EP0200641A1 - Ionenpumpe mit zur Gasmenge proportionalem Strom - Google Patents

Ionenpumpe mit zur Gasmenge proportionalem Strom Download PDF

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Publication number
EP0200641A1
EP0200641A1 EP86400885A EP86400885A EP0200641A1 EP 0200641 A1 EP0200641 A1 EP 0200641A1 EP 86400885 A EP86400885 A EP 86400885A EP 86400885 A EP86400885 A EP 86400885A EP 0200641 A1 EP0200641 A1 EP 0200641A1
Authority
EP
European Patent Office
Prior art keywords
chamber
electrode
networks
pump according
ion pump
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.)
Granted
Application number
EP86400885A
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English (en)
French (fr)
Other versions
EP0200641B1 (de
Inventor
Patrice Le Baud
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.)
FRAMATOME TE COURBEVOIE, FRANKRIJK.
Original Assignee
Novatome SA
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 Novatome SA filed Critical Novatome SA
Publication of EP0200641A1 publication Critical patent/EP0200641A1/de
Application granted granted Critical
Publication of EP0200641B1 publication Critical patent/EP0200641B1/de
Expired legal-status Critical Current

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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
    • H01J41/18—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

  • the invention relates to an ion pump with a current proportional to the flow rate such as used for example to create a high vacuum or ultra-vacuum conditions in an enclosure or to determine quantities or flow rates of substances present in small quantity in an enclosure.
  • Such ion pumps include a chamber whose internal wall is coated at least partially with a chemically active metallic trapping material or “getter” and an electrode placed inside the chamber and electrically insulated from the walls of this chamber.
  • An electrical supply to the electrode makes it possible to give it an anodic polarity with respect to the walls of the chamber which are earthed.
  • This electrode has a hollow structure delimiting a set of cells inside the chamber which are as many pumping cells. When the electrode is supplied with electric current, it thus constitutes a Faraday cage, inside the pump chamber.
  • An active magnetic circuit generally comprising permanent magnets is placed around the chamber so as to create a magnetic field in the interior volume of this chamber.
  • the electrode with anodic polarity is generally constituted by the assembly with parallel axes of small cylindrical tubes joined in stainless steel, each tube constituting an elementary pumping cell.
  • This anode is fixed inside the chamber and supplied with electric current by means of elements which are electrically insulated from the walls of the chamber.
  • the flow-current characteristic of this pump evolves to become non-linear. This change in the characteristic of the pump is a major drawback in the case where it is used for flow measurement or for dosing of substance in an enclosure.
  • wearter material which can be for example titanium
  • the getter pieces placed on the walls of the chamber generally being constituted by flat plates having tendency to widen.
  • a deposit of getter metal is observed inside the cells, on the anode supports and on the insulating bushing of the wall through which the electrical conductor supplying the connected anode passes, outside the pumping chamber, to a high voltage supply.
  • the object of the invention is therefore to propose an ion pump with a current proportional to the flow rate comprising a chamber whose internal wall is coated at least partially with a chemically active metallic trapping material such as titanium, an electrode connected to an electrical conductor. ensuring its anodic potential and its supply electric and its attachment in the chamber, placed inside the chamber and electrically insulated from the walls of this chamber, a power supply means of the electrode, and a magnetic circuit creating a magnetic field in the chamber , the electrode delimiting at least one cell inside the chamber and thus constituting a Faraday cage, this ion pump keeping a linear flow-current characteristic during long-term use, having an extended service life without degradation of its conditions of use and having a simple structure allowing an inexpensive construction.
  • a chemically active metallic trapping material such as titanium
  • the electrode is constituted by a metal wire structure comprising two parallel planar networks linked together by wires substantially perpendicular to the planes of the networks.
  • Fig. 1 we see the chamber 1 of an ion pump, the walls of which are coated internally with titanium plates 2 constituting the getter material of the pump. All the interior walls of chamber 1 are coated with smooth titanium plates, without surface layer and chemically active.
  • the surface of the chamber can also be coated with several types of getter materials. It may be advantageous to provide different materials for coating the perpendicular faces of the chamber, that is to say, for example, a first getter material for the horizontal faces and a second material for the vertical faces, in the case of chamber 1 shown in FIG. 1.
  • An electrode 3 is placed inside the chamber, in a central position, without contact with the walls of this chamber coated with titanium.
  • the electrode 3 is connected to an electrical conductor 5 allowing the supply of the electrode 3 by a high voltage electric current source 6, of the order of 4 kV.
  • the conductor 5 passes through the wall 1a of the enclosure 1 thanks to an insulating bushing part 7 fixed in this wall. The attachment of the electrode 3 inside the chamber 1 is ensured only by the conductor 5.
  • the walls of the enclosure 1 are earthed by means of a conductor 9.
  • the current source 6 imposes a positive polarity on the electrode 3 which thus constitutes an anode, relative to the walls of the enclosure.
  • An active magnetic circuit 10 comprising permanent magnets is placed around the chamber 1 so that its pole pieces 10a and 10b concentrate the magnetic field in the central part of the chamber.
  • the pole pieces 10a and 10b have, in the configuration of the electrode 3 according to FIG. 5, a shape such that the air gap 8 is smaller at the central part of the chamber 1.
  • the electrical conductor 5 is seen passing through the wall 1a of the chamber 1 at the level of the crossing piece 7 which at the same time seals the wall 1a.
  • the wall 1a has a protruding part 11 on its internal surface, of annular shape and coaxial with the conductor 5.
  • the conductor 5 carries a hollow washer 12 coaxial with the conductor and the protruding part 11 of the wall 1a so that the flange cylindrical exterior of the washer 12 surrounds the projecting part 11 and covers it over part of its length in the axial direction.
  • a baffle is thus produced separating the insulating part 7 from the interior walls 2 of titanium from the chamber 1.
  • the baffle is such that there is no point on the interior wall of the chamber 1 coated with titanium which can be joined to a point of the insulation by a straight path avoiding the two barriers of the chicane.
  • the residual pressure can be between 10 - and 10 - 1 Torr, the titanium of the walls can be caused to vaporize, even at a moderate temperature.
  • the titanium vapor produced is deposited on all parts of the pump, inside the enclosure, in direct view with respect to the walls.
  • the baffle 11, 12 thus makes it possible to avoid metallization of the insulating part 7 which is not in direct view of the walls 2.
  • the insulation of the conductor 5 therefore remains satisfactory during the operation of the pump, even under ultrahigh vacuum.
  • FIG. 3 an embodiment of the anode 3 of a pump according to the invention is seen.
  • This anode is produced in the form of a structure made of stainless steel wires with a diameter of 5 ⁇ 10 m.
  • the structure comprises two planar networks 13 and 14 each consisting of a set of circular turns 15 of metal wire each connected by solder points 17 to the neighboring turns of the network which thus comprises circular meshes and meshes in the shape of a curvilinear triangle.
  • the two planar arrays 13 and 14 are connected by a set of rectilinear wires 16 which are mutually parallel and perpendicular to the planes of the arrays 13 and 14.
  • the assembly of the electrode thus constitutes a cage-shaped structure comprising juxtaposed cells.
  • One of the vertical wires 16 is connected by welding to the electrical conductor 5 which allows the supply and the anodic potential of the electrode 3 which thus constitutes, inside the pump chamber, a Faraday cage .
  • the electrode 3 in the form of a metal wire structure of small diameter is very light so that it can be easily suspended inside the pump chamber via the electrical conductor 5 only . It is interesting that the axis of the electrode 3 is horizontal so that the conductor 5 is vertical, which gives this conductor which is also the support of the electrode 3, better resistance (work in traction rather than in bending). In addition, the electrode offers a small surface exposed to titanium vapors, which reduces the metallization of this electrode made of metal wire.
  • the power flow-current characteristic of this pump is perfectly linear throughout the range of use of the pump and during its entire service life.
  • the currents measured for a supply voltage of a few kV range from a few microamps to a few hundred milliamps.
  • the pump according to the invention is therefore perfectly suitable when it is desired to measure flow rates or quantities of gas entering a vacuum enclosure.
  • Fig. 4 an alternative embodiment of the electrode 3 is seen, the cells 15 ′ of the two planar networks 13 ′ and 14 ′ all having a hexagonal shape; each of the cells 15 ′ has wire sides which are common from one cell to the neighboring cell, as in the production of a grid.
  • rectilinear wires 16 ' make it possible to join the two planar networks 13' and 14 'and are perpendicular to these two planar networks.
  • a second embodiment of an electrode 3 according to the invention is seen, the flat networks 23 and 24 of this electrode comprising meshes open inwards, in the radial direction.
  • the flat networks 23 and 24 are constituted by a peripheral contour of circular shape 26 of metal wire on which are welded successive rectilinear wires of radial direction 27a and 27b, the wires 27a being of a length greater than the wires 27b .
  • the two networks 23 and 24 are interconnected by rectilinear wires 28 perpendicular to the planes of the networks 23 and 24.
  • the wires 28 are connected by welding to the networks 23 and 24, at the junction point of the wires 27a and 27b with the circular wire periphery as 26 as well as at the interior ends of the radial wires 27a and 27b.
  • the cage-shaped structure of the electrode 3 made of metal wire thus comprises two circular contours made of metal wire joined via two sides of rectangular contours 30 perpendicular to the planes of the circular contours. It is preferable to round off the angles of the rectangular contours 30 to avoid the peak effects of the electric current.
  • the successive rectangular contours are of large and small widths corresponding to the length of the successive radial wires 27a, 27b.
  • wires 29 perpendicular to the planes of the networks 23 and 24 can be welded to the wires 27a of great length, approximately at their middle part.
  • the electrode made of metal wire has a great lightness and a small surface offered to metallization.
  • the supply conductor 5 is generally fixed to the middle part of one of the connecting wires between the two plane networks of the electrode.
  • the electrode wires can be made with a getter metal.
  • the main advantages of the pump according to the invention are a very good proportionality between the supply current and the flow rate, a great lightness of the electrode which allows an extremely simple assembly of this electrode without supporting part, a reduced metallization of the electrode and the insulating part of the power supply and a very good yield obtained thanks to the increase in the surface covered by the metal getter and the improvement of the magnetic field.
  • the invention is not limited to the embodiments which have been described. This is how we can imagine other forms of planar networks with closed cells of square or triangular shape for example or open cells with radial or other arrangement.
  • the maximum dimension of each of these cells can be variable and for example between 5 mm and 100 mm.
  • the length of the rectilinear son of junction between the flat networks can be variable and between 5 mm and 50 mm.
  • baffle of different shape from that which has been described, to protect the insulating part from penetration of the electrical conductor, against metallization by the metal getter.
  • the walls of the chamber parallel to the gratings of the electrode can be coated with a getter material different from the getter material for coating the walls of the chamber perpendicular to the flat gratings of this electrode. , in order to increase the efficiency of the pump.
  • the invention applies to all ion pumps for the creation of a high vacuum or of the ul travides in an enclosure or for the measurement of flow rate or quantity of residual gaseous substance in an enclosure.

Landscapes

  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Electron Tubes For Measurement (AREA)
EP19860400885 1985-04-23 1986-04-23 Ionenpumpe mit zur Gasmenge proportionalem Strom Expired EP0200641B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8506160A FR2580866B1 (fr) 1985-04-23 1985-04-23 Pompe ionique a courant proportionnel au debit
FR8506160 1985-04-23

Publications (2)

Publication Number Publication Date
EP0200641A1 true EP0200641A1 (de) 1986-11-05
EP0200641B1 EP0200641B1 (de) 1989-08-16

Family

ID=9318571

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860400885 Expired EP0200641B1 (de) 1985-04-23 1986-04-23 Ionenpumpe mit zur Gasmenge proportionalem Strom

Country Status (3)

Country Link
EP (1) EP0200641B1 (de)
DE (1) DE3665112D1 (de)
FR (1) FR2580866B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2740607A1 (fr) * 1995-10-27 1997-04-30 Commissariat Energie Atomique Pompe ionique a anode ajouree

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11615948B1 (en) * 2021-11-08 2023-03-28 Hamilton Sundstrand Corporation Ion pump for use in low gravity environments

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2993638A (en) * 1957-07-24 1961-07-25 Varian Associates Electrical vacuum pump apparatus and method
DE1539132A1 (de) * 1966-01-18 1969-09-18 Leybold Heraeus Gmbh & Co Kg Ionenvakuumpumpe

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6011423B2 (ja) * 1982-03-25 1985-03-26 日本真空技術株式会社 カソ−ド面清浄化手段を有するスパツタイオンポンプ

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2993638A (en) * 1957-07-24 1961-07-25 Varian Associates Electrical vacuum pump apparatus and method
DE1539132A1 (de) * 1966-01-18 1969-09-18 Leybold Heraeus Gmbh & Co Kg Ionenvakuumpumpe

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENTS ABSTRACTS OF JAPAN, vol. 7, no. 288 (E-218)[1433], 22 décembre 1983; & JP - A - 58 164 137 (NIPPON SHINKU GIJUTSU K.K.) 29-09-1983 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2740607A1 (fr) * 1995-10-27 1997-04-30 Commissariat Energie Atomique Pompe ionique a anode ajouree
WO1997015943A1 (fr) * 1995-10-27 1997-05-01 Commissariat A L'energie Atomique Pompe ionique a anode ajouree

Also Published As

Publication number Publication date
FR2580866A1 (fr) 1986-10-24
DE3665112D1 (en) 1989-09-21
FR2580866B1 (fr) 1989-01-06
EP0200641B1 (de) 1989-08-16

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