US2715993A

US2715993A - Ionization pump

Info

Publication number: US2715993A
Application number: US292213A
Authority: US
Inventors: Jerome R Batina
Original assignee: W M WELCH Manufacturing Co
Current assignee: W M WELCH MANUFACTURING Co
Priority date: 1952-06-06
Filing date: 1952-06-06
Publication date: 1955-08-23
Anticipated expiration: 1972-08-23

Description

Aug. 23, 1955 J. R. BATINA 2,715,993

IoNIzATIoN PUMP Filed June e, 1952 2 sheets-sheet 1 IN V EN TUR.

Aug. 23, 1955 .1. R. BATINA IoNIzATIoN PUMP 2 Sheets-$heet 2 Filed June 6, 1952 JNVENTOR.Y Jerome Rfza,

United States Patent hun! INIZATIN PUM? Jerome R. Batina, Chicago, lil., assigner to W. M. Welch Manufacturing Company, Chicago, El., a corporation of Illinois Application .lune 6, 1952, Serial No. 292,213

Claims. (Cl. 2313-59) The present invention relates to improvements a high vacuum pump, afording a unit capable of obtair-'ng a pressure substantially lower than the pressures att inable by present day diffusion pumps. More particularly', the invention relates to a vacuum pump by means oi which the interior of a vessel to be evacuated is subjected to the direct ionizing action of a space discharge voltage, and/ or some other externally energized source of ioniri action, and to the action of alpha particles or other ra active particles independent of any externally impressed voltage source. Such combined electrical and radioactive sources complete the ionization and evacuation of gas in the vessel to a degree substantially greater than is possible by any other pumping operation of which l am aware, mechanical, diffusion or combined.

The production of an electrical discharge in an enclosed system is ltnown to result in lowering of the pressure therein. Thus, one known technique of reducing pressure involves the production of an electrical discharge between two electrodes in a vessel communicating directly with a space containing a rarified gas, such as a vacuum type radio tube. As a result, gaseous molecules in the tube are ionized, the ions are displaced in the electric iield existing between the electrodes, arrive rapidly at one thereof, lose their charge and are carried away, with consequent drop in the pressure in the space.

However, it has been found necessary to use a high electrical potential for this operation. it is also found that the pressure rises again upon interruption of the discharge. Likewise, the electrical discharge relied on to ionize the gas is itself dependent upon the existence of a gas pressure in the vessel in question to maintain the discharge; hence when a predetermined, minimum vacuum is obtained the discharge carl no longer be maintained. Operation of the unit ceases. Aside from this inherent and inescapable limitation in such an externally energized vacuum pumping system, the requisite voltage is so high as to constitute a factor of danger.

The present invention provides an ionizon type pump which is of the above general classification, but one in which there are multiple sources of ionization of the gaseous molecules remaining in a system or vessel to be evacuated, including a source independent of external electrical space discharge voltage, hence independent oi the '-egree of pressure of the gas remaining in the system or vessel. In the illustrated embodiment alpha particles, or equivalent particles of any Seli-sustaining source of emission, are utilized to ionize such remaining gas, assisting in the separation oi the gas molecules from the walls or the vessel and expediting removal of the ionized particles. Pihese are recombined at an electrode or electrodes of a further, externally energized source of ionization by direct current space discharge voltage. They are eventually discharged, as by the use of a mechanical or diliusion pump. A still further high frequency excitation by an external voltage source is preferably resorted to, as shown in one o the embodiments of the invention illustrated herein, for the purpose of exciting the molecules independently, and in CAD order to improve rthe ionizing eliect of the inter-electrode ionizing liov.' and the radio-emissive ionizing charge upon the gaseous molecules in the vessel. A

The independent source of particle emanation which is 'posed to gas i'i the system, or a vessel communicating with that syste n, n accordance with the invention, may be a capsule containing radium, radioactive derivative, nuclear fission 4ivy-product, and the like. The life cycle of such an emitter is iniiuite, for all practical purposes. The voltages required for the other purposes referred t0 above are simply obtained non-excessive in value. Likewise no particular maintenance is required as regards ser ,cement of parts, etc.

iererore be seen that it is a general object of invention to provide an improved high vacuum pump, which ma" incidentally, he used by itself or as one stage stage unit incorporating an associated pump stage or stages or" mechanical or didusion type, which improved pump utilizes the principle of ionization of gaseous molecules to substantially lower pressure, by subjecting such molecules to the combined action of an externally energized controlled electrical field or space discharge and i..dependent source or radioactive electrical particle emission; which is very inexpensive to produce and operate and, moreover, to operate with entire safety; which is rendered self-sustaining to the extreme limit of its almost indefinite age d ionizing capacity; and which calls for little or no maintenance worl; in operation over a long period of time.

The foregoing statements are indicative in a general way of the nature ot' the invention. @ther and more specic objects will be apparent to those skilled in the art upon a full understanding of the construction and operation of the improved pump.

Several embodiments of the invention are presented herein for purpose of illustration. lt will be appreciated that the invention may be incorporated in still other modified forms coming equally within the scope of the appended claims.

In the drawings:

Fig. l is a fragmentary ront elevational View, quite diagrammatic in character, illustrating structural components and associated wiring provisions of a high vacuum, ionization type pump in accordance with one embodiment of my invention;

Fig. 2 is a fragmentary plan view or" the pump provsions shown in ig. l, being partially broken away and in horizontal section along a line corresponding to line 2-2 of Fig. l; and

Figs. 3, 4 and 5 are fragmentary schematic elevational views of pumps in accordance with modified adaptations or the invention, Figs. 4 and 5, in particular, illustrating staged arrangements of pump units similar to those of Figs. l, 2 and 3.

Referring to Figs. l and 2 of the drawings, the reference numeral itl generally designates a vacuum chamber and the reference numeral l1 generally designates an arrangement of electrode chambers and associated electrical operating means for the pump, to be hereinafter described in detail. in the form of the invention shown, vacuum chamber l@ is provided with a laterally opening coupling tube or intalienipple l2 by means of which it is adapted to be connected, as by suitable high vacuum connection (not shown), with any vessel to be evacuated. As stated above, the pump of the present invention may also be employed as a staged unit with other pumps of known type and, moreover, either as a roughing or nishing stage. Hence the intake nipple 12 may be connected to the discharge side of a preceding, nish stage pump; alternatively, the present ionization pump' may be used as a finishing stage, its discharge end (to be described) being coupled to a succeeding stage of any desired type.

Vacuum chamber 1t? has a radially extending discharge neck 13 which is coupledin sealed relation to the intake passage'li of the unit l1. Passage V14.' opens in opposite lateral directions to a pair of aligned'brauch passages 15,

@each of which in turnV opens to an enlargedglass or insulated electrode chamber 16.

As illustrated in Fig. 2, each of the electrode chambers 16 has a lateral discharge Vport 17, the ports 17 being communicated by discharge passages 1S with a common central discharge tube or pipe 19. This pipe may open to Vcommunicating passages 1S, when the electrodes are properly energized. Conductors 22 are provided for the last Vnamed purpose, extending rearwardly in opposite directions from the electrodes to which they are connected and through enlargements Z3 on the rear walls of the electrode chamberslo. The conductors are of course in air-tight, electrically insulated krelationship to the charn- Vbers 16, and they. are'connected to the positive and negative poles of a suitable steady D. C. potential of, say, 800

'Y volts. Of course, this value as well as the amperage value may vary in `accordance with the pumping pressure and other factors.

Primary and

secondary coils

24, 25 are coiled about the branch passages 15 of unit 11. Conductor coil 24 is the output coil of a suitable high frequency oscillator circuit (not shown)jand coil 25 is a step-up secondary excited by the high frequency current in coil 2.4.A

Y The functions of the electrodes 2? and A. C. 'coils will be enlarged on at a later point. For the present it sufices to point out that the former are relied on to give mobility and'direction to the dissociated molecules, and in certain pressure ranges, to furnish an electron stream yto ionize gaseous molecules in branches 15, and space terior of unit llis subjected) also has a similar ionizing action. VMore important thanthis, however, the high fre- VVquency field has the eect of causing a swirl or turbulence ticles, or like independent source of radioactive emission.

This source is generally designated S. As stated, it may t be in the form of a capsule of a suitable radioactive deriva- Ative, a suitable by-product of nuclear fission, radium, radium-bearing compound, or the like. The capsuleV or other container may be held in `place in unit 11 by any `specifically deal. Y

In use, with the vacuum chamber connected directly .orindirectly by coupling 12 with a vessel to be evacuated,

the sets of conductors Z?. and 24 are electrically energized by their respective D. C. and A. C. sources. The electron stream between electrodes Ztl substantially ionizes gaseous molecules in the electrode vessel. The same result is Y producd by the high frequency field of

coils

24, 25. Both of these effects continue, with resultant dropping of pressure in the vessel, but at a diminishingrate, so far as these externally energized sources Vare concerned. The field created

Vbycoils

24, 25 disturbs and irriparts swirlto the d. electron stream, as roughly depicted by brokenv lineV and stippling in Fig. 2.

Therradioactive emission source S continues to Vionize Y` lmolecules practically indefinitely, and is reduced in its ionizing rate only to the extent that rarification of ther. -vesSel leaves fewer gas molecules to be'struck and ionized.

However, the field of, coils 24, 25 continues to impart energy to the lower energy radioactive particles and rays,Y

and to the respective particles of the molecules which -they ionize in branches 15 and passage 14, producing a swirl and turbulence, increasing the likelihood of Vcollision with other gas molecules and thus maintaining a desired rate of ionization, notwithstanding the Votherwise deteriorated 'communicating therewith, while the high frequency field Y Y Vof coils 24, 25 (or any equivalent fieldto which the in- Yappropriate means, with which the invention does not Y conditions for ionization. The high frequencyl fleld substantially expedites attraction of ionized particles to electrodes 2).

While I have illustrated a pair of coils 24, 25V for Y the purpose of producing a high frequency field in the unit 11, it should be understood that other structural provisions may be employed to this same end, such as rings or clips applied to branches 15 and energized from a suitable alternating source..

A modified embodiment of the invention is illustrated in Figure 3 Of the drawings. Its structural components are, in most respects, similar to those illustrated in Figs. l and 2, hence corresponding reference numerals, primed,

are employed in Fig. 3 to designate corresponding parts.

Further description of such parts is dispensed with.

A suitable external support 28 is providedV for the radioactive source, here designated S', adjacent the junction Vofthe passage'14 with the branch passages 15.

As illustrated, support 28 is provided withra cavity 30l in which the capsule or source S' is'disposed.Y Alternatively, Vthe source Smay be mounted within the unit 11',v 'K

branches 15 of the same with its poles in opposed rela- Y tion to one another at Vthe junction of branches 15 with passage 14. In other respects the embodiment of Fig. 3 is like that of Figs. l and 2. The eld of magnet 32 imparts swirl or turbulence to the electron stream between electrodes 20 and to the radio-active` particles emitted from the source S. Efliciency of ionization of lthe gas molecules remaining in the space to be evacuated is thus promoted.V in other respects the operation of the unit of Fig.,3 is as described in connection with Figs. l, and 2, with the exception that fno high frequency field phenomenon is involved. However, thehighV frequency field may be added to increase the efficiency of the pump. Figs. 4 and 5 illustrate seriesand parallel-staged arrangements of ionization pump units of the character described above. Inasmuch as these two forms differ primarily only as to the physical arrangement of certain chambers, conducting passages, etc., with relation to one another, rather than in details of those individualV components themselves, only general reference will beV made to such details.

VReferring kto Fig. 4, the vacuum chamber is con-V nected by'a quadruple branched supply conduit 36 with two sets of electrode chambers, marked 37 3Iand 38, 3S, respectively. Lateral intake passages 39 open from Vconduit 36 yto the laterally aligned chambers V37 and corresponding intake passages 40 open from the conduit to the chambers 38. The respective pairs of 'chambers 37, 33 are each provided with a common discharge conduit .41 which is communicated by piping 42,with a common discharge line 43. The independent source of radia parallel, arrangement. Hence corresponding parts are designated by the same reference numerals, primed, as are employed in Fig. 4.

A branched discharge line 50 leads from the respective electrode chambers 37 and joins a common discharge passage 51, which in turn communicates through branch passages 52 with the electrode chambers 38'. The source of radioactive particle emanation 53 is disposed in a recess 54 between the branch passages 52. Discharge passages 55 from the chambers 38 meet at a common exhaust line 56.

It will be understood that secondary externally energized excitation means, corresponding to coils 24, 25 of Figs. l and 2 or to magnet 32 of Fig. 3, or any equivalent means to agitate the path of electronic particles, thereby adding to the path length, increasing the likelihood of molecular impact, and speeding ionized particles to the electrodes, may be employed in the forms of the invention shown in Figs. 4 and 5, having been omitted solely for the sake of simplicity.

While I have illustrated various embodiments of the invention, involving a pair of electrodes in a sealed pump chamber which are externally energized electrically by a direct current voltage source, these electrodes may also be energized by a high frequency alternating current source, with or without further internal or external ion path disturbing provisions such as the radio-active source magnet or coils, with similar, though less thoroughly effective ionization of gaseous molecules. Accordingly, with this in mind, the electrodes and their connected conductors 22 may be considered illustrative of such a high frequency field adaptation. in this alternative respect the electrodes have much the same function as the high frequency coils 24, of the modification of Figs. 1 and 2.

l claim:

l. An ionization vacuum pump comprising a casing defining a sealed, air-tight pumping chamber, which chamber has a gas intake opening adapted to be connected to a space to be evacuated and a gas discharge opening to the exterior of said casing, a pair of spaced electrodes mounted in said chamber at opposite ends of a path of electron flow therethrough, conductors connected to said electrodes and extending through said casing in sealed relation thereto, which conductors are adapted to connect said electrodes with terminals of an external voltage source and thereby cause ionization of molecules in said chamber by electron ow along said path, followed by attraction of ionized particles to one of the electrodes and electrical discharge thereof, and an independent source of emission of radioactive particles located between said electrodes, said source being sufficiently closely adjacent said electron ow path to supplement the ionization in said chamber created by said electrodes, which independent source becomes the predominant source of ionization under an extremely high degree of evacuation of said chamber.

2. An ionization vacuum pump comprising a casing detining a sealed, air-tight pumping chamber, which chamber has a gas intake opening adapted to be connected to a space to be evacuated and a gas discharge opening to the exterior of said casing, a pair of spaced electrodes mounted in said chamber at opposite ends of a path of electron flow therethrough, conductors connected to said electrodes and extending through said casing in sealed relation thereto, which conductors are adapted to connect said electrodes with terminals of an external voltage source and thereby cause ionization of molecules in said chamber by electron flow along said path, followed by attraction of ionized particles to one of the electrodes and electrical discharge thereof, an independent source of emission of radioactive particles located between said electrodes, said source being suiliciently closely adjacent said electron flow path to supplement the ionization in said chamber created by said electrodes, which independent source becomes the predominant source of ionization under an extremely high degree of evacuation of said chamber, and means creating a field acting to disturb the iiow of electrons in said path and to cause turbulence in the movement of radioactive particles emitted by said independent source.

3. An ionization vacuum pump comprising a casing defining a sealed, air-tight pumping chamber, which chamber has a gas intake opening adapted to be connected to a space to be evacuated and a gas discharge opening to the exterior of said casing, a pair of spaced electrodes mounted in said chamber at opposite ends of a path of electron iloW therethrough, conductors connected to said electrodes and extending through said casing in sealed relation thereto, which conductors are adapted to connect said electrodes with terminals of an external voltage source and thereby cause ionization of molecules in said chamber by electron ilow along said path, followed by attraction of ionized particles to one of the electrodes and electrical discharge thereof, an independent source of emission of radioactive particles located between said electrodes, said source being sufficiently closely adjacent said electron flow path to supplement the ionization in said chamber created by said electrodes, which independent source becomes the predominant source of ionization under an extremely high degree of evacuation of said chamber, and means creating a high frequency eld acting to disturb the iiow of electrons in said path and to cause turbulence in the movement of radioactive particles emitted by said independent source.

4. An ionization vacuum pump comprising a casing defining a sealed, air-tight pumping chamber, which chamber has a gas intake opening adapted to be connected to a space to be evacuated and a gas discharge opening to the exterior of said casing, a pair of spaced electrodes mounted in said chamber at opposite ends of a path of electron iiow therethrough, conductors connected to said electrodes and extending through said casing in sealed relation thereto, which conductors are adapted to connect said electrodes with terminals of an external voltage source and thereby cause ionization of molecules in said chamber by electron flow along said path, followed by attraction of ionized particles to one of the electrodes and electrical discharge thereof, an independent source of emission of radioactive particles located between said electrodes, said source being suiiiciently closely adjacent said electron ow path to supplement the ionization in said chamber created by said electrodes, which independent source becomes the predominant source of ionization under an extremely high degree of evacuation of said chamber, and a coil energized at high frequency and surrounding said casing between said electrodes, said coil creating a high frequency field acting to disturb the ow of electrons in said path and to cause turbulence in the movement of radioactive particles emitted by said independent source.

5. An ionization vacuum pump comprising a casing deiining a sealed, air-tight pumping chamber, which chamber has a gas intake opening adapted to be connected to a space to be evacuated and a gas discharge opening to the exterior of said casing, a pair of spaced electrodes mounted in said chamber at opposite ends of a path of electron flow therethrough, conductors connected to said electrodes and extending through said casing in sealed relation thereto, which conductors are adapted to connect said electrodes with terminals of an external voltage source and thereby cause ionization of molecules in said chamber by electron flow along said path, followed by attraction of ionized particles to one of the electrodes and electrical discharge thereof, an independent source of emission of radioactive particles located between said electrodes, said source being suiciently closely adjacent said electron flow path to supplement the ionization in said chamber created by said electrodes, which independent source becomes the pre- 7 dominant source of ionization under an extremely high degree of evacuation of said chamber, and magnetic means creating a magnetic eld acting to disturb the How of electrons in said path and to cause turbulence in the movement of radioactive particles emitted by said independent source.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain Apr. 17, 1945

Claims

1. AN IONIZATION VACUUM PUMP COMPRISING A CASING DEFINING A SEALED, AIR-TIGHT PUMPING CHAMBER, WHICH CHAMBER HAS A GAS INTAKE OPENING ADAPTED TO BE CONNECTED TO A SPACE TO BE EVACUATED AND A GAS DISCHARGE OPENING TO THE EXTERIOR OF SAID CASING, A PAIR OF SPACED ELECTRODES MOUNTED IN SAID CHAMBER AT OPPOSITE ENDS OF A PATH OF ELECTRON FLOW THERETHROUGH, CONDUCTORS CONNECTED TO SAID ELECTRODES AND EXTENDING THROUGH SAID CASING IN SEALED RELATION THERETO, WHICH CONDUCTORS ARE ADAPTED TO CONNECT SAID ELECTRODES WITH TERMINALS OF AN EXTERNAL VOLTAGE SOURCE AND THEREBY CAUSE IONIZATION OF MOLECULES IN SAID CHAMBER BY ELECTRON FLOW ALONG SAID PATH, FOLLOWED BY ATTRACTION OF IONIZED PARTICLES TO ONE OF THE ELECTRODES AND ELECTRICAL DISCHARGE THEREOF, AND AN INDEPENDENT SOURCE OF EMISSION OF RADIOACTIVE PARTICLES LOCATED BETWEEN SAID ELECTRODES, SAID SOURCE BEING SUFFICIENTLY CLOSELY ADJACENT SAID ELECTRON FLOW PATH TO SUPPLEMENT THE IONIZATION IN SAID CHAMBER CREATED BY SAID ELECTRODES, WHICH INDEPENDENT SOURCE BECOMES THE PREDOMINANT SOURCE OF IONIZATION UNDER AN EXTREMELY HIGH DEGREE OF EVACUATION OF SAID CHAMBER.