US3118077A - Ionic vacuum pumps - Google Patents

Ionic vacuum pumps Download PDF

Info

Publication number
US3118077A
US3118077A US68183A US6818360A US3118077A US 3118077 A US3118077 A US 3118077A US 68183 A US68183 A US 68183A US 6818360 A US6818360 A US 6818360A US 3118077 A US3118077 A US 3118077A
Authority
US
United States
Prior art keywords
electrode
electrons
outer electrode
wall
electron
Prior art date
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
US68183A
Other languages
English (en)
Inventor
Gabor Dennis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Research Development Corp UK
Original Assignee
National Research Development Corp UK
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by National Research Development Corp UK filed Critical National Research Development Corp UK
Application granted granted Critical
Publication of US3118077A publication Critical patent/US3118077A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

Definitions

  • Ionic vacuum pumps have been known for a long time in which electrons are made to oscillate between ,two electrodes at cathode potential which the electrons cannot reach, being prevented by a strong magnetic fie1d from escaping sideways.
  • Pumps of this type have: been successfully embodied in sealed-off vacuum devices. i 'lheir disadvantage is the large weight of the permanent magnets, and also their strong magnetic stray field which prevents their application in electron-optical devices sensitive to magnetic fields, such as cathode ray tubes or electronic cameras.
  • This invention relates to an ionic vacuum pump in which the movements of the ionising electrons are governed by purely electrostatic fields in such a way that, at least for the most part, they do not land on the appropriate electrode unless they have collided with a gas molecule.
  • an ion-getter pump comprises a box or outer electrode presenting a surface of gettering material and having a rotationally symmetrical wall, said electrode being adapted to be maintained at a I negative potential to serve as an ion collector, an axial electrode lying on the axis of symmetry of said wall and adapted to be maintained at a positive potential to serve as an anode, and means comprising an electron gun for producing ionising electrons, said gun being positioned to direct an electron stream tangentially into the device, the arrangement being such that in, operation the ionising electrons are caused to travel in extended paths within the space encircled by said rotationally symmetric wall without the aid of a magnetic field.
  • the space encircled by said rotationally symmetric wall is, of course, in communication with the space to be evacuated, the outer electrode operating as the cathode and the axial electrode as the anode.
  • tangentially is meant in a direction tangential to any rotationally symmetric surface centered on the axis of symmetry of the outer electrode and removed from the axis, that is to say between the axial electrode and the wall.
  • the device is operated with a potential difference between the outer and the axial electrodes high enough for ionization and producing a generally radial electric field between the electrodes.
  • the potential of the outer electrode is equal to or lower than the potential of the cathode in the electron gun, so that electrons fired from the gun cannot land on any point of the outer electrode. They are also prevented from landing immediately on the positive axial electrode by their momentum, which carries them past the axial electrode and makes them orbit around it, under the influence of the electric field, until they strike a gas atom or molecule, the electrons being ultimately collected at the axial electrode.
  • Positive ions produced by the electron stream will move to the outer electrode which is made of or coated with gettering material which permanently absorbs or adsorbs at least a considenable proportion of the atoms formed by the neutralization of the ions.
  • the invention has particular advantages for use in association with electronic devices such as cathode ray tubes and the like. in which voltages sufficiently high for the operation of the device are available, so that no separate supply is required.
  • the invention is of special value in cathode ray devices such as projection tubes or colour tubes, in which gas development is strong owing to highpower o eration, or to tubes containing complicated electrode structures or large metal walls which cannot be perfectly outgassed.
  • the invention makes it possible to embody in such devices insulating materials such as silicones for example, which could not otherwise be employed in sealed-off high vacuum devices, because of their tendency to release gas continuously.
  • FIG. 1 is a plan section of an ionic vacuum pumping device according to the invention.
  • FIG. 2 is an axial section thereof.
  • the outer or negative electrode is in the form of a box having a cylindrical wall 1, and end-plates 2 and 3, the latter being made of metal gauze to give access to the gas in the vacuum envelope (not shown) which surrounds the structure.
  • the axial or positive electrode or anode is a wire or rod 4, supported on but insulated from the end-plates by insulating bushes 5.
  • An electron gun 6 comprising a hot cathode 7, a grid 8 and anapertured anode 9 is mounted in the wall 1 withits axis directed in a tangential direction at radius R from the axis of the wall 1.
  • the grid 8 is preferably of cathode potential and the anode 9 is at a potential high enough to draw a sufiicient electron current from the cathode, but preferably well below that of the anode 4.
  • This choice of the potential arises from economy of power, and also from the requirement that the anode 9 shall not'much dis- :turb the rotational symmetry of the electric field inside the box.
  • FIG. 1 A typical electron trajectory is indicated in FIG. 1 in dotted lines. It will be seen from this figure that the electrons (due to their momentum and the generally radial electric field between the outer and the axial electrodes) orbit around the axis in approximately cycloidal trajectories, and that the radius R of the imaginary cylindrical surface to which the axis of electron gun 6 is tangent is several times larger than the radius of the wire or rod anode 4.
  • V be the potential of the apertured anode 9; at the instant of leaving the aperture the electrons have an angular momentum around the axis proportional to RV which they will preserve in their motion.
  • r be the radius of the anode 4, and V its potential. If
  • the device may, of course, differ from that shown in the above described example in a number of ways.
  • the cylir-.drical wall of the outer electrode is deep enough in the axial direction the end walls need not be provided since there will be little likelihood of electrons.
  • the axial electrode or anode may be supported independently of the outer electrode.
  • the axial extent of the outer electrode and the provision or not of the end plates or flanges will depend in some measure upon the care with which the electron gun 7, 3', 9 is focussed and the divergence of electron paths from planes perpendicular to the axis of the outer electrode avoided.
  • the walls of the outer electrode are preferably made of solid gettering metals, such as zirconium or titanium, or they are coated by evaporation, with getters such as barium.
  • barium has a gettering effect also for neutral gases, it is known that barium getters soon go inert, and become practically inactive for gas pressures below a certain minimum, which fall far short of the re quirements in cathode ray devices and the like. They become, however, active in the presence of ions. Experimentally it was found that even after long operating times the sticking factor in the device according to the invention well exceeded that is to say more than a tenth of the ions which struck the wall were permanently eliminated.
  • the pumping power of the device according to the invention is about 2 litres/sec. at l() mm. pressure per milliampere of ion current if every ion is permanently removed, and 200 cmfi/ sec. if the sticking ratio is 10%.
  • 10* mm. Hg which is the minimum vacuum at which cathode ray devices can operate normally, these figures increase to 200 litres/sec. and 20 litres/sec. respectively.
  • 200-litres/sec. is about as much as a gauze-covered endplate of 6 cm. diameter can transmit; hence at even lower pressures the current can be reduced to about 100 microamperes, without loss of pump efficiency. Beam currents of this order can be taken from the high tension supply of television tubes and the like without having to increase the power packs beyond their normal size.
  • An ionic vacuum pumping device comprising an outer electrode having a surface of gettering material and a rotationally symmetric wall defining a space adapted to contain gas molecules, said electrode being adapted to be maintained at a negative potential to serve as anion collector, a second electrode within said space adapted to be maintained at a positive potential to serve as an anode, and means for producing ionizing electrons, said means comprising an electron gun positioned to direct an electron stream tangentially into said outer electrode, whereby the electrons are caused to travel in exte ed paths within said space without the aid of a magnetic eld.
  • An ionic vacuum pumping device comprising an outer electrode having a rotationally symmetric wall, an axially extending electrode lying on the axis of symmetry of said wall, and an electron gun positioned to direct an electron stream into said outer electrode in a direction tangential to an imaginary rotationally symmetric surface centred on said axis of symmetry and spaced from said axially extending electrode, said outer electrode having two end walls, substantially perpendicular to said axis of symmetry, one of said end walls being foraminous.
  • An ionic vacuum pumping device in which said outer electrode includes a foraminous wall which affords communication with a space to he evacuated.
  • An ionic vacuum pumping device in which said electron gun penetrates said rotationally symmetric wall and is positioned to direct an electron stream tangentially to an imaginary cylindrical surface centred on the axis of symmetry of said wall and nearer said said wall than to said axis.
  • An ionic pumping device comprising an outer electrode having a rotationally symmetric wall, an axially extending rod electrode lying on the axis of symmetry of said wall, and an electron gun penetrating said rotationally symmetric wall and positioned to direct an electron stream tangentially to an imaginary cylindrical surface centred on the axis of symmetry of said wall and nearer to said wall than to said axis the radius of said imaginary cylindrical surface being several times larger than the radius of said axially extending electrode.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US68183A 1959-11-12 1960-11-09 Ionic vacuum pumps Expired - Lifetime US3118077A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB38372/59A GB887251A (en) 1959-11-12 1959-11-12 Improvements in or relating to ionic vacuum pump devices

Publications (1)

Publication Number Publication Date
US3118077A true US3118077A (en) 1964-01-14

Family

ID=10403041

Family Applications (1)

Application Number Title Priority Date Filing Date
US68183A Expired - Lifetime US3118077A (en) 1959-11-12 1960-11-09 Ionic vacuum pumps

Country Status (5)

Country Link
US (1) US3118077A (US20020051482A1-20020502-M00057.png)
DE (1) DE1177278B (US20020051482A1-20020502-M00057.png)
FR (1) FR1273299A (US20020051482A1-20020502-M00057.png)
GB (1) GB887251A (US20020051482A1-20020502-M00057.png)
NL (2) NL131435C (US20020051482A1-20020502-M00057.png)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3244990A (en) * 1963-02-26 1966-04-05 Wisconsin Alumni Res Found Electron vacuum tube employing orbiting electrons
US3343781A (en) * 1965-04-28 1967-09-26 Gen Electric Ionic pump
US5697827A (en) * 1996-01-11 1997-12-16 Rabinowitz; Mario Emissive flat panel display with improved regenerative cathode
US11569077B2 (en) 2017-07-11 2023-01-31 Sri International Compact electrostatic ion pump

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3339106A (en) * 1965-05-28 1967-08-29 Canadian Patents Dev Ionization vacuum pump of the orbitron type having a porous annular grid electrode

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528541A (en) * 1945-11-01 1950-11-07 Standard Telephones Cables Ltd Electron discharge device
US2925214A (en) * 1953-04-24 1960-02-16 Gen Electric Ionic vacuum pump

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1068561B (US20020051482A1-20020502-M00057.png) * 1959-11-05
DE1046249B (de) * 1956-04-05 1958-12-11 Dr Gerhard Fricke Verfahren und Vorrichtung zur Erzeugung eines hohen Vakuums

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528541A (en) * 1945-11-01 1950-11-07 Standard Telephones Cables Ltd Electron discharge device
US2925214A (en) * 1953-04-24 1960-02-16 Gen Electric Ionic vacuum pump

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3244990A (en) * 1963-02-26 1966-04-05 Wisconsin Alumni Res Found Electron vacuum tube employing orbiting electrons
US3244969A (en) * 1963-02-26 1966-04-05 Wisconsin Alumni Res Found Electron orbiting tubes for ion measurement and gettering pumps
US3343781A (en) * 1965-04-28 1967-09-26 Gen Electric Ionic pump
US5697827A (en) * 1996-01-11 1997-12-16 Rabinowitz; Mario Emissive flat panel display with improved regenerative cathode
US5764004A (en) * 1996-01-11 1998-06-09 Rabinowitz; Mario Emissive flat panel display with improved regenerative cathode
US5967873A (en) * 1996-01-11 1999-10-19 Rabinowitz; Mario Emissive flat panel display with improved regenerative cathode
US11569077B2 (en) 2017-07-11 2023-01-31 Sri International Compact electrostatic ion pump

Also Published As

Publication number Publication date
NL131435C (US20020051482A1-20020502-M00057.png)
FR1273299A (fr) 1961-10-06
DE1177278B (de) 1964-09-03
GB887251A (en) 1962-01-17
NL257827A (US20020051482A1-20020502-M00057.png)

Similar Documents

Publication Publication Date Title
US2755014A (en) Ionic vacuum pump device
US3460745A (en) Magnetically confined electrical discharge getter ion vacuum pump having a cathode projection extending into the anode cell
US2856532A (en) Pulsed ion source
US3118077A (en) Ionic vacuum pumps
US3274436A (en) Ion source with selective hot or cold cathode
US2888189A (en) Vacuum pump
US3339106A (en) Ionization vacuum pump of the orbitron type having a porous annular grid electrode
US3718836A (en) Multipactor ion generator
GB684710A (en) Improvements relating to high vacuum pumps
US3161802A (en) Sputtering cathode type glow discharge device vacuum pump
US3614440A (en) Gas ionizer devoid of coaxial electrodes
US2925504A (en) High-vacuum pumps for high-voltage acceleration tubes
US3535055A (en) Cold-cathode discharge ion pump
USRE26138E (en) Ionic vacuum pumps
GB1336126A (en) Ion gauges
US2937295A (en) Ionization gauge for the measurement of low pressures
US2848620A (en) Ion producing mechanism
US3240421A (en) Ion transport pump
US3465189A (en) Ionization vacuum gauge with x-ray shielding and ion reflecting means
US3341727A (en) Ionization gauge having a photocurrent suppressor electrode
US3176906A (en) Ion pump
US3343781A (en) Ionic pump
US3073987A (en) Electron discharge device with getter
US3510712A (en) Electron orbiting getter vacuum pump employing a time varying magnetic field
US3176907A (en) Ion pump