Circulation-type low temperature maintenance device having dual pump, and low temperature maintenance method using same

Abstract

The present disclosure relates to a circulation-type low temperature maintenance device having a dual pump, and a low temperature maintenance method using same, the device dually providing an adsorption pump connected in parallel to a dry pump so that the temperature of helium can be implemented in a wide range, thereby enabling a low temperature of 1.8-300 Ks and a sub-Kelvin of 1 Ks or lower to be implemented such that helium can be efficiently cooled at low cost.

Description

Circulating cryogenic maintenance device equipped with a dual pump and a cryogenic maintenance method using the same

[0001] The present disclosure relates to a circulating cryostat equipped with a dual pump and a cryostat method using the same, wherein the circulating cryostat equipped with a dual pump is equipped with an adsorption pump connected in parallel to a dry pump so as to realize helium-4 at a low temperature of 1.8 K to 300 K and at the same time realize it at a sub-Kelvin temperature of 1 K or less, and a cryostat method using the same.

[0002] The boiling point of helium is about 4.2 K, and helium remains in a liquid state only at extremely low temperatures lower than 4.2 K. Liquid helium is divided into helium-4 and helium-3, and generally helium-4 can cool substances to 1.5 K and helium-3 to 0.3 K. However, since the price of helium-3 is much higher than that of helium-4, much research is being conducted to maintain a low temperature state and an ultra-low temperature sub-Kelvin state in a cyclic manner using helium-4. Previously, Korean Patent Publication No. 10-2002-0080122 disclosed a low-temperature thermostatic bath that combines a helium gas refrigerator and a continuous cooling refrigerator, which operate in parallel with a helium gas refrigerator that can lower the temperature to 10 K and a continuous cooling refrigerator that can quickly lower the temperature to 4.2 K with a small amount of liquid helium. However, conventional cryogenic devices can only lower helium within a low-temperature temperature range of 10 K to 4.2 K, which has the problem of not being able to maintain a variety of helium temperatures.

[0003] According to the present disclosure, there is provided a circulating cryogenic maintenance device having a dual pump capable of maintaining a low temperature state and a sub-Kelvin temperature of 1 K or less by connecting an adsorption pump in parallel to a dry pump, and a cryogenic maintenance method using the same.

[0004] A circulating cryostat equipped with a dual pump according to the present disclosure comprises: a sample space in which liquid helium is stored and one end of a modular probe is inserted; a cooler equipped with a compressor and one or more cold heads; a buff tank in which gaseous helium is stored, a liquefaction tank in which gaseous helium stored in the buff tank is liquefied and stored; a first heat exchange line disposed between the buff tank and the liquefaction tank and exchanging heat with the cooler; a dry pump having one end connected to the sample space and the other end connected to the first heat exchange line; and a first cooling unit including a first valve disposed between the sample space and the dry pump; and an adsorption pump including an adsorbent, a second heat exchange line having one end connected to the adsorption pump and exchanging heat with the cooler, and a second valve connected to the sample space and the other end connected to the second heat exchange line.

[0005] Next, the cryogenic maintenance method using a circulating cryostat equipped with a dual pump according to the present disclosure includes: a cooler cooling step of cooling a cooler equipped with a compressor and one or more cold heads; a liquid helium storage step of liquefying and moving gaseous helium stored in the buffing tank through the first heat exchange line through the cooling of the cooler and storing it as liquid helium in the liquefaction tank; a first cooling step of opening a first valve of the first cooling unit while the second valve of the second cooling unit is closed, and operating the dry pump so that the liquid helium in the liquefaction tank moves to the sample space, and the liquid nucleus in the sample space is cooled to a first temperature in the range of 1.8 K to 300 K; and a second cooling step of opening a second valve of the second cooling unit while the first valve of the first cooling unit is closed, and operating the adsorption pump so that the liquid nucleus in the sample space is cooled to a second temperature of less than 1 K.

[0006] According to the present disclosure, a dual-suction pump is connected in parallel to a dry pump to enable temperature implementation for helium in a wide range, thereby enabling low temperatures of 1.8 to 300 K and sub-Kelvin temperatures of 1 K or less, thereby enabling inexpensive and efficient cooling of helium.

[0007] Figure 1 is a graph showing the relationship between vapor pressure and temperature of helium-3 and helium-4 of the present disclosure.

[0008] Figure 2 is a schematic diagram of a circulating cryogenic device equipped with a dual pump according to one embodiment of the present disclosure.

[0009] Figure 3 is a schematic diagram of a modular probe of a circulating cryogenic device equipped with the above-mentioned dual pump.

[0010] Figure 4 is a schematic diagram of a circulating cryogenic device equipped with a dual pump according to another embodiment of the present disclosure.

[0011] Figure 5 is a flow chart of a low-temperature maintenance method using a circulating low-temperature maintenance device equipped with a dual pump according to one embodiment of the present disclosure.

[0012] Figure 6 is a schematic diagram of a liquid helium storage stage according to one embodiment of the present disclosure.

[0013] Figure 7 is a schematic diagram of a first cooling stage according to one embodiment of the present disclosure.

[0014] Figure 8 is a schematic diagram of a second cooling stage according to an embodiment of the present disclosure.

[0015] Figure 9 is a schematic diagram of a recondensation step according to one embodiment of the present disclosure.

[0016] A circulating cryostat equipped with a dual pump according to the present disclosure comprises: a sample space in which liquid helium is stored and one end of a modular probe is inserted; a cooler equipped with a compressor and one or more cold heads; a buff tank in which gaseous helium is stored, a liquefaction tank in which gaseous helium stored in the buff tank is liquefied and stored; a first heat exchange line disposed between the buff tank and the liquefaction tank and exchanging heat with the cooler; a dry pump having one end connected to the sample space and the other end connected to the first heat exchange line; and a first cooling unit including a first valve disposed between the sample space and the dry pump; and an adsorption pump including an adsorbent, a second heat exchange line having one end connected to the adsorption pump and exchanging heat with the cooler, and a second valve connected to the sample space and the other end connected to the second heat exchange line.

[0017] In addition, the circulating cryogenic device equipped with the dual pump according to the present disclosure further includes a cooling column that contacts the sample space and guides the liquid helium.

[0018] In addition, in the circulating low-temperature maintenance device equipped with the double pump according to the present disclosure, the first heat exchange line is configured in a form wound around the cooler, and connects the buff tank and the liquefaction tank to exchange heat with gaseous helium supplied from the buff tank.

[0019] In addition, in the circulating cryogenic device equipped with the dual pump according to the present disclosure, the second heat exchange line is configured in a form wound around the cooler, and is connected to the cooling column and the adsorption pump so that the liquid helium in the sample space moves and is adsorbed by the adsorption pump, thereby exchanging heat with the gaseous helium supplied from the cooling column.

[0020] In addition, in the circulating cryogenic device equipped with the dual pump according to the present disclosure, the helium is characterized in that it is helium-4.

[0021] In addition, the circulating cryogenic device equipped with the dual pump according to the present disclosure includes a thermal switch that enables the adsorption pump to be driven to vaporize liquid helium stored in the sample space.

[0022] In addition, in the circulating low-temperature maintenance device equipped with the dual pump according to the present disclosure, the adsorption pump further includes a heater that can control the operating temperature of the adsorption pump.

[0023] In addition, in the circulating cryogenic device equipped with the dual pump according to the present disclosure, the first cooling unit including the dry pump and the second cooling unit including the adsorption pump are connected in parallel to the sample space into which one end of the modular probe is inserted, and the inside of the sample space can be maintained at a low temperature of sub-Kelvin by opening and closing the first valve of the first cooling unit and the second valve of the second cooling unit.

[0024] Next, the cryogenic maintenance method using a circulating cryostat equipped with a dual pump according to the present disclosure includes: a cooler cooling step of cooling a cooler equipped with a compressor and one or more cold heads; a liquid helium storage step of liquefying and moving gaseous helium stored in the buffing tank through the first heat exchange line through the cooling of the cooler and storing it as liquid helium in the liquefaction tank; a first cooling step of opening a first valve of the first cooling unit while the second valve of the second cooling unit is closed, and operating the dry pump so that the liquid helium in the liquefaction tank moves to the sample space, and the liquid nucleus in the sample space is cooled to a first temperature in the range of 1.8 K to 300 K; and a second cooling step of opening a second valve of the second cooling unit while the first valve of the first cooling unit is closed, and operating the adsorption pump so that the liquid nucleus in the sample space is cooled to a second temperature of less than 1 K.

[0025] In addition, in the circulating low-temperature maintenance device equipped with the dual pump according to the present disclosure, the second cooling step is performed by, after the second cooling step, operating the heater provided in the adsorption pump to liquefy the helium adsorbed in the adsorption pump and recondensing it into a liquefaction tank.

[0026] In addition, in the circulating cryogenic device equipped with the dual pump according to the present disclosure, the re-condensation step is characterized in that the heater is driven, the second valve is opened so that the helium adsorbed by the adsorption pump moves to the sample space, and the first valve is opened so that the helium moved to the sample space moves to the liquefaction tank and is re-condensed.

[0027] In addition, in the circulating cryogenic device equipped with the dual pump according to the present disclosure, the helium is characterized in that it is helium-4.

[0028] A typical refrigerator-based cryostat can achieve a variable temperature from 1.8 K to 300 K using only a rotary pump or a dry pump. However, dry pumps are very expensive, costing tens of millions of won, and have the problem of not being able to achieve a sub-Kelvin temperature. On the other hand, an adsorption pump composed of an adsorbent is inexpensive, costing less than 1 million won, and can form a vacuum of 0.01 mbar using an adsorption pump, enabling a sub-Kelvin temperature of 1 K or less. Fig. 1 illustrates a graph showing the relationship between vapor pressure and temperature of helium-3 and helium-4 of the present disclosure. Referring to Fig. 1, a dry pump can form a vacuum of 1 to 3 mbar, allowing for maintaining a temperature of 1.8 K or higher, while an adsorption pump can form a vacuum of 0.01 mbar or less, enabling a sub-Kelvin temperature of 0.8 K or less. Therefore, in the present disclosure, a circulating cryostat equipped with a dual pump is proposed, in which a dry pump and an adsorption pump are dually connected in parallel to the sample space, thereby enabling helium-4 to be realized at a low temperature of 1.8 K to 300 K and a sub-Kelvin temperature of 1 K or less.

[0029] The present disclosure will be described in detail below with reference to the attached drawings. However, these are merely exemplary and the present disclosure is not limited to the specific embodiments illustrated by way of example.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein for purposes of description is merely for the purpose of describing specific embodiments and is not intended to be limiting.

[0031] Additionally, the singular forms used in the specification and the appended claims are intended to include the plural forms, unless the context clearly dictates otherwise. Furthermore, when a part is said to "include" a component, this does not exclude other components, but rather includes other components, unless otherwise specifically stated.

[0032] FIG. 2 illustrates a circulating cryostat equipped with a dual pump according to one embodiment of the present disclosure, wherein an adsorption pump is connected in parallel to a dry pump to enable the realization of helium-4 at low temperatures of 1.8 K to 300 K and sub-Kelvin temperatures of 1 K or less.

[0033] Referring to FIG. 2, the circulating cryostat equipped with a dual pump of the present disclosure includes a sample space. Liquid helium is stored inside the sample space. At this time, the sample space is configured such that one end of a modular probe is inserted. To this end, the circulating cryostat further includes a cooling column. The cooling column contacts the sample space to guide liquid helium and may be configured such that one end of the modular probe is inserted. FIG. 3 is a schematic diagram of a modular probe of a circulating cryostat (1000) equipped with a dual pump. The modular probe (900) is configured such that one end is positioned outside the housing, and the other end is inserted into a refrigerant column inside the housing, thereby supplying a sample to a liquid helium storage unit. The modular probe (900) is composed of a head portion (920) at one end of the modular probe (900) and an injection portion (910) at the other end. The injection portion (910) at the other end is injected into a cooling column (500) and a sample space (400) inside the case, so that a sample mounted on the injection portion (910) of the modular probe (900) is cooled. In addition, the modular probe (900) can be injected into or removed from the cooling column (500), so that it can be easily replaced. Accordingly, when the inside of the sample space (400) becomes a first temperature formed in the range of 1.8 K to 300 K or a second temperature formed in the range of 0.8 K to 300 K, a sample can be mounted on the injection part (910) of the modular probe (900) and inserted into the cooling column (500) inside the housing to analyze the characteristics of the sample at the first temperature or the second temperature. In addition, the modular probe (900) can be manufactured as a DC-only, AC-only, optical fiber, etc., so that it can be manufactured in various ways according to the purpose, and can be replaced depending on the purpose, so that the sample can be easily replaced.

[0034] In addition, the circulating low-temperature device equipped with a dual pump of the present disclosure further includes a cooler, and the cooler is equipped with a compressor and one or more cold heads. Here, the one or more cold heads may be multiple cold heads, and the multiple cold heads are divided into a first cold head (110) and a second cold head (120). In addition, the cooler further includes a compressor (130) and a rotary valve (140). The compressor (130) compresses a refrigerant to a high pressure. In addition, the compressed high-pressure refrigerant is conveyed through the rotary valve (140), and the conveyed high-pressure refrigerant expands to enable the cooler to form a low temperature.

[0035] In addition, the circulating low-temperature device equipped with a dual pump of the present disclosure can be divided into a first cooling unit and a second cooling unit. The first cooling unit has a buff tank in which gaseous helium is stored. In addition, the first cooling unit includes a liquefaction tank in which the gaseous helium stored in the buff tank is liquefied and stored. Specifically, the liquefaction tank (320) stores gaseous helium liquefied at a low temperature by the buff tank (300) that supplies helium. Here, the first cold head (110) provided in the cooler is cooled to a temperature of 50 K, and the second cold head (120) is cooled to a temperature of 3 K. Since the first cold head (110) and the second cold head (120) are configured to be cooled to different temperatures, helium in a gaseous state at 300 K can slowly decrease in temperature through heat exchange with the first heat exchange tube (310) and condense into helium in a liquid state. At this time, the temperature of the second cold head (120) becomes 3 K, which is lower than the condensation point of helium, so it can be condensed in the liquefaction tank (320) and stored as liquid helium.

[0036] In addition, the first cooling unit further includes a first heat exchange line. The first heat exchange line is arranged between the buff tank and the liquefaction tank and is configured to exchange heat with the cooler. The first heat exchange line is configured to be wound around the cooler, and thus, the first heat exchange line connects the buff tank and the liquefaction tank and exchanges heat with gaseous helium supplied from the buff tank.

[0037] Additionally, the first cooling unit further includes a dry pump. The dry pump is arranged so that one end is connected to the sample space and the other end is connected to the first heat exchange line. The dry pump lowers the pressure in the sample space so that the liquid helium stored in the liquefaction tank is cooled to a temperature range of 1.8 K to 300 K.

[0038] In addition, the first cooling unit is connected to the cooling column (500) and the dry pump (600), and includes a fluid transfer line (610) connected to the first heat exchange line (310). In addition, the first cooling unit includes a liquid helium transfer line (330) that connects the liquefaction tank (320) and the sample space (400) so that the liquid helium inside the liquefaction tank (320) is moved by the pressure of the dry pump (600). Therefore, in order to lower the sample space (400) to the first temperature, the dry pump (600) is driven so that the liquid helium liquefied and stored in the liquefaction tank (320) is moved to the sample space (400) through the liquid helium transfer line, and the liquid helium moved to the sample space (400) is vaporized into the sample column. At this time, the sample space (400) is equipped with a second heater (410). By driving the second heater, the inside of the second heater (410) can be formed in a range of 1.8 K to 300 K. Accordingly, by driving the second heater (410), the internal temperature of the sample space (400) can be implemented to be 1.8 K or higher. At this time, the second heater (410) is equipped with a temperature sensor so that a target temperature can be set, and the inside of the sample space (400) can be made to reach a desired target temperature by the set target temperature. In addition, at this time, a first valve is arranged between the sample space (400) and the dry pump (600). Therefore, the movement of helium transferred to the dry pump (600) can be controlled.

[0039] The second cooling unit includes an adsorption pump containing an adsorbent, and thus one end of the second cooling unit is connected to the adsorption pump and configured to be connected to a second heat exchange line that exchanges heat with the cooler and the sample space. The adsorption pump (800) serves to lower the temperature of the sample space (400) so that liquid helium is vaporized to a sub-Kelvin temperature of less than 1 K or to a temperature of 0.8 K to 300 K. At this time, the liquid helium may be helium-4.

[0040] In addition, the second cooling unit further includes a second heat exchange line. The second heat exchange line is configured in a form that is wound around the cooler, and is connected to the cooling column (500) and the adsorption pump (800) so that the liquid helium in the sample space (400) moves and is adsorbed by the adsorption pump (800), thereby exchanging heat with the gaseous helium supplied from the cooling column (500).

[0041] Therefore, in order to lower the sample space (400) to the second temperature, the adsorption pump (800) is driven so that the liquid helium stored in the sample space (400) is vaporized, so that the inside of the sample space (400) can be formed in the range of 0.8 K to 300 K. In addition, the adsorption pump (800) includes a thermal switch (810) so that the adsorption pump (800) can be driven to vaporize the liquid helium stored in the sample space. Therefore, in order to lower the inside of the sample space (400) to the second temperature, the thermal switch (810) is first driven to the On state so that the adsorption pump (800) can be operated at a low temperature. The other end of the second cooling unit may be provided with a second valve connected to the second heat exchange line. Therefore, the movement of helium transferred to the adsorption pump (800) can be controlled. Accordingly, in order to lower the sample space (400) to the second temperature, the adsorption pump (800) is driven so that the liquid helium stored in the sample space is vaporized, so that the inside of the sample space (400) can be formed in a range of 0.8 K to 300 K. In addition, the sample space (400) is configured to operate only until the liquid helium inside the sample space (400) is completely evaporated.

[0042] In addition, the adsorption pump (800) includes a first heater (820) that can control the operating temperature of the adsorption pump (800). By driving the first heater (820) provided in the adsorption pump (800), the inside of the sample space (400) can be implemented at 0.8 K or higher.

[0043] In addition, the circulating cryostat equipped with a dual pump of the present disclosure can be configured so that the vaporized helium is recondensed by being dually provided with a dry pump and an adsorption pump connected in parallel to the sample space (400). At this time, both the first valve (620) and the second valve (710) are opened, and the first heater (820) provided in the adsorption pump (800) is heated to 40 K. The helium adsorbed in the adsorption pump is vaporized by the heating of the first heater (820), and at this time, the dry pump (600) connected in parallel to the sample space (400) is driven so that the liquefied helium can be collected in the liquefaction tank. At this time, a buff tank (300) may be required for the remaining gaseous helium that has not been liquefied.

[0044] As described above, the circulating low-temperature device equipped with a dual pump of the present disclosure is configured such that the first cooling unit including the dry pump (600) and the second cooling unit including the adsorption pump (800) are connected in parallel to the sample space (400) into which one end of the modular probe (900) is inserted. With this configuration, the inside of the sample space can be maintained at a low temperature of sub-Kelvin by opening and closing the first valve of the first cooling unit and the second valve of the second cooling unit. Specifically, the first cooling unit opens the first valve (620) of the first cooling unit while the second valve (710) of the second cooling unit is closed, and the dry pump (600) is operated so that the liquid helium in the liquefaction tank (320) moves to the sample space (400), and at this time, the liquid helium-4 in the sample space (400) is cooled to a temperature in the range of 1.8 K to 300 K. In addition, the second cooling unit opens the second valve (710) of the second cooling unit while the first valve (620) of the first cooling unit is closed, and drives the adsorption pump (800) to cool the liquid helium in the sample space (400) to a temperature below 1K.

[0045] Accordingly, since the first cooling unit including the dry pump (600) and the second cooling unit including the adsorption pump (800) are configured to be connected in parallel to the sample space (400) into which one end of the modular probe is inserted, the liquid helium in the sample space (400) can be cooled to a temperature in the range of 0.8 K to 300 K by driving the dry pump, and the liquid helium-4 in the sample space (400) can be cooled to a temperature of less than 1 K by driving the adsorption pump (800), so that the temperature of helium can be implemented in a variety of ranges.

[0046] FIG. 4 illustrates a circulating cryostat (1000) equipped with a dual pump according to another embodiment of the present disclosure. Referring to FIG. 4, a first cooling unit and a second cooling unit including an adsorption pump (800) are configured to be connected in parallel to a sample space into which one end of a modular probe (900) is inserted, and a first heat exchange line is provided to include a first valve (620), and a second heat exchange line (700) is provided so as not to include a second valve (710). In addition, it can be seen that a second heat exchange line (700) connecting a cooling column (500) and an adsorption pump (800) is provided inside a case (200). In addition, compared with the second heat exchange line (700) of FIG. 2, the second heat exchange line (700) of FIG. 2 is provided outside the case (200), and the second heat exchange line (700) provided outside the case (200) includes a second valve (710), whereas the second heat exchange line (700) of FIG. 3 is provided inside the case (200) and does not include a second valve (710). Since the second heat exchange line (700) is provided inside the case (200), efficient cooling of the helium fluid is possible when the liquid helium stored in the sample space (400) is transferred to the second heat exchange line (700) according to the operation of the adsorption pump (800). In detail, when liquid helium at 4 K inside the sample space (400) is transferred to the second heat exchange line (700) provided inside the case (200), the temperature of the helium fluid is maintained at 10 K to 40 K, and is absorbed at 4 K when absorbed by the adsorption pump (800). Accordingly, efficient cooling of the helium is possible. On the other hand, in the case (200) of FIG. 2, the second heat exchange line (700) provided outside the case (200) is located outside the case (200), so that when the liquid helium stored in the sample space (400) is transferred to the second heat exchange line (700) according to the operation of the adsorption pump (800), the second heat exchange line (700) is easily controlled for the flow of helium in the room temperature portion.In detail, when liquid helium at 4 K is transferred to the second heat exchange line (700) provided inside the case (200) inside the sample space (400), the temperature of the helium fluid is maintained at 300 K, and when adsorbed by the adsorption pump (800), it is adsorbed at 4 K. Therefore, it is easy to control the flow of helium at room temperature.

[0047] Fig. 5 is a schematic diagram illustrating a liquid helium storage step according to one embodiment of the present disclosure. Referring to Fig. 5, a low-temperature maintenance method (S1000) using a circulating low-temperature maintenance device equipped with a dual pump of the present disclosure includes a cooler cooling step (S100), a liquid helium storage step (S200), a first cooling step (S300), a second cooling step (S400), and a re-condensation step (S500).

[0048] The chiller cooling step (S100) is a step of cooling a chiller equipped with a compressor and one or more cold heads. Here, the one or more cold heads are divided into a first cold head (110) and a second cold head (120). In addition, the chiller (100) further includes a compressor (130) and a rotary valve (140). The compressor (130) compresses a refrigerant to a high pressure. In addition, the compressed high-pressure refrigerant is transported through the rotary valve (140), and the transported high-pressure refrigerant expands to allow the chiller (100) to form a low temperature.

[0049] The liquid helium storage step (S200) is a step in which gaseous helium stored in a buff tank is liquefied and moved through a first heat exchange line by cooling of a cooler and stored as liquid helium in a liquefaction tank. At this time, the helium may be helium-4. FIG. 6 illustrates the liquid helium storage step (S200) according to one embodiment of the present disclosure. Referring to FIG. 6, the liquid helium storage step (S200) is a step in which gaseous helium supplied by a buff tank (300) that supplies helium is liquefied and stored as liquid helium in a liquefaction tank (320) provided inside a case (200). In the liquefaction tank (320), gaseous helium supplied by the buff tank (300) is liquefied at a low temperature and stored. Here, the first cold head (110) provided in the cooler (100) is cooled to a temperature of 50 K, and the second cold head (120) is cooled to a temperature of 3 K. Since the first cold head (110) and the second cold head (120) are configured to be cooled to different temperatures, the helium in a gaseous state at 300 K can slowly decrease in temperature through heat exchange with the first heat exchange tube (310) and be condensed into liquid helium. At this time, the temperature of the second cold head (120) becomes lower than the condensation point of helium at 3 K, so that it can be condensed in the liquefaction tank (320) and stored as liquid helium. The case (200) includes a sample space (400) in which liquid helium is stored. The condensed liquid helium is stored in the sample space (400). At this time, the first cooling unit including the dry pump and the second cooling unit including the adsorption pump are configured to be connected in parallel to the sample space into which one end of the modular probe is inserted. Accordingly, the liquid helium in the sample space can be vaporized by the operation of the first cooling unit, so that a first temperature in the range of 1.8 K to 300 K can be formed. In addition, the liquid helium in the sample space (400) can be vaporized by the operation of the second cooling unit, so that a second temperature in the range of 0.8 K to 300 K can be formed. In addition, the cooling column (500) is in contact with the sample space (400) and serves to guide the liquid helium.

[0050] FIG. 7 is a schematic diagram illustrating a first cooling step (S300) according to an embodiment of the present disclosure. Referring to FIG. 7, the first cooling step (S300) is a step in which the first valve of the first cooling unit is opened while the second valve of the second cooling unit is closed, the dry pump is operated so that the liquid helium in the liquefaction tank moves to the sample space, and the liquid helium in the sample space is cooled to a first temperature in the range of 1.8 K to 300 K. The dry pump (600) is provided outside the case (200) and serves to lower the pressure of the sample space (400) so that the liquid helium is cooled to the first temperature. The first cooling unit is configured in a form wound around a cooler, and includes a first heat exchange line (310) that connects the buff tank (300) and the liquefaction tank (320) and exchanges heat with the gaseous helium supplied from the buff tank (300). In addition, it includes a fluid transfer line (610) that is connected to a cooling column (500) and a dry pump (600) and is connected to a first heat exchange line (310). In addition, the first cooling unit includes a liquid helium transfer line (330) that is connected to a liquefaction tank (320) and a sample space (400) so that liquid helium inside the liquefaction tank (320) is moved by the pressure of the dry pump (600). Therefore, in order to lower the temperature of the sample space (400) to 1.8 K to 300 K, the dry pump (600) is driven so that the liquid helium liquefied and stored in the liquefaction tank (320) is moved to the sample space (400) through the liquid helium transfer line (330), and the liquid helium moved to the sample space (400) is vaporized into a sample column so that the inside of the sample space (400) can be formed at a first temperature in the range of 1.8 K to 300 K. At this time, the sample space (400) is equipped with a second heater (410). By driving the second heater (410), the internal temperature of the sample space (400) can be implemented to be 1.8 K or higher. In addition, the fluid transfer line (610) may be equipped with a first valve (620). Therefore, the movement of the helium transferred to the dry pump (600) can be controlled.

[0051] FIG. 8 is a schematic diagram illustrating a second cooling step according to an embodiment of the present disclosure. Referring to FIG. 8, the second cooling step (S400) is a step in which the second valve of the second cooling unit is opened while the first valve of the first cooling unit is closed, and the adsorption pump is operated to cool the liquid nucleus in the sample space to a second temperature of less than 1 K. The adsorption pump (800) is provided inside the case (200) and serves to lower the temperature of the sample space (400) so that the liquid helium is vaporized at the second temperature. Here, the sub-Kelvin temperature of less than 1 K can be formed in a range of 0.8 K to 300 K. In addition, the second cooling unit is configured in a form that is wrapped around the cooler (100), and further includes a second heat exchange line (700) that connects the cooling column (500) and the adsorption pump (800) and exchanges heat with the gaseous helium supplied from the cooling column (500) so that the liquid helium in the sample space (400) moves and is adsorbed by the adsorption pump (800). At this time, the sample space (400) is configured to operate only until the liquid helium inside the sample space (400) completely evaporates. Therefore, in order to lower the sample space (400) to the second temperature, the adsorption pump (800) is driven so that the liquid helium stored in the sample space is vaporized and the inside of the sample space (400) can be formed in a range of 0.8 K to 300 K. Additionally, the sample space (400) is configured to operate only until all liquid helium inside the sample space (400) evaporates.

[0052] In addition, the second cooling step (S400) further includes a re-condensation step (S500) in which, after the second cooling step (S400), the heater provided in the adsorption pump is operated to liquefy the helium adsorbed by the adsorption pump and re-condense it into a liquefaction tank. Fig. 9 is a schematic diagram illustrating the re-condensation step (S500) according to one embodiment of the present disclosure. Referring to Fig. 9, the re-condensation step (S500) operates the heater, opens the second valve, moves the helium adsorbed by the adsorption pump to the sample space, and opens the first valve, moves the helium moved to the sample space (400) to the liquefaction tank, and re-condenses it. At this time, the adsorption pump (800) includes a thermal switch (810) that enables the adsorption pump (800) to be operated. Therefore, in order to lower the interior of the sample space to the second temperature, the heat switch (810) is first turned on so that the adsorption pump (800) can operate at a low temperature. In addition, a second valve (710) may be provided in the second heat exchange line (700). Accordingly, the movement of helium transferred to the adsorption pump (800) can be controlled.

[0053] In addition, the adsorption pump (800) includes a first heater (820) that can control the operating temperature of the adsorption pump (800). In order to realize the inside of the sample space (400) to be 0.8 K or higher, the first heater (820) provided in the adsorption pump (800) can be additionally driven. Therefore, the circulating cryogenic device (1000) equipped with a dual pump of the present disclosure is configured to recondense the vaporized helium. At this time, both the first valve (620) and the second valve (710) are opened, and the first heater (820) provided in the adsorption pump (800) is heated to 40 K. The helium adsorbed in the adsorption pump (800) is vaporized by the heating of the first heater (820), and at this time, the dry pump (600) is driven so that the liquefied helium can be collected in the liquefaction tank (320).

[0054] As described above, the circulating cryogenic maintenance method using the circulating cryogenic device equipped with a dual pump of the present disclosure is configured such that a first cooling unit including a dry pump and a second cooling unit including an adsorption pump are connected in parallel to a sample space into which one end of a modular probe is inserted. By this configuration, the circulating cryogenic device of the present disclosure is divided into a first cooling unit and a second cooling unit, and can be further divided into a first cooling stage depending on the operating state of the first cooling unit and a second cooling stage depending on the operating state of the second cooling unit.

[0055] In the first cooling step, the first valve of the first cooling unit is opened while the second valve of the second cooling unit is closed, and the dry pump is operated so that the liquid helium in the liquefaction tank moves to the sample space, and at this time, the liquid helium-4 in the sample space is cooled to a temperature ranging from 1.8 K to 300 K. In addition, in the second cooling step, the second valve of the second cooling valve is opened while the first valve of the first bag section is closed, and the adsorption pump is operated so that the liquid helium in the sample space is cooled to a temperature below 1 K.

[0056] Accordingly, since the first cooling unit including the dry pump and the second cooling unit including the adsorption pump are configured to be connected in parallel to the sample space into which one end of the modular probe is inserted, the liquid helium-4 in the sample space can be cooled to a temperature in the range of 0.8 K to 300 K by driving the dry pump, and the liquid helium in the sample space can be cooled to a temperature of less than 1 K by driving the adsorption pump, thereby enabling the implementation of the temperature of helium in a variety of ranges.

[0057] The above description is merely an example of applying the principles of the present disclosure, and other configurations may be included without departing from the scope of the present invention.

[0058] The present disclosure relates to a circulating cryostat equipped with a dual pump and a cryostat method using the same, wherein the dual pumps are configured in parallel to enable temperature control for helium in a wide range, thereby enabling helium cooling at low cost and efficiency, and thereby providing stable cooling performance, which can be utilized in high-precision industrial fields such as semiconductor manufacturing and superconductor cooling.

Claims

1. A sample space in which liquid helium is stored and one end of a modular probe is inserted; A chiller having a compressor and one or more cold heads; A first cooling unit including a buff tank in which gaseous helium is stored, a liquefaction tank in which gaseous helium stored in the buff tank is liquefied and stored, a first heat exchange line disposed between the buff tank and the liquefaction tank and exchanging heat with the cooler, a dry pump having one end connected to the sample space and the other end connected to the first heat exchange line, and a first valve disposed between the sample space and the dry pump; and A circulating low-temperature maintenance device equipped with a dual pump, comprising: an adsorption pump containing an adsorbent; a second cooling unit including a second heat exchange line that is connected to the adsorption pump at one end and exchanges heat with the cooler, and a second valve that is connected to the sample space and has the other end connected to the second heat exchange line; 2. In paragraph 1, A circulating cryostat equipped with a dual pump, further comprising a cooling column that is in contact with the sample space and guides the liquid helium.

3. In the first paragraph, the first heat exchange line, A circulating low-temperature maintenance device having a double pump, configured in a form wound around the above cooler, and connecting the above buff tank and the above liquefaction tank to exchange heat with gaseous helium supplied from the above buff tank.

4. In paragraph 1, the second heat exchange line, A circulating cryogenic maintenance device having a dual pump, configured in a form wound around the above cooler, and connected to the cooling column and the adsorption pump so that liquid helium in the sample space moves and is adsorbed by the adsorption pump, and exchanges heat with gaseous helium supplied from the cooling column.

5. In paragraph 1, the helium is A circulating cryostat equipped with a dual pump, characterized by helium-4.

6. In the first paragraph, the circulating low-temperature maintenance device, A circulating cryogenic device having a dual pump including a thermal switch that enables the adsorption pump to be driven to vaporize liquid helium stored in the sample space.

7. In the first paragraph, the adsorption pump, A circulating low-temperature maintenance device having a dual pump further including a heater capable of controlling the operating temperature of the above adsorption pump.

8. In paragraph 1, A first cooling unit including the dry pump and a second cooling unit including the adsorption pump are connected in parallel to the sample space into which one end of the modular probe is inserted, A circulating low-temperature device equipped with a dual pump, capable of maintaining a low temperature of sub-Kelvin within the sample space by opening and closing the first valve of the first cooling unit and the second valve of the second cooling unit.

9. A low-temperature maintenance method using a circulating low-temperature maintenance device equipped with a double pump according to any one of Articles 1 to 8, A chiller cooling step for cooling a chiller having a compressor and one or more cold heads; A liquid helium storage step in which gaseous helium stored in the buffing tank is liquefied and moved through the first heat exchange line through cooling of the cooler and stored as liquid helium in the liquefaction tank; A first cooling step in which the first valve of the first cooling unit is opened while the second valve of the second cooling unit is closed, the dry pump is operated so that the liquid helium in the liquefaction tank moves to the sample space and the liquid nucleus in the sample space is cooled to a first temperature in the range of 1.8 K to 300 K; and A low-temperature maintenance method using a circulating low-temperature maintenance device equipped with a dual pump, comprising: a second cooling step in which the second valve of the second cooling unit is opened while the first valve of the first cooling unit is closed, and the adsorption pump is operated to cool the liquid nucleus in the sample space to a second temperature of less than 1 K.

10. In the 9th paragraph, the second cooling step, After the second cooling step, A low-temperature maintenance method using a circulating low-temperature maintenance device equipped with a dual pump, which performs a re-condensation step in which the helium adsorbed in the adsorption pump is liquefied and re-condensed into a liquefaction tank by operating a heater provided in the adsorption pump.

11. In paragraph 10, the re-condensation step, The above heater is driven and the second valve is opened so that the helium adsorbed by the adsorption pump moves to the sample space. A low-temperature maintenance method using a circulating low-temperature maintenance device equipped with a dual pump, characterized in that the helium moved to the sample space by opening the first valve is moved to a liquefaction tank and re-condensed.

12. In paragraph 9, the helium is A low-temperature maintenance method using a circulating low-temperature maintenance device equipped with a dual pump, characterized by being helium-4.

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