Superconducting magnet efficient cooling system based on self-adaptive thermal switch

Abstract

The utility model discloses a superconducting magnet efficient cooling system based on a self-adaptive thermal switch, and relates to the superconducting magnet cooling technology. Comprising a vacuum Dewar and a cold shield arranged in the vacuum Dewar, a magnet is placed in the cold shield, and a first-stage cold head and a second-stage cold head of a GM refrigerator make contact with the cold shield and the magnet correspondingly to provide a cold source; and a heat conduction assembly is arranged between the cold shield and the magnet and can realize on-off controlled heat conduction between the primary cold head and the magnet. Dynamic on-off of a heat conduction link is realized through the temperature-sensitive deformation sheet, the link is closed in a high-temperature stage to accelerate cooling, and the link is disconnected in a low-temperature stage to isolate a heat source. By means of the design, the problems that a traditional fixed conduction structure is long in refrigeration time and waste in cooling capacity are solved; and meanwhile, the shape change of the adopted heat conduction assembly is realized based on thermal expansion and cold contraction or phase change of a material, so that the on or off state of a heat conduction link is automatically switched, no extra control equipment is needed, and the stability is high.

Description

TECHNICAL FIELD

[0001] The utility model relates to superconducting magnet cooling technology, concretely is superconducting magnet high -efficient cooling system based on adaptive thermal switch. BACKGROUND

[0002] Superconducting magnet usually adopts (GM) two stage refrigerator. One stage cold head cold quantity is big (usually higher than 40w) but temperature is higher (such as 20K-80K), two stage cold head cold quantity is small (usually lower than 2w) but temperature is low (can reach 4K below).

[0003] In the traditional cooling process, the first stage cold head will cool the cold screen to near the limit temperature (such as 50K) in a short time, and the second stage cold head is used to cool the magnet alone. Because the cold quantity of the second stage cold head is limited, after the first stage cold head cools the cold screen to near the limit temperature, the second stage cold head usually needs more than 3 times of time to approach the target temperature 4K. After the first stage cold head reaches temperature balance, it is idle, and the remaining cold quantity cannot assist the second stage cold head to cool, causing invalid energy consumption. It should be noted that in the early stage of cooling, if the surplus cold quantity of the first stage cold head is used to assist the second stage cold head, the total cooling time can be significantly shortened. Therefore, we provide a superconducting magnet high-efficiency cooling system based on adaptive thermal switch, which establishes a dynamic thermal link in the early stage of cooling to accelerate the second stage cooling by using the first stage cold quantity. When the first stage cold head reaches the target temperature, the thermal link is disconnected to avoid reverse thermal interference. SUMMARY

[0004] The utility model discloses a superconducting magnet high-efficiency cooling system based on adaptive thermal switch to solve the problems raised in the background art.

[0005] The utility model can realize the following technical scheme: a superconducting magnet high-efficiency cooling system based on adaptive thermal switch, comprising a vacuum dewar and a cold screen arranged inside the vacuum dewar, a magnet placed inside the cold screen, a first stage cold head and a second stage cold head of a GM refrigerator in contact with the cold screen and the magnet to provide a cold source.

[0006] A thermal conduction assembly is arranged between the cold screen and the magnet, and the thermal conduction assembly can realize the on-off controlled thermal conduction between the first stage cold head and the magnet.

[0007] Further technical improvement of the utility model lies in that the thermal conduction assembly comprises a thermal conduction fixed plate fixed to the inner side wall of the cold screen and a thermal switch driving mechanism fixed at the corresponding position of the magnet, a first stage heat sink is connected between the thermal conduction fixed plate and the first stage cold head, and the thermal switch driving mechanism and the thermal conduction fixed plate realize the switching between the contact state and the non-contact state with the temperature change.

[0008] The further technical improvement of the utility model lies in: the thermal switch driving mechanism comprises a thermal conduction base plate fixed with a magnet, a thermal conduction contact plate is arranged above the thermal conduction base plate, and the two are connected through a flexible heat conduction chain.

[0009] The top of the thermal conduction base plate is fixed with a heat conduction block, and the top of the heat conduction block is provided with at least one temperature-sensitive deformation sheet.

[0010] The further technical improvement of the utility model lies in: the temperature-sensitive deformation sheet adopts at least one metal sheet or shape memory alloy with a certain expansion coefficient.

[0011] The further technical improvement of the utility model lies in: when the temperature-sensitive deformation sheet adopts a laminated bimetallic sheet structure, the structure is composed of a low-expansion coefficient metal sheet and a high-expansion coefficient metal sheet.

[0012] The further technical improvement of the utility model lies in: when the temperature-sensitive deformation sheet adopts a shape memory alloy, it is trained to restore to a low-temperature shape when being lower than a set temperature threshold, so that the heat conduction link is disconnected; and when being higher than the set temperature threshold, it restores to a high-temperature shape, so that the heat conduction link is connected.

[0013] Compared with the prior art, the utility model has the following beneficial effects:

[0014] 1、The utility model discloses a temperature-sensitive deformation sheet to realize the dynamic on-off of the heat conduction link, and the link is closed in the high-temperature stage to accelerate cooling, and the link is disconnected in the low-temperature stage to isolate the heat source. The design avoids the waste of cold energy of the traditional fixed conduction structure, and the total time consumed from 300K cooling to 4K is reduced from 32 hours of the traditional GM refrigerator to 24 hours, and the comprehensive energy consumption is obviously reduced by 20%.

[0015] 2、The heat conduction assembly adopted by the utility model realizes shape change based on the thermal expansion and contraction or phase change of the material itself, and then automatically switches the on or off state of the heat conduction link, so that no additional control equipment is needed, and the stability is high. DRAWINGS

[0016] In order to facilitate the understanding of those skilled in the art, the utility model will be further described below with reference to the drawings.

[0017] Fig. 1 It is a schematic view of the overall internal connection structure of the utility model;

[0018] Fig. 2 It is a schematic view of the on state of the heat conduction link of the utility model;

[0019] Fig. 3 It is a schematic view of the off state of the heat conduction link of the utility model.

[0020] In the figure: 1, GM refrigerator; 2, vacuum Dewar; 3, cold shield; 4, magnet; 5, primary heat sink; 6, heat conduction fixed plate; 7, heat switch driving mechanism; 101, primary cold head; 102, secondary cold head; 701, heat conduction base plate; 702, flexible heat conduction chain; 703, heat conduction contact plate; 704, heat conduction block; 705, temperature-sensitive deformation sheet; 7051, low-expansion coefficient metal sheet; 7052, high-expansion coefficient metal sheet. DETAILED DESCRIPTION

[0021] In order to further illustrate the technical means and effects adopted by the utility model to achieve the predetermined utility model purposes, the specific embodiments, structures, features and effects according to the utility model are described in detail as follows in combination with the drawings and preferred embodiments.

[0022] Please refer to Figs. 1-3 As shown in the figure, the superconducting magnet high-efficiency cooling system based on adaptive heat switch comprises a vacuum Dewar 2, a cold shield 3 arranged in the vacuum Dewar 2, and a magnet 4 placed in the cold shield 3; a GM refrigerator 1 is fixed with the vacuum Dewar 2, and the working end of the GM refrigerator 1 is arranged in the vacuum Dewar 2;

[0023] The GM refrigerator 1 comprises a primary cold head 101 and a secondary cold head 102, wherein the primary cold head 101 is in close contact with the cold shield 3 for cold source conduction, and the secondary cold head 102 is in close contact with the magnet 4 for cold source conduction;

[0024] A heat conduction assembly capable of realizing temperature control on-off is arranged between the cold shield 3 and the magnet 4, the heat conduction assembly comprises a heat conduction fixed plate 6 fixed to the inner side wall of the cold shield 3, a heat switch driving mechanism 7 fixedly installed at the corresponding position of the magnet 4, and the heat switch driving mechanism 7 and the heat conduction fixed plate 6 realize switching between contact state and non-contact state with temperature change; a primary heat sink 5 is connected between the primary cold head 101 and the heat conduction fixed plate 6 for cold quantity conduction; the heat conduction fixed plate 6 adopts a contact surface made of high-conductivity material (such as copper or aluminum).

[0025] Specifically, the heat switch driving mechanism 7 comprises a heat conduction base plate 701 fixed with the magnet 4, a heat conduction contact plate 703 arranged in parallel above the heat conduction base plate 701, and the heat conduction base plate 701 and the heat conduction contact plate 703 are flexibly connected through a flexible heat conduction chain 702, and the distance between the heat conduction base plate 701 and the heat conduction contact plate 703 is adjustable.

[0026] A heat conduction block 704 for compensating height is fixed to the top of the heat conduction base plate 701, at least one temperature-sensitive deformation sheet 705 is arranged on the top of the heat conduction block 704, the deformation threshold of the temperature-sensitive deformation sheet 705 corresponds to a certain set temperature of the target temperature zone of the primary cold head 101, the temperature-sensitive deformation sheet 705 can adopt a bimetallic sheet or a shape memory alloy, the more the number of temperature-sensitive deformation sheets 705, the more stable the support provided.

[0027] If the temperature-sensitive deformation sheet 705 adopts at least one metal sheet with a certain expansion coefficient, in order to meet the height compensation;

[0028] Preferably, a bimetallic sheet is adopted, including a low-expansion coefficient metal sheet 7051 and a high-expansion coefficient metal sheet 7052 without distinguishing the upper and lower stacking order, and the bimetallic sheet is curved at high temperature, the thermal conduction contact plate 703 is lifted to contact the thermal conduction fixed plate 6 to form a closed thermal conduction link, and the two metal sheets are compressed to be flattened at low temperature, the height is reduced, and thus the thermal conduction link is disconnected;

[0029] If the temperature-sensitive deformation sheet 705 adopts a shape memory alloy, the double-path memory effect is utilized, the shape memory alloy is trained to restore the high-temperature shape at high temperature to make the thermal conduction link connected, and to restore the low-temperature shape at low temperature to make the thermal conduction link disconnected, and the temperature threshold is set to be close to the limit temperature of the primary cold head 101.

[0030] The utility model discloses a three-stage working process, including the initial stage, the middle stage and the later stage: in the initial stage, the thermal conduction link is closed due to the high temperature, the primary cold head 101 can conduct cold to the magnet 4, and the primary cold head 101 cools the cold screen 3 and the magnet 4 simultaneously; in the middle stage, the thermal conduction link is disconnected by triggering the thermal switch driving mechanism 7 after the temperature of the primary cold head 101 reaches the threshold; in the later stage, the secondary cold head 102 works independently to complete the final cooling.

[0031] The above is only the preferred embodiment of the utility model, and does not limit the utility model in any form, although the utility model has been disclosed as above, however, it is not used to limit the utility model, any person skilled in the art, within the scope of the utility model technical scheme, can make some changes or modifications to the equivalent embodiment of equivalent change, but as long as it does not deviate from the utility model technical scheme content, according to the technical essence of the utility model, any simple modification, equivalent change and modification of the above embodiment are still within the scope of the utility model technical scheme.

Claims

1. A superconducting magnet high efficiency cooling system based on adaptive thermal switch, characterized in that: The application relates to a GM refrigerator (1) comprising a vacuum Dewar (2) and a cold shield (3) arranged in the vacuum Dewar (2), wherein a magnet (4) is arranged in the cold shield (3), and wherein a primary cold head (101) and a secondary cold head (102) of the GM refrigerator (1) are in contact with the cold shield (3) and the magnet (4) respectively to provide a cold source. A heat conduction assembly is arranged between the cold shield (3) and the magnet (4), and the heat conduction assembly can realize the on-off control of the heat conduction between the primary cold head (101) and the magnet (4).

2. The adaptive thermal switch based superconducting magnet high efficiency cooling system of claim 1, wherein, The heat conduction assembly comprises a heat conduction fixed plate (6) fixed to the inner side wall of the cold shield (3) and a heat switch driving mechanism (7) fixed at a corresponding position of the magnet (4), a primary heat sink (5) is connected between the heat conduction fixed plate (6) and the primary cold head (101), and the heat switch driving mechanism (7) and the heat conduction fixed plate (6) realize the switching between the contact state and the non-contact state with the change of temperature.

3. The adaptive thermal switch based superconducting magnet high efficiency cooling system of claim 2, wherein, The heat switch driving mechanism (7) comprises a heat conduction base plate (701) fixed to the magnet (4), and a heat conduction contact plate (703) is arranged above the heat conduction base plate (701), and the two are connected through a flexible heat conduction chain (702). A heat conduction block (704) is fixed to the top of the heat conduction base plate (701), and at least one temperature-sensitive deformation sheet (705) is arranged on the top of the heat conduction block (704).

4. The adaptive thermal switch based superconducting magnet high efficiency cooling system of claim 3, wherein, The temperature-sensitive deformation sheet (705) is at least one metal sheet with a certain expansion coefficient or shape memory alloy.

5. The adaptive thermal switch based superconducting magnet high efficiency cooling system of claim 4, wherein, When the temperature-sensitive deformation sheet (705) adopts a laminated bimetallic sheet structure, the structure is composed of a low-expansion coefficient metal sheet (7051) and a high-expansion coefficient metal sheet (7052).

6. The adaptive thermal switch based superconducting magnet high efficiency cooling system of claim 4, wherein, When the temperature-sensitive deformation sheet (705) adopts a shape memory alloy, it is trained to restore to a low-temperature shape when the temperature is lower than a set temperature threshold, so that the heat conduction link is disconnected; and the temperature-sensitive deformation sheet (705) is trained to restore to a high-temperature shape when the temperature is higher than the set temperature threshold, so that the heat conduction link is connected.

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