US3228589A - Ion pump having encapsulated internal magnet assemblies - Google Patents

Ion pump having encapsulated internal magnet assemblies Download PDF

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Publication number
US3228589A
US3228589A US316694A US31669463A US3228589A US 3228589 A US3228589 A US 3228589A US 316694 A US316694 A US 316694A US 31669463 A US31669463 A US 31669463A US 3228589 A US3228589 A US 3228589A
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magnet
magnets
anode
pump
enclosure
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US316694A
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William J Kearns
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General Electric Co
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General Electric Co
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Priority to US316694A priority Critical patent/US3228589A/en
Priority to GB38064/64A priority patent/GB1073168A/en
Priority to FR991338A priority patent/FR1415012A/fr
Priority to US488543A priority patent/US3325086A/en
Application granted granted Critical
Publication of US3228589A publication Critical patent/US3228589A/en
Priority to GB40255/66A priority patent/GB1158486A/en
Priority to FR76932A priority patent/FR90880E/fr
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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
    • H01J41/18—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes
    • H01J41/20—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes using gettering substances

Definitions

  • This invention relates to ionic vacuum pump apparatus and more particularly to ionic vacuum pumps incorporating a plurality of encapsulated magnets utilized in an internal modular arrangement within ionic pump apparatus being evacuated.
  • the ion-type vacuum pump does not lend itself readily to ordinary scaling up or interchangeable techniques since these techniques lack a complete underlying theoretical understanding of the operative concepts involved, and this understanding is necessary in order to establish changes which provide increased pump capacity or wide applicability of the pumps to varying and differing applications.
  • this invention in one preferred form includes a cylindrical enclosure member subjected to evacuating conditions, with a circular row of specifically shaped encapsulated and vacuum sealed magents therein.
  • the circular row of magnets is positioned adjacent to but spaced from the inner periphery of the enclosure member and concentric therewith.
  • the encapsulated magnets "ice are also retained in lateral spaced-apart relationship peripherally, and in each space between magnets there is positioned an anode-cathode assembly to provide, in overall configuration, a circular row of interdependent ionic pump configuration cooperatively acting to remove gases from the defined peripheral enclosure.
  • FIG. 1 is a cross-sectional view of one preferred embodiment of this invention.
  • FIG. 2 is a top view of the embodiment of FIG. 1.
  • FIG. 3 is a partial view of one anode structure which is employed in the embodiment of FIG. 1.
  • FIG. 4 is a partial view of one cathode structure which is employed in the embodiment of FIG. 1.
  • FIG. 5 is an illustration of supporting and mounting means for an anode-cathode assembly of this invention.
  • FIG. 6 shows a series of curves indicating pumping speed vs. magnetic field strength in an ionic vacuum pump.
  • FIG. 7 illustrates a hysteresis curve for a permanent magnet material.
  • FIG. 8 illustrates a series of curves of unit property characteristics of magnet materials in Alnico 5, Alnico 8 and barium ferrite magnets.
  • FIG. 9 is a schematic illustration of a magnet circuit.
  • One measure of efficiency of an ion pump is the ratio of the pumping speed to the pump volume or weight. It is a continuing desirable feature of ionic pumps that this ratio be increased to more optimum or maximum values. It has been discovered that this ratio may indeed be increased to approach optimum values by utilizing a plurality of encapsulated magnets which, together with their cooperating electrode structures, are positioned within the evacuation enclosure. The enclosure may thus be of simple design and minimum weight. Referring now to FIGS. 1 and 2, there is shown a preferred embodiment of an ionic pump utilizing the specific features of this invention.
  • ionic pump 10 includes in one preferred form, a cylindrical enclosure or cylinder 11 suitably supported by one or more support or mounting members 12 and 13.
  • Enclosure member 11 is ordinarily a gas-impervious material, preferably a metal, for example stainless steel, which may be formed by a hydroforming process so that no welds or seams are necessary.
  • enclosure member 11 is a closed bottom hydroformed stainless steel cylinder or can about 20 inches internal diameter, about 20 /2 inches height and about A inch thick.
  • Enclosure member 11 is provided with a top or cover assembly 14 which may be suitably sealed by suitable flange gasketing arrangements 14' or by welding to the enclosure member 11 to provide a vacuum tight volume.
  • cover assembly 14 is provided with a large neck conduit or flanged aperture member 15. Enclosure 11 together with cover assembly 14 constitutes the ionic pump housing which houses the magnet assemblies 16 and anode-cathode electrode assemblies 17.
  • magnet assemblies 16 are arranged in a peripheral array of circular row, in lateral spaced-apart relationship to each other, and also concentrically positioned in enclosure 11 to define a central open space 18.
  • Each of the magnet assemblies 16 as illustrated is positioned adjacent but spaced from the internal periphery or wall of the enclosure 11, and each magnet assembly is of the illustrated trapezoidal cross-sectional configuration with the smaller faces directed inwardly or towards the center of enclosure 11.
  • each magnet assembly 16 is encapsulated by an encapsulating material 19 as illustrated in FIG. 2.
  • a material 19 may be either metallic or non-metallic provided it performs the function of encapsulating or vacuum sealing the inner magnet material without gas leakage.
  • material 19 may be of stainless steel in folded sheet form or as a seamless can, channel or enclosure, having a wall thickness of about .060 inch, and suitably vacuum sealed.
  • encapsulating material 19 is in sheet form and suitably folded about individual columns of magnets for welding along the backside of the assemblies as at 20. Referring again to FIG.
  • each magnet assembly 16 includes one or more individual magnets 21-24, the particular number being chosen with respect to availability of the magnets and the economic circumstances of their manufacture.
  • a block 25 of stainless steel is suitably welded to encapsulating material 19 so that each magnet assembly is provided with an encapsulating envelope.
  • the thicker blocks 25 lend structural rigidity to the magnet assemblies and further provide attaching means therefor.
  • encapsulation is employed to prevent outgassing of the magnetic material during pump operation, a problem previously deterring the use of internal magnets subjected to high vacuum conditions.
  • the magnet assemblies 16 are prepared by evacuating the encapsulating envelope to only a few microns of mercury internal pressure, baking out the magnets at a temperature at least as high as that to be encountered in intended use, and then backfilling the encapsulating envelope with a gas such as helium which is used as a tracer gas in the event of leakage of the envelope at a future time. Backfilling is limited to between about 100 microns to a few torr of helium. Evacuated conditions in the magnet assemblics is also desirable to prevent dimensional &
  • Each magnet assembly .thus represent-s a column of enclosed stacked magnets, and in a preferred embodiment of this invention for a 1000 liter/sec. pump, ten magnet assemblies are employed within enclosure 11.
  • the crosssectional dimensions of the trapezoid magnets are: a base of about 4V2 inches, a face of about 2 /2 inches and about 3 inches therebetween.
  • the use of a smooth cylindrical configuration for the outer enclosure member 11, together with the thin encapsulating material 19 about the magnet assemblies 16 provides an optimum clearance or lateral spacing between each pair of magnet assemblies 16 of about 1.625 inches.
  • the magnet assemblies 16 are premounted in a module type assembly. More particularly, and referring to FIG. 1, the magnet assemblies 16 in the form of columns are positioned in a peripheral row between and perpendicular to the plane of atying ring 26 at the base of the circular row of magnet assemblies 16, and a tying ring 27 at the top of the circular row of magnet assemblies 16.
  • These tying rings 26 and 27 are in the form of circular outgassed stainless steel disks having very large apertures 28 and 29 respectively therethrough.
  • These rings 26 and 27 define a washer-like or annular flange structure to which magnet assemblies 16 are attached.
  • Suitable attachment devices may be employed to afiix a magnet column assembly 16 to tying rings 26 and 27.
  • bolts 30 may pass through apertures in the rings and threadedly engage blocks 25 or studs on blocks 25 may pass through the rings et cetera.
  • Ring 26 or ring 27 may then be suitably attached to the enclosure 11 also by a threaded, connection illustrated generally for example at 31.
  • Tying rings 26 and 27 in their respective relationship provide rigid lateral space relationship of the magnet assemblies while at the same time performing the function of providing an integral modular structure, or unit assembly 32 of the ring of magnets.
  • the number of magnets may vary from as low as three to as many as ten (FIG. 2). A lower limit of four magnet assemblies is preferable.
  • the modular structure or unit assembly 32 of the magnet assemblies 16 is an important feature of this invention since these unit assemblies may be made inv a wide variety of predetermined shapes and sizes, not only for standardization purposes but also for interfitting or" replacement relationships in the same or different pumps. or as a pumping unit in a large vacuum enclosure. In'. this manner the overall capacity of a given ion pump may be changed by merely inserting Within the enclosure: 11 of FIG. 1 the proper magnet unit assembly which: will provide the pump with, for example, a liter/sec.,. 250 liter/see, 500 liter/see,- or 1000 liter/sec. capacity. In this respect for example a given modular structure: magnet unit assembly of a height H may provide 100 liter/sec.
  • capacity and a height of 2H may provide a. 250 liter/sec. capacity, et cetera. Therefore, one may reduce or increase the capacity of this pump merely by inserting or removing the type of magnet structure described.
  • a given pump design may be scheduled or assembled for varying pump requirements merely by the insertion of the proper and standard modular magnet unit assembly.
  • anode-cathode electrode assembly 17 to provide ionic pumping means between adjacent magnet assemblies 16.
  • each of the electrode assemblies 17 included spaced-apart cathode elec trodes 33 and 34 with an intermediate electron and ion transparent grid-type anode 35.
  • anode 35 comprises a square grid structure, as illustrated in FIG. 3, composed of a plurality of longitudinal strips 36 and transverse strips 37. These strips are provided with spaced transverse slots along their longitudinal length and thereby the strips interengage with each other to provide the familiar eggcrate type or general honeycomb structure. In one operative practice of this invention these strips 36 and 37 were on the order of about 7 /2 inches length, /2 inch width, and were made of .012 inch thick titanium.
  • anode electrode configurations may also be employed in this invention in addition to the composite grid or honeycomb design.
  • a plurality of separate and. discrete anodes may be employed, or suitable open meshes, a plurality of spaced meshes, et cetera.
  • One or more of the anode grid structures are provided to extend vertically along the full height of the magnet column assemblies 16 although the capacity of the pump may be varied where less anode structure is employed. It is preferred, however, to have similar heights for magnets as well as electrodes.
  • the cathode electrodes 33 and 34 are positioned one on each side of the grid anode 35 as shown in FIG. 2.
  • the construction of the cathodes is best shown in FIG. 4 where each cathode 33 and 34 in one preferred example comprises an electron and ion transparent honeycomb or grid structure of long thin titanium strips 38 and 39 of about .008 to .015 inch thickness and /s inch height or depth to provide a nominal dimension of about inch across the individual grid openings, as compared to about /2 inch across the individual grid openings of the anode 35.
  • Each of the cathodes 33 and 34 is enclosed within a suitable supporting frame 40.
  • the supporting means for an anode-cathode assembly 17 may best be described as follows. All metal parts are of stainless steel or other material of non-magnetic and gas-free characteristics.
  • a series of metal supports or columns 41 are suitably attached to rings 26 and 27 for example by threaded connection means 42.
  • the anode-cathode assemblies 17 are then attached to and supported by supports 41 as illustrated in FIG. 5.
  • the individual attaching means for an anode 35 may comprise a suitable machine screw 43 which passes through an aperture in an end strip 36 of anode 35, an aperture through support 41, and threadedly engages a cylindrical electrically insulating alumina or ceramic block 44 on the opposite side of support 41.
  • a metal sputter cap or shield 45 is fitted over the exposed end of block 44. Thereafter a U-shaped clip 46 is suitably attached to block 44 by means of screw 47 passing through clip 46 and threadedly engaging block 44.
  • the upstanding or extending arms of clip 46 are in parallel relationship to anode 35, and frame 40 containing a cathode 33 or 34 is attached thereto by means of a screw 48 passing through an arm of clip 46 and threadedly engaging frame 40.
  • suitable small clips are welded across the unsupported ends of cathodes 33 and 34 as illustrated.
  • Sputter shield 45 prevents short circuiting of the anode and cathodes due to sputtered cathode material.
  • a pair of the described attaching means (other than support 41) is employed for each anode-cathode assembly 17, and a pair of anode-cathode assemblies 17 is attached to each support 41 in end-to-end or vertical relationship.
  • a disengagement of connections 42 on a rod 41 permits removal of a mounted vertical pair of electrodes.
  • a plurality of supports 41 may be suitably joined together by means of one or more connecting strips 49 as illustrated in FIG. 2 to provide an electrode unit assembly.
  • stainless steel strip 49 is 30 inches long, inch wide by .035 inch thick, and contains transverse slots therein which are adapted to be slidably engaged under screws 47.
  • cover assembly 14 includes electrical connection means 50 and 51 which are adapted to provide suitable electrical connections from an external source of electrical power to the pump.
  • connection means for example 50 an electrical stainless steel wire lead 52 connects to an upper connector strip 49, with a jumper stainless steel lead 53 connecting to a lower strip 49.
  • the electrical connection is, therefore, made to upper and lower anode-cathode assemblies as a unit and to /2 the number of units or five laterally adjacent units. The same connection is utilized for the remaining five units.
  • a suitable ground connection 52 is made to the enclosure 11 to complete an electrical circuit and establish the desired electrical potential.
  • FIG. 6 is illustrative of a series of curves showing the dependence of the speed of an ionic pump on the associated magnetic field. From an inspection of these curves it can be seen that the pumping speed increases for increased magnetic field, especially for the higher voltages for a given set of pump electrodes up to about for example 3000 gausses. Beyond this field. strength, the increase in pumping speed may not justify the economics of higher magnetic field strength.
  • A, B and C represent area dimensions of opposed spaced magnet poles.
  • the magnets employed in the practice of this invention are permanent magnets produced from permanent magnet materials which are characterized by a very wide hysteresis loop such as is shown schematically in FIG. 7.
  • FIG. 7 the heavy dashed line illustrates the initial magnetizing curve. If the magnetizing force denoted as H increase-s beyond the saturation level H there is no further increase in the induction B. When the current is reduced, B does not retrace the dashed line but remains high and crosses the axis H at zero at a high value B the residual induction. In order to reduce B to zero a high demagnetizing field equal to the coercive force I-I must be applied, resulting in the curve B H in the second quadrant.
  • this curve B H the demagnetization curve, is determined entirely by the ma netic properties of the permanent magnet material.
  • the preferred materials are Alnico 5, Alnico 8, and in some instances barium ferrite, the choice depending upon the nature of the pump service and. the required gap length.
  • Alnico 5 is generally used because it is relatively inexpensive and can be cast into a variety of useful shapes. (Permanent Magnets and Their Applications, R. 1. Parker & R. J. Studders, Wiley & Sons, New York, 1962).
  • the demagnetization curves for these materials are shown in FIG. 8 which is the second quadrant of the total hysteresis loop showing the relationship of the magnetizing force H and the residual induction B. Superimposed on these curves are the contour lines of constant energy product BE in units of gaussoersteds. The contour line tangent to the demagnetization curve of a particular material establishes the maximum energy product (maximum gaussoersted). The maximum energy point on the demagnetization curve is the operating point of the magnet where the maximum field is obtained for a minimum magnet volume. The sloping straight lines 2 L H L H Since flux lines are continuous the following relationship also holds:
  • barium ferrite magnets are probably the most efficient to use since the length of the magnet (i.e., in the direction of magnetization) is roughly equal to the length of the gap. It is particularly useful for magnetic circuits containing a number of gaps and magnets in series to form a closed loop as in many multiple stack ion pumps. Alnico 5 is seen to require the greatest amount of magnetic material for a given gap length. However, it is also capable of producing the highest field in the gap and fields of 5000 gausses are not uncommon in Alnico 5 magnets with large gaps.
  • Alnico 8 has a demagnetization curve approaching the straight line of barium ferrite but has a much higher induction so that a reasonably high field can be produced in gaps suitable for ion pumps without excessively long magnets. Thus a magnetic circuit with multiple gaps can easily be obtained using Alnico 8 with fields up to 2500 gausses.
  • barium ferrite would be a desirable material. However, according to the curves in FIG. 7 it is more desirable to use larger fields than 1500 gausses.
  • many pumps are subjected to bakeout processes to at least 250 C. and on some occasions to 400 C.
  • the ferrite magnets must be removed from the pump to prevent demagnetizing, whereas Alnico magnets may be baked to 500 C. safely. Removing large magnets from their magnetic circuit is quite difiicult because of the large mechanical forces involved.
  • Alnico 8 is a preferred optimum magnet material for larger ion pumps.
  • the design equations given above do not include the problem of leakage flux and are presented to show the various parameters important to the design of ion pumps.
  • the magnet modules or unit assemblies themselves include two sizes, a small liter/sec. module having a magnetic field area of about 3 inches by 3 inches and a large nominal 50 liter/ sec. module having a magnetic field area of about 3 inches by 7 /2 inches. It is desirable that both of these triode-type magnet pumping units have a close spacing between the collector surfaces of about 1% inches.
  • the modular concept may provide a series of magnet units and anode-cathode units or sub-units where the units are interchangeably mounted in a suitable enclosure.
  • the protrusion of the vacuum enclosure wall has been eliminated in the design of the magnet assemblies of this invention by encapsulating the magnets themselves in thin wall stainless steel envelopes or cans and placing them inside of the vacuum enclosure. Thus there is no need for any part of the heavy enclosure wall 11 to project or protrude into the space between magnets.
  • the cans are evacuated and baked to remove the water vapor and gases from the metal casings so that on subsequent heating the can will not experience an internal pressure.
  • the cans are backfilled with helium to a few torr pressure so that they can be leak checked and are then sealed off by welding a stainless steel tubulation.
  • Magnetizing a ring magnet unit may be carried out by magnetizing each magnet element separately and then assembling the individual magnets in assembly 16, or magnetizing the entire modular unit 32 with the magnet assemblies 16 bolted in place.
  • the first method is easier as far as obtaining a high field in each magnet.
  • the field drops along the demagnetization curve, and when reassembled as part of the magnet unit, the final gap field will be somewhat lower than that which could be obtained if the magnets retained their original magnetism.
  • the magnet assembly is magnetized as a unit by placing it into a toroidal field and reducing the reluctance of the gaps with soft iron keepers.
  • the most important result of this method is that the magnetic field is quite uniform across the gap because the toroidal magnetizing field coincides exactly with the desired field pattern.
  • the fringing field produced by the magents represents wasted magnetic energy and is a disturbance to meters and instruments.
  • the ring magnet assembly of this invention produces a low fringing field considering the field strength produced in the gap. Its intensity varies around the circumference of the magnet assembly, being a maximum along the centerline of a gap and a minimum along the centerline of a magnet. For example, about four inches from the pump wall the maximum fringe field is gausses and about six inches away it is less than about 10 gausses.
  • This invention thus provides a magnet construction which permits the use of the attractive properties of Alnico magnets and particularly Alnico 8. By eliminating the protrusion or heavy vacuum or enclosure wall from between magnet spaces the amount of magnet material has been minimized.
  • Encapsulation may take the form of magnets or magnet material which has been suitably impregnated or otherwise treated to reduce outgassing under pumping conditions. There is no need to disassemble the magnet unit assembly for bakeout since the magnet material can be baked at 400 to 500 C. The conductance or pumping path to the electrodes is quite large, permitting the full utilization of the pumping elements capability.
  • the ring magnet assembly together with the pumping elements may be mounted directly inside of large vacuum systems with no conductance limitation due to connecting piping.
  • the magnet assembly and position in this invention utilizes magnet material at as high an efiiciency as possible thereby providing a high pump speed to weight ratio for the pump.
  • a magnet unit assembly comprising in combination,
  • a magnet unit assembly comprising in combination
  • a magnet unit assembly comprising in combination,
  • each of said magnet assemblies being evacuated and partially filled with helium tracer gas
  • (e) means releasably securing said rings and said magnet assemblies into a rigid unit capable of handling as a single structure for mounting in an ionic pump.
  • An ionic vacuum pump comprising in combination,
  • each of said encapsulated magnets is of trapezoidal cross-section with the smaller faces facing the center of said circle.
  • An ionic vacuum pump comprising in combination,
  • each of said cathodes having substantial transparency with respect to gas ions between adjacent magnet assemblies
  • An ionic vacuum pump comprising in combination,
  • each of said cathode having substantial transparency with respect to gas ions between adjacent magnet assemblies
  • An ionic pump comprising in combination,
  • an integral anode-cathode unit comprising a series of laterally paced cathode-anode-cathode electrode assembly units releasably secured in a circle relationshi
  • 5nd means slida-bly engaging and attaching said units in interleaved relationship with said spaced magnets to provide a series of interdependent ionic pumping elements.
  • An ionic pump comprising in combination,
  • an integral modular magnet assembly unit comprising a series of laterally spaced magnets releasably secured in a circle relationship, in said enclosure member,
  • an integral anode-cathode unit comprising a series of laterally spaced cathode-anode-cathode electrode assembly units releasably secured in a circle relationship
  • planar electron transparent multicellular grid anode (a) a planar electron transparent multicellular grid anode, (b) a pair of electron transparent multic-ellular planar grid oath-odes positioned one on each side of and parallel With said planar grid anode and electrically connected together,
  • (d) means maintaining the other end of said cathodes in spaced relationship to each other.
  • planar cathodes having substantial depth and grid openings of a predetermined ize smaller than the grid openings of said anode

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US316694A 1963-10-16 1963-10-16 Ion pump having encapsulated internal magnet assemblies Expired - Lifetime US3228589A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US316694A US3228589A (en) 1963-10-16 1963-10-16 Ion pump having encapsulated internal magnet assemblies
GB38064/64A GB1073168A (en) 1963-10-16 1964-09-17 Ion pump
FR991338A FR1415012A (fr) 1963-10-16 1964-10-14 Perfectionnements aux pompes à ionisation
US488543A US3325086A (en) 1963-10-16 1965-09-20 Triode ionic vacuum pump
GB40255/66A GB1158486A (en) 1963-10-16 1966-09-08 Improvements in Triode Ionic Vacuum Pump
FR76932A FR90880E (fr) 1963-10-16 1966-09-20 Perfectionnements aux pompes à ionisation

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Application Number Priority Date Filing Date Title
US316694A US3228589A (en) 1963-10-16 1963-10-16 Ion pump having encapsulated internal magnet assemblies
US488543A US3325086A (en) 1963-10-16 1965-09-20 Triode ionic vacuum pump

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US488543A Expired - Lifetime US3325086A (en) 1963-10-16 1965-09-20 Triode ionic vacuum pump

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US488543A Expired - Lifetime US3325086A (en) 1963-10-16 1965-09-20 Triode ionic vacuum pump

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FR (2) FR1415012A (fr)
GB (2) GB1073168A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3353054A (en) * 1964-06-09 1967-11-14 Edwards High Vacuum Int Ltd Penning type vacuum pumps
US4890029A (en) * 1986-08-20 1989-12-26 Kabushiki Kaisha Toshiba Electron beam apparatus including plurality of ion pump blocks
US5655886A (en) * 1995-06-06 1997-08-12 Color Planar Displays, Inc. Vacuum maintenance device for high vacuum chambers
US6616417B2 (en) * 2000-03-13 2003-09-09 Ulvac, Inc. Spatter ion pump
US10460917B2 (en) * 2016-05-26 2019-10-29 AOSense, Inc. Miniature ion pump

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5495145B2 (ja) * 2010-04-02 2014-05-21 独立行政法人情報通信研究機構 イオンポンプシステム

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2906910A (en) * 1958-10-30 1959-09-29 Westinghouse Electric Corp Spark gap device
US2926276A (en) * 1959-06-02 1960-02-23 Saburo M Moriya Apparatus for the ionization of electrons of flowable materials
US2983433A (en) * 1958-08-01 1961-05-09 Varian Associates Getter ion vacuum pump apparatus
US3112401A (en) * 1957-09-27 1963-11-26 Philips Corp Shielding to confine magnetic field to ion source area of a neutron generator
US3117247A (en) * 1961-05-29 1964-01-07 Varian Associates Vacuum pump

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2993638A (en) * 1957-07-24 1961-07-25 Varian Associates Electrical vacuum pump apparatus and method
GB924918A (en) * 1958-06-16 1963-05-01 Varian Associates Electrical vacuum pump apparatus
US3141986A (en) * 1961-09-18 1964-07-21 Varian Associates High vacuum sputter-ion gettering apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3112401A (en) * 1957-09-27 1963-11-26 Philips Corp Shielding to confine magnetic field to ion source area of a neutron generator
US2983433A (en) * 1958-08-01 1961-05-09 Varian Associates Getter ion vacuum pump apparatus
US2906910A (en) * 1958-10-30 1959-09-29 Westinghouse Electric Corp Spark gap device
US2926276A (en) * 1959-06-02 1960-02-23 Saburo M Moriya Apparatus for the ionization of electrons of flowable materials
US3117247A (en) * 1961-05-29 1964-01-07 Varian Associates Vacuum pump

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3353054A (en) * 1964-06-09 1967-11-14 Edwards High Vacuum Int Ltd Penning type vacuum pumps
US4890029A (en) * 1986-08-20 1989-12-26 Kabushiki Kaisha Toshiba Electron beam apparatus including plurality of ion pump blocks
US5021702A (en) * 1986-08-20 1991-06-04 Kabushiki Kaisha Toshiba Electron beam apparatus including a plurality of ion pump blocks
US5655886A (en) * 1995-06-06 1997-08-12 Color Planar Displays, Inc. Vacuum maintenance device for high vacuum chambers
US6616417B2 (en) * 2000-03-13 2003-09-09 Ulvac, Inc. Spatter ion pump
US10460917B2 (en) * 2016-05-26 2019-10-29 AOSense, Inc. Miniature ion pump

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FR90880E (fr) 1968-03-01
GB1073168A (en) 1967-06-21
US3325086A (en) 1967-06-13
GB1158486A (en) 1969-07-16
FR1415012A (fr) 1965-10-22

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