US3532917A - Getter ion pump employing high frequency electric field between two electrodes one of which is secondary emissive - Google Patents

Getter ion pump employing high frequency electric field between two electrodes one of which is secondary emissive Download PDF

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Publication number
US3532917A
US3532917A US718048A US3532917DA US3532917A US 3532917 A US3532917 A US 3532917A US 718048 A US718048 A US 718048A US 3532917D A US3532917D A US 3532917DA US 3532917 A US3532917 A US 3532917A
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United States
Prior art keywords
electrode
electrodes
electric field
grid
high frequency
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Expired - Lifetime
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US718048A
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English (en)
Inventor
Robert Evrard
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US Philips Corp
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US Philips Corp
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Publication date
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Publication of US3532917A publication Critical patent/US3532917A/en
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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J27/00—Ion beam tubes
    • H01J27/02—Ion sources; Ion guns
    • H01J27/16—Ion sources; Ion guns using high-frequency excitation, e.g. microwave excitation
    • 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

Definitions

  • said electrode is either sputtered or is coated with sputtered material. In both cases the secondary emission coefficient will be reduced. In this arrangement the electrons are therefore mainly formed by ionisation of the gase. The result of this is that the generation of electrons is considerably reduced when the gas pressure is reduced.
  • the pump comprises at least three electrodes, the outermost of which are plate-shaped and the intermediate electrode is gridshaped, the high-frequency electric field being present between the grid-like electrode and one of the plate-like electrodes which has a secondary-emission coefficient exceeding 1 for electrons having the energies which are obtained on an average in the high-frequency field, the amplitude and the frequency of the high-frequency electric field having such values in connection with the distance over which said field extends that the produced secondary electrons return to the secondary-emitting electrode after approximately a whole cycle, an electrostatic field being present between the grid and the other plate-like electrode so that the ions are accelerated to said electrode and produce sputtering there.
  • the drawback of deposition of sputtered material on the secondary-emitting electrode can be prevented substantially entirely by arranging between the grid-like electrode and the ion collecting electrode, an extra electrode which consists of plate-like parts parallel to the electrostatic field between the two surrounding electrodes, and making the voltage difference between said electrode and the grid-like electrode considerably smaller than between the grid-like electrode and the ion collecting electrode.
  • the extra electrode itself will sputter little and, on the other hand, receive the sputtered material of the ion collecting electrode in favour of the geometry of the arrangement.
  • the ion collecting electrode is preferably cooled to the temperature of liquid air or nitrogen.
  • FIG. 1 is a cross-sectional view at right angles to the axis of an ion pump for a device according to the invention.
  • FIG. 2 shows a cross-sectional view parallel to the axis.
  • FIG. 1 shows only one half and FIG. 2 only a short Y portion of the length.
  • reference numeral 3 denotes a sheath of stainless steel coated with a layer 2 of oxidized silver.
  • a grid-like electrode is denoted by 4.
  • An electrode 10 inside the grid 4 consists of radially arranged strips 11 of stainless steel.
  • the innermost electrode consists of a layer 8 of titanium on a stainless steel cylinder in which cooling liquid 14 is provided, in this case liquid nitrogen.
  • the diameter of electrode 2 is approximately 24 cm., that of electrode 4 is 18 cm., that of electrode 8 is 5 cm.
  • the proportions are approximately to scale so that the dimensions of the electrode 10 can be derived herefrom.
  • a voltage is set up having a frequency of approximately 40 mHz. from source 15 and an amplitude of approximately v. electrons emitted by the electrode 2 describe paths 6 in the figure in the period of one cycle so that multiplication occurs.
  • ignition of the discharge may occur by setting up the high frequency voltage and hence electron bombardment of the electrode 2. Formed ions are accelerated from the electrode 4 to the axis since the electrodes 10 and 8 have negative potentials from battery 16 with respect to the electrode 4 of 500 volts and 2000 volts, respectively. T itam'um which is sputtered from electrode 8 is received substantially entirely on the electrode 10.
  • the flow of electrons between 2 and 4 reduces until at the pressure of 10-4 torr stabilisation occurs since the formation of electrons in the gas then has substantially no influence and only the secondary emission is decisive.
  • a device comprising a getter ion pump in which the electrons, which effect ionization of the gases present, perform oscillatory movements under the influence of highfrequency electric fields and in which secondary electron multiplication occurs, said pump comprising at least three spaced concentric electrodes, the outermost of which are tubular and the intermediate electrode is grid-shaped, at least one of said tubular electrodes having a secondary emission coefficient exceeding l for electrons having the energies which are obtained on an average in a high-frequency field, means to produce between one of said tubular electrodes and said grid-like electrode an electric eld having an amplitude and frequency such that the secondary electrons produced return to the secondary-emitting electrode after substantially one whole cycle, and means to produce an electrostatic field between the grid and the other tubular electrode so that ions are accelerated to said other electrode and produce sputtering thereon.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Electron Tubes For Measurement (AREA)
  • Particle Accelerators (AREA)
US718048A 1967-04-07 1968-04-02 Getter ion pump employing high frequency electric field between two electrodes one of which is secondary emissive Expired - Lifetime US3532917A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR101911A FR1525369A (fr) 1967-04-07 1967-04-07 Pompe ionique et dispositif d'ionisation de gaz utilisable notamment dans cette pompe

Publications (1)

Publication Number Publication Date
US3532917A true US3532917A (en) 1970-10-06

Family

ID=8628392

Family Applications (2)

Application Number Title Priority Date Filing Date
US353291D Pending USB353291I5 (xx) 1967-04-07
US718048A Expired - Lifetime US3532917A (en) 1967-04-07 1968-04-02 Getter ion pump employing high frequency electric field between two electrodes one of which is secondary emissive

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US353291D Pending USB353291I5 (xx) 1967-04-07

Country Status (6)

Country Link
US (2) US3532917A (xx)
CH (2) CH473474A (xx)
DE (1) DE1764099A1 (xx)
FR (1) FR1525369A (xx)
GB (1) GB1213498A (xx)
NL (1) NL6804402A (xx)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994002957A1 (en) * 1992-07-17 1994-02-03 Saes Getters S.P.A. High capacity getter pump
DE102009042417A1 (de) * 2009-07-16 2011-01-27 Vacom Steuerungsbau Und Service Gmbh Orbitron-Ionengetterpumpe

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3236442A (en) * 1964-01-20 1966-02-22 Morris Associates Ionic vacuum pump
CA729786A (en) * 1966-03-08 N.V. Philips Gloeilampenfabrieken Ion pump
US3424936A (en) * 1965-02-10 1969-01-28 Nippon Electric Co Metal sleeve ionization gauge having controlled spacing between grid and shield electrodes for optimization of sensitivity

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA729786A (en) * 1966-03-08 N.V. Philips Gloeilampenfabrieken Ion pump
US3236442A (en) * 1964-01-20 1966-02-22 Morris Associates Ionic vacuum pump
US3424936A (en) * 1965-02-10 1969-01-28 Nippon Electric Co Metal sleeve ionization gauge having controlled spacing between grid and shield electrodes for optimization of sensitivity

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994002957A1 (en) * 1992-07-17 1994-02-03 Saes Getters S.P.A. High capacity getter pump
DE102009042417A1 (de) * 2009-07-16 2011-01-27 Vacom Steuerungsbau Und Service Gmbh Orbitron-Ionengetterpumpe
DE102009042417B4 (de) * 2009-07-16 2011-11-24 Vacom Steuerungsbau Und Service Gmbh Orbitron-Ionengetterpumpe

Also Published As

Publication number Publication date
GB1213498A (en) 1970-11-25
DE1764099A1 (de) 1971-04-15
NL6804402A (xx) 1968-10-08
USB353291I5 (xx)
CH473474A (de) 1969-05-31
CH469348A (de) 1969-02-28
FR1525369A (fr) 1968-05-17

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