US3614264A - Ionization getter pump - Google Patents

Ionization getter pump Download PDF

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Publication number
US3614264A
US3614264A US818322A US3614264DA US3614264A US 3614264 A US3614264 A US 3614264A US 818322 A US818322 A US 818322A US 3614264D A US3614264D A US 3614264DA US 3614264 A US3614264 A US 3614264A
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US
United States
Prior art keywords
cathode
anode
housing
getter
ionization
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Expired - Lifetime
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US818322A
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English (en)
Inventor
Kart-Georg Gunther
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Siemens AG
Siemens Corp
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Siemens Corp
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Publication date
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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
    • H01J41/18—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

  • a magnetic field is impressed upon the discharge space and has field lines extending from one collector electrode toward the other.
  • Each of the cathodes defines at least one aperture therein having an axis parallel to the magnetic field lines and through which ions from the discharge space and material sputtered from the cathodes pass to the collector electrodes.
  • My invention relates to evacuating pumps operating on the ionization getter principle according to which the gases to be removed from the pump chamber are permanently bonded to absorptive substances, called getters", while anelectric discharge is effective within that chamber.
  • Pumps of this type are applicable, for example, continuously maintaining a vacuum within the evacuated envelope of a vacuum switch, an electronic transmitter tube, a corpuscle accelerator and the like devices.
  • ionization getter pump whose pumping action is predicated upon continuous formation of fresh absorption layers by cathode sputtering and simultaneous ionization and excitation of the gas molecules, and in which-seen from the viewpoints gained by the present invention and more fully explained below-two different area groups are used for sputtering or spattering the getter substance on the one hand and for receiving the resulting absorption layers on the other hand.
  • the area group for receiving the absorption layers of getter substance enclose or border the electric discharge space at least on those sides that extend at a right angle to the electric and magnetic field lines that control the electric discharge in the space subjected to pumping action.
  • an ionization getter pump according to the invention is to a large extent free of maintenance requirements, possesses a long useful life, and exhibits a very high evacuating action relative to any given size of the pump.
  • the high evacuating action of the novel pump can be explained as follows.
  • the ionized or excited gas molecules impinge upon surfaces of substances that are freshly formed and are particularly absorptive because of their chemical composition.
  • the absorptive action depends upon the rate of formation of these layers on the one hand, and upon the impinging density of the gas ions and excited gas molecules on the other hand.
  • the already absorbed gas molecules may again be knocked out by impinging new particles of high velocity, and may then return into the gas space.
  • FIG. I shows in longitudinal section a first embodiment
  • FIG. 2 illustrates, also in section, a somewhat modified embodiment
  • FIG. 3 illustrates a third embodiment likewise in longitudinal section
  • FIG. 4 illustrates a longitudinal section of another embodiment of the invention.
  • the pump housing is denoted by I and the appertaining suction conduit by 2.
  • Mounted in the pump housing and insulated therefrom is the anode 3 of the electric discharge gap.
  • the anode has the shape of a helix and consists of a metal having a high-melting point, for example tungsten or molybdenum.
  • the anode 3 is connected through a lead 4 to a positive potential U
  • An electrically insulating seal 5 serves for passing the lead 4 through the wall of the pump housing I.
  • the pump housing may be grounded. as shown in FIG. I. it consists of nonmagnetic metal such as copper or stainless steel.
  • Two metallic plates 6 and 7 are mounted in coaxial relation to the helical anode 3.
  • the plates may be attached to the wall of pump housing 1, for example by soldering or welding. In this manner or by any other suitable :means the plates 6 and 7 are both in electrically conducting connection with the pump housing I and thus are kept at zero (ground) potential. If desired, however, the two plates may be insulated from the housing 1 and can then be connected by a separate lead to any desired potential, for example different from zero. In any event, the plate potential must considerably differ from the potential U, of the anode 3, because the plates 6 and 7 constitute the main cathode of the discharge gap.
  • the cathode plates 6 and 7 consist of getter substance, for example of pure, vacuum-degassed titanium or zirconium. Since the cathode plates have no extraneous source of heat they are generally termed cold cathodes.
  • the surfaces for receiving the absorptive layers are arranged about the plates 6 and 7.
  • these surfaces are formed by two ringshaped discs 8 and 9 preferably of a high-melting material such as molybdenum, tungsten or stainless steel.
  • the discs 8 and 9 are in electrically conducting connection with each other and are connected by a lead 10 to a potential U
  • An electrically insulating seal 11 serves to pass the lead 10 through the wall of the pump housing 1.
  • the magnetic field required for the operation of the pump is preferably produced by means of a permanent magnet as shown at 12.
  • the pump housing 1 is mounted, in the position apparent from the drawing, between the pole shoes N, S of the permanent magnet R2.
  • the magnet serves, as known, for extending the effective travel path of the electrons thus expanding the working range of the pump toward small pressures.
  • a potential difference U is applied by leads 4 and I0 between the anode 3 and the pump housing 1 with the plates 6 and 7; and a potential difference U of about 400 to 800 volts is applied between the anode 3 and the mutually-intercom nected annular discs 8, 9.
  • the performance is as follows. Under the effect of the high voltage U between the plates 6, 7 and the anode 3, some of the getter substance of which the plates are made is atomized by cathode spattering.
  • the spattered particles continuously precipitate in form of absorptive coatings mainly upon the plates 8 and 9 which constitute the second surface group in the sense of the foregoing explanations.
  • the particles coming from plate 6 reach particularly the top side of plate 9, relative to the position shown in FIG. ll, whereas the particles spattered from plate 7 mainly reach the bottom side of plate 8.
  • Those particles that pass from plate 6 onto plate 7, and from plate 7 to plate 6, contribute little or nothing to the suction effect because they are again subjected "to spattering.
  • the spattered particles that precipitate upon the anode 3 do contribute to the pumping action, but their share is slight since the anode surface is relatively small.
  • the absorption coatings thus being formed continuously are impinged upon the ionized and excited gas molecules due to the effect of the voltage U, These two molecule groups are permanently captured by the absorption coatings as no spattering or sputtering takes place at these cations. This is because the impinging velocity is too low for appreciable spattering due to the relatively small voltage U, for example 400 to 800 volts, obtaining between the anode 3 and the annular discs 8, 9.
  • the second surface group upon which the absorption coatings are formed can readily be enlarged by joining, according to FIG. 2, the annular discs 8 and 9 with a metallic cylinder 13, the embodiment of FIG. 2 being otherwise in accordance with that of FIG. 1.
  • the annular discs 8 and 9 form together with the cylinder 13 a unit of the same potential.
  • the entire inner surface of this unit constitutes the second surface group for receiving the absorption layers, thus greatly increasing the area of the second surface group.
  • the unit formed of parts 8, 9 and 13 is mounted in the pump housing 1 in insulated relation thereto and is connected to the potential U, by the lead 10.
  • the anode 3 is mounted within the unit 8, 9, 13 and is insulated therefrom.
  • the anode 21 mounted in the pump housing 1 is ring-shaped. If the anode is to be connected to the same potential as the housing 1, namely preferably to ground potential, then the anode can be directly attached to the housing 1, in which case the seal shown at 28 need not be electrically insulative.
  • FIG. 4 otherwise corresponding to FIG. 3.
  • the plates 22 and 23 consist of getter substance.
  • the anode 21 may consist of highmelting metal, for example tungsten or molybdenum.
  • the pump housing is located between the pole shoes N and S of a permanent magnet 26 serving the same purposes as the magnet 1 in the embodiment of FIG. 1.
  • the potential U is to be so chosen that a potential difference of about 2,000 to 4,000 volt obtains between the anode 21 and the two screen plates 22, 23 jointly forming the cathode of the discharge gap.
  • the performance of the pump according to FIG. 3 is as follows. Getter substance is spattered from the plates 22 and 23 under the effect of the high voltage U,. The getter substance precipitates upon the entire inner wall of the housing 1, but collects predominantly at the surface areas located behind the openings of the screen plates 22 and 23. The ionized and excited gas molecules impinge upon the continuously precipitating absorption coatings. Since in the operation of the embodiment of FIG. 3 described above these coatings have the same potential as the anode, the ions arrive with zero velocity so that no spatter-ing of the absorption surfaces can occur. However, the embodiment of FIG.
  • the 3 may be modified by insulating the anode 21 from the housing 1 and maintaining a potential difference U, of approximately 400 to 800 volts between the anode and the housing with the aid of the lead 27 passing through an insulating seal 28 in the housing wall.
  • U potential difference
  • the amount of ion capture by the absorptive coating is increased because these coatings are also impinged upon these molecules that are ionized only at some distance from the anode.
  • the arriving velocity is small, there cannot occur any appreciable spattering of the ion layers being formed.
  • An ionization getter pump for pumping action by continuous formation of cathode-sputtered getter layers and simultaneous ionization of the gas molecules being evacuated, comprising a pump housing having an intake opening for gas to be pumped, an anode and a first group of surface members mounted in said housing, said first group of members being interconnected to form a cathode and being located on opposite sides respectively of said anode to define together therewith a discharge axis directed from anode to cathode, said members having respective surfaces formed by getter substance, magnetic field means having between said anode and cathode a field parallel to said discharge axis, electric connecting means extending out of said housing for applying cathode-sputtering voltage between said anode and cathode, a second group of surface members surrounding said axis between said anode and said first-group members respectively, said second-group members having respective surface areas extending transverse to the magnetic and electric field lines for receiving getter substance from said first-group members, and mutually
  • An ionization getter pump for pumping action by continuous formation of cathode-sputtered getter layers and simultaneous ionization of the gas molecules being evacuated, comprising a pump housing having an intake opening for gas to be pumped, a generally ring-shaped anode and two cathode plates of getter substance mounted in said housing in coaxial relation to said anode and on opposite sides respectively thereof, so as to jointly define a discharge axis directed from cathode to anode, magnetic field means having between said anode and cathode a field parallel to said discharge axis, a surface structure having two getter-receiving areas around said axis between said anode and said two cathode plates respectively, said areas extending transverse to said axis and to the magnetic and electric field lines, and mutually insulated electric conductor means extending from said anode and said cathode plates out of said housing for applying a cathode-sputtering potential between the cathode and anode.
  • said surface structure comprising two ring-shaped discs having respective ring surfaces extending about said discharge axis and at a right angle thereto.
  • An ionization getter pump wherein ionization of gas takes place in a cold cathode discharge, and whose pumping action is based upon continuous cathode sputtering and simultaneous ionization and excitation of the gas molecules being pumped, comprising a pump housing having an intake opening for gas to be pumped, an anode and a cathode insulated from each other in the housing, the cathode comprising getter substance, the space between the said anode and cathode defining a discharge space, magnetic field means for impressing a magnetic field upon the discharge space, means providing a surface inside said housing upon which getter substance removed from the said cathode is received, said means comprising an electroconductive vessel having a wall, the anode being within the vessel, the vessel having apertures in its wall, the cathode comprising plates of getter substance mounted upon the inner walls of the housing opposite said apertures, the housing being electroconductive and being grounded, said vessel bordering the discharge space at least at those sides that extend perpen
  • An ionization getter pump wherein ionization of gas takes place in a cold cathode discharge, and whose pumping action is based upon continuous cathode sputtering and simultaneous ionization and excitation of the gas molecules being pumped, comprising a pump housing having an intake opening for gas to be pumped, an anode and a cathode insulated from each other in the housing, the cathode comprising getter substance, the space between the said anode and cathode defining a discharge space, magnetic field means for impressing a magnetic field upon the discharge space, means providing surface area inside said housing upon which getter substance removed from the said cathode is received, said means comprising muand magnetic field lines, the magnetic field lines being longitudinal of the electric field lines, electric connections for passing cathode-sputtering voltage between said anode and said cathode and for passing a voltage between said anode and said surface which is less than that between the anode and cathode.

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  • Electron Tubes For Measurement (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US818322A 1958-06-06 1959-06-05 Ionization getter pump Expired - Lifetime US3614264A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES0058505 1958-06-06

Publications (1)

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US3614264A true US3614264A (en) 1971-10-19

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US818322A Expired - Lifetime US3614264A (en) 1958-06-06 1959-06-05 Ionization getter pump

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US (1) US3614264A (enrdf_load_stackoverflow)
CH (1) CH366625A (enrdf_load_stackoverflow)
DE (1) DE1075272B (enrdf_load_stackoverflow)
FR (1) FR1226838A (enrdf_load_stackoverflow)
GB (1) GB915748A (enrdf_load_stackoverflow)
NL (2) NL132318C (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746474A (en) * 1971-04-02 1973-07-17 W Lloyd Ionic vacuum pump
WO2003058069A3 (en) * 2002-01-14 2004-01-29 Varco Ltd Arc vacuum pump
US9053917B2 (en) 2013-03-29 2015-06-09 Agilent Technologies, Inc. Vacuum fired and brazed ion pump element

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3391303A (en) * 1965-01-25 1968-07-02 Lewis D. Hall Electronic vacuum pump including a sputter electrode

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2197079A (en) * 1936-05-29 1940-04-16 Philips Nv Method and device for measuring pressures
GB797232A (en) * 1955-07-11 1958-06-25 Manfred Von Ardenne Improvements in or relating to high vacuum ion pumps

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2197079A (en) * 1936-05-29 1940-04-16 Philips Nv Method and device for measuring pressures
GB797232A (en) * 1955-07-11 1958-06-25 Manfred Von Ardenne Improvements in or relating to high vacuum ion pumps

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746474A (en) * 1971-04-02 1973-07-17 W Lloyd Ionic vacuum pump
WO2003058069A3 (en) * 2002-01-14 2004-01-29 Varco Ltd Arc vacuum pump
US9053917B2 (en) 2013-03-29 2015-06-09 Agilent Technologies, Inc. Vacuum fired and brazed ion pump element

Also Published As

Publication number Publication date
CH366625A (de) 1963-01-15
NL132318C (enrdf_load_stackoverflow)
NL239135A (enrdf_load_stackoverflow)
FR1226838A (fr) 1960-08-16
GB915748A (en) 1963-01-16
DE1075272B (de) 1960-02-11

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