US3156406A - High vacuum pumping method and apparatus - Google Patents

High vacuum pumping method and apparatus Download PDF

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Publication number
US3156406A
US3156406A US182528A US18252862A US3156406A US 3156406 A US3156406 A US 3156406A US 182528 A US182528 A US 182528A US 18252862 A US18252862 A US 18252862A US 3156406 A US3156406 A US 3156406A
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United States
Prior art keywords
vacuum
pump
cryogenic
manifold
vacuum chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US182528A
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English (en)
Inventor
William A Lloyd
Zaphiropoulos Renn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Varian Medical Systems Inc
Original Assignee
Varian Associates Inc
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Filing date
Publication date
Application filed by Varian Associates Inc filed Critical Varian Associates Inc
Priority to US182528A priority Critical patent/US3156406A/en
Priority to GB10850/63A priority patent/GB977185A/en
Priority to CH382563A priority patent/CH421370A/de
Application granted granted Critical
Publication of US3156406A publication Critical patent/US3156406A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F9/00—Diffusion pumps
    • 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

Definitions

  • Another feature of the present invention is the provision of a cryogenic vacuum pump of the above featured types in a complete high vacuum system whose compact design provides a highly accessible work area within the vacuum system.
  • Another feature of the present invention is the provision of a novel manifold mounted cryogenic vacuum pump whichis especially adapted for use with existing bell jar vacuum systems so as to greatly increase the utility thereof.
  • Another feature of the present invention is the method of producing extremely clean high vacua in a very short period of time with the strategic use of sorbent vacuum pumps, cryogenic vacuum pumps and electrical sputter ion pumps.
  • FIG. 3 is an enlarged cross section of a preferred cryogenie vacuum pump shown in the vacuum system of FIG. 2 as indicated by the line 3-3,
  • FIG. 4 is an operating diagram showing pressure vs. pump-down time characteristics for the vacuum system of FIGS. 1- and 2,
  • FIG. 7 is a cross section. view of another embodiment of the cryogenic. vacuum pump shown in FIG. 3, and
  • FIG. 8 is a perspective view of still another cryogenic vacuum pump embodiment of the present invention.
  • the vacuum system 11 has a hollow manifold 12 which is rectangular in both its plan andside views.
  • a circular opening 14 In the center of the manifold top 13 is a circular opening 14 which is covered by a removable elongated vacuum bell jar 15.
  • a pair of high vacuum valves 16 are attached over apertures in a side wall of the manifold 12' so as to provide gas communication therewith.
  • a sorption vacuum pump 17 is connected to each of the high vacuum valves 16..
  • Mounted on one side of the bell j-ar 1-5 is a valve assembly 11% supported by a flange: plate 19' which covers a second circular opening 21 in the manifold cover 13.
  • the cryogenic pump opening 33 is covered by a circular mounting flange 34 which is bolted to the manifold cover plate 13 and a vacuum seal provided therebetween by the O-ring 35.
  • the circular mounting flange has a central aperture 36 formed by a recessed shoulder portion 37 which supports an annular washer 33.
  • An annular bellows plate 41 and associated O-ring 42 are attached in a vacuum tight manner to the underside of the recessed shoulder 37 by a plurality of bolts 43 which extend through the annular washer 33.
  • the high vacuum tight bellows 44 is attached, for example, by brazing at its upper end to the bellows plate 41 and at its lower end to a mounting nut
  • the mounting nut 45 is attached by, for example, brazing to the inner bottom of a cup-shaped valve plate 46.
  • he flanged rim 47 of the cup-shaped valve plate 46 includes an O-ring 48 adapted to make a vacuum seal with the underside of circular mounting flange 34 so as to form an auxiliary vacuum compartment 49.
  • the cup-shaped valve plate 46 is held in alignment by a plurality of guide rods 51 which screw into the underside of circular mounting flange 34 and pass through apertures in the flanged rim t7.
  • a hollow metallic donut structure 52 Mounted within the auxiliary vacuum compartment is a hollow metallic donut structure 52 whose top surface has a plurality of apertures 53 which communicate with attached inner tubes 54.
  • the inner tubes 54 extend through apertures 55 in the circular mounting flange 34 and terminate in outwardly flared portions 56. These outwardly flared portions 56 are attached by, for example, brazing to the inwardly flared portions 57 of outer tubes 8 which enclose and are spaced from the inner tubes 54.
  • the outer tubes 58 are attached vacuum tightly to the surfaces of apertures 55 thereby supporting the donut structure 52.
  • the inner tubes 54 provide inlets for filling the hollow donut structure 52 with a liquid coolant.
  • the double spaced apart tubing structure provides a long heat conduction path including the lengths of both inner tubes 54 and outer tubes 55 between the donut structure 52 and the circular cover plate 34. This design greatly reduces the loss of cooling liquid by evaporation from the outer vacuum wall surface.
  • One end of a hollow elbow tube 59 is attached to the surface of another aperture 61 in circular mounting flange 34 to provide gas communication into the auxiliary vacuum compartment 49.
  • the other end of hollow elbow tube 59 is attached to a vacuum flange 62 adapted for connection to another pumping mechanism (not shown) whose utility will be explained below.
  • annular washer 33 Mounted on the annular washer 33 is a pair of annular ball bearing assemblies 65 which straddle an externally extending circular shoulder 64- of a hollow internally threaded nut shaft 63.
  • a domed cover 66 Secured to the circular mounting flange 34 by bolts 66 is a domed cover 66 which encloses the ballbearing assemblies 65 and which has a central aperture through which the nut shaft 63 passes.
  • a screw shaft 67 passes entirely through the nut shaft 63 and has external threads which engage the internal threads of nut shaft 63 and of mounting nut 45.
  • Supported by the domed cover 66 is a hand wheel 68 which is secured to nut shaft 63 by a set screw 69.
  • the nut shaft 63 and the hand wheel 68 are prevented from movement in the vertical direction by the domed cover 66 and recessed mounting flange shoulder 37 while the cup-shaped valve plate 46 and attached mounting nut 45 are prevented from rotational movement by the guide rods 51.
  • rotational movement of the hand wheel 68 will produce a vertical movement of screw shaft 67 and a corresponding vertical movement of cup-shaped valve plate 46.
  • the valve plate 4-6 can be lowered on the guide rods 51 to expose the donut structure 52 as shown in FIG. 2.
  • the main vacuum chamber 71 including the area within the bell jar 15 and the manifold 12 is first evacuated to about 50 mm. Hg by an oil free vacuum pump such as, for example, a water jet exhauster vacuum pump (not shown) with the valve plate 24 and the cup-shaped valve cover 46 in the closed positions and the sorption pumps 17 valved off.
  • the water jet forepump is then valved off and the liquid nitrogen cooled sorption pumps 17 sequentially utilized to further reduce the pressure Within the main vacuum chamber 71 to about 10* millimeters of mercury.
  • both E the sorption pumps 17 are valved off and both the valve plates 24 and 46 are opened to provide gas access between the main vacuum chamber 71 and both the sputter-ion pump 31 and the donut structure 52.
  • Condensablc vapors within the main vacuum chamber 71 are then condensed at an extremely rapid rate upon the outer surface of the donut structure 52 which has been previously filled through tubes 54 with a cooling fluid such as, for example, liquid nitrogen.
  • This pumping action in addition to that provided by the sputter-ion pump 31 will quickly reduce th system pressure to a desired value.
  • the gases condensed on the cold donut structure 52 have a high vapor pressure (for example, 16- mm.
  • valve cover 46 can again be closed at about this pressure to isolate the donut structure 52 from the main vacuum chamber 71 thus preventing re-evolution of these condensed vapors.
  • auxiliary vacuum chamber 49 With cup-shaped valve cover 46 closed the auxiliary vacuum chamber 49 will maintain the vapors in condensed form upon the outer surface of the cold donut structure 52.
  • the vacuum cover 50 can then be removed from the flange 62 and another vacuum pump (not shown) connected thereto to remove the gases formed by the evolution of the condensed vapors after elimination of the cooling fluid from the donut structure 52. In this way, the cryogenic cold surface 52 can be cleaned of .condensables and again utilized for further pumping action by re-chilling of the donut 52 and opening of cup-shaped valve cover 46.
  • FIG. 4 illustrates the dramatic effect achieved by the use of the cryogenic pump 32 in the pump-down sequence described above.
  • Curve A represents a pump-down curve of the vacuum system 11 in the sequence described above with pressure within the system 7i plotted on the vertical log scale and pump-down time on the horizontal log scale wherein zero time begins with the system at atmospheric pressure.
  • Curve B is a similar pump-down curve for the vacuum system 11 in the sequence described above except that the cryogenic vacuum pump 32 is not utilized.
  • the use of the cryogenic pump 32 produced a pressure below 10- millimeters of mercury in approximately 40 minutes.
  • Curve B shows that the same vacuum system operated without the cryogenic vacuum pump 32 achieved a pressure of only slightly below 10" millimeters of mercury in the same period of time.
  • the main vacuum chamber 71 comprised a volume of about 4 cubic feet and the cryogenic vacuum pump donut 52 exhibited an exposed outer surface area of about 100 square inches.
  • a sputterion pump having a rated pumping speed of 400 liters per second and sorption pumps of the type described in US. patent application No. 91,837 were used.
  • FIG. 5 shows another cryogenic vacuum pump embodiment wherein elements which are the same as those shown in FIG. 3 are given identical reference numerals.
  • the valve control mechanism 72 passes through the bottom of manifold 12 rather than through the manifold cover plate 13 and the guide rods 73 are embedded in manifold cover 13 rather than in circular mounting flange 34.
  • This embodiment otters the advantage that the cupshaped valve cover 46 can be vacuum sealed against the manifold cover 13 to isolate the donut structure 52 from the main vacuum system 71 after which the entire cryogenic pump structure 74, including donut structure 52, inlet tubes 54, circular mounting flange 34 and elbow tube 59 can be removed from manifold cover 13 without letting the main vacuum system 7 1 up to atmospheric pressure.
  • an operator could remove an exceptionally contaminated donut structure 52 for chemical cleaning While maintaining the main vacuum system 71 under high vacuum.
  • FIG. 6 shows another embodiment of a cryogenic vacuum pump for mounting in a vacuum system such as that shown in FIGS. 1 and 2.
  • a hollow cylindrical casing 80 having a top end wall 81 which supports an inner bellows 82 and a spaced apart outer bellows 83
  • the concentric bellows 82 and 83 are sealed at their upper ends to the inside of the topend wall 81 and at their lower ends by a circular bellows plate 84 which supports a valve plate 85.
  • a plurality of guide rods 99 are embedded into the underside of manifold cover 13 and provide guidance for vertical movement of the valve plate 85.
  • a plurality of tubes 86 extend through the top end wall 8 1 into the chamber 87 formed between inner bellows 82.
  • a driving mechanism 89 similar to that shown in FIG. 3, extends through top end wall 8 1 and inner bellows S2 and is attached to bellows plate 84-.
  • the bellows 82 and 83 can be placed in their extended position as shown in FIG. 6 or can be withdrawn into the cylindrical casing till while the attached valve plate 85 forms a vacuum seal on the underside of manifold cover 13.
  • a disadvantage of this embodiment as opposed to the embodiments of FIGS. 3 and 5 is that the entire liquid coolant container (the bellows 82 and 83) must be raised or lowered by the driving mechanism 89 rather than merely the valve plates as is the case in the embodiments of 3 and 5. This somewhat complicates the mechanical structural problems because of the increased mass it is neces- I sary to move. Also, in the embodiments of FIGS. 3 and 5 the containers for the liquid coolant (donut structure 52'.) are completely stationary and thereby require no moving liquid seals to allow filling thereof.
  • FIG. 7 illustrates another embodiment of the donut structure 52 of FIG. 3.
  • a plurality of compartments 91 are formed by brackets 92 which extend about and are attached, for example, by brazing, to the outer circumferential surface 93 of the donut structure 52.
  • the compartments 91 are filled with a highly gas sorbent material 94;
  • the vacuum system adaptor 11%) allows an existing vacuum system to be easily converted to a system having a cryogenic vacuum pump positioned within the main vacuum chamber. Without conductance limitations the cryo genic pump may then function to greatly increase the system performance as described above,
  • compartments adjacent the outer surface of said container portion, and wherein the additional compartments formed by said means contain a gas absorbent material.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US182528A 1962-03-26 1962-03-26 High vacuum pumping method and apparatus Expired - Lifetime US3156406A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US182528A US3156406A (en) 1962-03-26 1962-03-26 High vacuum pumping method and apparatus
GB10850/63A GB977185A (en) 1962-03-26 1963-03-19 High vacuum pumping method and apparatus
CH382563A CH421370A (de) 1962-03-26 1963-03-26 Hochvakuum-Pumpvorrichtung

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US182528A US3156406A (en) 1962-03-26 1962-03-26 High vacuum pumping method and apparatus

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CH (1) CH421370A (de)
GB (1) GB977185A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811794A (en) * 1972-11-22 1974-05-21 Bell Telephone Labor Inc Ultrahigh vacuum sublimation pump
JP2004502094A (ja) * 2000-06-29 2004-01-22 ビーコン・パワー・コーポレーション 並列ポンプ装置を備えるフライホイールシステム
US9960025B1 (en) * 2013-11-11 2018-05-01 Coldquanta Inc. Cold-matter system having ion pump integrated with channel cell

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117212127B (zh) * 2023-09-27 2026-03-06 中国科学院沈阳科学仪器股份有限公司 一种可调参数的离子泵测试工装

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR376565A (fr) * 1906-06-16 1907-08-13 Ion Des Procedes Georges Claude) Perfectionnements dans les appareils à vide par les basses températures
US2197079A (en) * 1936-05-29 1940-04-16 Philips Nv Method and device for measuring pressures
US2897036A (en) * 1957-04-18 1959-07-28 High Voltage Engineering Corp Method of evacuation
US2985356A (en) * 1958-12-04 1961-05-23 Nat Res Corp Pumping device
US3009629A (en) * 1957-07-05 1961-11-21 Commissariat Energie Atomique High vacuum pumps
US3027651A (en) * 1958-07-23 1962-04-03 Leybold Hochvakuum Anlagen Process and system for removing condensable vapors
US3056740A (en) * 1956-10-12 1962-10-02 Edwards High Vacuum Ltd Vapourisation of metals

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR376565A (fr) * 1906-06-16 1907-08-13 Ion Des Procedes Georges Claude) Perfectionnements dans les appareils à vide par les basses températures
US2197079A (en) * 1936-05-29 1940-04-16 Philips Nv Method and device for measuring pressures
US3056740A (en) * 1956-10-12 1962-10-02 Edwards High Vacuum Ltd Vapourisation of metals
US2897036A (en) * 1957-04-18 1959-07-28 High Voltage Engineering Corp Method of evacuation
US3009629A (en) * 1957-07-05 1961-11-21 Commissariat Energie Atomique High vacuum pumps
US3027651A (en) * 1958-07-23 1962-04-03 Leybold Hochvakuum Anlagen Process and system for removing condensable vapors
US2985356A (en) * 1958-12-04 1961-05-23 Nat Res Corp Pumping device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811794A (en) * 1972-11-22 1974-05-21 Bell Telephone Labor Inc Ultrahigh vacuum sublimation pump
JP2004502094A (ja) * 2000-06-29 2004-01-22 ビーコン・パワー・コーポレーション 並列ポンプ装置を備えるフライホイールシステム
EP1297257A4 (de) * 2000-06-29 2007-09-19 Beacon Power Corp Schwungradenergiespeicher mit pumpen, um im schwungradgehäuse ein vakuum zu erzeugen
US9960025B1 (en) * 2013-11-11 2018-05-01 Coldquanta Inc. Cold-matter system having ion pump integrated with channel cell

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Publication number Publication date
GB977185A (en) 1964-12-02
CH421370A (de) 1966-09-30

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