US3646775A - Cryostat - Google Patents

Cryostat Download PDF

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Publication number
US3646775A
US3646775A US3646775DA US3646775A US 3646775 A US3646775 A US 3646775A US 3646775D A US3646775D A US 3646775DA US 3646775 A US3646775 A US 3646775A
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United States
Prior art keywords
liquid
container
duct
cryostat
vapor
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Expired - Lifetime
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English (en)
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Jacques Bonnerot
Henri Paradan
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US Philips Corp
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US Philips Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C3/00—Vessels not under pressure
    • F17C3/02—Vessels not under pressure with provision for thermal insulation
    • F17C3/08—Vessels not under pressure with provision for thermal insulation by vacuum spaces, e.g. Dewar flask
    • F17C3/085—Cryostats
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/05—Applications for industrial use
    • F17C2270/0509—"Dewar" vessels

Definitions

  • Appl' 17560 comprising an outer container which can be evacuated and in which a liquid container for cryogenic cooling liquid is [30] Foreign Application Priority Data disposed, the liquid container being annular and closed and substantially surrounding the object to be cooled an inner Mar. 10 1969 France ..6906690 container being present in the space between the annular liquid container and the object to be cooled which inner con- [52] US.
  • CL ....62/216, 62/514 tamer likewise substantially surrounds the ob ect to be cooled and is in thermal contact therewith, a system of liquid ducts Searc and a system of vapor ducts present for communicating between said containers with a blowoff valve in a va r duct 6 P 1 References cued opening to the atmosphere outside the cryostat, and a control UNlTED STATES PATENTS device present for controlling the pressure in at least the liquid 3 195 620 7H9 St hard: 62/514 container and the temperature in the inner container.
  • the invention relates to a cryostat which is suitable for keeping an object at a constant low temperature, and comprises an outer container which can be evacuated and in which a liquid container for cryogenic cooling liquid is arranged.
  • cryostats are frequently used for this purpose in which a cryogenic cooling liquid, for example, liquid nitrogen or liquid helium, is provided.
  • a cryogenic cooling liquid for example, liquid nitrogen or liquid helium.
  • the known cryostats are not suitable for use in certain investigations, for example, space research where it is required that the cryostat, in addition to an independent self-supporting operation, be able to operate in any position and in a rare atmosphere having a low or no atmospheric pressure, while the weight and the dimensions of the cryostat must remain restricted.
  • cryostats having a stationary liquid bath have comparatively large dimensions, while the cryostats in which the cryogenic liquid is circulated often have a considerable store of gas which necessitates extra space and a fixed position of the cryostat.
  • a pumping device is moreover necessary to maintain the circulation of the cooling medium which also requires considerably extra space.
  • the cryostat according to the invention is characterized in having a liquid container that is annular, and is closed, and mainly surrounds the object to be cooled, and an inner container which also surrounds the cooling object mainly and is in thermal contact therewith being present in the space between the annular liquid container and the object to be cooled; a system of liquid ducts is present within the closed outer container, which system communicates (a) via at least one first and at least one second liquid duct at different levels, with the liquid container, and (b) via at least one third and at least one-fourth liquid duct at different levels, with the inner container.
  • the closed outer container furthermore comprises a system of vapor ducts which communicate on the one hand, via at least one first and at least one second vapor duct at different levels, with the inner container, and on the other hand, via at least one vapor outlet duct in which a blowoff valve is incorporated, opens outside the cryostat; a control device is present for controlling the pressure in at least the liquid container and the temperature in the inner container.
  • a cryostat is extremely suitable for use in spacecraft, for example, airplanes, rockets, balloons and the like.
  • the liquid container and the inner container arranged around the object to be cooled both form effective radiation screens against the thermal radiation originating from outside the cryostat, while the cryostat can operate in any position notably by the presence of the closed liquid container and the closed system of ducts. Since the liquid container is annular, the object to be cooled is not fully surrounded by the said container and hence space is available for an entrance window which allows entrance for radiation to the object to be cooled.
  • the inner container situated between the object to be cooled and the liquid container comprises cryogenic liquid originating from the said liquid container and therefore forms an auxiliary storage container. This arrangement guarantees an excellent transfer of cold from the cryogenic liquid to the object to be cooled.
  • the quantity of liquid which can flow from the liquid container to the inner container to be evaporated there by thermal contact with the object to be cooled is determined by controlling the pressure in the said liquid container. It is also ensured that the object to be cooled always remains at a constant low temperature. Since the evaporation of liquid in the inner container is also determined by the pressure in the vapor outlet duct, the outlet valve ensures a control of said pressure and also serves as an extra safety.
  • the outside of the object to be cooled also forms the boundary of the inner container.
  • a further favorable embodiment of the cryostat according to the invention is characterized in that the first and second liquid duct communicate, via a common communication duct, with the third and fourth liquid duct, and a control valve is incorporated in the common communication duct for controlling the quantity of the cooling liquid flowing from the liquid container to the inner container. This provides an extra possibility of controlling the flow of liquid to the inner container in such manner that the quantity supplied to the inner container corresponds to the quantity evaporated in said container.
  • control device is formed on the one hand by at least one pressure gauge which switches on a heating device for supplying thermal energy to the liquid container when the pressure in said container falls below a given minimum value, and on the other hand by a number of temperature-sensitive elements arranged on the inner container and switching off the said heating device when the temperature of the cooling liquid in the inner container exceeds the evaporation temperature which corresponds to a given maximum permissible pressure.
  • the heating device may be formed by a number of electric resistance elements which are arranged in the liquid container at different levels.
  • the temperature-sensitive elements may be germanium resistance elements.
  • the temperature of the liquid in the inner container depends upon the quantity of cooling liquid supplied to said container, and on the extent of evaporation.
  • a temperature-sensitive element assumes a different temperature according as said element is situated in vapor or in liquid, which enables the determination of the liquid level.
  • the determination is made independent of the position of the cryostat by using several elements preferably placed at some distance from one another.
  • the temperature-sensitive elements which can switch off the heating device in the liquid container determine the maximum pressure which can occur in the cryostat.
  • Such a control system has minimum dimensions and a minimum response time while notably when helium is used as a cooling medium, the quantity of thermal energy which must be supplied to increase the pressure in the liquid container sufficiently is extremely small.
  • the electric heating resistance elements can be supplied with low voltage and dissipate a low power of, for example, one-tenth of a watt.
  • a number of radiation screens are present which are arranged within the outer container and at least substantially entirely surround the liquid container, the inner container, and the object to be cooled, the radiation screens being cooled by parts of the system of vapor ducts provided around the radiation screens and constructed as cooling spirals, the cooling spirals which communicate with the vapor outlet duct on their one side communicating on their other side with liquid-vapor separators in the first and the second liquid duct, and with the first and second vapor duct, respectively.
  • a communication duct is present between the vapor outlet duct and the vacuum space in the outer container, in which communication duct a control valve is incorporated.
  • the cooling liquid is helium. In this manner, cooling of objects at a very low temperature (4 K.) is possible.
  • FIG. 1 is a cross-sectional view of a cryostat
  • FIG. 2 is a cross-sectional view of the cryostat taken on the line ll--Il of FIG. 1.
  • Reference numeral 1 denotes a recording apparatus 1 having at one end a photocathode 2 facing an entrance window 3, and at the other end a photographic apparatus 4.
  • the cylindrical part of the recording apparatus situated between the photocathode 2 and the photographic apparatus 4 is to be kept at a low temperature.
  • the cylindrical outer wall of the recording apparatus 1 forms the inner wall 5 of the inner container 6 the outer wall 7 of which is also cylindrical.
  • a hermetically sealed annular liquid container 8 is situated which is arranged coaxially with the inner container and has substantially the same height so as to serve both as a radiation screen and as a storage container for cryogenic liquid.
  • the assembly is housed in a hermetically sealed outer container 9 in which the entrance window 3 is incorporated which passes radiation which is of importance for the apparatus 1.
  • Two radiation screens 10 and 11 are situated between the liquid container 8 and the outer container 9 and fully surround the liquid container 8 and the apparatus 1 with the exception of the passage 12 opposite to the entrance window 3.
  • the liquid container 8 comprises a tube 13 passed through the wall of said container and having incorporated therein a valve 14, which tube, through the radiation screens 10 and 11 and through the outer container 9, opens outside the cryostat and is provided there with a stopper 56.
  • This pipe serves for emptying and filling the liquid container 8.
  • the valve 14 is a maximum pressure valve and therefore serves as a safety valve for the liquid container 8.
  • the liquid container 8 furthermore comprises an absolute pressure gauge 15 which comprises a contact which, when the pressure in the liquid container 8 falls below a given adjusted value, switches on heating coils 52 and 53.
  • the place of the pressure gauge is not critical for the variation in pressure as a result of the variation in the liquid level above the pressure gauge, is nearly always negligible relative to the admissible minimum pressure.
  • Two separators 16 and 17 in which vapor and liquid are separated from each other and which are situated at oppositely located places, communicate with the liquid container 8.
  • the liquid flows through the ducts l8 and 19, respectively, which open into a control valve 20, after which the liquid is conducted, via ducts 21 and 22 which open in the inner container 6 at oppositely located places 23 and 24, respectively, to said container.
  • From the separators 16 and 17 vapor is conducted, via ducts 25 and 26, respectively, to cooling spirals 27 and 28 which cool the outermost radiation screen 11.
  • blowoff valve 30 is a maximum pressure valve which releases the communication with the ambient air at a pressure in the duct 29 which is slightly higher than the atmospheric pressure.
  • the vapor which has formed in the inner container 6 is conducted at two oppositely located places 31 and 32, via ducts 33 and 34, to two cooling spirals 35 and 36 to cool the innermost radiation screen 10. From the cooling spirals 35 and 36 the vapor flows, via ducts 39 and 40, to the vapor outlet duct 29.
  • Two temperature-sensitive element 41 and 42 are provided on the outer wall 7 of the inner container 6 at oppositely located places. In circumstances, however, it may be of advantage to place the temperature-sensitive elements in the area which is nearest. to those parts of the apparatus 1 which must be kept at the lowest temperature.
  • the temperature-sensitive elements in this case are direct current supplied germanium detectors but may also be semiconductor diodes.
  • the temperature-sensitive elements can switch off the heating coils 52 and 53 by means of relays.
  • a vacuum space 43 is present inside the outer container 9 .
  • the vacuum pump can be made to communicate with said space at the area of the stopper 44.
  • the material and the dimensions of the entrance window 3 are determined by the use for which the apparatus 1 is destined.
  • the apparatus may comprise electrodes, which necessitates electric supply. These electrodes can be provided without difficulty on the wall 5; contact pins can then accordingly be placed in an insulated manner in the wall 7 of the inner container 6 and in the wall of the outer container 9.
  • liquid container 8 the assembly of apparatus 1 and photographic apparatus 4, as well as the radiation screens 10 and 11, and the various parts of the ducts must be kept in place with suitable means.
  • the necessary supports are preferably formed by thin pipes which have a maximum thermal resistance.
  • the cryostat can be extended with components which are useful for practical purposes. Therefore H6. 2 shows the control valve 20 provided with a rod 49 which is passed out through the outer container 9. The control valve 20 can then be operated from outside the cryostat at the area 50.
  • the ducts are mutually provided in such manner that all the necessary detachable connections are situated on the same side of the cryostat corresponding to the plane in which the radiation screens are mounted and to the plane 46 in which the parts of the outer container 9 are combined. As a result of this the connections are easily accessible and detachable.
  • the cryostat is particularly simple in operation. Filling of the liquid container 8 with cryogenic liquid is effected by siphoning or by means of a transport duct according to conventional methods. The evacuation of the vacuum space 43 is carried out also according to known methods.
  • control valve 20 is adjusted so that the supply of liquid corresponds to the quantity necessary to compensate for the losses of the cryostat. Too large a quantity would involve the danger of cryogenic liquid coming in the cooling spirals for the radiation screens, which is unfavorable for the thermal efficiency.
  • the valve 20 enables the liquid ducts to be constructed with wide diameters the advantages of which are large heat-exchanging areas and low resistances to flow.
  • the temperature-sensitive element 41 and 42 ensure that the heating of cryogenic liquid in the liquid container 8 is switched off as soon as the temperature exceeds the evaporating temperature associated with the permitted pressure in the system of ducts.
  • the pressure gauge 15 ensures that, by heating of the liquid in the liquid container 8, said pressure does not fall below the permitted minimum pressure.
  • cryostat In these circumstances independent operation of the cryostat is possible for more than hours with a liquid container having a capacity of to 30 liters placed in a cylindrical outer container having a diameter of 400 mm. and a power dissipation in the order of 1 watt.
  • the assembly has a light weight by using the light aluminum or magnesium alloys where this is possible.
  • cryostat Although in the embodiment of the cryostat described a recording apparatus having a photocathode and a photographic apparatus are arranged in the cryostat, it is obvious that all kinds of other measuring and recording instruments are possible.
  • a cryostat for keeping an object at a constant low temperature comprising an outer container to be evacuated and in which a liquid container for cryogenic cooling liquid is arranged, characterized in that the said liquid container is annular and is closed and substantially surrounds the object to be cooled, an inner container which likewise substantially surrounds said object and is in thermal contact therewith, being present in the space between the annular liquid container and said object, a system of liquid ducts being present in the closed outer container and communicates with the liquid container via at least one first and at least one second liquid duct at different levels, and communicates, via at least one-third and at least one-fourth liquid duct at different levels with the inner container, :1 system of vapor ducts being furthermore present in the closed outer container and communicates via at least one first and at least one second vapor duct at different levels, with the inner container, and at least one vapor outlet duct, a blowoff valve incorporated therein which opens outside the cryostat, and a control device being furthermore present for controlling the pressure in at least
  • a cryostat according to claim 1 wherein the first and the second liquid ducts communicate, via a common communication duct, with the third and fourth liquid ducts, the apparatus further comprising a control valve for controlling the quantity of cooling liquid flowing from the liquid container to the inner container incorporated in the common communication duct.
  • a cryostat according to claim 1 further comprising heating means for supplying thermal energy to the liquid container, and said control device is formed by at least one pressure gauge which switches on said heating means when the pressure in said container falls below a given minimum value, and the control device further comprises a temperature-sensitive element provided on the inner container for switching off the said heating means when the temperature of the cooling liquid in the inner container exceeds the evaporation temperature which corresponds to a given maximum permissible pres sure.
  • thermosensitive element is a germanium resistance element.
  • a cryostat according to claim 1 further comprising radiation screens arranged within the outer container and at least substantially entirely surrounding the liquid container, the inner container, and the object to be cooled, the radiation screens being cooled by parts of the vapor duct system provided around the radiation screens and constructed as cooling spirals, the apparatus further comprising liquid-vapor separators incorporated in the first and the second liquid duct, the cooling spirals communicating on their one side with the vapor outlet duct communicating on their other side with said separator and with the first and second vapor duct, respectively.
  • a cryostat according to claim 1 further comprising a communication duct between the vapor duct and the vacuum space in the outer container, said communication duct including a control valve 45.
  • a cryostat apparatus for cooling an object to be cooled, the apparatus operable with evacuating means and with cryogenic cooling liquid, and comprising: a closed inner container that surrounds the object to be cooled and is in thermal contact therewith, a closed annular liquid container that generally surrounds the inner container and object to be cooled therein with said cryogenic liquid disposable therein, a closed outer container that surrounds the liquid container with an evacuable space defined within said outer container, first duct means for communicating cryogenic liquid between the outer container and the liquid and inner containers, second duct means for communicating vapor of said cryogenic liquid between the outer and inner containers, valve means for venting the second duct means externally of the apparatus, and means for controlling the pressure in the liquid container and the temperature in the inner container.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Temperature (AREA)
US3646775D 1969-03-10 1970-03-09 Cryostat Expired - Lifetime US3646775A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR6906690A FR2036292A5 (enrdf_load_stackoverflow) 1969-03-10 1969-03-10

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US3646775A true US3646775A (en) 1972-03-07

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US3646775D Expired - Lifetime US3646775A (en) 1969-03-10 1970-03-09 Cryostat

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US (1) US3646775A (enrdf_load_stackoverflow)
CH (1) CH514820A (enrdf_load_stackoverflow)
DE (1) DE2010967C3 (enrdf_load_stackoverflow)
FR (1) FR2036292A5 (enrdf_load_stackoverflow)
GB (1) GB1307236A (enrdf_load_stackoverflow)
NL (1) NL7003198A (enrdf_load_stackoverflow)
SE (1) SE362295B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4432216A (en) * 1981-11-06 1984-02-21 Hitachi, Ltd. Cryogenic cooling apparatus
US4445790A (en) * 1982-04-07 1984-05-01 United Technologies Corporation Apparatus for cryogenic proof testing of rotating parts
US11209125B2 (en) * 2017-02-13 2021-12-28 Linde Gmbh Transport container
KR20220031869A (ko) 2016-06-08 2022-03-14 신에쓰 가가꾸 고교 가부시끼가이샤 광경화성 플루오로폴리에터계 고무 조성물로 이루어지는 고무계 접착제

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2906153C2 (de) * 1979-02-17 1984-10-31 C. Reichert Optische Werke Ag, Wien Kühlkammer zur Aufnahme von zu bearbeitenden Objekten, insbesondere biologischen Objekten
RU2404092C1 (ru) * 2009-10-12 2010-11-20 Федеральное Государственное Унитарное Предприятие Государственный научно-производственный ракетно-космический центр (ФГУП "ГНПРКЦ "ЦСКБ-Прогресс") Система терморегулирования космического объекта

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3195620A (en) * 1963-06-14 1965-07-20 Hollins College Corp Process and apparatus for maintaining constant low temperatures
US3364687A (en) * 1965-05-03 1968-01-23 Massachusetts Inst Technology Helium heat transfer system
US3424230A (en) * 1966-12-19 1969-01-28 Andonian Associates Inc Cryogenic refrigeration device with temperature controlled diffuser

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3195620A (en) * 1963-06-14 1965-07-20 Hollins College Corp Process and apparatus for maintaining constant low temperatures
US3364687A (en) * 1965-05-03 1968-01-23 Massachusetts Inst Technology Helium heat transfer system
US3424230A (en) * 1966-12-19 1969-01-28 Andonian Associates Inc Cryogenic refrigeration device with temperature controlled diffuser

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4432216A (en) * 1981-11-06 1984-02-21 Hitachi, Ltd. Cryogenic cooling apparatus
US4445790A (en) * 1982-04-07 1984-05-01 United Technologies Corporation Apparatus for cryogenic proof testing of rotating parts
KR20220031869A (ko) 2016-06-08 2022-03-14 신에쓰 가가꾸 고교 가부시끼가이샤 광경화성 플루오로폴리에터계 고무 조성물로 이루어지는 고무계 접착제
US11209125B2 (en) * 2017-02-13 2021-12-28 Linde Gmbh Transport container

Also Published As

Publication number Publication date
FR2036292A5 (enrdf_load_stackoverflow) 1970-12-24
DE2010967A1 (de) 1970-09-24
DE2010967C3 (de) 1979-02-22
SE362295B (enrdf_load_stackoverflow) 1973-12-03
GB1307236A (en) 1973-02-14
NL7003198A (enrdf_load_stackoverflow) 1970-09-14
DE2010967B2 (de) 1978-06-22
CH514820A (de) 1971-10-31

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