US2993638A

US2993638A - Electrical vacuum pump apparatus and method

Info

Publication number: US2993638A
Application number: US673816A
Authority: US
Inventors: Lewis D Hall; John C Helmer; Robert L Jepsen
Original assignee: Varian Associates Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1957-07-24
Filing date: 1957-07-24
Publication date: 1961-07-25
Anticipated expiration: 1978-07-25

Description

July 25, 1961 1.. D. HALL EFAL ELECTRICAL VACUUM PUMP APPARATUS AND METHOD Filed July 24, 19 7 7 Sheets-Sheet 1 Lewis 0 Hall John C Helmer pRoberf L. Jepsen INVENTORS K M Attorney July 25, 1961 L E L 2,993,638

ELECTRICAL VACUUM PUMP APPARATUS AND METHOD Filed July 24, 1957 7 Sheets-Sheet 2 Fig.5

"Ill" 1 18 E I Q 39 v INIfENTORS 44 ewls J0 n C. He/mer Robert L. Jepsen Attorney 25, 1961 L. D. HALL EIAL 2,993,638

ELECTRICAL VACUUM PUMP APPARATUS AND METHOD Filed July 24, 1957 7 Sheets-Sheet 3 INVENTORS Lewis D. Hall Y John C. Helmer B Robert L. Jepsen ELECTRICAL VACUUM PUMP APPARATUS AND METHOD Filed July 24, 1957 July 25, 1961 D. HALL ET AL 7 Sheets-Sheet 4 INVENTORS Lewis D Hall John C. Helmer Robert L. Jepsen fl /Y M A orney Juiy 25, 19 D. HALL ETAL ELECTRICAL VACUUM PUMP APPARATUS AND METHOD 7 Sheets-Sheet 5 Filed July 24,

mmwl I INVENTORS Lewis D. Hall John C Helmer BY Robert L. Jepsen rorney Juiy 25, 196 D. HALL ETAL ELECTRICAL VACUUM PUMP APPARATUS AND METHOD 7 Sheets-Sheet 6 Filed July 24, l 57 all John C He/mer oberf L. Jepsen m Arfo ney INV NTO 5 Lewis D.

1961 L. D. HALL ETAL 2,993,638

ELECTRICAL VACUUM PUMP APPARATUS AND METHOD Filed July 24, 1957 7 Sheets-Sheet 7 -2 I LQQ LQ5 i 24 A A A f 19 g;

5 I4 1" F i g. 20 r INKENTORJ Lew/s D.Hall John C. Helmer Robert L. Jepsen Attorney United States Patent O This invention relates in general to electrical vacuum pumps and more particularly to a novel method and apparatus for improving the pumping characteristics of electrical vacuum pumps. tremely useful in providing uncontaminated vacuums having extremely low pressures as required in many devices such as, for example, vacuum tubes, linear acceler- The present invention is exators, electron microscopes, ammonia masers and the llke.

Heretofore electrical vacuum pumps have been proposed having for their principle of operation the establishment of a glow or Penning discharge within an envelope attached to a structure it is desired to evacuate. The glow discharge produces positive ions which are accelerated through an electric field to bombard a reactive cathode member whereby portions of the reactive cathode member are caused to be dislodged or disintegrated. The disintegrated particles of the cathode are sputtered to and condense upon other portions and surfaces of the apparatus. Upon condensation the cathode material forms a layer of material which will serve to entrap molecules in the gaseous state coming in contact therewith. It is through this entrapment mechanism that the pressure within the structure is reduced. The pumping speeds of these prior art devices have not been sufficient to make them commercially feasible.

The principal object of the present invention is to provide a novel improved electrical vacuum pump having extremely simple design and greatly enhanced pumping speeds.

One feature of the present invention is the method for enhancing the pumping speed of electrical vacuum pump apparatus comprising the step of providing a condensing structure having substantial surface area thereon in close proximity to the cathode structure whereby the area coated by the disintegrated cathode particles may be greatly increased to substantially enhance the pumping action of the apparatus Another feature of the present invention is the provision of a cellular or sectionalized anode structure disposed in close proximity to the cathode surface whereby coating of the anode structure by disintegrated cathodematerial is facilitated and redisintegration of the con-j densed cathode material prevented, in use, thereby greatly enhancing the pumping speed of the vacuum pump.

Another feature of the present invention is the provision of an anode structure having a plurality of separated openings therein distributed transversely to the direction of the magnetic field threading through the anode and defining a plurality of glow discharge passageways, cells or sections extending in the same direction as the magnetic field for containing therewithin a plurality of separated simultaneous glow discharge por' "ice creased to increase the pumping speed of the vacuum pump.

Another feature of the present invention is the pro vision of cathode plates within the vacuum envelope and forming substantially the entire interior wall portions thereof whereby the deleterious effects of undesired disintegration of parts of the envelope is prevented and the attendant unwanted evolvement of trapped gas avoided.

Another feature of the present invention is the provision of a shield means for preventing the condensation of disintegrated cathode material upon the cathode to anode insulator means whereby high potentials may be applied between cathode and anode members without arcing over or producing a leakage current across the insulator means.

Another feature of the present .invention is the provision of a substantial portion of the cathode member disposed at an oblique orglancing incidence to the impinging ion trajectories whereby disintegration of the cathode member is increased thereby enhancing the pumping action of the apparatus.

Another feature of the present invention is the provision of a sputter cathode grid structure formed by individual cathode louvers or slats disposed such that the plane of the louver or slat is tilted at an oblique or glanc ing angle to a preponderance of the impinging incident ion trajectories to increase the cathode grid disintegration and thereby enhance the pumping action of the apparatus.

Another feature of the present invention is the provision of a sputter cathode gn'd structure having the physical configuration of a closely woven mat or mesh whereby the probabilities of an oblique or glancing incidence of an ion with the cathode structure is increased to enhance disintegration of the cathode structure and thus improve the pumping speed of the apparatus.

Another feature of the present invention is the pro-- vision of a cathode structure comprising a rod having a plurality of radial projections thereon, said radial projections being disposed substantially at right angles to a DC. magnetic field whereby a substantial portion of the cathode structure is disposed at an oblique angle with respect to the impinging ion trajectories for increasing cathode disintegration and thereby enhancing the pumping speed of the apparatus.

Another feature of the present invention is the pro-' vision of interleaved and spaced-apart planar cathode and anode members whereby the elfective anode and cathode area is increased to substantially enhance the pumping speed of the apparatus.

Another feature of the present invention is the provision of interleaved concentric cathode and anode members whereby the effective cathode an anode surface area is increased to enhance the pumping speed of the apparatus.

Another feature of the present invention is the provision of a novel anode and cathode physical configuration wherein the anode comprises a cellular structure 1 and the cathode includes a plurality of rods disposed tions in use, whereby the glow discharge current is in-' coaxially within the cells of the anode member whereby the effective surface area of the anode is greatly increased to enhance the pumping speed of the apparatus.

Another feature of the present invention is the provision of a novel anode configuration wherein the anode structure includes a plurality of mutually spaced apart apertured planar members, the apertures in the spaced planar members being aligned with the magnetic field direction and said planar anode members being disposed with the plane of the members substantially at right angles to a magnetic field to separate the glow discharge into a plurality of glow discharge portions contained Within the aligned anode openings thereby increasing glow discharge ion current for disintegration of the cathode structure and attendant coating of the anode structure whereby the pumping lspeed of the apparatus is reat y enha ce Another feature of the present invention is the provision of a novel power supply incorporating a means for n faslii' s h i r e n w h r l gfi overa Wi e ang' of urren a es; sai Po r pply ing b hne e'ted betweenano defandcathode elements of electricalvacuum pump ana'tnecunem measuring means serving as a monitor of the pressure the gpp m Another feature of the present invention is the provisionof an automatic curreut limiting means associated with the power supply of the electrical vacuum whereby damage to the system due to drawing excessive currents for too long a time is prevented.

Another feature of the present invention is the provision of comb-like anode structure disposed adjacent a cathode structure for facilitating flow of gas therethrough whereby the pumping speed of the electrical vacuum pu p'appar t enemy e h e W Another feature of the piesent invention is the provision of a plurality of gas" access passageways directed transversely of the magnetic field direction threading the cellular or sectionalized -anode structurefthe gas access passageways communicating with the glow discharge SagQWQYS for lowi g g fi se'mor re il n o the glow discharge passageways within theiriterior of the cellular or sectionalized anode structure to enhance the pumping speed of the electrical vacuum pump apparatus. i Z

Another feature of the present invention is the provision of a condensing member for catching sputtered cathode material and made of a material having substantially the same coefiicient of thermal expansion as the sputtered cathode material whereby enhanced adhesion is obtained between the condensed cathode material and; the'condensing'm mher the eby pre enting nd r d f king Q cathode material.

7 Another feature of the present invention is the provision of a novel shallow cup-shaped pump housing member flanged at the open end for mating with a cover plate whereby an extremely simple and inexpensive housing is obtaine These and other features and advantages of the present invention will be more apparent "after a perusal of the following specification taken in connection with the accompany g w g he in,

1 is a schematic block diagram depicting a typical evacuation system utilizing the novel vacuum pump of the present invention,

FIG. 2 is a cross-sectional plan viewv of a novel electrical vacuum pump apparatus of the present invention, FIG. 2a is a fragmentary view of an alternative anode structure,

7 FIG. 3 is a cross-sectional view of the structure of FIG. 2 taken along line 3-3 in the direction of the arrows,

FIG. 4 is a cross-sectional plan view of a novel pump apparatus of the present invention, i FIG. 5 is a cross-sectional view of a portion of the structure of FIG. 4 taken along line 5- -5 in the direction of the arrows, L FIG. 6 is an enlarged perspective View of a portion of the cathode structure of FIG. 4, 4

FIG. 7 is an enlarged fragmentary view of a portion of the structure of FIG. 5 taken along line 7--7.

FIG. 8 is an enlarged fragmentary view of an alternate cathode and anode member similar to the structure of FIG. 7,

FIG. 9 is a cross-sectional view of a novel electrical vacuum pump apparatus of the present invention,

FIG. 10 is a cross-sectional plan view of a novel vacuum pump apparatus of the present invention,

FIG. 11 is a cross-sectional view of the structure of FIG. 10 taken along line 1 1-1 1 in the direction of the arrows,

FIG. 12 is a perspective cross-sectional view of a novel ri a a um pu p appa atus o he pre ent n tion,

FIG. 13 is a cross-sectional plan view of a portion of the structure, of FIG. 12 taken along line 13- 13 in the direction of the arrows,

FIG. 14 is a cross-sectional plan view of a novel electrical vacuum pump apparatus of the present invention,

FIG. 15 is a cross-sectional view of the structure of l4 taken along line 15 15 in the direction of the arrows, 7

FIG. 16 is a cross-sectional plan view of a novel electrical vacuum pump apparatus of the present invention,

FIG. 17 is a perspective cross-sectional view of the structure of FIG. 16 taken along line 1 717 in the direction of the arrows,

FIG. 18 is a schematic circuit diagram of a novel power supply for the electrical vacuum pump apparatus of the present invention,

FIG. l9 is a cross-sectional plan view of a novel vacunm pum apparatus of the present invention, and

FIG, 20 is a cross-sectional perspective view of a portion of the structure of FIG. 19 taken along line 20-2 0 in the direction of the arrows.

Referring now to FIG. 1 there is shown in schematic block diagram form the novel electrical vacuumpump of the present invention as utilized for evacuating a given structure. More specifically, the novel electrical vacuum pump 1 is connected via hollow conduit 2 to a con1- press-ion port 3 and thence via hollow conduit 4 to the structure 5, which it is desired to evacuate. The compression port 3 serves to provide a valve mechanism whereby the structure 5 and associated conduit 4 may be removed and replaced by another structure and conduit for successive evacuation of a plurality of structures. A mechanical vane vacuum pump 6 is also connected to the eornpression port 3 via conduit 7 and pinch-off valve 8.

To evacuate the structure 5 the mechanical vane pump is turned on serving to reduce the pressure within the structure 5 to approximately 109 microns at which point the valve '8 is closed and the electrical vacuum pump 1 started.

The electrical vacuum pump is supplied with operat ing potentials from a source 9 as, for example, a 60 cycle line via a transformer 11. The secondary of the transformer 11 is provided with a rectifier 12 and a shunting smoothing capacitor 13 whereby a D.C poten: tial may be applied between anode and cathode members of the electrical vacuum pump 1 which will be more fully described below.

Utilizing the electrical vacuum pump of the present invention, as previously described with relation to FIG. 1, a structure may be evacuated to an extremely low pressure such as, for example, 10* microns. The vacuum obtained in this manner is an extremely clean one since the usual contaminants such as, for example, oilvapors and the like associated with oil diffusion pumps do not have a chance to enter the system. In addition, utilizing the improved method and apparatus in the present invention considerably enhanced pumping speeds have been obtained as, for example, speeds in excess of 5 l t s P v at 10-2 m r ns wi h. a pum ho e v l m s nl c bic inch encased Referring now to FIGS 2. and 3 one embodiment of the novel electrical vacuum pump 1 of the present invention will be more fully described. A hollow open ended rectangular metallic tube 14 as of, for example, copper is closed off at one end by a rectangular wall 15. The other end of the hollow rectangular tube 14 is provided with a flanged portion 16 and is closed off by a flanged closing wall 17. 7

A cylindrical cellular anode'structure 18 as of, for example, molybdenum is carried upon a conductive rod 19 as of, for example, copper which extends outwardly of the rectangular envelope 14 through an aperture in transverse wall 17. .The conductive rod 19 is insulated from and carried by the transverse closing wall 17 through the intermediaries of annular insulator frames 21 and 22 as of, for example, Kovar and cylindrical insulator 23 as of, for example, alumina ceramic. Rod 19 is terminated in a cylindrical block 24 which is provided with a plurality of radial fins thereon and which is made of a good thermal conducting material as of, for example, aluminum. The finned block 24 serves to radiate heat away from rod 19 and anode 18.

Cathode plates 25 which are made of a reactive metal are mechanically locked together to form a liner within the rectangular vacuum tight envelope 20 formed by rectangular tube 14 and the

end enclosing walls

15 and 17. The envelope 20 is adapted to be connected to a structure to be evacuated by a tubing 2. The cathode plates 25 may be made of any one of a number of reactive substances such as metals, for example, molybdenum, chromium, tungsten, tantalum, niobium, iron, titanium, zirconium, nickel, barium, aluminum, thorium, magnesium, calcium, strontium plus other transition elements of the fourth, fifth and sixth groups ofthe periodic table, including the rare earths. Cathode plates 25 are centrally apertured at the end closing portions as are the

end closing Walls

17 and 15. The hollow conduit 2, which may be of any convenient inside diameter commensurate with the desired pumping speed, is carried by the end closing wall 17 in alignment with the aperture therein for connecting the electrical vacuum pump 1.

to the structure 5 it is desired to evacuate.

The cathode plates 25 are mechanically locked in position within the interior of the rectangular metallic envelope 20 rather than being brazed or soldered in place in order to prevent the outgassing of gases that may be trapped in the solder or brazing material when the pump is operating at reduced pressures. The end closing cathode plate 25 disposed adjacent the rectangular end closing wall 17 is centrally apertured to permit the entry of conductive rod 19.

A circular radial sputter shield 26 as of, for example, molybdenum is carried transversely of conductive rod 19 and disposed inwardly of the cathode plate 25. The circular sputter shield 26 serves to prevent disintegrated cathode material from being sputtered into the region of the insulator 25 where it could coat the insulator and produce unwanted voltage breakdown thereof or undesired current leakage thereacross.

A horseshoe-shaped permanent magnet 27 is positioned with regard to the rectangular tubular housing 14 such that the magnetic field of the magnet threads through the rectangular tube in parallelism to the shallow side Walls thereof. The strength of magnetic field utilized in a preferred embodiment is approximately 800 gausses or higher, as desired.

In operation a positive potential in the order of 2 to 6 kw. DC. is applied to the anode 18 via conductive rod 19 and conducting block 24. The housing and therefore the cathode plates 25 are grounded and thus operate at zero potential. With these potentials applied a region of intense electric field is produced between the anode 18 and the cathode plates 25.

.Within the region between the anode 18 and the cathode plates 25 a stray electron will be attracted toward the positive anode 18. In its flight toward the anode 18 the electron will gain in kinetic energy and may collide with a neutral gas molecule within the device. If the electron has gained sufficient energy it will ionize the neutral molecule producing a free electron and a positive ion. The positive ion will then be attracted to the cathode plate.

The positive ion will pick up a considerable amount of kinetic energy in its flight to the cathode plate and upon collision with the cathode will disintegrate portions of the cathode and will also knock out secondary electrons and photons which may further enhance the ionization of the gas. In this manner distintegration of the cathodeis produced. The particles of cathode material which are dislodged by the ion bombardment are sputtered in rays within the interior of the apparatus and condense upon the interior surfaces thereof. In particular a high percentage, as in excess of 50%, of the cathode material will be condensed upon surfaces not subject to resputtering by positive ion bombardment such as, for example, the anode structure 18. Since the cathode material is of a reactive metal it will serve to entrap other gaseous molecules that happen to come in contact therewith. It is through this entrapment mechanism that the pressure within the electrical vacuum pump is reduced hence reducing the pressure in the connected structure 5.

By making the anode structure 18 of the cellular or sectional construction, as shown, the surface area of the anode which is in close proximity to the disintegrated cathode 25 is substantially increased as, for example, to at least ten times the maximum normal projected area of said anode structure 18. Also the glow discharge is thereby partitioned into a plurality of separated discharge portions grouped transversely of the magnetic field direction. The sectionalized or cellular construction of the anode structure 18 formed by a plurality of openingsin the anode 18, the openings being distributed or grouped transversely to the direction of the magnetic field threading through the anode, provides a plurality of glow discharge passageways extending in the direction of the magnetic field. These glow discharge passageways serve to contain therewith in a plurality of separated simultaneous glow discharge portions or columns in use. It has been found that the pumping speed of the electrical vacuum pump is increased manyfold by the provision of the cellular or sectionalized anode construction.

Although the present invention is described utilizing a DC. power supply, i.e., DC. potential supplied to the anode 18, the apparatus operates well at pressures higher than 1O mm. Hg with an A.C. voltage or a pulsating DC. voltage applied between anode and cathode at some convenient frequency as of, for example, 60 cycles. It has been found that substantially every molecule of reactive cathode material that is dislodged from the cathode plates 25 serves as an effective getter for absorbing a molecule of the gas it is desired to pump.

The magnetic field produced by magnet 27 serves to impart a cycloidal or spiral trajectory to electrons which have a slight transverse velocity to the direction of the magnetic field. The electrons are essentially trappeddue to the magnetic field and are reflected back and forth in spiral trajectories between mutually opposed, spacedapart negative cathode plates 25 and through the openings in the anode structure 18. The openings in the anode define the anode sections or compartments and provide the glow discharge passageways serving to contain therevvithin the separated glow discharge portions or columns. Pennings US. Patent Number 2,146,025 shows a nonpartition glow discharge of the above-mentioned type, and this type of glow discharge has become known in the art as a Penning discharge. Thus the path length of the electrons is increased by the presence of the magnetic field for enhancing collisions between the elec. trons and the neutral molecules in the gaseous state.

Referring now to FIGS. 4 through 7 there is shown another embodiment of the present invention. ln'this embodiment the outer envelope of the electrical vacuum pump comprises a length of cylindrical tube 29 which is flanged at one end. The cylindrical tube 29 is closed ofl. at both ends via circular

metallic discs

31 and 32. Disc 32 is provided with a thin annular flange as of, for example, copper which is welded to the similar flange carried" upon cylindrical tube 29. These flangeportions are welded together at the extremities as by, for example, heliarc to avoid contamination of the envelope with material tending to entrap gases which may later evolve and produce a deleterious effect upon the operation of the device.

'Ilwo apertured

circular cathode plates

33 and 34 are positioned

adjacent'closing plates

31 and 32 respectively. Two semicylindrical'

cathode plates

35 and 36 are disposed adjacent the inner surface of the cylindrical tube 29 and extend longitudinally thereof in proximity of the cellular anode 18. The two

cathode plates

35 and 36 are coupled together at the free edges thereof by a plurality of parallel louvers or slats 37 forming a cathode sputter grid made of the same material as the

cathode plates

35', 36, 34, and 33. The cathode slats or louvers 37 are slanted or turned edgewise toward the magnetic field direction and extend transversely of the cylindrical tube 29 with the slat edges in substantial parallelism with the plane of the anode 18, and are slightly spaced from the anode 18. The cathode louvers 37 are held in position with respect to the

cathode plates

35 and 36 as by, for example, spot welding the louvers or slats 3 7 at the ends thereof to the free edges of the

cathode plates

35 and 36.

The embodiment of FIGS. 4, 5, 6 and 7 operates similarly to the previously described embodiment of FIGS. 2 and 3. However, increased pumping speed is obtained because the plane of the broad side of the individual cathode louvers or slats 37 is disposed at an oblique or glancing incidence to the impinging ion trajectories thereby increasing the rate of cathode disintegration.

. When an ion having a certain kinetic energy collides with the surface of the slat or louver 37 at an oblique or glancing incidence more cathode material will be sputtered than if the ion collided with the cathode surface at a normal incidence. In addition, the cathode configuration of this embodiment provides an additional advantage in that the back surface of an adjoining cathode louver is disposed in close'proximity to the incident louver whereby the surface area in close proximity to the cathode is substantially increased. Moreover, additional surface area or structure is provided for collection of. sputtered cathode substance and therefore gettering by the interior surfaces of the semicylindrical chamber 38 on the back side of the louvered cathode 37 and gas flow into the glow discharge area is facilitated by the cathode openings between adjacent louvers 37. Referring now to FIG. 8- there is shown an alternative cathode configuration of the present invention which is adapted for use and is substantially similar to the cathode apparatus of FIGS. 4, 5, 6 and 7 with the exception that the cathode louvers 3-7 are replaced by a closely woven wire mat 39 forming a cathode sputter mesh. The wires of the mat or mesh are made of the reactive cathode material, as previously described, and due to the irregularity of the surface the probability of an ion-cathode collision at an oblique or glancing incidence is greatly enhanced. Due to this oblique incidence of the impinging ion the cathode disintegration is enhanced resulting in increased pumping speeds. Also a certain percentage of the ions will proceed through the openings in the cathode sputter grid or mesh 39 and are collected on interior surfaces of the collecting structure or walls 29 of the chamber 38 where they are buried and covered over by subsequent sputtered material.

Referring now to FIG. 9 there is shown another embodiment of the present invention. In this embodiment a hollow cylindrical vacuum tight envelope 41 as of, for

example, copper is closed oflz at one end and flanged-at the other. The flanged portion of the envelope 41 meets other end of the short cylindrical portion of the. en--.

velope 42 is secured to a cylindrical insulator 43 which in turn is secured to the wide opening of a cylindrical; cup member 44. Members, 42 and 44 are: made of a material having a coefficient of thermal expansion'which is substantially the same as that of the insulator 43' such; as, for example, Kovar.

Cup member 44 is centrally apertured to permit the entry of a cathode rod 45. The cathode-rod 45 may be made of, for example, copper and is provided with a plurality of radial annular projections 46 which form aportion of the cathode and are made of a reactive material, as previously described. The annular radial projections 46 are separated by hollow cylindrical spacers 47 which are also made of reactive cathode material.

A hollow cylindrical insulator shield 48 as of, for: example, molybdenum is afiixed in the inside diameter of envelope section 42, as by welding and extends coaxially of and inwardly of insulator 43 bet-ween the insulator 43 and the cathode rod 45 to prevent condensation of cathode'material upon the insulator 43. A hollow cylindrical anode plate 49 as of, for example; titanium is positioned adjacent the cylindrical envelope 41 and is mechanically held in position in spaced apart relation to the envelope 41 to prevent the unwantedevolvement of gases trapped therebetween. The cylindrical anode plate 49 maybe made of the same material as the cathode members or of other suitable material. When the cathode and condensing members are made of the same material enhanced adhesion is obtained between the condensed sputtered cathode material and the condensing member because the thermal coefiicient of expansion is substantially the same. The envelope 41 is centrally apertured at the transverse closing-wallthereoffor connecting to the hollow evacuating conduit tube 2. A magnetic solenoid 51 is concentrically disposed of the cylindrical envelope 41 and is energized by a suitable currentsource (not shown) to produce a magnetic field which is axial of the envelope 41.

In operation a suitable negative potential such as, forexample, 2 to 6 kv. is applied to the cathode rod 45; The envelope 41 and therefore the anode plate .49 is operated at ground potential. In this manner a strong electric field is established between the cathode and anode members. A free electron within the apparatus isthen drawn toward the anode plate 49 and, due to the axial magnetic field, it will cause the electron to have a cycloidal trajectory, such as found in a magnetron. The'electron gains kinetic energy from the electric field and upon collision with a neutral gas molecule produces a positive ion.

The positive ion is accelerated toward the cathode members 45, 46 and 47. Due to the presence of the annular radially projecting cathode flanges 46 the probability of an oblique incidence of the positive ion with the cathode member is increased thereby producing'i'n creased cathode disintegration and therefore enhanced pumping speed of the apparatus.

Referring now to FIGS. 10 and 11 there is shown another embodiment of the present invention. This embodiment is similar to that of FIGS. 2 and 3 with the exception of the cathode and anode member configuration. In particular the anode comprises a U-shaped channel 53 having a plurality of planar partitions 54 extending longitudinally of the channel 53 in substantial parallelism with the side walls thereof thereby defining a plurality of separated glow discharge passageways between mutually spaced-apart planar anode portions 54. The planar partitions 54 are held in position withrespect to the U-shaped channel 53 by tabs 55 which extend through the channel 53 and are then bent over.

The cathode comprises a plurality of cathode plates 25 which line the interior of the rectangular vacuum tight envelope 20. The bottom cathode plate 25 carries a plurality of planar cathode plates 56 which are disposed substantially at right angles to the cathode plate 25 and extend longitudinally of the apparatus in substantial parallelism with the planar anode plates 54. As with the anode plates 54 the cathode plates 56 are mechanically held in position with respect to the cathode plates 25 via a plurality of tabs 57 which extend through the cathode plates and are bent over on the back side thereof. The shallow side wall of the rectangular tubular envelope 20 is centrally apertured to accommodate hollow conduit 2 for evacuating a structure. The cathode plate 25 disposed adjacent the apertured side wall of the rectangular tubular envelope 14 is similarly apertured.

In operation a positive potential is applied to the planar anode 53 via conductive rod 19 and finned block 24. The rectangular tubular envelope 20 is operated at ground potential and thus

cathode plates

25 and 56 are operated at the ground potential. In this manner a strong electric field is established between the interleaved planar anode and cathode plates 54 and 56 as well as between cathode plates 25 and the side walls of anode channel 53. A free electron when subjected to the electric field established between anode and cathode members will be accelerated toward the particular anode member. Due to the presence of the magnetic field at substantially right angles to the electric field the electron will be forced into a cycloidal trajectory thereby establishing separated glow discharge portions in the passageways between the spaced-apart planar anode and

cathode plates

53, 54 and 25, 56 respectively for enhancing the probability of a collision between the electron and neutral gas molecules within the apparatus.

Positive ions produced by collision between the electron and the neutral gas molecule will be accelerated toward the

cathode plates

25 or 56. Upon collision with the plates the positive ion will disintegrate a portion of the cathode member which will be sputtered away from the cathode and be collected upon the closely spaced anode surfaces.

Due to the interleaved cathode and anode surfaces of the present embodiment, a large anode surface is provided in close proximity to the cathode member to facilitate coating of the anode member. Due to the efiicient use of the electric fields and anode surfaces withinthe apparatus, as atforded by the embodiments of FIGS. and 11, the pumping speed of the apparatus is substan tially increased.

Referring now to FIG. 12 there is shown another embodiment of the present invention. In this embodiment the vacuum tight envelope of the electrical vacuum pump comprises a length of hollow cylindrical tube 61 as of, for example, copper. Tube 61 is closed 011 at both ends by circular

transverse walls

62 and 63 thereby forming a shallow cylindrical envelope. Cylindrical tube 61 is flanged at one end thereof the flange meeting with a similar flange provided on closing wall 63. The flanges are sealed together in a vacuum tight manner by a weld at the extremities thereof.

The anode configuration comprises a plurality of concentrically disposed hollow cylinders 64 which are carried upon a circular plate 65 by tabs provided on one end of the hollow concentric cylinders 64. The innermost concentric anode member portion 66 comprises a cylindrical rod carried transversely of the disc 65. The mutually spaced-apart anode cylinders form a sectionalized anode, the side walls of the anode cylinders defining the side walls of a plurality of glow discharge passageways grouped transversely of the magnetic field direction for containing therewithin separated glow discharge portions.

The cathode members comprise a first cylindrical tu' bular member portion 67 disposed concentrically of and adjacent the inside surface of the hollow cylindrical envelope 61. Two thin

circular cathode plates

68 and 69 are disposed adjacent and inwardly of the circular

end closing walls

62 and 63. The bottom cathode plate 69 carries a plurality of concentrically disposed hollow cylindrical cathode plates 71 which are secured to the cathode disc 69 via tabs which are bent over on the back side of the circular cathode plate '69. The

cathode member portions

67, 68, 69 and 71 are mechanically locked in position within the interior of the cylindrical envelope and are made of a reactive material, as previously described.

The cylindrical side wall of the vacuum tight envelope 61 is apertured near the flanged end thereof in alignment with the hollow conduit 2 to permit the electrical vacuum pump 1 to be connected to an apparatus which it is desired to evacuate. The cylindrical cathode plate 67 is similarly apertured inwardly of the hollow conduit 2 to permit the fiow of gases into the electrical vacuum pump.

In operation positive potential is applied to the

anode member portions

64, 65 and 66 via conductive rod 19. The

cathode plates

67, 68, 69 and 71 are connected to the envelope of the electrical vacuum pump which is grounded and thus operate at ground potential. With the potentials applied, a strong electric field is established between the concentrically disposed anode and cathode members. The DC. magnetic field applied via permanent magnet 27 runs axially of the pump apparatus. A free electron disposed in the spaces between the concentric anode and the cathode plates in the presence of the DC. electric field therebetween will be accelerated toward an anode member. In its fiight to the anode member the electron will enter into a cycloidal trajectory due to the presence of the axial magnetic field.

Positive ions created by collisions between such elec-' trons and the neutral gas molecules within the device will be attracted toward the cathode and upon collision therewith will disintegrate cathode material which may then readily be sputtered to and condense upon nearby anode members for pumping, as previously described.

The particular anode and cathode physical configuration as described with relation to FIGS. 12 and 13 is characterized by interleaved concentric cathode and anode members. This configuration provides an extremely efiicient utilization of the applied electric and magnetic fields as well as eflicient utilization of anode and cathode surfaces whereby a high proportion of anode surface is provided in close proximity to the cathode surface to greatly enhance the pumping speed of the apparatus.

Referring now to FIGS. 14 and 15 there is shown another embodiment of the present invention. This embodiment is similar to the apparatus as shown in FIGS. 2 and 3 with the exception of the novel anode and cathode physical configuration. In particular, the bottom rectangular cathode plate 25 carries a plurality of cathode rods 73 substantially at right angles to the plane of the cathode plate 25 and in coaxial relationship to the cellular compartments or sections of the anode 18 defining the side walls of the glow discharge passageways therein. The cathode rods 73 are made of cathode material, as previously described, and are mechanically held within the cathode plate as by, for example, peening a portion of the rod which extends through apertures provided in the cathode plate 25.

In operation a DC. positive potential as of, for example, 2 to 6 kv. is applied to the anode 18 via conductive rod 19. The cathode plates 25 and cathode rods 73 are mechanically coupled to the rectangular envelope of the'pump which is connected to ground potential. Thus when operating potentials are applied to the apparatus a strong electric field will exist between the cathode rods 73 and'theinner surfaces of each of the cellular compartments or glow discharge-passageways of the anode structure 18 as well as between the outer surfaces of the anode 18 and the surrounding cathode plates 25.

The cathode disintegration and pumping action associated with the fields between the outer surfaces of the anode 18 and the cathode plates 25 has previously been described with regard to FIGS 2 and 3. However, the apparatus of FIGS. 14 and 15 includes another type of discharge action. More specifically, an electron within the region between the cathode rods 73 and the anode 18 will be accelerated toward the anode 18. In its flight toward the anode it will enter into a cycloidal trajectory due to the DC. axial magnetic field thereby greatly extending the path length of the electron and increasing the probability of a collision with a neutral gas molecule. When a collision occurs the positive ion created thereby is drawn toward the cathode rod 73 and upon collision therewith disintegrates a portion thereof which sputters to and condenses upon the nearby inner surfaces of the cellular anode compartments or glow discharge passageways. The condensed cathode material then serves to en trap neutral gas molecules that come in contact therewith, as previously described. The particular anode and cathode configuration as described with regard to FIGS. 1-4 and 15 and characterized by a cellular or sectionalized anode having a plurality of cathode rods coaxially disposed of the cellular elements or glow discharge passageways provides an extremely efficient electrical vacuum pump device because of the close proximity of the anode surfaces to the cathode members and due to the provision of adequate cathode surface disposed in the region of strong electric field. In addition, the mixed array of open anode cells and cells with axial cathode rods 73 provides uniform pumping characteristics over a wide range of pressures as the open anode cells operate well at low pressures while the anode cells with axial cathode rods provide improved high gas pressure pumping.

Referring now to FIGS. 16 and 17 there is shown another embodiment of the present invention. The apparatus of this embodiment is substantially similar with the apparatus of FIGS. and 11 with the exception of the anode and cathode physical configuration and disposition.

In particular, the anode structure includes a U-shaped channel 75 providing upper and lower substantially parallel plates and a member interconnecting the same carried upon the innermost extremity of the conductive rod 19. These spaced anode plates are disposed with their planes substantially in parallelism with the broad side of the rectangular vacuum tight envelope 20 of the pump apparatus. An additional planar anode member portion or plate 76 is shown carried centrally of the two side plates or walls of the channel 75 from the bottom transverse wall of the channel 75 and in substantial parallelism with the side walls or plates of the channel.

The cathode structure includes a plural-ity of cathode plates 25 which are disposed adjacent the inside walls of the rectangular vacuum envelope 20 serving to line the interior thereof. The cathode plate 25 disposed inwardly of the end closing plate carries a U-shaped cathode channel 78 therefrom as by, for example, tabs which extend through the cathode plate 25 and which are bent over on the back side therof. The side walls or spaced plates of the cathode channel 78 are disposed in substantial parallelism with the

anode plates

75 and 76 and are interleaved therewith. A series of apertures 81, substantially aligned with the magnetic field produced by magnet 27, and distributed transversely to the direction of the magnetic field are provided in each of the interleaved cathode and anode plates, except cathode broad side wall plates 25, thereby forming a sectionalized anode structure disposed between the broad side wall cathode plates 25. The aligned apertures 81 define a plurality of mutually separated glow discharge passageways in said anode structure extending in the direc- 12 tion of the magnetic field and containing there-within separated glow discharge portions distributed transversely to the direction of the magnetic field.

In operation a positive DC potential as, for example 2 to 6 kv. is applied to the anode structure formed by parallel anode plates and 76 via conductive rod 19and conducting block 24. Cathode plates 78 are mechanically coupled to the vacuum envelope of the pump apparatus and are adapted to operate at ground potential. When energized a strong electric field is established between the anode and cathode plates. In particular, strong fringing fields are established in cose proximity to the apertures 81 provided in the interleaved cathode and anode plates. These fringing fields will provide substantial components thereof at an angle with regard to the axial magnetic field. Thus an electron which is disposed within the apparatus in a region of strong electric field will be accelerated toward an

anode plate

75 or 76, as the case may be. i

In the region of the strong fringing fields the electron will have a component at right angles to the axial magnetic field and as such the electron will enter into a cycloidal or spiral trajectory whereby collision between the electron and neutral gas molecules within the apparatus is enhanced. The positive ion produced by collision of an electron with neutral gas molecules will be accelerated toward the cathode plates 78. Upon collision with the cathode plate reactive cathode material will be disintegrated and sputtered to and condensed upon the closely spaced anode plates to entrap neutral gas molecules coming in contact therewith.

The probability of an oblique incidence of a positive ion with the cathode plate in the vicinity of the apertures 81 is increased due to the strong fringing fields in close proximity to the apertures 8-1 which has a tendency to direct the impinging ion into the side walls of the aperture 81. In this manner cathode disintegration is increased resulting in enhanced pumping speed, as previously described. Also the spaces between mutually spaced-apart

anode plates

75 and 76 define gas access passageways communicating with the glow discharge passageways, the gas access passageways being directed transversely to the direction of the magnetic field thereby enhancing the pumping speed by facilitating the flow of gas into the glow discharges.

Thus the novel anode and cathode physical configuration of FIGS. 16 and 17 characterized by the apertured interleaved planar cathode and anode structures provides an electrical vacuum pump having enhanced pumping characteristics.

Referring now to FIG. 18 there is shown the novel power supply for the electrical vacuum pump of the present invention. The primary of a transformer 85 is connected to the 60 cycle line'via a two wire transmission line 86. The primary of a filament transformer 87 is connected in parallel with transmission line 86 via a second transmission line 88. A switch 89 is provided in the parallel branch of transmission line 86 which feeds the primary of transformer 85. A second switch 91 is provided in the transmission line 86 which feeds the two

parallel branches

86 and 88. Switch 89 serves to control the power supplied to the primary of transformer'85 and switch 91 serves to control thepower supplied to both the transformer 85 and the filament transformer 87.

One end of the secondary of transformer 85 is connected to the plate of a rectifier 93 via a current limiting resistor 94 as of, example, 8 to 12 watt volt bulbs in series. A smoothing capacitor 95 is connected between the cathode of rectifier 93 and the other end of the secondary of transformer 85. A bleeder resistor 96 is connected in parallel with smoothing capacitor 95. The electrical vacuum pump 1 together with a microammeter 97 and series resistance 98 are connected in paral lel across smoothing capacitor 95.

A plurality of shunting resistors 99 of several discrete 13 magnitudes are parallel connected with ammeter 97 and are provided to be selectively shunted across the microammeter 97 and resistor 98 through the intermediary of a rotary switch 101, as desired. Also parallel connected with the shunting resistors 99 and rotary switch 101 is a push-to-read switch 102 which provides a substantial short circuit bypassing the microammeter 97 and resistor 98 when readings are not being taken of the current flowing to the electrical vacuum pump -1.

In operation of the vacuum pump the amount of current drawn through the pump is a measure of the pressure therewithin. Accordingly, the microammeter 97 and associated shunting resistors and push-to-read switch 102 have been provided for monitoring the current drawn by the vacuum pump 1 and thus the pressure therewithin. The current is read by selecting the proper range via rotary switch 101 and pushing the push-to-read switch 102. The current drawn by the pump is read from the meter 97 which may be calibrated in units of pressure, as desired.

At relatively high pressures within the electrical vacuum pump, as encountered during starting of the pump, the current drawn therethrough may be large resulting in excessive power dissipation within the pump which may result in meltling internal parts thereof. To prevent this sort of damage to the vacuum pump the current limiting resistor 94 has been provided such that when the electrical vacuum pump tends to draw excessive currents these currents will produce a high voltage drop across the resistor 94 resulting in automatically lowering the voltage applied to the pump and accordingly the current drawn thereby.

Although the preferred embodiments of the present escapes of the impinging ions to have the higher average kinetic energy, as the gas may more easily diffuse to the interior portions or glow discharge passageways of the anode structure without first diifusing through a portion of the apparatus where the average kinetic energies of ions produced is low. Since the amount of cathode disintegration is proportional to the average ion energy the pumping of the apparatus will be enhanced by use of the comblike or parallel plate anode configuration just described.

An alternative to the comb-like anode for improving the pumping action of the pump is to provide the cellular or sectionalized anode structure, exemplified by anode 18 of FIGS. 2 and 3 with a plurality of gas access passageways transversely directed of the magnetic field and lar or sectionalized anode 18. This embodiment is exinvention have utilized a DC. power supply wherein a positive direct voltage is applied'to the anode with respect to the cathode this is not a requirement for operation. In particular, the electrical vacuum pump 1 may be operated with alternating voltages applied between anode and cathode inwhich case both the anode and the cathode may be made of a reactive material, as previously described.

When alternating potentials are applied to the pump 1 an A.C. meter may be utilized for monitoring the current flow and thus determining the pressure within the electrical vacuum pump.

Referring now to FIGS. 19 and 20 there is shown another embodiment of the present invention. In this embodiment the structure is substantially similar to that of .FIGS. 2 and 3 with the exception of the physical configuration of the anode -18. More specifically, the anode structure comprises a plurality of planar partitions or parallel plates 105 disposed in spaced-apart parallel relationship with respect to each other and carried at one end thereof from a transverse planar member 106 which in turn is carried at the extremity of conducting rod 19. Thus the planar anode members or plates -105 are disposed like fingers of a comb in spaced-apart relation to the planar cathode plates 25. The open end of the comb-like anode structure is disposed adjacent the hollow conduit 2 such that the gas, which is diifusing into the electrical vacuum pump apparatus, may readily diffuse into the spaces between the parallel fingers of the comb .105.

In operation the apparatus of FIGS. Y19 and 20 operates substantially similar to the. apparatus of FIGS. 2 and 3 with the exception that the novel comb-like anode structure more easily permits the gas which it is desired to pump to circulate within the spaces between the plates 105. It has been found that ions which are created or generated by electron collision within the interior portions of the anode structure rather than in close proximity to the cathode plates will have attained a higher average kinetic energy before impinging upon the cathode plates 25. Therefore, the anode configuration of FIGS. 19 and 20 permits a higher percentage emplified by the structures of FIGS. 2A, 16 and 17 of the drawings.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An electrical vacuum pump apparatus utilizing the principle of cathode disintegration by ion bombardment including, a vacuum envelope enclosing a volume it is desired to evacuate, a cathode structure for disintegration by ion bombardment contained within said envelope, means for bombarding said cathode structure with positive ions to produce disintegration thereof, means for condensing disintegrated cathode material having a total surface area exposed to direct rays of sputtered disintegrated cathode substance which is at least 10 times greater than the maximum normal projected area of said condensing means in any direction, and said condensing means being disposed adjacent said cathode structure for condensing thereupon sputtered disintegrated cathode material to absorb gases from within the apparatus and thereby evacuate the apparatus. 2. In an apparatus as claimed in claim 1 including means partitioning said condensing means into a plurality of cellular compartments defining a plurality of glow discharge passageways therewithin.

3. In an apparatus as claimed in claim 1 wherein said condensing means comprises a comb-like anode member having a plurality of planar comb-like teeth, the plane 'of the comb-like teeth disposed substantially at right angles to said cathode structure.

4. In an apparatus as claimed in claim 1 wherein said condensing means comprises an anode structure, and

wherein said cathode and anode structures have a plu- 'ratus.

5. In an apparatus as claimed in claim 1 wherein said condensing means comprises an anode structure, and wherein said anode and cathode structures comprise a plurality of interleaved concentrically disposed members whereby the cathode and anode surface is increased to enhance the pumping speed of the apparatus.

6. The apparatus according to claim 1 wherein said cathode structure and said condensing means are made of materials having substantially the same coeificient of thermal expansion whereby undesired flaking of condensed cathode material is prevented in use.

7. In an apparatus as claimed in claim 2 wherein said condensing means comprises a perforated cellular membet to facilitate diffusion of gas into said cellular memberto enhance the pumping speed of the apparatus.

8. In an apparatus as claimed in claim 2 wherein said cathode structure comprises a planar member having a plurality of projections extending outwardly therefrom, said. projections being disposed substantially coaxially. of the cellular compartments of said condensing means.

9. In an apparatus as claimed in claim 4 wherein said interleaved planar cathode and anode portions are provided with a plurality of apertures therein, including. means for producing a magnetic field, and said anode and cathode structures are immersed in the magnetic field directed substantially at right angles to the plane of the interleaved planar portions of said anode and cathode structures.

10. In an electrical vacuum pump utilizing the principle of cathode disintegration by ion bombardment, a gas-tight vacuum envelope means for containing there: within the elements of the pump, an anode means extending into the interior of said vacuum envelope means, a cathode means disposed within said vacuum envelope means and forming a lining over substantially the entire interior wall portions of said vacuum envelope means, and said cathode means made of a reactive material for disintegration by ion bombardment whereby maximum disintegration of cathode material is obtained.

11. The apparatus according to claim wherein said cathode means is mechanically interlocked within said vacuum envelope.

12. In a cathode disintegrating electrical vacuum pump, a metallic vacuum tight envelope means for containing therewithin the elements of the pump, an anode means disposed within. the interior of said vacuum envelope means and having a portion thereof extending outwardly of said vacuum envelope means through an aperture therein, insulator means physically interconnecting said anode means and said vacuum envelope means and serving to insulate said anode means from said vacuum envelope means, and shield means disposed within said vacuum envelope means in close spatial proximity to said insulator means to prevent the condensation of disintegrated cathode material upon said insulator means whereby arcing over of said insulator means is prevented in use.

13. In a cathode disintegating electrical vacuum pump apparatus, means forming a vacuum envelope communicating with a device to be evacuated, a reactive cathode member disposed within said envelope, means for establishing a glow discharge over said cathode member for disintegrating said reactive cathode member by ion bombardment, and said cathode member having a' substantial surface portion thereof exposed to ion bombardment, said ion bombarded surface portion of said cathode being disposed at an oblique angle with respect to the preponderance of the impinging ion trajectories whereby disintegration of said cathode member is increased thereby enhancing the pumping speed of the apparatus.

14. In an apparatus as claimed in claim 13 wherein said cathode member portion which is exposed to ion bombardment comprises a plurality of louver portions, said ion bombarded louver portions having the plane of the bombarded surface portion disposed at an oblique angle to a preponderance of the impinging ion trajectories impinging upon said louvers to thereby enhance the pumping action of the apparatus.

15. In an apparatus as claimed in claim 13 wherein said reactive cathode member comprises a closely woven mat whereby the probabilities of an oblique incidence of an impinging ion with said cathode member is increased to enhance disintegration of said cathode member and thus improve the pumping speed of the apparatus.

16. In a cathode disintegrating electrical vacuum pump apparatus, a vacuum tight envelope, a cathode member contained within said envelope for disintegration by ion bombardment for pumping matter in the gaseous state, an anode electrode within said envelope for establishing a glow discharge over said cathode, power supply means for supplying current and voltage to said anode and said cathode for sustaining the glow discharge to produce the ions for cathode bombardment, andjautornatic current limiting means connected in circuit with said power sup; ply means for limiting the current drawn therethrough by the pump apparatus whereby damage to the electrical vacuum pump apparatus due to dissipation. of excessive power therewithin is prevented in use.

17. Apparatus according to claim 16 wherein saidculfrent limiting means includes means having an impedance to current which is automatical y variable in response to the magnitude of current drawn therethrough.

18. Apparatus according to claim 16 including rneans for producing and directing a magnetic field threading through said anode electrode for enhancing the glow discharge, of said anode electrode structure having at least four openings therein defining at least four simultaneous glow discharge passageways extending in the direction of the magnetic field threading said anode, and said glow discharge passageways being distributed transversely to the magnetic field threading said anode electrode.

19. In a cath de disin e ratin le tri a m p mp, a tubular anode member, a cathode member disposed coaxially of said anode and having a plurality of longitudinally spaced-apart radial projections thereon, said cathode member made of a reactive material for disintegration by ion bombardment, means for applying different potentials to said anode and cathode members in use to produce a glow discharge therebetween for ion bombardment of said radially projecting catho e portions, means for producing a magnetic field directed axially. of said tubular anode, and said anode and cathode members immersed in the magnetic field directed axially of said tubular anode member and said cathode member and said radial cathode projections having a substantial portion of the ion bombarded surfacei thereof disposed at an oblique incidence to a preponderance of the impinging ion trajectories in use thereby enhancing the cathode disintegration and thus the pumping speed of the armratus.

20. The method for pumping a structure it is desired to evacuate comprising the steps of, establishing a glow discharge within the structure, accelerating ions produced by the glow discharge to high velocities, bombarding a reactive cathode electrode with high velocity positive ions produced by the glow discharge to produce sputtering of the cathode material, condensing the sputtered reactive cathode material upon surfaces within the structure for gettering of gas molecules coming in contact therewith, and directing said bombarding ions against the reactive cathode electrode at glancing incidence to thereby enhance cathode sputtering to increase the. pumping speed of the apparatus.

21. The method for pumping gases from within an evacuable structure comprising the steps of, establishing a glow discharge between an anode and a reactive cathode member disposed within the structure, bombarding the reactive cathode member with high speed positive ions produced by the glow discharge to produce sputtering of the reactive cathode material within the structure,

condensing the sputtered reactive cathode material upon surfaces within the structure for gette nggas coming in contact therewith, automatically limiting the" current drawn by the glow discharge whereby overheating of the electrical vacuum pump is prevented use.

22. An electrical vacuum pump apparatus utilizing the principle of cathode disintegration by particle bombardment including, an anode structure having a plurality of glow discharge passageways, said glow discharge passageways being grouped transversely to'the longitudinal axes of said passageways, said anode structure adaptedto be contained within an envelope including the envelope of a structure to be pumped, a reactive cathode structure for disintegration by particle bombardment, means for applying a potential difference between said anode" and cathode structures of sufiicient magnitude to produce assesses 1'?- simultaneous glow" discharges within a: plurality of said glow dischargepassageways and to bombardsaid cathode structure with positiveion particles of suifi'cientvelocity the lengths of a plurality of said individual glow discharge.

passageways are greater than theminimum characteristic transverse dimension thereof.

24. The apparatus according to claim 22'where1n, a

plurality of said glow discharge passageways have at least one open end apiece, and portions of said reactive cathode structure are disposed opposite the open ends of said glow discharge passageways and are-spaced apart:

therefrom.

25. The apparatus according to claim 22 whereinsaid glow discharge passageways are formed by hollow open ended cellular compartments formed in saidanode structure.

26. The apparatus according to claim'22 wherein said cathode structure includes a'plurality of openings therein to facilitate the flow of gas therethrough and thus enhance the pumping speed of thepump.

27. The apparatus according to claim 22' whereinsaid anode and cathodestructures are made ofmaterials having substantially the same coefiicient of thermal expansion whereby undesired flaking of condensed cathodematerial is prevented'in use.

28. In an apparatus" as calledfor'in claim 25 wherein a portion of said reactive cathode" structure includes a rod disposed centrallyofat lea-stone of said hollow anode compartments, and said rod" being disposed substantially inalignment with the longitudinal axesof said anode compartments.

29. The apparatus according toclaim 22- wherein said anode structure includes a" plurality of' openings in said anode structure; the openings being distributed transversely tothe direction of the magnetiefield; and the margins of the anode openings defining said glow di'scharge passageways.

30. The apparatus according to" claim- 22" wherein; said cathode structure includes a-sputter cathode-grid portion for disintegration by ion bombardment; said sputter cathode grid structure having a substantial surface portion* thereof subject to'bomba'rdinent byions and being disposed atglancingangles of incidence to apreponderance'of the impinging ions whereby disintegration ofsaid sputter cathode grid structure i'sprodiiced to enhance pumping action of the pump.-

31. The apparatus according to claiin wherein-said cathode rod ismade of a. reactive material having; a secondary emission ratio greater than-one.

3.21 The apparatus according toclaim 28" including portions of said reactivecathode structure disposed opposite the open ends of said cellular compartments and being spaced apart therefrom= 33; The apparatus according to-claim- 32-wherein only certain: of said open ended anode compartments contain saidcentrall'y disposed icathodero'ds.

3.4.- The: method: for pumping: a structure it: is desired to evacuatecomprising. the stepsof, establishing a'iplurah ity of separated glow discharge portions: in: a: magnetic field Within. the: structure, grouping; saidseparated glow discharge portions transversely' to the direction of the magnetic field,, bombarding. a. reactive cathode member with positive. ions, produced by,-the separatedl glow dis charge. portions to. produce sputteredirays-of. the reactive cathode material, condensing. more: than: 50% of. the sputtered rays of cathode material on portionsof. mem: bers within the structure which are not subject to bombardment with positiverionsof suflicientvelocity to pro- 8 duce re-sputtering of the condensedcathode material, whereby the pumping speed of the pump is greatly enhanced.

35. The apparatus according to claim 27 whereintliematerials having substantially the same coefiicientofthermal expansion are substantially the same materials.

36; A glow discharge getter ion' vacuurnpump appa ratus including, a-vacuum tight envelope defining a spacetherewithin which it is desired to evacuate, ananode structure contained within said vacuum envelope, means for partitioning said anode structure into a plurality of anode sections, each of said anode sections having at" least one open end thereto, means for producing and directing a magnetic field through-the open ends of said anode sections defining successive glow discharge passageways extending in the approximate direction of the magnetic field, successive anode sections being positioned in-a group distributed transversely to the direction of the magnetic field directed through said anode sections, acathode' structure disposed adjacent said sectioned anode structure and spaced apart therefrom, means for main-' taining said anode structure at a potential more positive than said cathode structure to produce a glow discharge in the magnetic field for ionizing gases within'sai d envelope at gas pressure less than microns ofmercury, the potential difierence between said anode and cathode structuresserving to accelerate positive ions within the spacesadjacent saidanode and cathode structures and to' direct the positive ions against portions of said cathode struct'urefor disintegrating and sputtering rays-of cathode material by' ion bombardment, said ion bombarded portions ofsaid cathode structure being made of a' reactive substance, and said sputtered cathode substance being condensed upon structure within said envelope' and-tliere I serving to getter gas coming in contact" therewith;

37. A glow discharge getter ion vacuum pump appa ratus including, a vacuum tight envelope adapted to be connected to a structure to be evacuated; ananodestructure contained within said' vacuum envelope, means; for partitioningsaid anode structure into atleast four anode sections defining at least" four glow discharge passageways, each of said anode sections having at least one open end thereto, means for producing anddirecting amagnetic field through the open ends of said anode: sections transversely of'the plane of the anodesection end openings, said anode sections being positioned in a=group transversely of the direction of the magnetic field directed through said anode sections'and said glow'discharge passageways extendingin the direction of the magn'etic'fi eld, a cathode structure disposed adjacent saidse'cti'oned anodestructure and spaced apart therefrom, means'for maintaining said anode structure at a potential more posh tive thanz said cathode structure to produce a glow'dis charge in the magnetic held for ionizing gases within said envelope" at gas pressures less than 10.0 microns-of mercury, the potential difference between said anodei and cathode structures servingto-accelerate positive ionspro; duced by the glow discharge within the spaces adjacent said anode and cathode structuresand to-direct the positive 1OI1S against portions of said cathode structure-for disintegrating and sputtering rays-of cathode materialtby ion bombardment,' said ion bombarded portions of. said cathode structure being made ofa reactive substance. 2. plurality'of said anode. sections each having a typical minimum transverse dimension defined by the diameter of a circle inscribed in said anode section, the. planeof the circle being transverse to the direction of the mag: netic field'and said minimum transverse dimension being less than the typical dimension of said anode section lengthwise of the magnetic field whereby said anode structure serves for intercepting. and condensing there uponsputtered' rays of cathode materialin' proportion to the ratio of saidanode section length totransve'rse dimen; sion wherebythe 1 pumping performance of' the pump" is enhanced.

38. The apparatus according to claim 37 wherein said ion bombarded portions of said cathode structure are madefrom reactive cathode material selected from the class consisting of titanium, chromium, molybdenum and zirconium.

39. The apparatus according to claim 37 wherein, said anode structure has an area exposed to direct rays of sputtered disintegrated cathode substance which is greater than times the maximum normal projected area of said anode structure in any direction.

40. In a glow discharge getter ion vacuum pump apparatus, a vacuum tight envelope for communicating with a structure to be evacuated, an anode structure contained Within said vacuum envelope, means for partitioning said anodestructure into a plurality of anode sections, each of said anode sections having at least one open end thereto, means for producing and directing a magnetic field through the open ends of said anode sections, successive anode sections defining successive glow discharge passageways being positioned in a group transversely of the direction of the magnetic field directed through said anode sections and extending in the direction of the magnetic field, a cathode structure disposed adjacent said sectioned anode structure and spaced apart therefrom, means for maintaining said anode structure at a potential more positive than said cathode structure to produce a glow discharge in the magnetic field for ionizing gases within said envelope at gas pressures less than a 100 microns of mercury, the potential diflerence between said anode and cathode structures serving to accelerate positive ions within the space adjacent said anode and cathode structures and to direct the positive ions against portions of said cathode structure for disintegrating and sputtering rays of cathode material by ion bombardment, said ion bombarded portions of said cathode structures being made of reactive substance, said rays of sputtered cathode substance being condensed upon members within said envelope and there serving to getter gas coming in contact therewith, and means connected in circuit with said potential maintaining means and being responsive to the magnitude of current drawn through the vacuum pump by the glow discharge over several decades of current values for measuring the pressure within the electrical vacuum pump apparatus.

41. A glow discharge getter ion vacuum pump apparatus including, a cathode member, an anode member, means for applying operating potentials to said anode and cathode members for initiating a glow discharge therebetween and to bombard said cathode member with particles of sutficient velocity to produce sputtering of portions of said cathode member, a flanged open end cupshaped housing member, said flanged cup-shaped member having a depth less than the minimum characteristic transverse dimension thereof thereby forming a shallow cup-shaped member, and a cover member closing oii and being vacuum sealed at its periphery to the flange portion of said shallow cup-shaped member, and said sealed cover and cup members enveloping said cathode and anode members thereby forming a simple vacuum tight pump housing.

42. A glow discharge getter ion vacuum pump including, means forming a vacuum tight envelope for containing therewithin the elements of the pump, means forming an anode disposed within the interior of said vacuum envelope means, means for supporting said anode means within said envelope means and said support means extending outwardly of said vacuum envelope means through an aperture therein, means for insulating said anode means from said envelope means and physically interconnecting said anode means and said vacuum envelope means, and a sputter shield member transversely disposed of said anode support means and carried therefrom and disposed within said vacuum envelope means between said cathode member and said insulator to prevent the condensation of disintegrated cathode material on said insulator means whereby arcing over and undesired current leakage across said insulator means is prevented in use.

43. The apparatus according to claim 29 wherein said anode structure contains at least four simultaneous glow discharge passageways.

44. The apparatus according to claim 43 wherein said anode structure includes a plurality of gas access passageways directed transversely of the magnetic field direction threading through said anode structure, said gas access passageways communicating with said glow discharge passageways for allowing gas to diffuse more readily into said glow discharge passageways within the interior of said anode structure to enhance pumping speed of the pump apparatus.

45. The apparatus according to claim 44 wherein said anode structure includes a plurality of approximately parallel-directed mutually spaced-apart plates, said gas access passageways in said anode structure being defined by the space between said mutually spaced-apart approximately parallel directed anode plates, the transversely distributed openings in said anode structure which define said glow discharge passageways including aligned openings in said mutually spaced-apart anode plates, the aligned openings being aligned with the direction of the magnetic field, said cathode structure including a plurality of approximately parallel directed mutually spaced-apart cathode plates, and said anode plate structure being disposed between and in approximate parallelism with and spaced-apart from two of said cathode plates.

46. The apparatus according to claim 30 wherein, said sputter cathode grid portion includes a plurality of cathode slats disposed in spaced-apart relationship, said slats being oriented edgewise toward the magnetic field direction with the broad sides of said cathode slats disposed at an oblique angle to a preponderance of the slat impinging ion trajectories thereby increasing the rate of cathode disintegration.

47. The apparatus according to claim 30 wherein a certain proportion of the ions created by the glow discharge between said anode and cathode structures pass through said sputter cathode grid portion, and including an ion collector structure disposed on the opposite side of said sputter cathode grid structure from said anode structure for receiving and collecting the ions which pass through said sputter cathode grid portion and for condensing sputtered cathode material thereon sputtered from said sputter cathode grid.

48. Apparatus according to claim 30 including, a condensing structure disposed on the opposite side of said sputter cathode grid structure from said anode structure for receiving and condensing sputtered cathode material thereon sputtered from said sputter cathode grid for gettering gas coming in contact therewith.

49. An electrical vacuum pump apparatus utilizing the principle of gas pumping by particle bombardment of a cathode structure including, an anode structure having at least four glow discharge passageways, said glow discharge passageways being grouped transversely to the longitudinal axes of said passageways, said anode structure adapted to be contained within an envelope including the envelope of a structure to be pumped, a reactive cathode structure for particle bombardment, means for applying a potential difference between said anode and cathode structures of suflicient magnitude to produce simultaneous glow discharges within at least four of said glow discharge passageways and to bombard said cathode structure with positive ion particles of suflicient velocity to produce pumping within the envelope, and means for producing and directing a magnetic field coaxially of and within at least four of said glow discharge passageways for enhancing the glow discharge and thus the pumping speed of the pump.

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Discharge-Type Vacuum Meter, C. Hayashi, Oyo Butsuri (Applied Physics), volume 17, No. 11-12 (1948).

Etude dune source dions due type Penning, Helvetica Phys. Acta, volume 22 (1949) Ionic Pump, by A. M. Gurewitsch and W. F. Westendorp, Rev. of Scientific Instruments, volume 25 (1954).

The Pumping Properties of Cold Cathode Ionization Gauge, L. Paty, Czechoslovak Journal of Physics, volume 7 (1957).

Ion Pump With Cold Electrodes and Its Characteristics, E. M. Reikhrudel et al., Radiotekhnika i Elektronika, volume No. 2, (1956).

The Discharge Tube Vacuum Meter, K. Hachiya, M. Michijima and Z. Uzawa, Scientific Papers from the Osaka 15 University No. 11 (1949).