US3141605A

US3141605A - Magnetron type getter ion pump

Info

Publication number: US3141605A
Application number: US132468A
Authority: US
Inventors: Asamaki Tatuo
Original assignee: Nippon Electric Co Ltd
Current assignee: NEC Corp
Priority date: 1961-08-18
Filing date: 1961-08-18
Publication date: 1964-07-21
Anticipated expiration: 1981-07-21

Description

July 21, 1964' TATUO ASAMAKI 3,141,605

MAGNE'IRON TYPE GETTER ION PUMP Filed Aug. 18, 1961 2 Sheets-Sheet 1 I I IP43 a 1/6 66 INVENTOR- I /4 6/ 7-00 JJ'JMJK/ July 21, 1964 l TATUO ASAMAKI 3,141,605

meuz'raon ms cm ION PUMP Filed Aug. 18, 1961 2 Sheets-Sheet 2 INVENTOR. a 7' 71/0 474M States-Q Patent" 3,141,605;- MAGNETRONTYPE- GE'ITER ION PUMP.

Tamo Asamaki',.Tokyo', Japangassignor'to Nippon Electric:

Company Limited; Tokyo; Japan"- FiledzA'ug; 18,1961, S'er. .No-r 132,468 6 Claims." ((1 230 459) This: invention relates to: a. magnetrontype": getter-ion pumpxor a. vacuum pump1.employing;:a magnetron type.

vacuum-= gauge; S'omeqof thecprior 'art methods: forobtaining'a .higlr'vacuumzsare: the. employment" of" an. oil" diifiision' pump; or' the" utilizationof a gas adsorption action offcharcoal. at an extreme 'low 'temperature. as. of"

liquid airs,v orathe utilization of'a gas adsorptiomactionof getter.

Any ofi thesedevices'which: areemployed: to: produce. a high vacuum:maybeconsideredtas. a vacuum pump-.1 Fun thfil, another: method of obtainingaa high'vacuum is. set forth. in theareporrby Mr; L.. Jespen '(page 80, No. 80, French: Ma'gazineaLe .Vide, 1958).

aside" from"'being=.;small in -size; is capablewof obtainingga.

highivacuumz'ofth'e.order'of .10 mmz. Hg: Pumping; speedsito'f approximately liters/sec. are obtainable. even withsasmall-size pump; and large-size pumpshave a pumping .speedot tens of thousands of liters per"s econd,..

and these: pumping speeds are almost constant lnTthB degree of vacuum" whichzis maintained: within the. range: of

* mm". Hg'tol( )*"mm. Hg.

It'is. also. possible: to-measure the degree of"v vacuum.

while. performing; an: exhaust operationt On;v the: other hand; a. magnetron"typenvacuum. gauge; as described in the'report by Mr. P. A. Redhead ..(American" publication Fifth National Symposium on. Vacuum Technology Transthe'region occupied by the-vacuum gauge,..that-i is, the;

regionz where the. measurement of vacuum; is takingplace, must be considered. Thus-the: pumpingspeed is a major factor=which must be. taken into account ACCOIdiXlgLIOI the-report by Mr. Redhead; set forthab'ove; thevpumping speed: in. amagnetrontype vacuumwgaugeiis in 'thewrange' of 0.15 L/sec; for helium, which-is: a reasonably large:

value; 1 1 g The. instant invention-is designed to"'p'rovide: a new magnetron-type getter-iom pump" arrangement in order to obtain a higher pumpinguspeed: at anwultra highWacuum' which. hasnot been at tained by theconventional getter ion pump of' the prior art as Well as improving the efiective' attainable degree?v of vacuum" for the getter=ion pump" as described. above".

The ultra" high-5 vacuum pump of this invention is comprised of an anode and a cooperating'cathodexwhich'are immersed in .an'" air-tight container.

should' be made. from'a material e thibitingqa substantial amount of getteringsaction such as titanium; zirconium,

This method: employs agetter=iorvpump or a cold cathode ionization vacuum? gauge 'typenvacuum-pumpt This type of getter-ion pump,

I At least the surface of the cathode of themagnetron typewvacuum gauge- 334L605 Patented: 1.964

ice

2:; magnesium, molybdenum'orrhafiiiumafor example. One or a. multiple ofi pump: elements...(thea puinp.=. element-'r-being.

the COIHblHZtiOHiOf'IhC anode of a. magnetronztypevacuumi gauge andcthe:eathodexwhichtistreated: asisets forthlahove) are housed in; a-.vacuum:.vesseh:w Fiirthergr. inrsomea cases,

fini-shaped' portionsrmade;.fromathersame:materialt preferably as .thepumprelectrodes; are; secured. :tOiIhfila electrode; especially to-thevanodetelectrode;in: suclrfaway that said fin portions face: projectttoward 'lthe: opposingrlelectrodet Thevacuum.vesselof amagnetromtypezgetterviompump which is .constructedtas" describedeabovet-isiplaced inma magnetic. fieldtand. is fposition'ed.toi'communicate 1with;bothi a vacuum. system: to be evacuated, as in? the: case; of ex-. haust-"bycharcoalvor by ordinary?getteviomzpump; and the. highsvacuum-system; Thatris, thew-magnetron: type.

getter-ionr pump andithe. vacuumrsystem;is-evacuated '10; a low" vacuumi of=about-r-l0 mmzzI-Igby meanszof auxiliary pumprwhi'chathen: initiates the. magnetron type' getter ion 'pumprintor operation: by applying: anrenergizing voltage whenathe vacuum: at 10-. mmsHgaisi attained. Soonsafter thestart. ot'this-pumping; actiomz'thetconnectione between: the hi gh 'vacuum': .system and: .therairxiliary' vac uum pump; :is. cutoff-Q" allowing; only r the .magnetr.on :type getter: ionzpumputo continue.- its; pumpingmoperation; The; vacuum". system reaches: a:. high. 'vacuumzquickl-y' througlli. the: getteringcaction: oflztheeconstithenbematerialnofiithesun face of theqanode; WhiGiI-I SQIJHM'ST'011i}.OfT-thfitGflflJDdBISIHZ?- face;

It is. therefore one: object *ofithis inventiom-toazprovidea vacuum"pumpzdesigned-sto produce.anrultra higlr vacuumo condition and to. maintaina'saici condition:

Another: object; of. this-:- invention: is. to: provide. anrela atively small vacuum: pump. capable ofiuproducinga annultra high: vacuum; wherein-x saidtpumps is. designeduto; pum sub:

st'antiall'y"largerquantities of gases'.

Another object ofinventiorrcisrto: PIOVIdBCiHQPUITlP I structurerwhichz' employs materials having; substantially i large. gettering. characteristics2..

Still another objectof this..inventioniiiswtorprovide: .a. vacuum-pump. havingzia novel; electrode.. anrangement for" obtaining; large. pumpingsacapabilitiew.

Another'objecttofthis'inventiomisatorprovidezavacuum" I pumpvhavingz-a .novelaarrangementv which2. ;includes:aplureality of tanode-cathoderpump' elements:

These, and. other: objects; of the:; invention: will? brbesti understood. from? the following-. de'scziptio elmn'iplifi'.- cations thereof; reference:beingrnade to:the-accompanying:drawings,-..whereinsz;

FIGS.. 1a.. and. 1b 'are :top ands. sideilelevation'ala views.

respectively-"of onevacuum-pump zimaccordancerwithitthe.

instantinventionv.

FIG. 2 is a .diagrammaticwview'of amsentirewvacuum'.

pump. system-.1

FIG. 3awis a"perspectiveeviewrofi anotherremhodiment of this invention:

FIGS; 3bandJ3c. are. side and 'endiviewsrespectively of a .portion'ofthe; vacuum: pump; of FIG 3iit withzportionsx of. the pump-cover'removeds. Y

FIG. 4 isanother' preferred embodimentotitheselectrode:

portionof the ultra' high: vacuumz'pumpgt FIG. 5. is. still. another: preferrediiembodimentwofthe.

electrode. arrangement;

Prior art: operationsiand devices: with svhiehEthe-present. application is" concerned','..arewdescribed; fora'instance-,-. in:

the prior artflpublieations listed-below:

fThe Production and Measurement of Ultra-High Vacuum 40- mm. Hg), by RA. Redhead, published in Fifth National Symposium on Vacuum Technology Transactions, 1958, pp. 148-152.

A Cylindrical Magnetron Ionisation Gauge, by A. H. Beck and A. D. Brisbane, published in Vacuum, vol. II, No. 2, April 1952, pp. 137-146.

The Interplay of Electronics and Vacuum Technology, by I. M. Latferty'and T. A. Vanderslice, published in Proceedings of the IRE, July 1961, pp. 1136-1154.

To simplify the description of the present invention, it is assumed that all operations and operating elements of such known systems are to be considered part of the present disclosure, except for the modifications and features of the present invention as hereinafter described.

Referring now to the drawings, FIGS. la-lb show a magnetron type getter-ion pump 10 according to this invention which is comprised of a cylindrical cathode 11 made of titanium and a cylindrical anode 12 made of titanium plate, said cylindrical anode 12 being so arranged as to coaxially surround the cathode. The cathode 11 should employ, at least upon its surface, a material having strong getter properties, such as titanium, zirconium, magnesium, molybdenum or hafnium. As to the electrode shape, it is sufficient if the cathode has an elongated configuration and not necessarily a cylindrical shape. Also, it does not effect operating efliciency if the electrode surface is uneven. The anode 12 also may be made of a metal other than titanium plate, and it is .not necessary that its shape be cylindrical. gon as will be described later.

The pump assembly 13, ,that is, the combination of anode 12 and cathode 11, is put in a vacuum vessel 14 made of a stainless steel plate. This vacuum vessel 14 may be made of glass or porcelain, or any other metal provided that it is not a magnetic material having extremely high magnetic permeability such as an ordinary steel or a soft steel. Lead wires 15 and 16 which are connected to anode 12 and cathode 11, respectively, are inserted through apertures in vessel 14. Sealing means 17 and 17a are provided for maintaining the vessel 14 in an air-tight condition. The sealing means 17 and 17a which are made of porcelain or other suitable insulating materials further act to electrically insulate leads 15 and 16 from vessel 14.

The vacuum vessel 14 is provided'with an exhaust extension 18 which acts to place the interior of the vacuum vessel 14 in communication with the vacuum system to be evacuated (not shown in FIGS. 1a and 1b). The dimensions of anode 12, cathode 11 and vacuum vessel 14, as well as the construction of pump 10 according to this invention will be more fully described in conjunction with the practical example shown in FIG. 3.

Pump 10 according to this invention is operated with a magnetic field in the direction of the longitudinal axis of cathode 11. In FIGS. 1a and 1b a horseshoe shaped permanent magnet 20 is so positioned with respect to pump 10 that it is substantially perpendicular to the axis of

magnetic poles

21 and 22 and to the longitudinal axis 11a of pump element 13, and preferably magnet 20 and pump 10 should be firmly fixed relatively by means of suitable supporting metal fittings or screws (not shown in drawing) applied in any well known manner. An electromagnet may be used instead of the permanent magnet 20 shown in FIGS. 1a and lb, or a magnetic field may be produced by applying D.-C. or A.-C. current to a coil which is positioned coaxial to the axis 11a of pump element 13. Also, the polarity of the magnetic field is not important, it can be in either the upward or down ward vertical direction. A power source 30 shown in FIGS. 1a and 1b provides a potential difference between anode 12 and cathode 11. In the case when the power source 30 is to supply D.-C. power, the positive terminal of this power device is connected to anode lead wire 15, and the negative terminal is connected to cathode lead It can be a square or a hexarespectively. But, in the case where the power source 30 is to supply A.C. power, either of the terminals of the power device can be connected to either of the lead wires. Usually, electrical conductor 32 which is connected to cathode lead wire 16 is grounded. In this case, electrical conductor 31 which is connected to anode lead wire 15, will have a relatively high voltage and it should be sufliciently insulated. The reason why vacuum pump 10 according to this invention is operative even when A.C. voltage is applied to pump element 13 is that the cathode 11 and the anode 12 are non symmetrical elements.

In FIG. 2, a flange 41 is provided at the end of the exhaust pipe 18 for securing the pump 10 to an exhaust system 40. In the case where the exhaust extension 18 in theexhaust system 10 is a metal pipe, a mating flange 42 for the flange 41 is fitted-at one end of the exhaust pipe by soldering, argon arc welding, etc., while in the case of a glass exhaust pipe, an adaptor with a flange which is attached by means of vacuum sealing material, as is well known in the art of vacuum sealing of glass and metal, is fitted at one end of the exhaust pipe. Both

flanges

41 and 42 should be tightened so that they form an air tight seal by means of suitable bolts and nuts (not shown) after inserting a gasket 49 between the flanges, said gasket; being composed of oxide free copper, Teflon or silicon rubber. Further, in FIG. 2 the axis of pump element 13 (not shown) of pump 10 is made perpendicular to the surface of FIG. 2 which shows only the permanent magnet 20, power supply 30. and electrical conductors 31 and 32. As will be subsequently explained with reference to FIGS. 3a-3c, lead wire 43 to the anode of the pump 10 is fitted to the end portion of branch pipe 44 which forms an air tight seal for vacuum vessel 14 in cooperation with electrical insulator 45 which corresponds to electrical insulator 17 as shown in FIG. 1. The lead wire 32 is connected to the pump element cathode (not shown) by electrical connection with vacuum vessel 14 directly at point 46. The body 50 to be evacuated is connected to an auxiliary vacuum pump 52, such as an oil rotary pump, through a cock or a seal valve 51. Pump 10 according to this invention is placed between the body to be evacuated 50 and the cock 51 and communicates with the body 50 by means of the

flanges

41 and 42 as described before. A

vacuum gauge 53 capable of measuring vacuum up to 10" mm. Hg is positioned between the cock 51 and the auxiliary pump 52. In a case when a substance of high vapour pressure is present in the exhaust system due to the use of a vacuum gauge such as the Maclead vacuum gauge, insertion of a trap (not shown in thedrawing) which is designed to cool by liquid air is necessary. The trap should be installed between the high vacuum system 54 and the cock 51, said high vacuum system consisting of the body to be evacuated 50 and the pump 10 according to this invention. In the case Where vacuum pumping of a plurality of bodies of the type of body 50 is desired, it is advantageous toprovide another cock (not shown in the figure) at the opposite side of the pump 10 with respect to the flange 42, thereby enabling maintenance of the interior of the pump 10 at high vacuum by dividing the high vacuum system 54 into two regions by the closing of said cock whenever the high vacuum system 54, that is the region between the body to be evacuated 50 and pump 10 according to this invention, is open to the atmosphere for changing the body 50 to be evacuated.

The auxiliary vacuum pump 52 is operated by open? ing the cock 51, and, when the degree of vacuum in the exhaust system reaches 10" mm. Hg, impressing a voltage of 1 to 5 kv. to the pump 10 by means of the power supply 30. The power supply 30 has a maximum load current preferably of 200 ma. (which is employed for a 15 minute period). The intensity of a magnetic field should be approximately 700 gauss. When such as voltage is impressed upon the pump 10 according to this invention. a cold cathode discharge occurs in the interior of the pump. At the start, the electric current is approximately 100 ma., but this gradually decreases and finally it becomes nearly 20 ma. This change in the electric current can be read by means of an ammeter which is fitted at the power supply 30; As an alternative n electric lamp which gradually becomes dim, and, finally goes out, may be installed as part of the power supply 30 which lamp may further act as a resistance element for limiting the discharge electric current. When the discharge current decreases to the above mentioned magnitude, the pump, according to this invention, is in perfect operating condition,.enabling the cock 51 to be closedthereby isolating. the-high vacuum system 52 from thebody 50. Instead u of using cock 51, the same elfect can be obtainedby sealing' that part of the exhaust pipe which corresponds to the cock 51 In the interiorof the pump according. tov this'invention, charged bodies, such as electrons, are produced by the cold cathode discharge. Of these charged: bodies, electrons and other negative charged bodies will travel from cathode 11 to anode 12, along avery long path whose length isdetermined by the magnitudes ofthe electric' field and the magnetic field which are in existence in the space between anode 12and cathode 11. The accelerated negative particles moving towards the anode collide with=theresidual airmoleculescausing ionization'to occur. The positive charged bodies formed by ionization reach cathode 11 which collision emits electrons again,. while spattering titaniurnout of the: surface-of thescathode 11.

Generally, there are two ways of producing theexhaust actionof the getter, i.e., the dispersal gettering: and the contact gettering, as is explained on page 13 in, a. JapanesebooFSinkukan no Getta'nikansuru kenkyo. (Studies on vacuum tube getter)," by Dr. Osamu Harashima, published February'1950 by Maruzen Book store. In the dispersal gettering, the getter molecules and the gas molecules are combined and adhere to the wall of a vessel when. the getters fly, thus exhibiting a high adsorption power although for a very short time. Inv the: contact gettering, a. gettering film which has been formed on a vessel wall adsorbs the residual gas molecules for a long time, although it does not show a high adsorption P wer. The pump 10 according to this invention designed to perform the contact gettering by' adhering titanium to anode 12. The reason why the magnetron type getter ion pump of this design has an effective attainable high. vacuum, is as described before, that in the magnetron type vacuum gauge a cold cathode discharge is-continued at an ultra highvacuum. By this fact and together with a. gettering action, especially bythe dispersal gettering, the pumping speed at high vacuum becomes larger and it is possible to measure the pumping speed at ultrahigh vacuums. Further, insthe magnetron type getterion pump of this invention, the cathode 11 will normally be consumed, but when operated in a vacuum of 10- mm. Hg it is possible to continue use of the cathode without trying to improve its performance even. when it has been operating for more than 40,000 hours, which means it has morev than 40,000 hours of successful operating life.

In: FIGS. 3a3c, the pump 10 according to this inven-- tion. consists of nine individual pump elements 13. The cathode 11 of each pump element 13 is a titanium rod (about 6 mm. dia. and 3.0 mm. length). Both ends of each of the rods 11 are provided with projections 61 (about- 3 mm. dia. and 15 mm. length) which areintegral with and coaxial with the main cathodeportion 11. The anode. 12' is made of titanium plate: (about 0.4 mm. thick, and mm..height) and isso constructed, by means .of spot welding, as to form a regular square: electrode with each side being 13 mm. It should bev understood.

that the dimensions given are merely exemplary and. play no novel part in the instant invention. A notched anode arrangement 100 is employed where the titanium plates intersect. The vacuum vessel 14 is comprised of a dish shaped body 62' and a planar cover 63 each made of stainless steel of about 1.5 mm. thick. The dish shaped body 62 may be formed by pressing" a stainless steel plate and is designed to form substantially a regular square pole interior space having about. 60 mm. side An electrical insulator 45, formedof. aninsulating ma-- terial suchas porcelain, is positioned. toform an airtight seal by means of a' 'vacuum' seal body such as an ironni'ckel-cobalt' alloy known. as Kovar. A. Kovar" wire 43 of approximately 6.0 mm: dia; is sealed in. electrical insulator 45 in main tight arrangement. The wire which is a Monel wire extends slightly into the interior of the vacuum vessel 14 to serve as theanodelead wire 43. A cathode 11 is insertedat the bottom of the dish shaped body 62 (which corresponds to topmost portion in the elevation at view of: FIG. 321).. A cathode supporting body 64, consisting of a titanium plate of about, 1.6 mm. thickness, is provided with an aperture to. re-- ceive the projection 61 of the cathode 11 when it is positioned therein. Said cathode supporting. plate 64 is inserted in such' a waythat the'upper surface of the platetouches the inner surface 62a; of' the dish shaped, body 62. Thus the cathode 11 is. maintained. inv a. predetermined position by fitting one of the. projected. portions 61a into the aperture inthef-supporting: body 64, and the anode 12 is positioned in thevregi'on enclosed by the dish. shaped body 62 and cover plate 63:": Thez anode is secured to the. predetermined: position shown: in FIGS. 3b: and. 30 by spot welding an anode: supporting; element (not shown in the drawing) and the end of' the Monel wire extension (not shown) of the anode lead wire 43. The anode supporting element consists of at shaped projection which isspot welded to the exterior of the anode. Next, the cathode 11 is secured to azdesired'position by fitting. the other-projection 61b of: the cathode 1 1 into a cooperating aperture in the cathode: supporting body 65 which is similar: to the cathode supporting body 64. The cover p1ate'63'fits over thecathode supporting body 65 so that the surfaces of. b'oth members. contact each. other (members 63 and 65), sealing. the circumference of the plate 63- and' the flangedportionof the dish shaped body 62' by meansof argon: arcweldingrwhich creates an. air tight seal. The electrical" connection between the cathode 11 and. thevacuum vessel14is'eifected merely by the pressure fitting. of the: elements and: by en-- gagement of the surfaces of'the cathodes 1'1 and members 62 and 63', since the discharge current is: approximately 200 ma. at. the'maximum. As: previously described, a cathode of'the type of cathode 11 is worn'out by sputtering, the percentage. of wearing-out being approximately 5% out of in cases. where thepump 10 has been operated for 40,000 hours at pressuresv 1.0" mm. Hg. Regarding materials. and types: for-'each element, only those restrictions as previously described. are.

to be followed, while no other restrictions are present with respect to special materials, types. and dimensions? arranged in suclr a manner: that their planesare parallel I to the. longitudinal ,axis'of the pump.- element' 13: (see FIGS. 1b and 3b). The fins 71. are spot weldedi so as to project inwardly towards the region bounded by the regular square pole between plates which constitute the beforementioned anode.

As shown in FIG. 5, anode 12 is provided with

finshaped portions

72, 73 or 74 the planes of which are perpendicular to the aforementioned cathode longitudinal axis, but in this case it is necessary that these finshaped parts should be provided with apertures 75 having diameters which are greater than the outer diameter of the cathode (not shown) so that they do not come into engagement with each other. FIG. also discloses lugs 76 which are employed for, spot welding the fin shaped

members

72, 73 and 74 to the main body of the anode 12.

In the pump according to this invention whichvemploys the modified anodes as shown in FIG. 4, the mean free path of charged body is longer than the path of prior art devices, resulting in higher pumping speed, as described on page 60 in a Japanese book Tyokoshuha Densikan (Ultra-high-frequency Electron Tube), by Dr. Kenjiro'Okabe and others (Shukyosha, 1953). In the pump according to this invention, which uses the modified anodes, as shown in FIG. 5, the pump electric current or pumping speed is much higher, by the same reason as in the case where the electric current of a vacuum gauge is made larger by making projections on the surface of.:the anode of a magnetron vacuum gauge as described in the report by A. H. Beck in English magazine Vacuum, 1952, volume 2, starting on page 137.

The outline of the present invention, together with the several embodiments have been given. The features and principles underlying the invention described above in connection with specific exemplifications thereof will suggest to those skilled in the art many other modifications thereof. It is accordingly desired that the appended claims shall not be limited to any specific features or details described in connection with the exemplifications thereof.

I claim:

1. A magnetron type getter ion pump comprising a plurality of pump elements each of which consists of a cathode of predetermined length, said cathode being cylindrical in shape, at least the surface of said cathode being formed of material having high gettering action, a cylindrical shaped metallic anode arranged around the cathode and electrically insulated therefrom; the longitudinal axes of said anode and said cathode being'arranged substantially in parallel; first means for generating a magnetic field in the region of said pump element, a vacuum vessel for housing said pump elements; said vessel having at least one cylindrical portion extending from the body of said vessel suitable for connection to a vacuum system to be evacuated; second means positioned outside of said vessel for applying a voltage across said anode and said cathode, the longitudinal axes of each of said pump elements being arranged in parallel relation with said magnetic field, a planar member arranged perpendicular to said longitudinal axes and having apertures for receiving said cathode, each of said apertures having a diameter greater than the diameter of said cathode; said planar member being secured to said anode at one end thereof.

2. A magnetron type getter ion pump comprising a plurality of pump elements each of which consists of a cathode of predetermined length, saidcathode being cylindrical in shape, at least the surface of said cathode being formed of material having high gettering action, a cylindrical shaped metallic anode arranged around the cathode and electrically insulated therefrom; the longitudinal axes of said anode and said cathode being arranged substantially in parallel; first means for generating a magnetic field in the region of said pump element, a vacuum vessel for housing said pump elements; said vessel having at least one cylindrical portion extending from the body of said vessel suitable for connection to a vacuum system to be evacuated; second means positioned outside of said perpendicular to said longitudinal axes and having aper-" tures for receiving said cathode, said planar members being electrically insulated from said cathode, each of said apertures having a diameter greater than the diameter of said cathodes; said planar members each being secured to said anodes at opposite ends thereof.

3. A magnetron type getter ion pump comprising a plurality of pump elements each of which consists of a cathode of predetermined length, said cathode being cylindrical in shape, at least the surface of said cathode being formed of material having high gettering action, a cylindrical metallic anode arranged around the cathode and electrically insulated therefrom; the longitudinal axes of said anode and said cathode being arranged substantially in parallel; first means for generating a magnetic -=field in the region of said pump element, a vacuum vessel for housing said pump elements; said vessel having at least one cylindrical portion extending from thegbody of said vessel suitable for connection to a vacuum system to be evacuated; second means positioned outside of said vessel for applying a voltage across said anode and said cathode, the longitudinal axes of each of said pump elements being arranged in parallel relation with said "magnetic field, a planar member arranged perpendicular to said longitudinal axes and having apertures for receiving said cathode, said planar member being electrically insulated from said cathode and electrically connected to said anode, each of said apertures having a diameter greater than the diameter of said cathodes; said planar member being secured to said anode at one end thereof,

4. A magnetron type getter ion pump comprising a plurality of pump elements each of which consists of a cathode of predetermined length, said cathode being cylindrical in shape, as least the surface of said cathode being formed of material having high gettering action, a rectangular shaped metallic anode arranged around the cathode and electrically insulated therefrom; the longitudinal axes of said anode and said cathode being arranged substantially in parallel; first means for generating a magnetic field in the region of said-,pump element, a vacuum vessel for housing said pump elements; said vessel having at least one cylindrical portion extending from the body of said vessel suitable for connection to a vacuum system to be evacuated; second means positioned outside of said vessel for applying a voltage across said anode and said cathode, the longitudinal axes of each of said pump elements being arranged in parallel relation with said magnetic field, a planar member arranged perpendicular to said longitudinal axes and having apertures for receiving said cathode, each of said apertures having a diameter greater than the diameter of said cathode; said planar member being secured to said anode at a point intermediate the ends thereof, said planar member being adapted to divide said pump elements into an upper and a lower pump region.

5. The getter ion pump of claim 2 further comprising a third planar member parallel to said first and second planar members and being secured to said anode at a point intermediate the ends thereof; said third planar member having apertures for receiving said cathode; said third planar member being adapted to divide each of said pump elements intovan upper and a lower-pump region, each of said apertures having a diameter greater than the diameter of said cathode; said planar member being sedrical shaped metallic anode arranged around the cathode and electrically insulated therefrom; the longitudinal axes 9 of said anode and said cathode being arranged substantially in parallel; first means for generating a magnetic field in the region of said pump element, a vacuum vessel for housing said pump elements; said vessel having at least one cylindrical portion extending from the body of said vessel suitable for connection to a vacuum system netic field; each of said cylindrical shaped anodes having a plurality of fins projecting towards said cathode; each of said fins being secured to said anode at the corners thereof and being substantially parallel to the longitudinal axis of said cathode.

References Cited in thefile of this patent UNITED STATES PATENTS Hall et al. July 25, 1961 Zaphiropoulos Jan. 39, 1962

Claims

1. A MAGNETRON TYPE GETTER ION PUMP COMPRISING A PLURALITY OF PUMP ELEMENTS EACH OF WHICH CONSISTS OF A CATHODE OF PREDETERMINED LENGTH, SAID CATHODE BEING CYLINDRICAL IN SHAPE, AT LEAST THE SURFACE OF SAID CATHODE BEING FORMED OF MATERIAL HAVING HIGH GETTERING ACTION, A CYLINDRICAL SHAPED METALLIC ANODE ARRANGED AROUND THE CATHODE AND ELECTRICALLY INSULATED THEREFROM; THE LONGITUDINAL AXES OF SAID ANODE AND SAID CATHODE BEING ARRANGED SUBSTANTIALLY IN PARALLEL; FIRST MEANS FOR GENERATING A MAGNETIC FIELD IN THE REGION OF SAID PUMP ELEMENT, A VACUUM VESSEL FOR HOUSING SAID PUMP ELEMENTS; SAID VESSEL HAVING AT LEAST ONE CYLINDRICAL PORTION EXTENDING FROM THE BODY OF SAID VESSEL SUITABLE FOR CONNECTION TO A VACUUM SYSTEM TO BE EVACUATED; SECOND MEANS POSITIONED OUTSIDE OF SAID VESSEL FOR APPLYING A VOLTAGE ACROSS SAID ANODE AND SAID CATHODE, THE LONGITUDINAL AXES OF EACH OF SAID PUMP ELEMENTS BEING ARRANGED IN PARALLEL RELATION WITH SAID MAGNETIC FIELD, A PLANAR MEMBER ARRANGED PERPENDICULAR TO SAID LONGITUDINAL AXES AND HAVING APERTURES FOR RECEIVING SAID CATHODE, EACH OF SAID APERTURES HAVING A DIAMETER GREATER THAN THE DIAMETER OF SAID CATHODE; SAID PLANAR MEMBER BEING SECURED TO SAID ANODE AT ONE END THEREOF.