CN113450996B - Two-stage G-M refrigerator cold conduction structure for conducting and cooling superconducting magnet - Google Patents
Two-stage G-M refrigerator cold conduction structure for conducting and cooling superconducting magnet Download PDFInfo
- Publication number
- CN113450996B CN113450996B CN202110797444.2A CN202110797444A CN113450996B CN 113450996 B CN113450996 B CN 113450996B CN 202110797444 A CN202110797444 A CN 202110797444A CN 113450996 B CN113450996 B CN 113450996B
- Authority
- CN
- China
- Prior art keywords
- cold
- primary
- helium
- stage
- refrigerator
- 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.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/04—Cooling
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
Abstract
The invention discloses a two-stage G-M refrigerator cold guide structure for conduction cooling of a superconducting magnet. The independent small cavity comprises a telescopic corrugated pipe, a primary thin-wall cylinder, a primary outer cone, a secondary thin-wall cylinder and a secondary heat sink. When the cold head needs to be maintained or replaced, the cold head only needs to be pulled out, and the interlayer vacuum of the superconducting magnet does not need to be damaged. In the primary stage of superconducting magnet cooling, the primary cold head and the secondary cold head of the refrigerator are both in the helium atmosphere, so that the cooling speed of the secondary heat load is accelerated. At the end of the cooling of the magnet, part of the helium gas is liquefied into liquid helium, and the convection heat transfer effect of the helium gas is weakened. The first-stage cold head transmits cold energy to components such as a cold screen and the like through the first-stage inner cone and the first-stage outer cone, and temperature separation of the magnet and the components of the cold screen is achieved.
Description
Technical Field
The invention relates to the technical field of superconducting magnet low-temperature structures, in particular to a two-stage G-M refrigerator cold-conducting structure for conducting and cooling a superconducting magnet.
Background
At present, the cooling mode of the low-temperature superconducting magnet is mainly that the cooling is directly conducted by a refrigerator or is assisted by low-temperature media such as liquid helium and the like. The temperature of the liquid helium soaked superconducting magnet is uniform, the cooling time is short, but the disadvantages of high liquid helium cost, high safety risk of a low-temperature system and the like exist at the same time. The conduction cooling superconducting magnet has good portability and compact structure, but also has the defects of temperature difference between the magnet and a cold head of a refrigerator, long cooling time, difficult maintenance of the cold head and the like. At present, a medical Magnetic Resonance Imaging (MRI) superconducting magnet, a Nuclear Magnetic Resonance (NMR) superconducting magnet and an accelerator superconducting magnet are cooled in a liquid helium soaking mode. Due to the shortage of helium resources, some domestic units have begun to develop conduction-cooled MRI and NMR superconducting magnets.
The average maintenance cycle of the cold head of the current commercial GM refrigerator is about 10000 hours, the maintenance operation difficulty of the cold head of the traditional conduction cooling superconducting magnet is high, and the connection form of the cold head of the refrigerator, the magnet and the cold shield determines that the assembly performance and the maintainability of the neck pipe of the superconducting magnet are poor. In addition, for most conduction cooling superconducting magnets, the cooling speed of the heat load of the primary cold head is higher than that of the heat load of the secondary cold head, how to fully use the primary cold quantity for cooling the cold screen and the magnet in the initial cooling stage is a big problem, and the primary cold quantity is effectively disconnected from the secondary cold quantity in the final cooling stage.
Disclosure of Invention
In order to solve the technical problem, the invention provides a two-stage G-M refrigerator cold conduction structure for conducting and cooling a superconducting magnet. The scheme is characterized in that two stages of cold heads of the G-M refrigerator 1 are both positioned in an independent small cavity, high-purity helium (the purity of the helium is higher and is usually more than 99.999%) is sealed in the cavity, the room-temperature helium forms convection in the small cavity after being precooled by a first-stage cold head heat exchanger, and the room-temperature helium is liquefied by a second-stage cold head heat exchanger.
According to the technical scheme, the independent small cavity comprises a telescopic corrugated pipe 2, a primary thin-wall barrel 3, a primary outer cone 5, a secondary thin-wall barrel 6 and a secondary heat sink 8.
According to the technical scheme, the G-M refrigerator 1, the primary inner cone 4 and the secondary condenser 7 are connected into a whole through screws and then are arranged in the small cavity, and the fit and the compression between the primary inner cone 4 and the primary outer cone 5 are ensured through a certain axial pretightening force for the telescopic corrugated pipe. A gap is left between the secondary condenser and the secondary heat sink.
After the superconducting magnet starts to cool, quantitative high-purity helium is injected into the small cavity through the matching of the one-way valve and the safety relief valve, when the superconducting magnet is accidentally lost, liquid helium volatilizes, the generated helium is discharged through the safety relief valve, and the thin-wall structure of the small cavity cannot be damaged. Furthermore, an optimal helium filling amount can be calculated according to the pressure bearing capacity of the thin-wall cylinder and the pressure change value caused by contraction of helium in cooling and expansion of helium in heating, so that extra helium cannot be lost by the small cavity when the magnet is quenched, and extra air supplement operation is not needed in the whole magnet cooling process.
The conduction cooling superconducting magnet system comprises a vacuum container 11, a cold shield 12, a shielding coil 13, a main coil 14, a secondary cold conduction band 15 and a primary cold conduction band 16.
One end of the secondary cold conduction band 15 is connected with the secondary heat sink 8, and the other end is connected with the shielding coil 13 and the main coil 14, and the function is to transmit the cold energy of the secondary heat sink 8 to the magnet coil; one end of the primary cold guide belt 16 is connected with the primary outer cone 5, and the other end is connected with the cold screen 12, and the function is to transmit the cold energy of the primary outer cone 5 to the cold screen 12.
Compared with the prior art, the invention has the following beneficial effects:
when the cold head needs to be maintained or replaced, the cold head only needs to be pulled out, and the interlayer vacuum of the superconducting magnet does not need to be damaged.
In the primary stage of superconducting magnet cooling, the primary cold head and the secondary cold head of the refrigerator are both in a helium atmosphere, and the cold quantity of the primary cold head is transferred to the secondary cold head through high-pressure helium convection, so that the cooling speed of the secondary heat load can be accelerated. At the end of the cooling of the magnet, part of helium is liquefied into liquid helium, the gas pressure in the small cavity is reduced, and the convection heat transfer effect of the helium is weakened. At the moment, the primary cold head transmits the cold energy to components such as a cold screen and the like through the primary inner cone and the primary outer cone, the condenser of the secondary cold head is soaked in liquid helium, the cold energy is transmitted to the magnet through the heat conduction of the liquid helium, and the temperature separation of the magnet and the cold screen components is realized.
Drawings
FIG. 1 is a schematic diagram of a two-stage G-M refrigerator cold-conducting structure;
FIG. 2 is a schematic view of a small animal imaging MRI conduction cooled superconducting magnet system;
in the figure, the 1-G-M refrigerator; 2-a collapsible bellows; 3-first-order thin-walled cylinder; 4-first-stage inner cone; 5-a first-level outer cone; 6-a secondary thin-walled cylinder; 7-a secondary condenser; 8-secondary heat sink; 9-a safety relief valve; 10-a one-way valve; 11-a vacuum vessel; 12-cold shielding; 13-a shield coil; 14-a main coil; 15-secondary cold conducting belt; 16-primary cold conduction band.
Detailed Description
The invention is described in detail below with reference to the figures and the embodiments. The following examples are only for explaining the present invention, the scope of the present invention shall include the full contents of the claims, and the full contents of the claims of the present invention can be fully realized by those skilled in the art through the following examples.
As shown in FIG. 1, the two-stage G-M refrigerator cold conducting structure for conducting and cooling the superconducting magnet. The two-stage cold heads of the G-M refrigerator 1 are both positioned in an independent small cavity, a certain amount of high-purity helium is sealed in the cavity, the room-temperature helium is pre-cooled by the first-stage cold head heat exchanger and then forms convection in the small cavity, and the room-temperature helium is liquefied near the second-stage cold head heat exchanger. The first-stage inner cone 4 with a plurality of diversion trenches on the conical surface is used as a first-stage cold head heat exchanger, and the second-stage condenser 7 is a second-stage cold head heat exchanger.
The independent small cavity consists of a telescopic corrugated pipe 2, a primary thin-wall cylinder 3, a primary outer cone 5, a secondary thin-wall cylinder 6 and a secondary heat sink 8. The telescopic corrugated pipe 2, the primary thin-wall barrel 3, the primary outer cone 5, the secondary thin-wall barrel 6 and the secondary heat sink 8 are connected together in a welding mode.
The G-M refrigerator 1, the primary inner cone 4 and the secondary condenser 7 are connected into a whole through screws and then are arranged in a small cavity, and the primary inner cone 4 and the primary outer cone 5 are well attached and pressed through a certain axial pretightening force for the telescopic corrugated pipe 2. A certain gap is left between the secondary condenser 7 and the secondary heat sink 8. The primary inner cone 4 is positioned below the primary cold head of the refrigerator, the secondary condenser 7 is positioned below the secondary cold head of the refrigerator, the primary inner cone 4 is well attached to the conical surface of the primary outer cone 5, the secondary condenser 7 is suspended above the secondary heat sink 8, and a 3-5mm gap is reserved between the primary inner cone and the secondary outer cone.
After the superconducting magnet starts to cool, quantitative high-purity helium is injected into the small cavity through the matching of the one-way valve 10 and the safety relief valve 9, when the superconducting magnet is accidentally lost, liquid helium volatilizes, the generated helium is discharged through the safety relief valve, and the thin-wall structure of the small cavity cannot be damaged. Furthermore, an optimal helium filling amount can be calculated according to the pressure bearing capacity of the thin-wall cylinder and the air pressure change value caused by contraction of helium when the helium is cooled and expansion of the helium when the helium is heated, so that extra helium cannot be lost in a small cavity when the magnet is quenched, namely, extra air supplement operation is not needed in the whole magnet cooling process.
Fig. 2 shows an example of the present invention applied to a small animal imaging MRI conduction cooling superconducting magnet, and the function and structure of the present invention are further explained with reference to fig. 2.
The conduction cooling superconducting magnet system consists of a vacuum container 11, a cold shield 12, a shielding coil 13, a main coil 14, a secondary cold conduction band 15 and a primary cold conduction band 16.
According to the scheme, one end of the secondary cold conducting belt 15 is connected with the secondary heat sink 8, and the other end of the secondary cold conducting belt is connected with the shielding coil 13 and the main coil 14, so that the cold energy of the secondary heat sink 8 is transferred to the magnet coil. One end of the primary cold guide belt 16 is connected with the primary outer cone 5, and the other end is connected with the cold shield 12, and the function is to transmit the cold energy of the primary outer cone 5 to the cold shield 12. The cold screen 12, the shielding coil 13, the main coil 14, the secondary cold conducting strip 15 and the primary cold conducting strip 16 are all arranged in the vacuum container 11 and are in a high vacuum environment.
Preferably, the secondary cooling conducting strip 15 and the primary cooling conducting strip 16 are made of high-purity annealed copper, so as to reduce the temperature difference between the far end and the near end of the primary cooling conducting strip 16 and the secondary cooling conducting strip 15 as much as possible.
Preferably, a certain amount of high-purity helium is sealed in the small cavity before cooling, and the superconducting magnet is accelerated to cool down by using primary cold energy through helium convection in the early stage of cooling. In the later stage of temperature reduction, helium is liquefied, the helium convection effect is weakened, and the temperature separation of the magnet and the cold screen 12 is realized.
Preferably, the first-stage outer cone 5 and the second-stage heat sink 8 are made of high-purity copper, the first-stage thin-wall cylinder 3 and the second-stage thin-wall cylinder 6 are made of 316L stainless steel, and the first-stage outer cone and the second-stage thin-wall cylinder are welded in a sealing mode through a vacuum furnace brazing process.
The invention can realize the quick replacement and maintenance of the refrigerator cold head and has positive significance for improving the cooling efficiency of the conduction cooling superconducting magnet.
The invention has not been described in detail and is part of the common general knowledge of a person skilled in the art. The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and the preferred embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Various modifications and improvements of the technical solution of the present invention may be made by those skilled in the art without departing from the spirit of the invention, and the technical solution is intended to be covered by the scope of the invention defined by the appended claims.
Claims (3)
1. A two-stage G-M refrigerator cold conduction structure for conducting and cooling a superconducting magnet is characterized in that two-stage cold heads of a G-M refrigerator (1) are located in an independent small cavity, high-purity helium is sealed in the cavity, room-temperature helium is pre-cooled through a flow guide groove in a first-stage inner cone (4) and then forms convection in the small cavity, and the room-temperature helium is liquefied at a second-stage condenser (7); the secondary heat sink (8) is connected with the shielding coil (13) and the main coil (14) through a secondary cold conducting belt (15), and the shielding coil (13) and the main coil (14) are cooled in a conduction cooling mode; the independent small cavity comprises a telescopic corrugated pipe (2), a primary thin-wall cylinder (3), a primary outer cone (5), a secondary thin-wall cylinder (6) and a secondary heat sink (8), and the telescopic corrugated pipe (2), the primary thin-wall cylinder (3), the primary outer cone (5), the secondary thin-wall cylinder (6) and the secondary heat sink (8) are connected together in a welding mode;
the two-stage cold head comprises a primary cold head of the refrigerator and a secondary cold head of the refrigerator, a primary inner cone (4) is positioned below the primary cold head of the refrigerator, a secondary condenser (7) is positioned below the secondary cold head of the refrigerator, the primary inner cone (4) is well attached to the conical surface of a primary outer cone (5), the secondary condenser (7) is suspended above a secondary heat sink (8), and a 3-5mm gap is reserved between the primary inner cone and the secondary outer cone;
the G-M refrigerator (1), the primary inner cone (4) and the secondary condenser (7) are connected into a whole through screws and then are arranged in the small cavity, and the primary inner cone (4) and the primary outer cone (5) are well attached and pressed by axial pretightening force of the telescopic corrugated pipe (2);
the conduction cooling superconducting magnet system consists of a vacuum container (11), a cold screen (12), a shielding coil (13), a main coil (14), a secondary cold conduction band (15) and a primary cold conduction band (16);
one end of the secondary cold conduction band (15) is connected with the secondary heat sink (8), and the other end is connected with the shielding coil (13) and the main coil (14) to transfer the cold energy of the secondary heat sink (8) to the magnet coil; one end of the primary cold guide belt (16) is connected with the primary outer cone (5), and the other end is connected with the cold screen (12) and is used for transmitting the cold energy of the primary outer cone (5) to the cold screen (12); the cold screen (12), the shielding coil (13), the main coil (14), the secondary cold conducting strip (15) and the primary cold conducting strip (16) are all arranged in a vacuum container (11) and are in a high-vacuum environment;
in the primary stage of superconducting magnet cooling, the primary cold head and the secondary cold head of the refrigerator are both in a helium atmosphere, and the cold energy of the primary cold head is transferred to the secondary cold head through high-pressure helium convection, so that the cooling speed of a secondary heat load can be accelerated; at the last stage of cooling the magnet, part of helium is liquefied into liquid helium, the air pressure in the small cavity is reduced, the convection heat transfer effect of the helium is weakened, at the moment, the first-stage cold head transfers the cold energy to the cold shield component through the first-stage inner cone and the first-stage outer cone, the condenser of the second-stage cold head is soaked in the liquid helium, and the cold energy is transferred to the magnet through the heat conduction of the liquid helium, so that the temperature separation of the magnet and the cold shield component is realized.
2. The structure of claim 1, wherein after the superconducting magnet begins to cool, a certain amount of high-purity helium is injected into the small cavity through the cooperation of the check valve (10) and the safety relief valve (9), and an optimal helium filling amount is calculated according to the pressure bearing capacity of the thin-wall cylinder and the air pressure change value caused by the contraction and the expansion of the helium when the helium is cooled, so that the small cavity does not lose additional helium when the magnet is quenched, namely, no additional air supplement operation is needed in the whole magnet cooling process.
3. The arrangement according to claim 1, characterized in that the G-M refrigerator (1) can be pulled out directly without breaking the vacuum of the vacuum vessel (11) when it needs maintenance or replacement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110797444.2A CN113450996B (en) | 2021-07-14 | 2021-07-14 | Two-stage G-M refrigerator cold conduction structure for conducting and cooling superconducting magnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110797444.2A CN113450996B (en) | 2021-07-14 | 2021-07-14 | Two-stage G-M refrigerator cold conduction structure for conducting and cooling superconducting magnet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113450996A CN113450996A (en) | 2021-09-28 |
| CN113450996B true CN113450996B (en) | 2022-11-29 |
Family
ID=77816399
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110797444.2A Active CN113450996B (en) | 2021-07-14 | 2021-07-14 | Two-stage G-M refrigerator cold conduction structure for conducting and cooling superconducting magnet |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113450996B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114284027B (en) * | 2021-12-27 | 2024-02-02 | 中国科学院电工研究所 | Portable conduction cooling high-temperature superconducting magnet |
| CN115388615B (en) * | 2022-04-19 | 2023-11-24 | 北京师范大学 | Argon liquefaction system |
| CN115289716A (en) * | 2022-06-09 | 2022-11-04 | 北京交通大学 | Cold plugging device of bipolar cold head refrigerator |
| CN115440536B (en) * | 2022-10-13 | 2024-06-14 | 中国人民解放军国防科技大学 | Thermal switch with inserted rod function for quick precooling of dry dilution refrigerator and method |
| CN115440461B (en) * | 2022-11-09 | 2023-01-24 | 上海超导科技股份有限公司 | Cold guide structure for sealing low-temperature cavity of high-temperature superconducting magnet and disassembling and assembling method |
| CN118209911B (en) * | 2024-05-21 | 2024-09-24 | 江苏力磁医疗设备有限公司 | Small nuclear magnetic resonance detection device |
| CN118299142B (en) * | 2024-05-31 | 2024-08-30 | 山东奥新医疗科技有限公司 | Cold conduction system for superconducting magnet |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69523883T2 (en) * | 1994-12-29 | 2002-08-29 | General Electric Co., Schenectady | Superconducting magnet with helium recondensation |
| JP2002270913A (en) * | 2001-03-09 | 2002-09-20 | Hitachi Ltd | Superconductive coil unit and mri device |
| JP2003059713A (en) * | 2002-08-01 | 2003-02-28 | Mitsubishi Electric Corp | Superconductive magnet |
| DE102005029151B4 (en) * | 2005-06-23 | 2008-08-07 | Bruker Biospin Ag | Cryostat arrangement with cryocooler |
| CN106298152A (en) * | 2015-05-11 | 2017-01-04 | 通用电气公司 | Superconducting magnet cooling system |
-
2021
- 2021-07-14 CN CN202110797444.2A patent/CN113450996B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113450996A (en) | 2021-09-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113450996B (en) | Two-stage G-M refrigerator cold conduction structure for conducting and cooling superconducting magnet | |
| CN108022711B (en) | Intelligent magnetic resonance whole-body imaging superconducting magnet system | |
| US5410286A (en) | Quench-protected, refrigerated superconducting magnet | |
| US4432216A (en) | Cryogenic cooling apparatus | |
| CN101012982B (en) | Refrigerator with magnetic shield | |
| JPH0340475A (en) | Low temperature precooler and low temperature cold head interface receptacle | |
| US10247451B2 (en) | Cryogenic regenerator and cryogenic refrigerator | |
| CN106960713A (en) | A kind of refrigeration machine for superconducting magnet it is jacket structured and its install, method for dismounting | |
| US6679066B1 (en) | Cryogenic cooling system for superconductive electric machines | |
| CN206546753U (en) | A kind of refrigeration machine for superconducting magnet is jacket structured | |
| US4667486A (en) | Refrigerated penetration insert for cryostat with axial thermal disconnect | |
| CN201463425U (en) | High-frequency regenerator adopting stainless steel fiber regenerative materials and pulse tube refrigerator thereof | |
| CN109243752B (en) | Auxiliary cooling device and cooling equipment | |
| CN113903541A (en) | Large high-temperature superconducting magnetic system based on small refrigerator and temperature control method | |
| CN114512295A (en) | High-uniform magnetic field conduction cooling superconducting magnet system | |
| CN212542070U (en) | Improved condenser for liquid helium volatilization-free superconducting magnet | |
| CN104900370A (en) | Superconducting magnet liquid helium container comprising vacuum chamber | |
| CN101603750B (en) | High-frequency heat regenerator adopting stainless steel fibre regenerative material and pulse tube refrigerator thereof | |
| CN204720270U (en) | A kind of superconducting magnet liquid helium container comprising vacuum chamber | |
| JPH0341704A (en) | Low temperature precooler for superconductive magnet | |
| CN213635558U (en) | Cold head transfer structure for superconducting magnet | |
| JP2008116171A (en) | Gas heat transfer device and superconductive device using the same | |
| CN212365633U (en) | Cooling system of liquid helium-free superconducting magnet | |
| CN116313372B (en) | Superconducting magnet and cooling system and method thereof | |
| CN215868846U (en) | Refrigerator mounting structure for cryogenic system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |