US3093298A

US3093298A - Ionic pump

Info

Publication number: US3093298A
Application number: US37780A
Authority: US
Inventors: James M Lafferty; Thomas A Vanderslice
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1960-06-21
Filing date: 1960-06-21
Publication date: 1963-06-11
Anticipated expiration: 1980-06-11
Also published as: DE1414554A1; GB965102A

Description

June 11,1963

' J. M. LAFFERTY -ETAL IONIC PUMP Filed June 21, leso /nvemors J James M. affer/ y Thomas A. Vanders//ce by Aforney.

' cathode.

UnitedStates Patent This invention relates to ionic pumps for lowering the pressure of evacuated systems to extremely low values and in particular to such pumps having improved etliciency.

Ionic pumps which are similar in certain respects to thek ionic pumps shown and described herein are disclosed in the copending application of T. A. Vanderslice, Serial- No. 763,293, led September 25, 1958, and assigned to the assignee of the `present invention, now Patent Number 3,080,104.

Ionic pumps such as disclosed and claimed in the above-identified application are highly useful for removing gases from low pressure vacuum systems. Such pumps are particularly useful for the removal of inert systems since these gases cannot be such pumps gases from'vacuum removed by chemical gettenng. Briefly, operate by causing ionizing electrons to traverse a large number of ionizing collisions with gaseous molecules. The ions so formed are accelerated toward a Some of these ions are collected by a collector electrode disposed in close proximity to the cathode. Ions striking the cathode at high velocity cause cathode material to be sputtered therefrom. This material deposits on the collector electrode, covering the ions collected on the surface thereof and removing them from the system.

The above described ionic pumps are of great utility and function to obtain extremely low pressure. It is always desirable, however, to seek to improve the etticiency of such devices.

.It is a general object of this invention therefore, to provide a new and improved ionic pump having greater pumping etliciency than any prior art device.

Briefly stated, accordance'with one aspect of this invention, an ionic pump comprises an evacuable envelope having in opposed spaced relationship therein a sputtering electrode member and an ion source. A`- collector electrode member is provided in close proximity to the sputtering electrode. The collector forms a surface for the collection of ions from the ion source and the deposition of metallic particles ejected lfrom the sputtering electrode. The ions are thus removed from the system and a pumping action results.

The novel features believed characteristic of the present are set forth in the appended claims. The in- Y invention vention itself, however, together with further objects and advantages thereof, may best be understood with reference to the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a vertical cross-sectional view of an ionic pump constructed in accordance with one embodiment of this invention,

FIG. 2 is a vertical cross-sectional view of an ionic pump constructed in accordance -with another embodiment of this invention; and

IFIG. 3 is a vertical cross-sectional view of an alternative embodiment of the device of FIG. 1.

lln FIG. l, an ionic pump constructed in accord with the present invention includes an evacuated envelope 1 having at one end thereof a sputtering electrode 2 and at the other end an ion source generally designated at 3. Ihe sputtering electrode 2 and ion source 3 lform the enclosing ends of envelope 1. The ionvsource includes a source of electrons which may be, for example, a thermielongated curvilinear paths through the pump volume and undergoV 2 onic cathode 4. Suitable electrical connections are provided for the thermionic cathode 4 through hermetically sealed apertures 5 and 6 and conventional pin-type electrodes 7 and 8 in base member 9. Apertured anode member 10 is provided to accelerate the electrons emitted from thermionic cathode 4 to an ionizing velocity of hundreds of volts. Anode member 10 is disposed in close proximity to cathode member 4 and possesses an annular portion 11 on the periphery thereof which is substantially the same diameter as base member 9. Means are provided to maintain -th'e electrons substantially at the ionizing velocity and for increasing their path length Aat:

this velocity before they are finally collected by anode member 10. In the arrangement illustrated in FIG. 1, this is provided by anode cylinder 12 associated with, and electrically connected to, anode member 10 and defining a region"13 wherein the electrons are maintained at substantially their accelerated velocity.`

A collector electrode 14 is in close proximity to sputtering electrode 2 and maintained at a 'negative potential with respect to anode 10. Collector electrode 14 has an annular portion 15 on the periphery thereof which is substantially the same diameter as the annular portion 11 of anode member 10.

Sputtering electrode 2, base member 9 and

electrodes

10 and 14 are separated by insulating ceramic members which are hermetically sealed to the adjacent members forming an evacuable envelope 1 having at one endthereof sputtering electrode 2 and at the other end ion source 3 with collector electrode 14 disposed therebetween. For example, sputtering electrode 2 is electrically separated from collector electrode 14 and hermetically sealed to the annular portion l5 thereof by annular insulating meml ber 16. In like manner collector electrode 14 is electricallyseparated from anode 10 and hermetically sealed to the annular portion 11 thereof by annular insulating member 17 and anode member' 10 is electrically separated from base member 9, and hermetically sealed thereto by annular insulating member 18. Each of the

annular insulating members

16, 17 and 18 have diameters substantially the same as the annular portions of sputtering electrode 2, control electrode 14, anode member 10 and base member 9 respectively.

Access to the ionic pump, suitable for connecting the device to a vacuum system, the pressure of which is to be lowered to an extremely low value, is achieved by means of tubulation 19.

The pumping process may be made more etlicient at low pressure by applying an -axial magnetic field, shown schematically by the arrow B. The axial magnetic field acts to further increase the path length the electrons traverse before being finally collected by anode 10 thereby increasing the number of ions produced per electron. The magnetic eld may be provided by a cylindrical permanent magnet 20 properly dimensioned so as to slip over the cylindrical envelope formed by the metallic and ceramic members comprising the ionic pump envelope 1.

and` suitably insulated therefrom so as not to short circuit the electrodes. Alternatively an electromagnetic coil may be utilized.

Operating potentials may 'be supplied in any conventional m-anner and may be obtained from either an alter` nating current or unidirectional power supply. Anode member 10 is biased positively withrespect to thermionic cathode 4 to a potential of hundreds of volts. Sputtering electrode 2 is ,biased negatively with respect to anode member 10 to several thousand volts. Collector electrode 14 is biased negatively with respectl to anode member 10 toa potential of hundreds of volts. The potential applied to collector electrode 14 should be sufficiently negative with -respect to the anode to cause some of the ions from ion source 3 to be attracted thereto, but not sufficiently 3 negative to cause these ions to impinge upon the collector electrode with a velocity high enough to cause any substantial sputtering therefrom.

Although these criteria may be met, in particular cases, by applying a potential to collector electrode 14 which is equal to or negative with respect to the sputtering electrode 2, in the preferred embodiment, the collector electrode 14 is maintained at a potential negative with respect to the anode but. positive with respect to the sputtering elecrode.

Sputtering electrode 2 is preferably fabricated of an active metal which is a good getter for chemically active gases and which further possesses the characteristic of being readily sputtered under positive ion bombardment. Such materials include titanium, zirconium, and like materials. Anode member 10and anode cylinder V12 are preferably also fabricated from such material, however, they Amay be fabricated from other materials if desired.

Anode member 10 may constitute a plurality of wires as illustrated in FIG. l, or may comprise a mesh, a honeycomb structure having a plurality of apertures or any other suitable electron accelerating structure. It is only necessary that anode member l establish -an accelerating electric field and be permeable to the majority of the electrons attracted thereto from thermionic cathode 4.

Preferably anode 10, anode cylinder 12, sputtering electrode 2, as well as collector electrode 14, are fabricated from titanium metal so that

annular insulating members

16, 17 and 18 may be composed of a suitable titaniummatching ceramic as, for example, a forsterite disclosed and claimed in application, Serial No. 546,215, Pincus, filed November 10, 1955, now Patent No. 2,912,340 and assigned to the assignee of the present invention. Assembly of the metal and ceramic members to form the evacuable envelope may be in accordance with the teaching of the copending Laterty application, Serial No. 690,849, filed October 17, 1957, now Patent No. 2,957,741 and assigned to the present assignee.

In the operation of the device of FIG. 1 when voltages as indicated hereinbefore are applied and a low pressure of gas as, for example, below -J millimeters of mercury is obtained within the device, electrons emitted from thermionic cathode 4 are accelerated by anode member ,10 to ionizing velocities of hundreds of volts. For example, in a typical device the anode voltage may be approximately 300 volts positive with respect to cathode 4, thus accelerating the electrons to an ionizing velocity of 300 volts. Within the region 13 of anode cylinder 12 there is substantially no field gradient and the electrons are maintained at substantially their accelerated velocity of several hundred volts within this region. Since the electrons are maintained at a relatively high velocity throughout the region 13 there is an increased probability for the occurrence of ionizing collisions with gas molecules present therein.

Sputterng electrode 2, maintained at a high negative potential with respect to anode l0 produces a strong negative electric field in the region 21 which acts to slow down electrons emerging from anode cylinder 12 to zero velocity. The decelerated electrons pass back into the region 13 of anode cylinder 12. They are then similarly repelled by the negative potential of 'cathode 4. Thus, the electrons oscillate back and forth within the region 13 at ionizing velocity many times, permitting of a large number of ionizing collisions and resulting in many positive ions being produced thereby before the electrons are finally collected by the anode members.

Since sputtering electrode 2 is maintained at a high negative potential with respect to anode 10, the ions produced by ion source 3 are accelerated toward sputtering electrode 2 and strike with very high velocity. Ions striking at this high velocity cause metallic particles to be sputtered from sputtering electrode 2. Collector electrode 14, being in close proximity to sputtering electrode 2, provides a surface for the deposition of this sputtered metal.

4 In addition, since collector electrode 14 is also maintained at a negative potential with respect to anode member 1I, some of the ions produced 'by ion source 3 are collected thereby, and are covered up by the metallic particles sputtered from sputtering electrode member 2. The ions covered fby the sputtered metal are removed from the system thus, constituting a pumping action. The newly deposited metal forms a clean surface on collector electrode 14 for further deposition of metal to cover additional ions collected thereby. In addition, chemically active gases are also removed by chemical reaction. with the sputtered metal from electrode 2. v

While certain specific operating potentials lfor the electrodes of the ionic pump have been given in the above description these values are intended as illustrative examples only. For example, while the relative polariu'es of the various electrodes must be maintained, with sputtering electrode 2 and collector electrode 14 negative with respect to the anode 10, a wide range of values are suitable. Ideally, the relative potentials of sputtering eletrode 2 and collector electrode 14 should be such that the metal sputtered from sputtering electrode 2 and deposited on collector electrode 14 covers up a maximum number of ions. Thus, there is an optimum potential relationship which will approach this ideal, although other values provide a successful pumping action. For example, an ionic pump of the type illustrated in FIG. 1 having an outside diameter of approximately 1%/4 inches, utilized a collector electrode cylinder 16 having a diameter of approximately 1%3 inch and an anode cylinder 12 of approximately 1% inch. The following potentials with respect to ground approaches the optimum in this particular device:

Sputtering electrode 2=l000 volts Collector electrode 16=500 volts Anode 10 and anode cylinder 12= +300 volts Sputtering electrode 2 preferably has a curved or discontinuous shape to increase the probability of metallic particles ejected therefrom being substantially all directed to the surface of collector electrode 14. The positive ions attracted to the collector electrode 14 remain at the surface thereof, are covered by metal ejected from sputtering electrode 2, and are thus completely removed from the pump volume, lowering the gas pressure therein.

Although the ionic pump operates very effectively as described above, its eiciency may be further increased by -applying to the ion source 3 an axial magnetic field, which may be, for example, approximately within the range of 500 to 2,000 gauss. This field is shown schematically by the arrow B. The action of this magnetic field tends to prevent the electrons from striking anode member 10 and its associated cylinder 12 serving to further increase the length of the electron paths by increasing the number of oscillations within the region 13 before the electrons are finally collected by the anode members. This increased path length of the electrons increases vthe opportunity for the production of ions per electron. The application of the axial magnetic field is particularly desirable at the lower gas pressures.

At gas pressures above lll-il millimeters of mercury the ionic pump operates in a slightly different manner. At these higher pressures a low voltage discharge is estab lished between thermionic cathode 4 and anode member 10. Ions may be removed from the plasma thus established by applying a negative potential of as little as several hundred volts to sputtering electrode 2. The potential to collector electrode 14 may remain at a value substantially the same as that suitable for pressures below 10-3 millimeters of mercury to provide effective pumping action.

The ionic pump may be made to operate at high etii ciency over a large pressure range by varying the voltagi on sputtering electrode 2 and anode member 10. Since cathode-anode current is larger at the higher gas pressur this variation of voltage may be conveniently provided, in a continuous mannerfby utilizing a suitable resistance in series with each of the electrodes 2 and 14and its respective voltage source. Thus, at the potential applied to these electrodes is automatically lowered and as the pressure is reduced the voltage is increased providing most ellicient operation throughout the entire range of pressures.

It will be readily understood by those skilled in the art that although utilizing a thermionic cathode aids in initiating the operation of the above-described ionic pump the electrons need not be produced in this manner. For example, electrons due to secondary emission may constitute a suitable source to effectively produce a supply of ions from ion source 3.

FIG. Z'illustrates another embodiment of the present invention. In FIG. 2 like parts to the device of PIG. 1 are identified by like reference numerals. In FIG. 2 evacuable envelope 1 has, at one end thereof, a sputtering electrode 2 and at the other end a magnetron-type ion source generally designated at 22. Interposed bethe higher pressures tween sputtering electrode 2 and ion source 22 and in insulating relationship therewith are a collector electrode 14, in close proximity to sputtering electrode 2, and an ion accelerating electrode 23 in close proximity to ion source 22.

Magnetron-type ion source 22 includes a cylindrical anode 24 and a doubled lilamentary thermionic cathode 25 extending along the longitudinal axis of anode cylinder 24. Means for applying an axial magnetic field, shown schematically by 4the arrow B, comprises an annular cylinder magnet 26 which may be either a permanent magnet or an electromagnetic coil. Suitable electrical connections are provided for thermionic cathode through hermetically sealed apertures 5 and 6 and pin-type electrodes 7 and 8 in ybase member 9.

Sputtering electrode 2, collector electrode 14, ion accelerating elect-rode 23, anode cylinder 24 and base member 9 are separated by insulating ceramic members which are hermetically sealed to adjacent members to form evacuable envelope 1.

In magnetron-type ion source 22, electrons are thermionically ejected from cathode 25 and migrate toward anode cylinder 24. During the passage from cathode to anode a fraction of the gaseous molecules present within the device are ionized by collisions with the migrating electrons. To provide the maximum number of ions per electron, the length of the path of the electrons between cathode and anode should be a maximum. Due to the action of the axial magnetic field on the electrons passing from cathode to anode, the electrons traverse a curvilinear path. This path taken by the electrons is longer than the straight path would be in the absence of a magnetic field. The maximum number of ions per electron are produced when the magnetic eld is increased to a degree that 'electrons emitted from therrnionic cathode 25 and accelerated underthe electric ield are curved to such an extent that they just fail to impinge upon the anode and curve back to the cathode region. When the magnetic field is of this order, the device is essentially cut olf and substantially no electron current ows between cathode and anode. Under this condition, the path length of the electrons through the gas filled region is a maximum and a maximum number of ionizing collisions occur. When the magnetic iield is of this order .the device is said to be operating at cutoi Under cutoff conditions, therefore, it is found that the above-described arrangement comprises a highly eicient source of positive ions.

The positive ions produced in the cathode-anode space of ion source 22 are removed therefrom by ion accelerating elect-rode 23 which is maintained negative with respect to anode cylinder 24. Sputtering electrode 2 is maintained highly negative with respect .to anode cylinder 24 so that the positive ions under the inuence of the electric field between cathode and anode j apparent that a similar arrangement, is embodiment of FIG. 2.

established by sputtering electrode 2 are further accelerated thereto. Since sputtering electrode 2 is at a high negative potential, positive ions strike its surface with high veloci-ty causing metallic particles to be sputtered therefrom. Again, as in the embodiment illustrated in F'IG. 1, a highly eicient pumping action results from the covering up of positive ions collected on the surface of collector electrode 14 by metallic particles ejected from sputtering electrode 2 and deposited on collector electrode 14.'

The device of FIG. 2 may be utilized as an ionization gauge if desired. This may be accomplished, for example, by connecting sputtering electrode 2, ion accelerating electrode 23 and collector electrode 14 together` and applying thereto a small negative voltage of approximately 45 volts. The current measured at the common connection of these electrodes is a measure of the gas pressure within the device envelope. Connecting ion accelerating eleotrode 23 to a similar small negative voltage but not in common with electrodes 2 vand 14, so that this current is not measured, provides a convenient means of minimizing leakage current across the ceramic members. Ion accelerating electrode 23 thus serves as an elective guard ring.

While the present invention has been described in detail for ionic pumps of metal and cer-amic construction it is readily apparent tha-t a conventional glass or vitreous envelope may be utilized if desired. For example, in FIG. 3, in which like numerals identify like parts to the parts of FIGS. 1 and 2, sputtering electrode 2, collector electrode 14 and ion source 3 have the same configuration and spatial arrangement as in the device of FIG. l. Magnet 20, which may be either a permanent magnet or an electromagnetic coil slipped closely over the glass envelope 28 enclosing the elements, establishes the desired axial magnetic eld for most efficient low pressure operation. Lead and support members 29 pass through re-entrant portions 30 of envelope 28 asis conventional in glass electron discharge devices. A breakdown shield 31 is built up upon each of members 29 -to prevent electrical breakdown occurring'from the pointat which these members enter re-entrant glass portion 30 of envelope 28.

The ionic pump of FIG. 3 functions substantially the same as the ionic pump illustrated in FIG. l, the difference being only that the envelope is of a vitreous material, such as glass, rather than metal and ceramic. It is readily Prom the foregoing description it is evident that there `has been disclosed a. new and improved ionic pump and embodimentsthereof capable of pumping evacuated systems to extremely low pressures in a most efficient manner.

While only certain preferred embodiments 'of the invention have been shown by way of illustration, many modifications and changes will occur to those skilled in the art. Itis, therefore, to be understood that the ap-'v pended claims are intended to cover all such modifications.

and changes as fall within the true spirit and invention.

scope of the What we claim as new and desire to secure by Letters Patent of the United States is:

l. An ionic pump comprising: an evacuable envelope; a sputtering electrode member disposed within said envelope; anion source within said envelope disposed opposite said sputtering electrode member, said ion source producing ions bythe ionization of gas molecules within said envelope without substantial sputtering therefrom; means for withdrawing and accelerating ions from said ion source to said sputtering electrode member so that such ions impinge upon said sputtering electrode member with sucient velocity to cause the ejectiony of metallic particles therefrom; a collector electrode member disposed in juxtaposition with both said sputtering electrode member and said ion source, said collector electrode member being so arranged and adapted to provide a surface for the collec-l tion of ions and deposition of metallic particles ejected possible for the from said sputtering electrode memberyand means for applying appropriate operating potentials to said sputter ing electrode member, said ion source, said ion withdrawing and accelerating means, and said collector electrode member respectively.

2. An ionic pump comprising: an evacuable envelope; a sputtering electrode member disposed within said envelope and near one end thereof; an ion source disposed within said envelope near the opposite end thereof, said ion source producing ions by the ionization of gas molecules within said envelope -without substantial sputtering therefrom; means for withdrawing ions from said ion source and accelerating said ions to said sputtering electrode member so that such ions impinge upon said sputtering electrode member with a velocity sufficient to cause the ejection of metallic particles therefrom; a collector electrode member disposedwithin said envelope and. m electrical insulating relationship between said sputtering electrode member and said ion source, said collector electrode member providing a surface for collection of some of the ions from said ion source and deposition of metallic particles ejected from said sputtering electrode member; and means for applying appropriate operating potentials to said sputtering electrode member, said ion source, said ion withdrawing and accelerating means, and said collector electrode member respectively.

3. .An ionic pump comprising: an evacuable envelope; a sputtering electrode member disposed Within said envelope; an ion source within said envelope disposed opposite said sputtering electrode member for producing ions by the ionization of gas molecules within said envelope without substantial sputtering therefrom, said ion source including an electron source, and anode means including means associated therewith for increasing the length of the electron paths from said electron source to said anode means, means for withdrawing ions from said ion source and for accelerating said ions -to said sputtering electrode member so that such ions impinge on said sputtering elec- -trode member with sufficient velocity to cause the ejection of metallic particles therefrom; a collector electrode member within said envelope in proximity to both said ion source and said sputtering electrode member, said collector electrode member providing a surface for collection of some of the ions produced by said ion source and deposition of metallic particles ejected from said sputtering electrode member; and means for applying appropriate operating potentials to said electron source, said anode means, said sputtering electrode member and said collector electrode member respectively to cause ions to be produced by said ion source, some of said ions to be withdrawn from said ion source and accelerated to said sputtering electrode member so as to impinge thereon with sufficient velocity to eject metallic particles, and some of said ions to be attracted yfrom said ion source and held by said collector electrode member.

4. The ionic pump of claim 3 wherein means are further provided for applying an axial magnetic tield to said ion source substantially parallel to the normal path of electrons from said electron source to said anode means to still further increase the length of the electron paths from said electron source to said anode means and permit of a larger number of ionizing collisions between said electrons and gas molecules within said envelope.

5. An ionic pump comprising: a sputtering electrode member; a collector electrode member; an ion source assembly, said sputtering and collector electrode members and said ion source assembly each having an extending metallic supporting portion thereon; a pair of apertured insulating ceramic members one interposed between the metallic supporting portions of said sputtering electrode member and said collector electrode member and the other between the metallic supporting portions of said collector electrode member and said ion source assembly and adapted to be hermetically sealed thereto to form an evacuable envelope having one enclosing end formed by said sputtering electrode member and the opposite enclosing end formed by said ion source assembly with said collector electrode member in insulating relationship therebetween providing a surface `for collection of ions and deposition of metallic particles ejected from said sputtering electrode by ions impinging thereon; and means for applying appropriate operating potentials to said ion source assembly, said collector electrode member, and said sputtering electrode member respectively to cause ions to be produced by said ion source assembly without substantial sputtering therefrom, some of said ions to be withdrawn from. said ion source assembly and accelerated to said sputtering electrode member so as to impinge thereon with sufiiciently high velocity to eject metallic particles therefrom, and some of said ions to be withdrawn from said ion source assembly and held by said collector electrode member.

6. An ionic pump comprising: an evacuable envelope;

an ion source disposed within said envelope and including a thermonic electron source and an anode means, said anod'e means including an apertured anode member for accelerating said electrons to a predetermined ionizing velocity and means associated therewith defining a region along the path of said accelerated electrons wherein said electrons are maintained at substantially said ionizing velocity; a sputtering electrode member disposed within said envelope opposite said ion source; means for maintaining said sputtering electrode member at a potential with respect to said anode means and said electron source to cause the electrons from said electron source to oscillate ybaclr and forth within the region dened 'by said means associated with said apertured anode member to increase the length of the paths of said electrons at said ionizing velocity before the same are finally collected by said anode means to permit of a large number of ionizing collisions between said electrons and gas molecules present within the region defined by said means associated with said apertured anode member, and to cause some of the ions produced as a result of said ionizing collisions to be withdrawn and accelerated to said sputtering electrode member so as to impinge thereon with a sutiiciently high velocity to cause metallic particles to be ejected thereom; a collector electrode member disposed within said envelope in proximity to -both said sputtering electrode member and said ion source, said collector electrode member forming a surface for collection of ions from said ion source and deposition of metallic particles ejected from said sputtering electrode member; and means for maintaining said collector electrode memberiat a potential with respect to both said sputtering electrode member and said anode means so that some of the ions produced by said ion source in the region defined by the means associated with said apertured anode member are attracted therefrom and held by said collector electrode member.

7. 'Ihe ionic pump of claim 5 wherein the means associated with said apertured anode member defining a region wherein the electrons are maintained at substantially said ionizing velocity is a hollow cylindrical member disposed within said envelope with one end directed toward said apertured anode member and said electron source and the other end directed toward said sputtering electrode mem-ber.

8. The ionic pump of claim 6 wherein said anode means is maintained at a positive potential with respect to said electron source, said sputtering electrode member is maintained at a negative potential with respect to said anode means, and said collector electrode member is maintained at a negative potential with respect to said anode means Ibut at a positive potential with respect to said sputtering electrode member.

9. An ionic pump comprising: an evacuable envelope; an ion source disposed within said envelope and including an electron emitter, an apertured anode member positioned and adapted to accelerate electrons from said electron emitter, a hollow cylindrical member having one end directed toward said apertured anode member and delining a region wherein said accelerated electrons are maintained at substantially said accelerated velocity, andmember; a sputtering electrode member disposed within said envelope opposite the other end. of said hollow cylindrical member; a collector electrode member disposed within said envelope and positioned relative to said ion source and said sputtering electrode member to provide a surface Afor' collection of ions from said ion source and deposition of metallic particles ejected from said sputtering electrode member; and means for maintaining said apertured anode and hollow cylindrical members at a positive potential'with respect to said electron emitter, for maintaining said sputtering electrode member at a negative potential with respect to said apertured anode and hollow cylindrical members, and Ifor maintaining said collector electrode member at a positive potential with respect to said sputtering electrode member but at a negative potential with respect to said apertured anode and hollow cylindrical members, the respective potentials being operative to cause ions to be produced by said ion source by electron collisions with gas molecules within said envelope without substantial sputtering therefrom, some of the ions so produced tojbe withdrawn and accelerated to said sputtering electrode member so as to impinge thereon with suicient velocity to eject metallic particles therefrom, and to cause some of the ions to be withdrawn from said ion source and held by said collector electrode member.

l0. An ionic pump comprising: anion source assembly for producing ions by ionization of gas molecules including a metallic base member, a thermionic electron emitter mounted on said base member, anode means in juxtaposition with said electron emitter and including a hollow cylindrical member and an apertured member disposed across one end thereof, said anode means being positioned so that said one end of said cylindrical member is directed toward said electron'emitter, an extending metallic supporting portion associated with said anode means, and an apertured insulating ceramic member interposed between the extending supporting portion of said anode means and said metallic base member and adapted to be hermetically sealed thereto to vform an enclosure having said anode means disposed above and in insulating relationship with said base member and said electron emitter; a collector electrode member; a sputtering elcctrode member, said collector and sputtering electrode members each having an extending metallic supporting portion thereon; a pair of apertured insulating ceramic members one interposed between the extending supportingportions of said anode means and said collector electrode member and the other between the extending supporting portions of said collector electrode member and said sputtering electrode member and adapted to be hermetically sealed thereto to form an evacuable envelope having one enclosing end formed by the metallic base member of said ion source assembly and the opposite enclosing end formed by said sputtering electrode member, said collector electrode member being in juxtaposition and insulating relationship with said anode means and said sputtering electrode member and providing a surface for collection of ions from said ion 'source assembly and deposition of metallic particles ejected from said sputtering `electrode member by ions impinging thereon; and means for applying appropriate operating potentials to said electron emitter, said anode means, said collector electrode member and said 'sputtering electrode member respectively to cause ions to be produced within said hollow cylindrical member by electron collisions with gas molecules therein, some of said ions to be withdrawn from said hollow cylindrical member and accelerated to said sputtering electrode member' `so as to impinge on said sputtering electrode member one end directed toward said ion source and the other end toward said sputtering electrode member, said collector electrode member forming a surface for collection of ions from said ion source and deposition of metallic particles ejected from said sputtering electrode member; an apertured ion accelerating electrode member disposed between said magnetron-type ion source and said one end of said collector electrode member; and

means for applying appropriate operating potentials to` said ion source, said sputtering electrode member, said collector electrode member, and said ion accelerating electrode member respectively for causing ions to be produced by said ion source, ions to be withdrawn from said ion source, some of said ions so withdrawn 'to be accelerated to said sputtering electrode member and to impinge thereon with suicient velocity to cause metallic particles to be `ejected therefrom, and some of said ions to be attracted to and held by said collector electrode member.

l2. An ionic pump comprising: an evacuable envelope; a sputtering electrode member disposed within said envelope; an ion source within said envelope disposed opposite said sputtering electrode member, said ion source adapted to produce ions by ionization ofv gas molecules within said envelope without substantial sputtering therefrom and including an' electron source, anode means disposed in proximity to said electron source and adapted to accelerate said electrons to a predetermined ionizing velocity; means for increasing the length ofthe electron paths from said electron source to .said anode means; a collector electrode member in juxtaposition with both said ion source and said sputtering electrode member, said collector electrode member forming a surface for collection of ions from saidion source and deposition of metallic particles ejected from said sputtering electrode member; and means for applying appropriate operating potentials to said ion source, said anode means, said sputtering electrode member, and said collectorl electrode member respectively to cause ions to be produced by said ion source by electron collisions with gas molecules, ions to be withdrawn from said ion source, some of said ions to be accelerated to said sputtering electrode member and to impinge thereon with sutlicient velocity to cause metallic particles to be ejected therefrom, and some ions to beattracted to and held -by said collector electrode member.

13. The ionic pump of claim 12 wherein said anode means includes a hollow cylindrical member having a multi-apertured member disposed at one end thereof positioned with said one end near and directed toward said anodefmeans.

14. The ionic pump of claim 12 wherein said anode means is a hollow cylindrical member disposed eo-axially around said electron source having one end of said cylindrical member directed toward said sputtering electrode member, and said means for increasing the length of the electron paths -from said electron source to said anode means is provided by an axial magnetic field, said magnetic field having a direction parallel with the longitudinal axis of said hollow cylindrical anode member and perpendicular to the normal path of electrons from said electron source to said anode means, the magnitude of said magnetic teld being correlated with respect to the electron source-anode means potential so that electrons' just fail to reach said anode means.

15. An ionic pump comprising: an evacuable envelope; a sputtering electrode member disposed within said envelope; an ion source within said envelope disposed opposite said sputtering electrode member producing ions by the ionization of gas molecules within said envelope and including a thermionic electron source, anode means including a hollow cylindrical member having a multiapertured member disposed at one end thereof and arranged within said envelope with said one end directed toward said electron source and the other end toward said sputtering electrode member, means for maintaining said anode means at a positive potential with respect to said electron source and said sputtering electrode member a-t a negative potential with respect to said anode means, said potentials being operative in cooperation with said anode means to cause electrons to -be accelerated to a predetermined ionizing velocity and to oscillate back and forth thereat within the region defined by said hollow cylindrical member to permit of a large number of ionizing collisions with gas molecules therein, said potentials being further operative to cause ions produced within the region defined by said hollow cylindrical member by such ionizing collisions to be withdrawn thereyfrom and accelerated to said sputtering electrode member so as to impinge thereon with suilicient velocity to cause metallic particles to be ejected; means for applying an axial magnetic field to said ion source substantially parallel to the normal path of electrons from said electron source to said anode means to further increase the length of the electron paths from said electron source to said anode means before said electrons are finally collected by said anode means; a collector electrode member disposed in juxtaposition to both said sputtering electrode member and said ion source, said collector electrode member forming a surfacefor collection of ions and deposition of metallic particles ejected from said sputtering electrode member; and means for maintaining said collector electrode at a potential with respect to said anode means and said sputtering electrode member to attract and hold some of the ions produced by said ion source.

16. An ionic pump comprising in stacked array: a metallic base member; a hollow anode cylinder having an annular supporting portion thereon; an electron emitter mounted on said base member and disposed axially within said anode cylinder; an apertured insulating ceramic member interposed -between the annular supporting portion of said anode cylinder and said base member and adapted to be hermetically sealed thereto to form an ion source assembly; means for applying an axial magnetic lield to the ion source assembly so formed, said magnetic lield having a direction parallel with the longitudinal axis of said hollow anode cylinder and perpendicular to the normal path of electrons from said electron emitter to said anode cylinder and being correlated with respect to the electron emitter-anode cylinder potential to establish cutol operating conditions for said ion source assembly; an apertured ion accelerating electrode; a sputtering electrode member; a hollow cylindrical electrode member concentric with said anode cylinder, said ion accelerating electrode, said sputtering electrode member and said collector electrode member each having an annular metallic supporting portion thereon; a plurality of apertured insulating ceramic members interposed 4between the annular supporting portions of said anode cylinder and said ion accelerating electrode, said ion accelerating electrode and said collector electrode member, and said collector electrode member and said sputtering electrode member and adapted to be hermetically sealed thereto to form an evacuable envelope wherein one enclosing end thereof is provided -by the metallic base member of said ion source assembly and the opposite enclosing end thereof is provided by said sputtering electrode member, said ceramic insulating members being so provided that said ion accelerating electrode is interposed in insulating relationship between said anode cylinder and said collector electrode member and said collector electrode member is positioned so that one end thereof is directed toward said ion accelerating electrode member and the other end thereof is directed toward said sputtering electrode member, said collector electrode member forming a surface Ifor the collection of ions and the deposition of metallic particles ejected from said sputtering electrode` member; and means for applying appropriate operating potentials to said electron emitter, said anode cylinder, said ion accelerating electrode, said collector electrode member, and said sputtering electrode member to cause ions to be produced in said ion source assembly by electron collisions with gas molecules therein, ions to be withdrawn from said ion source assembly by said ion accelerating electrode, some of said withdrawn ions to be accelerated to said sputteringvelectrode member so as to impinge thereon at a sutciently high velocity to cause the ejection therefrom of metallic particles, and some of said withdrawn electrons to be attracted by and held by said collector electrode member.

References Cited in the tile of this patent UNITED STATES PATENTS

Claims

1. AN IONIC PUMP COMPRISING: AN EVACUABLE ENVELOPE; A SPUTTERING ELECTRODE MEMBER DISPOSED WITHIN SAID ENVELOPE; AN ION SOURCE WITHIN SAID ENVELOPE DISPOSED OPPOSITE SAID SPUTTERING ELECTRODE MEMBER, SAID ION SOURCE PRODUCING IONS BY THE IONIZATION OF GAS MOLECULES WITHIN SAID ENVELOPE WITHOUT SUBSTANTIAL SPUTTERING THEREFROM; MEANS FOR WITHDRAWING AND ACCELERATING IONS FROM SAID ION SOURCE TO SAID SPUTTERING ELECTRODE MEMBER SO THAT SUCH IONS IMPINGE UPON SAID SPUTTERING ELECTRODE MEMBER WITH SUFFICIENT VELOCITY TO CAUSE THE EJECTION OF METALLIC PARTICLES THEREFROM; A COLLECTOR ELECTRODE MEMBER DISPOSED IN JUXTAPOSITION WITH BOTH SAID SPUTTERING ELECTRODE MEMBER AND SAID ION SOURCE, SAID COLLECTOR ELECTRODE MEMBER BEING SO ARRANGED AND ADAPTED TO PROVIDE A SURFACE FOR THE COLLECTION OF IONS AND DEPOSITION OF METALLIC PARTICLES EJECTED FROM SAID SPUTTERING ELECTRODE MEMBER; AND MEANS FOR APPLYING APPROPRIATE OPERATING POTENTIALS TO SAID SPUTTERING ELECTRODE MEMBER, SAID ION SOURCE, SAID ION WITHDRAWING AND ACCELERATING MEANS, AND SAID COLLECTOR ELECTRODE MEMBER RESPECTIVELY.