US2022465A - Electrical vacuum pump - Google Patents

Electrical vacuum pump Download PDF

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Publication number
US2022465A
US2022465A US647189A US64718932A US2022465A US 2022465 A US2022465 A US 2022465A US 647189 A US647189 A US 647189A US 64718932 A US64718932 A US 64718932A US 2022465 A US2022465 A US 2022465A
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United States
Prior art keywords
tube
vessel
pump
vacuum
discharge
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Expired - Lifetime
Application number
US647189A
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English (en)
Inventor
Clarence W Hansell
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RCA Corp
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RCA Corp
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Filing date
Publication date
Priority to BE400310D priority Critical patent/BE400310A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US647189A priority patent/US2022465A/en
Priority to US746060A priority patent/US2063249A/en
Priority to US47091A priority patent/US2063250A/en
Application granted granted Critical
Publication of US2022465A publication Critical patent/US2022465A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/14—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of thermionic cathodes

Definitions

  • This invention relates to apparatus for producing high vacua in closed receptacles, such as bulbs, electron discharge devices and the like, and has for its object to provide a simplified and improved type of vacuum pump.
  • the present invention comprises a vacuum pump wherein electrical forces are utilized .for effecting the evacuation process. This is accomplished by producing a direct current discharge through a tube or orifice between a vessel to be exhausted and the inlet'to the rough pump, the discharge consisting chiefly of a flow of electrons in one direction and a flow of gas ions and molecules in the other direction.
  • a vacuum pump wherein electrical forces are utilized .for effecting the evacuation process. This is accomplished by producing a direct current discharge through a tube or orifice between a vessel to be exhausted and the inlet'to the rough pump, the discharge consisting chiefly of a flow of electrons in one direction and a flow of gas ions and molecules in the other direction.
  • FIG. 3 and 4 illustrate simple forms of the present invention.
  • Figure 5 illustrates a further embodil0 ment of the invention which makes use of the principles of the Langmuir pump.
  • Figure 6 illustrates one method of starting the vacuum pump without the necessity for employing a source or very high direct current voltage.
  • a cathode 3 which may be in the form of an ordinary electric light filament, which is arranged when heated to emit electrons.
  • a metal electrode or anode 4 which is supplied with a positive potential from a high voltage rectifier arrangement 6 through an inductance l, is adapted to attract the electrons emitted by the filament through a tube of insulating material 5.
  • a suitable tubing 8 is arranged to extend from electrode 4 to vessel 9 which it is desired to exhaust.
  • Inductance 1 is of comparatively large value and serves, once the arc has been established at the beginning of the pumping process, to increase the potential as the current in the arc tends to decrease as the vessel is evacuated, thus making it possible to obtain a higher vacuum than would otherwise be possible.
  • any desired type of, electrical circuit such as l0, may be provided for lighting the filament in the bulb to produce electronic emission, and any well known source of direct current illustrated by the rectifier arrangement, such as shown in the drawings, may be used to place a positive potential on the anode 4 which is located at the end of the tubing'8.
  • FIG 2 shows a second embodiment of my invention in which the tubing 5, of insulating material, illustrated in Figure 1 is dispensed with.
  • is surrounded by a shielding element 53 and is placed near the opening of a metal inlet tube 52 which also acts as the anode.
  • is heated by an electrical current from source 54 over leads 55.
  • a positive potential is applied to the metal anode element 52 by a source of potential 53 over a circuit in series with a resistance 51, thus causing the setting up of a flow of electrons from the cathode 5
  • the shield member 53 may have the same potential as the cathode or itmay' have a negative potential applied to it through a resistance 58 in the manner shown in the drawings to increase the proportion of the total number of free electrons which enter the inlet tube of metal part 52.
  • a fair degree of vacuum is first established in the system by means of a rough pump, not shown, which may be connected to opening 53.
  • the cathode is then heated to a temperature where electrons are emitted and the potentials are applied to the other electrodes.
  • to the anode 52 begin to ionize the gases by collision, and the ions, being positively charged, are forced toward the negatively charged cathode 5
  • FIG. 3 shows an embodiment of my invention in which pumping is carried out by means of an electric discharge between relatively cold electrodes.
  • is connected to sections of metal tubing 32 and 33 which are separated by a tube of glass or other electrical insulating material 34.
  • the connection to tubing 32 is effected through the secondary or high voltage winding of an induction coil 35.
  • the induction coil from the ignition system of a Model T Ford automobile has been successfully used.
  • the induction coil is supplied with power from a battery, such as 36, or from any other suitable source, and serves to build up impulses of very high potential across the insulating tube 34. After a predetermined potential has been reached the gas within the insulating tube 34, which has previously been rarefied by the mechanical vacuum ,pump is broken down.
  • breaking down, or ionization, of the gas initia es an electrical discharge and permits the passage of direct current between the electrodes 32 and 33.
  • This current is set up by the motion of electrons from electrode 33 to 32 and by the movement of gas ions from the space within the tubes to 5 electrode 33.
  • the gas is de-ionized by contact with electrode 33 and passes into the mechanical pump chiefly as neutral molecules.
  • the resistance of the high voltage winding of the induction coll serves to limit the value of direct current through the discharge to a safe value. If desired, a series resistance, in addition, may be used.
  • the induction coil should be so connected that the peak pulses of potential from it are in the same direction across insulating tube 34 as the D. C. voltage from the generator.
  • the pumping action will be somewhat faster if the metal parts within the tube or vessel being evacuated are connected to the positive terminal of the generator through a current limiting resisv tor of proper value, such as 31.
  • the high potential on electrode 32 may be obtained from the secondary winding of a Tesla coil or transformer.
  • the Tesla coil has advantages over the use of the simple induction coil in that the resistance to direct current and the energy losses on the electrodes seem to be somewhat less. It is thought that the lower energy losses are due to the relatively short distance of travel by the ions between reversals of the radio frequency voltage from the Tesla coil, which makes the energy component of alternating current in the discharge relatively small.
  • Figure 4 shows a fourth embodiment of the present invention in which a generator 4
  • the secondary of a high voltage transformer 45 operated from ordinary alternating currents over leads 49, is used to impress a high voltage upon electrode 43.
  • the pumping process is started by starting up the mechanicalpump 49 which is drivenby the motor 41 through gear 48. After a fair degree of vacuum is obtained, the generator 4
  • FIG. 5 shows one way in which to apply the principles of the present invention for effecting an improvement in the Langmuir mercury condensation pump previously referred to.
  • a bulb II containing a filament I2 and a pool of mercury I3 through which an electric discharge may be considered to take place in the same manner as in the well known hot cathode mercury vapor rectifier tube.
  • the presence of this electrical discharge causes ions of mercury to exist within'the bulb II, which are drawn toward the electrode I2, to which there is applied a negative potential from a direct current generator Ill.
  • the vessel to be exhausted 9 is shown connected by tubing 8 to, an inlet passage I4 which, together with an orifice 39 extending from tube II to the inlet, connects with a condensing chamber I5.
  • This condensing chamber is arranged to be cooled by a fluid circulating in vessel 30, the cooling fluid being conducted into the vessel 39 by means of pipe I6 and withdrawn by suction on the pipe I1.
  • a rough vacuum pump 2 of a type similar to that shown in Figures 1 .and 4 connects with the condensing chamber through a passage or inlet I8.
  • the heating of the mercury in the chamber II due to the electrical discharge in it, will build up a mercury vapor pressure while the cooling inside the vessel 39 causes it to have a much lower pressure. Consequently, a blast of mercury vapor will issue from the orifice 39.
  • the presence of an electrical discharge will cause ions of mercury to exist within bulb II which, when drawn toward electrode 28 by the application of the negative potential thereto, will greatly increase the force of the blast of mercury ions in the orifice 39, which corresponds to the orifice in the Langmuir pump.
  • the blast of ions and mercury molecules will trap and carry out molecules of gas from the inlet or conduit I4 connected to the vessel 9 to be evacuated.
  • the ions passing through the orifice of the pump are neutralized when they come in contact with the electrode 28 and then pass as neutral mercury vapor into condensing chamber II where they are condensed by coolin from the cooling liquid circulated in vessel 90 around the chamber.
  • the condensed mercury is caused to fall by gravity into a tube I9 which returns the mercury to the 5 bulb II.
  • the rough exhaust pump 2 At the retum end of the condensing chamber I! there is shown the rough exhaust pump 2.
  • a very low temperature may also be applied to the tube I4 in the final stages of pumping to accomplish the same purpose.
  • the tube Il may be cooled to reduce the diffusion of mercury vapor into the rough pump.
  • Suitable circuits are shown, schematically, in a well known manner, for maintaining the electrical potentials and current discharges in the various parts of the pump.
  • the filament of the pumping bulb I in Figure 1 and the filament I2 of the mercury v bulb I I in Figurel 5 may be omitted.
  • the arc will be established between relatively cold electrodes and the apparatus is just as effective 25 for producing the pumping action as when a. heated, filament is used for the negative electrode.
  • the main reason for using filaments is to make the starting of the arc discharge easier, but this starting could also be accomplished by momen- 30 tarily applying a high voltage sufiicient to directly ionize the gas in the discharge path and start an arc.
  • Another manner of starting an arc is to bring into the vicinity of the discharge path the point of a Tesla coil which will set up very 35 high potentials around it and which will cause a break-down of the gas.
  • Figure 6 illustrates, in conventional form, one particular method of automatically starting the vacuum pump without the necessity for employ- 40 ing a very high D. C. voltage.
  • a moderately high voltage direct current source indicated as 20 which is arranged to be-automati- 45 cally connected at the proper time to contacts 2I, 2
  • a vacuum tube 23 having a grid 24 to which there is applied a low bias, which cooperates with a transformer 25 and condenser 26 to 55 produce oscillations.
  • the production of oscillations supplies high voltage pulses to the pump 22 which breaks down the gas in the discharge path of the pump.
  • current flowing through resistance 21 will bias 60 the grid 24 of tube 23 to a negative value and thus stop the oscillations.
  • tube 23 will have the bias on itsgrid 24 decreased so that it will again oscillate and re- 65 subject pump 22 to the very high voltage impulses.
  • Apparatus for producing a vacuum comprising, in combinationya tubing of insulating material forming part of a connection through which a vessel is to be. evacuated, conducting electrodes at each end of the tube, a source of direct current connected to the electrodes and means to produce. high momentary potentials within the tubing for initiating a gaseous discharge therein with consequent motionof gas out of the vessel to beevacuated.
  • Apparatus for producing a vacuum comprising, in combination, a tubing of insulating material forming part of a connection through which a vessel is to be evacuated/conducting electrodes at each end of the tube, a source of direct current, and connections from said source to said electrodes, a winding in one of said connections, a second winding coupled to said first winding,
  • Apparatus for producing a vacuum comprising, in combination, a tubing of insulating material forming part of a connection through which Fa vessel is to be evacuated, a metallic electrode incontact with said tube, a source of direct current connected to said electrode, and circuit -whereby there is initiated a gaseous discharge consequent motion of gas out of the vessel to be within said tube with consequent motion of gas out of the vessel to be evacuated.
  • Apparatus for producing a vacuum comprising, in combination, a tubing of insulating material forming part of a connection through which a vessel is to be evacuated, conducting electrodes at each end of the tube, a source of direct current, and connections from said source to said electrodes, an induction coil in one of said connections, and circuit means for producing in said induction coil interrupted high potentials whereby there is initiated a gaseous discharge within said tube with consequent motion of gas out of the vessel to be evacuated.
  • Apparatus for producing a vacuum comprising, in combination, a tubing of. insulating material forming part of a connection through which a vessel is to be evacuated, conducting electrodes at each end of the tube, a source of direct current, connections from opposite terminals of said source to said electrodes respectively, a resistance shunted by a condenser in one 'of said'connections, and means for producing a'g'aseous discharge across said electrodes with evacuated.
  • Apparatus for producing a vacuum comprising, in combination, a tubing of insulating material forming part of a connection through which a vessel is to be evacuated, said vessel having metallic parts therein, conducting electrodes at each end of the tube, a source of direct-current connected to the electrodes, the negative terminal of said source being connected to the electrode farthest away from said vessel and the positive terminal being connected to the other electrode and to the metallic parts of said vessel, and means to produce high momentary potentials within the tubing for initiating a gaseous discharge therein with consequent motion of gas out of the vessel to be evacuated.
  • Apparatus for producing a vacuum comprising, in combination, a vessel to be evacuated, a rough vacuum pump, a plurality of sections of insulating tubing arranged in series relation extending from said vessel to said pump, there being a metallic electrode at the junction of every two sections of tubing, and a metallic electrode at the end of the last section farthest removed from said vessel to be evacuated, a source of direct current, a connection from one terminal of said source to said last electrode, and a connec-- tion from the other terminal of said source to said other electrodes, and means for producing intermittent gaseous discharges between said electrode farthest removed from said vessel and one or more of said other electrodes with consequent motion of gas out of the vessel to be evacuated.
  • Apparatus for producing a vacuum comprising, in combination, three electrodes separated from one another by tubing material forming part of a connection through which a vessel is to be evacuated, a source of direct current having one of its terminals connected to that one of the electrodes which is farthest removed from the vessel to be evacuated and the other of its terminals connected to the other electrodes, and means in circuit with one of the connections from said source to one of the electrodes for producing therein, periodically, high frequency potentials whereby there are initiated gaseous discharges within said tubing with consequent motion of gas out of the vessel to be evacuated.

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  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US647189A 1932-12-14 1932-12-14 Electrical vacuum pump Expired - Lifetime US2022465A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE400310D BE400310A (enrdf_load_stackoverflow) 1932-12-14
US647189A US2022465A (en) 1932-12-14 1932-12-14 Electrical vacuum pump
US746060A US2063249A (en) 1932-12-14 1934-09-29 Electrical vacuum pump
US47091A US2063250A (en) 1932-12-14 1935-10-28 Electrical vacuum pump

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US647189A US2022465A (en) 1932-12-14 1932-12-14 Electrical vacuum pump

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US2022465A true US2022465A (en) 1935-11-26

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BE (1) BE400310A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2578009A (en) * 1947-12-23 1951-12-11 Rca Corp Electronic high vacuum apparatus
US2636664A (en) * 1949-01-28 1953-04-28 Hertzler Elmer Afton High vacuum pumping method, apparatus, and techniques
US2715993A (en) * 1952-06-06 1955-08-23 W M Welch Mfg Company Ionization pump
US2765975A (en) * 1952-11-29 1956-10-09 Rca Corp Ionic wind generating duct
US3172009A (en) * 1961-01-17 1965-03-02 Nippon Electric Co Voltage supply circuit for cold cathode ionization gauge type vacuum pump
US3223038A (en) * 1964-09-10 1965-12-14 Company Wachovia Bank An Trust Electrical thrust producing device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2578009A (en) * 1947-12-23 1951-12-11 Rca Corp Electronic high vacuum apparatus
US2636664A (en) * 1949-01-28 1953-04-28 Hertzler Elmer Afton High vacuum pumping method, apparatus, and techniques
US2715993A (en) * 1952-06-06 1955-08-23 W M Welch Mfg Company Ionization pump
US2765975A (en) * 1952-11-29 1956-10-09 Rca Corp Ionic wind generating duct
US3172009A (en) * 1961-01-17 1965-03-02 Nippon Electric Co Voltage supply circuit for cold cathode ionization gauge type vacuum pump
US3223038A (en) * 1964-09-10 1965-12-14 Company Wachovia Bank An Trust Electrical thrust producing device

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Publication number Publication date
BE400310A (enrdf_load_stackoverflow)

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