US1501070A

US1501070A - Vacuum pump

Info

Publication number: US1501070A
Application number: US405621A
Authority: US
Inventors: Homer C Snook
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1920-08-24
Filing date: 1920-08-24
Publication date: 1924-07-15
Anticipated expiration: 1941-07-15

Description

.July l5, |924.

1,501,070 H. C. SNOOK VACUUM PUMPv Filed Aug. 24*I 1920 elli) H0 C. M603, OF SOUTHORANGE, NEW BSEY, ASSIGNOB l TRIS CQMPAN'Y, INCORPORATED, '0F NEW YORK, N. Y., A. GORPOBATION' t appueauon anhang-m 24, ieee. semi no. 405,621.

ATo all whom t may concern:

Be it known that I, Homan C. SNooK, a citizen of the United States, residin at South Orange, in the county of Essex, tate of New Jersey, have invented certain new and useful Improvements in Vacuum Pumps, of which the lfollowing lis a full, clear, concise, and'exact description.

This inventionv relates to vacuum pumps of the entraining or aspirator type and to `methods of operating the same.

In the production of the high vacua employed in vacuum tubes ofthe pure electron discharge type, it heretofore has been customary to connect a tube to be evacuated to a low vacuum pump, for example, a mechanical pump capable of pumping out to a pressureo -s mm. of mercury and to produce a higher vacuum by the use oit an aspirator employing mercury vapor connected between the low vacuum or roughing pump and the device being exhausted. An example of apparatus of this kind is disclosed in the application of 0.143. Buckley, Serial No. 96,265, filed May 8, 1916. In

pumpingsystems of this type the flow of vapor through the aspirator is caused by a di'erence of pressure between the chamber in which the vapor is evolved and the pas sage leading to thepreliminary pump. In the flow of, a gaseous medium through a passage, not all 'of the particles move in the direction of the axis of the tube, and it -,has

been customary to 'provide special means for which are moving transversely to the desired direction or for otherwise controlling the stream.y so that there will be no appreciable back flow of pumping medium in the dii passage leading' from the container being evacuated. A The object ofthis 'invention is an im! proved means and method for producing and controlling the direction and velocity of a stream of `particles foruse in pumping.

The invention provides for ionizing a gaseous or vaporous pumping medium: by means of' an electron discharge, controlling the iiow of the electrically charged particles throu h electrical forces, and utilizing the electrically charged particles for entraming as to be removed from a vessel. According to the invention advanta e is taken of the fact that on the average t e mass of the than that of t e negatively charge from the stream those particlesv trodes. An

eater Paf? positively char particles is much ticles. Some of thepositively char ticles are permitted tobe carried y t eir inertia beyond the discharge path. Thesesimilarly charged articles4 are then subjected to a second eectric field and made to do thework of entraining the 's rom the 'devices to be evacuated. gm

The pumping medium is preferably a substance which will condense at the temperature of the as irator passage at its termina.- tion so that 51e medium may be recovered and returned to the main body of material. It may, for example, be a substance like mer- -cury 'which liquefes at roomtemperatures,

or it may be a substance like tin, lead, cad- 'mium or zinc which liquey or solidify at temperatures considerably above room temp'eratures. It is of'advantagez to employ a substance like those last mentioned, which at condensing temperatures has a vapor pressure less than the pressure to be4 obtained in the container being evacuated.

The invention resides further in the details of apparatus` and operationpointed out in the following descrlption and. claims taken in connection with the accompanying drawings, in'which Fig. 1 is a diagrammatic view showing one form` of apparatus employing the invention, and Fi 2, 3 and 4 are similar views showing m iications.

lReferring to the drawings by reference numerals, the prima or rou hing pump 10 is connected to the ulb 12- w 'ch is to be evacuated by a system of tubing which comprises an aspirator passage 15 and a asse e. 17 leading from bulb 12 and entering t e assager 15 at an angle as shown. At the ower part of passage 15 is a .chamber 20 which may contain a suitable pumping medium such as mercury shown at 21. Anannular chamber 23 above chamber 20 is also filled with mercury. A source of electrometive force 22 is connected between the bodies 'of mercury in chambers 23 and 2O and is so poled that the annular body of mercury in chamber 23 may serve as a cathode for an electric discharge between the two elecsmtable means (not shown) may be emp oyed for starting the dischar Some of the positively charged artic es travelin in the direction of catho e 23 are carriedl y their momentum into the passage 15. A grid-like cathode 25 at the upv vper end of the passage is connected through a source of potential 26 to the cirentered passage 15 to moye toward electnode lac 25 ata velocity Which'may be controlled by varying the potential applied between

thel electrodes

23 and 25 through the medium of the variable resistance 26. The flow of charged particles throu h passage 15 serves to entrain gas comin-.g om passage 17 and bulb 12 in a manner similar to the mercury vapor'methods preniously employed.

n case mercury or some substance having a vapor pressure at room temperatures higher than the pressure desired in bulb 12 is emplo ed as a pumping medium, a trap 30 may `e inserted between passage 15 and bulb 12, and trap '30 may be surrounded by a container of liquid air 81. This prevents the mercury-vapor from reaching bulb 12. In Fig. l 2 is shown an arrangement in which the operation is similar to that of Fig. 1, but in which the electrodes 23 and 21', corresponding to'electrodes 23 and 21, are arranged in a horizontal plane. The electrode 25 di'ers from electrode' 25 in that it comprises a plurality of grid-like surfaces.

In Figs. 3 and 11 are shown arrangements adapted to'use as a pumping medium a passage 15 and passage 17. While in this discharge ions are passing in both directions, positively charged particles moving in the direction of passage 15 have a reater kinetic energy than the negatively c arged particles. This discharge may therefore aid in the evacuation process.

In Fig. 4,

electrodes

35 and 36 are connected through battery 37, and an are discharge is maintained therebetween for the purpose of vaporizing the pumping medium. An ionized discharge then takes place b etween electrode 35 and electrode 40- which may or may not have the characteristics of an arc discharge. Electrode 40 is grid-like in form to permit the passage of positively charged carriers through the o enings thereof and the flow of posltively c arged bodies betweenelectrodes 40 and 25'is similar to giet described `above in connection with `Vhile various equivalents in materials, apparatus, and modes of procedure have been described, it is to-be understood that the invention is generic in certain o its aspects and embraces .other equivalents within the scope of the appended claims.

What is claimed is:

1. The method of pumping which comprises vaporizing a pumping medium and reducing-allow of particles of said me ium in response to an electric field applied thereto.

2. The method of operating a pump having an opening thereinto from a container to be evacuated, which comprises vaporizing a pumping medium and subjecting said medium to an electric field applied transversely to said opening.

3. The method of operating a pump havy ing an opening theremto from a container e to' be evacuated which comprises vaporizing a pumping medium, ionizing said vaporized medium and causinga How of charged particles adjacent said openin v 4. The method of operating a pump having an'opening thereinto rom a container to be evacuated, lwhich comprises ionizin a substance other than the gas to be removed and projecting particles of said substance across said o ening. 5. The met od of operating a pump having an openin thereinto from a container to be evacuate ,'Which comprises ionizing a substance and rojecting similarly charged particles of said substance across said -opening'to the exclusion of oppositely charged particles.

6.- The method of operating a pump. having an opening thereinto from a container to 'be evacuated, which comprises ionizing a substance and projecting positively charged particles of said substance across said open ing to the exclusion of negatively charged particles. Y

7. The method of operating a pump having an opening thereinto from a container to be evacuated, which comprises producing an ionized discharge, projecting particles from said discharge across said opening, and controlling the velocityot` said particles by an elect-ric field.

8. The method of operating a pump having an opening .thereinto from a container to be evacuated. which comprises producing an ionized discharge, projecting positivelyA charged particles from said discharge across said opening. and controlling the velocity of said particles by an electric field.

9. The method of evacuating, which comprises creating a partial vacuum in a container and a vpassage leading therefrom,

'ionizing a pumping medium .other than the in said passage to withdraw the residualgas to be removed, and projecting particles of said pumping medium through said passage in response to an electric eld in said passage to vvithd'ravvT the residual gas from saidl container. i f

10. The method of evacuating, which comprises creating a partial vacuum in a container and a passage leading therefrom, ionizing a pumping medium other than the gas to be removed, and projecting particles of said pumping medium through said passage in response to an electric space current gas from said container.

11..A vacuum pump comprising a passage, an opening thereinto from a container to be evacuated, a supply of pumping medium, means for vaporizing said pumping medium, and electrical means for projecting particles oi said medium across said opening'. v

12. A vacuum pump comprising a passage, an opening thereinto from a container to be evacuated, a supply of pumping medium, means for vaporizing s aid pumping medium, and means for producing an electric space current adjacent said opening.

13. In an evacuating system, a container to be evacuated, a space adapted to contain a gaseous pumping medium, means for ionizing said medium, and means for projecting 'charged particles therefrom in a direction to lassist. in the evacuation of said-container.

14. In an evacuating system, a passage adapted to be connected to a container to be evacuated and to a pump, a supply of pumping medium, means for vaporizing said pumping medium, and means for producing a iiow of charged particles of said medium in said passage in the direction of saidpump.

15. In an evacuating system, 7a passage adapted to be connected to a container .to be evacuated, a supply of pumping medium, -means for ionizing said pumping medium, and means for producing a iow of charged particles of said pumping' medium in said passage.

16. In an evacuating system, a passage adapted to be connected to a container to be evacuated and to a pump, electrodes spaced apart in said passage and adapted to be supplied with a difference of potential, a source of pumping medium and means for Vaporizing sziiid pumping medium.

17. y* n an evacuating system, a passage adapted to be connected to a container to be evacuated and to a pump, electrodes spaced apart in said passage and adapted to he supplied with a difference of otential, the electfrode nearest said pump eing grid-like'in orm.

18. In an evacuating system, 'a passage having an opening thereinto from a' con' tainer to be evacuated, a vaporizable sub stance adjacent saidv passage, means for vaporizing and ionizing said substance and means for producing a iow of \i nized particles thereof adjacent said openinQg\g 19. In an evacuating system, a passa e having an opening thereinto from acon-\ tainer to be evacuated, a vaporizable substance adjacent said passage, means for producing al flow of positively charged particles thereof adjacent said opening.

20. In an evacuating system, a cathode and an anode and means for'producing a gaseous discharge therebetween, one of said electrodes having an opening to permit the `passage therethrough ofsimilarly charged particles, a third electrode, and means for '8 producing a.low of said particles to `4said third electrode.- c. l

21. Inan evacuating system, a cathode\ and an anode and means for producing a gaseous discharge therebetweenfsaid cathode havin an opening to' permit the passage theret rough of positively charged particles,

a third electnode` and means for producin a How of said particles to said third electro/. 22. In a vacuumpump, a container of insulating material, a plurality of puddles of pumping medium in said container,elec trical connections whereby an arc may established between said puddles to4 causel the How of charged particles, and electrical means for controlling the direction of flow of said particles.

. 23. In a vacuum pump, a container of insulating material. a plurality of puddles of pumping medium in said container, a source of electrical energy, circuit connectionsbetweenv said puddles and said source to produce an arc for causing the ow of charged particles. and electrical means for controlling the direction of How of said particles.

24. In a vacuum pump. a central puddle of pumping material, an annular puddle of pumping material coaxial with said central puddle. a source of eleCtricalenGrgy and -connections between said puddles and said nonna o. sNooK.