EP0200641B1 - Ionenpumpe mit zur Gasmenge proportionalem Strom - Google Patents

Ionenpumpe mit zur Gasmenge proportionalem Strom Download PDF

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Publication number
EP0200641B1
EP0200641B1 EP19860400885 EP86400885A EP0200641B1 EP 0200641 B1 EP0200641 B1 EP 0200641B1 EP 19860400885 EP19860400885 EP 19860400885 EP 86400885 A EP86400885 A EP 86400885A EP 0200641 B1 EP0200641 B1 EP 0200641B1
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EP
European Patent Office
Prior art keywords
chamber
electrode
ion pump
networks
pump according
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
Application number
EP19860400885
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English (en)
French (fr)
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EP0200641A1 (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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    • 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 which, for some of them are called “diode pumps”, comprise 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. surrounded, at its entry into the room, by a piece of electrical insulation, carrying a piece constituting a baffle protecting the piece of electrical insulation and ensuring the setting of the anodic potention and the electrical supply as well as the fixing in the room, of the electrode placed inside the chamber and electrically isolated from the walls of this chamber, a means of electrical supply to the electrode, and a magnetic circuit creating a magnetic field in the chamber, said electrode being constituted by a metal wire structure defining at least one cell inside the chamber and thus constituting a Faraday cage, this ion pump keeping a c linear flow-current characteristic during long-term use, having an extended service life without degrading its conditions of use and having a simple structure allowing inexpensive construction.
  • a chemically active metallic trapping material such as titanium
  • the electrode comprises two substantially planar networks, made of metal wire, connected together by wires substantially perpendicular to the planes of the networks, the part carried by the conductor is a hollow washer comprising a cylindrical peripheral rim directed towards the wall of the chamber traversed by the conductor and a projecting part of this cylindrical wall, with a diameter less than the diameter of the peripheral part of the hollow washer penetrates over a certain length inside the hollow washer.
  • Fig. 1 we see the chamber 1 of an ion pump, the walls of which are coated internally with titanium plates 2 constituting the pump getter material. 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.
  • FIG. 2 we see the electrical conductor 5 passing through the wall 1a of the chamber 1 at 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 that may be between 2 and 1,333.10- 1,333.10- 10 Pa (10- 4 and 10- 12 Torr)
  • titanium walls can be caused to vaporize, even at temperatures moderate.
  • 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 metallic wire each connected by welding points 17 to the turns adjacent to the network which thus comprises circular meshes and meshes in the shape of a curvilinear triangle.
  • the two planar networks 13 and 14 are connected by a set of rectilinear wires 16 parallel to each other and perpendicular to the planes of networks 13 and 14.
  • the whole of the electrode thus constitutes a cage-shaped structure comprising juxtaposed cells.
  • Electrode 3 which thus forms a Faraday cage inside the pump chamber.
  • the electrode 3 in the form of a small diameter wire structure is very light tee so that it can be easily suspended inside the pump chamber through 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).
  • the electrode offers a small surface exposed to titanium vapors, which reduces the metallization of this electrode made of metal wire.
  • the electrode as described used in a pump as shown in FIG. 1 provides a high vacuum with excellent efficiency.
  • 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 metal 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 planar networks 23 and 24 are constituted by a peripheral contour of circular shape 26 made of metal wire onto which are successively 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 peripheral 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 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 mounting of this electrode without support piece, reduced metallization of the electrode and of the insulating part of the power supply and a very good yield obtained thanks to the increase in the surface covered by the getter metal 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 ultrahigh vacuum in an enclosure or for the measurement of flow rate or quantity of residual gaseous substance in an enclosure.

Landscapes

  • Electron Tubes For Measurement (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Claims (10)

1. lonenpumpe mit zur Rate bzw. Gasmenge proportionalem Strom, mit einer Kammer (1) deren innere Seitenwand wenigstens teilweise durch ein metallisches Scheide- bzw. Trennmaterial (matériau de piégeage) (2), welches chemisch aktiv ist, wie beispielsweise das Titan, überdeckt ist, einer Elektrode (3), die mit einem elektrischen Leiter (5) verbunden ist, der an seinem Eintritt in die Kammer (1) durch ein Elektroisolationsteil (7) umgeben ist, wobei er ein Teil (12) trägt, das eine Schikane bildet, welche das elektrische Isolationsstück (7) schützt und die Aussetzung der anodischen Potention und elektrische Zufuhr sowie die Festlegung in der Kammer (1) der Elektrode sicherstellt, die im Inneren der Kammer angeordnet und elektrisch von den Seitenwänden (1a) dieser Kammer isoliert ist, mit einer elektrischen Zuführeinrichtung (6) der Elektrode und einem Magnetkreis (10), der ein elektrisches Feld in der Kammer (1) erzeugt, wobei die Elektrode (3) aus einer Struktur aus metallischen Drähten gebildet ist, die wenigstens eine Zelle im Inneren der Kammer (1) begrenzen und so einen Faraday'schen Käfig bilden, dadurch gekennzeichnet, daß die Elektrode (3) zwei im wesentlichen ebene Gitter (13, 14; 13', 14'; 23, 24) aus Metalldraht aufweist, die untereinander durch Drähte (16, 16'; 28, 29) miteinander verbunden sind, die im wesentlichen senkrecht zu den Ebenen der Gitter (13, 14; 13', 14'; 23, 24) verlaufen, daß das Teil (12), welches von dem Leiter (5) getragen wird, eine mit einer Vertiefung versehene Scheibe ist, die einen zylindrischen Umfangsrand aufweist, der auf die Seitenwand (1a) der Kammer (1) gerichtet ist, die von dem Leiter (5) durchdrungen wird, und das ein Vorsprungbereich (11) dieser zylindrischen Seitenwand (1a) von einem geringeren Durchmesser als der Durchmesser des Umfangsbereichs der vertieften Scheibe (12) mit einer gewissen Länge in das Innere der vertieften Scheibe (12) eindringt.
2. lonenpumpe nach Anspruch 1, dadurch gekennzeichnet, daß die ebenen Gitter (13, 14) der Elektrode (3) durch kreisförmige Windungen (15) aus Metalldraht gebildet sind, die aneinander angeordnet sind, und ein Gitter aus kreisförmigen Maschen und aus Maschen in Form gekrümmter Dreiecke aufweist.
3. lonenpumpe nach Anspruch 1, dadurch gekennzeichnet, daß die ebenen Gitter (13', 14') Maschen in Form von regelmäßigen aneinandergelegten Polygonen, wie beispielsweise von Hexagonen aufweist.
4. lonenpumpe nach Anspruch 1 dadurch gekennzeichnet, daß die ebenen Gitter (23, 24) der Elektrode (5) jedes eine kreisförmige Außenkontur (26) und geradlinige Drähte (27a, 27b) in einer bezüglich der Kontur (26) radialen Richtung und mit einer Länge aufweisen, die geringer ist als der Radius der Kontur (26).
5. lonenpumpe nach Anspruch 4, dadurch gekennzeichnet, daß die radialen geradlinigen Drähte (27a, 27b) abwechselnd von großer und geringer Länge sind.
6. lonenpumpe nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß der Luftspalt des magnetischen Kreises (10) in Richtung auf die Mitte der Kammer geringer ist, die dem Zentrum der Elektrode entspricht.
7. lonenpumpe nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die maximale Abmessung der ebenen Gittermaschen zwischen 5 mm und 100 mm liegt und die Länge der geradlinigen Drähte (16) der Verbindung zwischen den ebenen Gittern (13,14) zwischen 5 mm und 50mm liegt.
8. lonenpumpe nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß die Elektrode (3) aus Trenn- bzw. Scheidematerial gebildet ist.
9. lonenpumpe nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß sie mehrere Trenn- bzw. Scheidematerialien aufweist.
10. lonenpumpe nach Anspruch 9, dadurch gekennzeichnet, daß das Trenn- bzw. Scheidematerial des Überzugs der Seitenwände der Kammer (1), die parallel zu den Ebenen der Gitter (13,14) der Elektrode (3) angeordnet sind, unterschiedlich ist zum Trenn- bzw. Scheidematerial des Überzugs der Seitenwände der Kammer (1), die senkrecht zu den Ebenen der Gitter (13,14) der Elektrode (3) verlaufen.
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
FR8506160 1985-04-23
FR8506160A FR2580866B1 (fr) 1985-04-23 1985-04-23 Pompe ionique a courant proportionnel au debit

Publications (2)

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

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EP19860400885 Expired EP0200641B1 (de) 1985-04-23 1986-04-23 Ionenpumpe mit zur Gasmenge proportionalem Strom

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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
EP4177929A1 (de) * 2021-11-08 2023-05-10 Hamilton Sundstrand Corporation Ionenpumpe zur verwendung in umgebungen mit niedrigem gewicht

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2740607B1 (fr) * 1995-10-27 1997-11-21 Commissariat Energie Atomique Pompe ionique a anode ajouree

Family Cites Families (3)

* 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
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

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4177929A1 (de) * 2021-11-08 2023-05-10 Hamilton Sundstrand Corporation Ionenpumpe zur verwendung in umgebungen mit niedrigem gewicht

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FR2580866A1 (fr) 1986-10-24
DE3665112D1 (en) 1989-09-21
EP0200641A1 (de) 1986-11-05
FR2580866B1 (fr) 1989-01-06

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