of gases to be scavenged so as to substantially isolate said scavenging pump means from non-dissociated gases.
  • catalysts include a material selected from the group consisting of activated alumina, activated silica, activated magnesium oxide, activated carbon and activated aluminum silicate.
  • Apparatus for scavenging organic gases from a partially evacuated environment comprising dissociator means for converting said organic gases into their molecular, parti-molecular, and atomic constituents, said dissociator means including gas molecule decomposing means and molecular filter means situated between the decomposing means and the source of said organic gases, and scavenging pump means coupled to said dissociator means for selectively eliminating said constituents.
  • the apparatus as set forth in claim 21 further including means for cooling said molecular filter means including a Peltier junction.
  • said filter means includes a charge of material selected from the group consisting of zeolites, activated alumina, and activated charcoal.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Catalysts (AREA)
US110055A 1961-05-15 1961-05-15 Scavenging system Expired - Lifetime US3221197A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL278453D NL278453A (2) 1961-05-15
US110055A US3221197A (en) 1961-05-15 1961-05-15 Scavenging system
CH577162A CH430024A (de) 1961-05-15 1962-05-14 Gasspül-Apparatur
GB18419/62A GB984893A (en) 1961-05-15 1962-05-14 Removing organic gases from electron discharge devices
DE19621464612 DE1464612C (de) 1961-05-15 1962-05-14 Vorrichtung zum Pumpen organischer Gase aus einem teilweise evakuierten Raum
FR897596A FR1321995A (fr) 1961-05-15 1962-05-15 Système de purification

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Application Number Priority Date Filing Date Title
US110055A US3221197A (en) 1961-05-15 1961-05-15 Scavenging system

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US3221197A true US3221197A (en) 1965-11-30

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CH (1) CH430024A (2)
GB (1) GB984893A (2)
NL (1) NL278453A (2)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3310227A (en) * 1965-04-12 1967-03-21 Milleron Norman Surge and backstreaming porous diaphragm filter for vacuum system
US3589791A (en) * 1969-09-02 1971-06-29 Zenith Radio Corp Processing of cathode-ray tubes
US3601503A (en) * 1969-08-08 1971-08-24 Thomas W Snouse Thin membrane ionization pump apparatus
US3619020A (en) * 1968-11-21 1971-11-09 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Method of introducing halogens into electric lamps
FR2548828A1 (fr) * 1983-07-05 1985-01-11 Gen Electric Pompe a piege d'hydrocarbures
EP0201877A3 (de) * 1985-05-09 1987-11-19 Nokia Graetz Gesellschaft mit beschränkter Haftung Direkt geheizter Sorptions-Getterkörper
US4789309A (en) * 1987-12-07 1988-12-06 Saes Getters Spa Reinforced insulated heater getter device
US4820226A (en) * 1987-10-14 1989-04-11 The United States Of America As Represented By The United States Department Of Energy Getter pump for hydrogen and hydrocarbon gases

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT998681B (it) * 1973-10-01 1976-02-20 Getters Spa Pompa getter
NL7808774A (nl) * 1978-08-25 1980-02-27 Philips Nv Zonnecollector.

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2796555A (en) * 1954-06-29 1957-06-18 High Voltage Engineering Corp High-vacuum pump
US2967012A (en) * 1957-04-15 1961-01-03 High Voltage Engineering Corp Getter-ion pump
US2988657A (en) * 1958-08-02 1961-06-13 Philips Corp Ion pump

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2796555A (en) * 1954-06-29 1957-06-18 High Voltage Engineering Corp High-vacuum pump
US2967012A (en) * 1957-04-15 1961-01-03 High Voltage Engineering Corp Getter-ion pump
US2988657A (en) * 1958-08-02 1961-06-13 Philips Corp Ion pump

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3310227A (en) * 1965-04-12 1967-03-21 Milleron Norman Surge and backstreaming porous diaphragm filter for vacuum system
US3619020A (en) * 1968-11-21 1971-11-09 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Method of introducing halogens into electric lamps
US3601503A (en) * 1969-08-08 1971-08-24 Thomas W Snouse Thin membrane ionization pump apparatus
US3589791A (en) * 1969-09-02 1971-06-29 Zenith Radio Corp Processing of cathode-ray tubes
FR2548828A1 (fr) * 1983-07-05 1985-01-11 Gen Electric Pompe a piege d'hydrocarbures
US4515528A (en) * 1983-07-05 1985-05-07 General Electric Company Hydrocarbon getter pump
EP0201877A3 (de) * 1985-05-09 1987-11-19 Nokia Graetz Gesellschaft mit beschränkter Haftung Direkt geheizter Sorptions-Getterkörper
US4820226A (en) * 1987-10-14 1989-04-11 The United States Of America As Represented By The United States Department Of Energy Getter pump for hydrogen and hydrocarbon gases
US4789309A (en) * 1987-12-07 1988-12-06 Saes Getters Spa Reinforced insulated heater getter device

Also Published As

Publication number Publication date
GB984893A (en) 1965-03-03
NL278453A (2)
DE1464612B2 (de) 1972-11-23
CH430024A (de) 1967-02-15
DE1464612A1 (de) 1969-01-23

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