Superconducting magnet device and vector magnetic field loading method

Abstract

The invention discloses a superconducting magnet device and a vector magnetic field loading method. The method comprises the following steps: step 1, determining the size and the direction of a vector magnetic field; the superconducting magnet device and the vector magnetic field loading method are provided. Under the same working magnetic field, the structure space is smaller, the magnetic field utilization rate is higher, the manufacturing cost can be remarkably reduced, meanwhile, the uniformity of the magnetic fields provided by the X coil and the Y coil is higher, meanwhile, the ultra-low vibration performance is achieved under the high magnetic field, the optical or magnetic measurement requirement with the very high vibration requirement can be met, and the application prospect is wide. The superconducting coil is cooled by using the flexible cold conduction belt, the vibration of the superconducting coil can be effectively reduced, the vibration stability of a magnetic field is improved, 0.5-1% of current is overshot when the magnetic field is loaded, and then the current is adjusted to be reduced to a target magnetic field, so that the magnetic field can be quickly stabilized, and the drift effect of the magnetic field is reduced.

Description

Technical Field

[0001] The present application relates to the field of superconducting magnets, and in particular to a superconducting magnet device and a vector magnetic field loading method. Background Art

[0002] A superconducting magnet refers to an electromagnet whose coil is made of a type II superconductor with a high transition temperature and a particularly high critical magnetic field at low temperatures. Its main characteristics are that there is no electrical loss caused by wire resistance and no magnetic loss caused by the presence of an iron core, and it has great practical value.

[0003] Conventional three-axis vector superconducting magnets at home and abroad are usually composed of three groups of solenoid magnets. Usually the Z axis is composed of a single or multiple solenoids, and the X / Y axis is composed of two split solenoids. The superconducting coil is large in size, the magnetic field utilization rate is low, and the cost is high. In addition, since the X and Y axes are far away from the center of the magnetic field, there is a problem of low uniformity. Summary of the invention

[0004] Based on the fact that the existing three-axis vector superconducting magnet has the problems of large superconducting coil volume, low magnetic field utilization, high cost, and low uniformity due to the X and Y being far away from the magnetic field center, the present invention proposes a superconducting magnet device and a vector magnetic field loading method.

[0005] The present application provides a superconducting magnet device and a vector magnetic field loading method, which adopts the following technical solutions:

[0006] A vector magnetic field loading method includes: step 1: determining the magnitude and direction of the vector magnetic field.

[0007] Step 2: Perform orthogonal decomposition of the magnetic field to determine the magnetic field size required in the X, Y, and Z directions.

[0008] Step 3: Calculate the ratio of magnetic field to current using the coil size.

[0009] Step 4: Calculate the magnitude of the current applied in the X, Y, and Z directions based on the proportional relationship of the magnetic field.

[0010] Step 5: Determine the superconducting magnet device without a superconducting switch based on the design input.

[0011] Step 6: Use the excitation power supply to load current to the X, Y, and Z coils, and adjust the current to reach the target current.

[0012] Step 7: When there is a superconducting switch, it is necessary to turn on the superconducting switch heater and wait for 30 or 60 seconds to put the superconducting switch in a non-superconducting state. Use the excitation power supply to load current to the X, Y, and Z coils, and overshoot about 0.5% to 1% of the current before entering step 6.

[0013] Step 8: Detect the magnetic field to determine whether the magnetic field is reached. If the corresponding magnetic field is not reached, fine-tune each group of currents again until the target magnetic field and target magnetic field direction are reached.

[0014] Step 9: If the superconducting magnet system is equipped with a superconducting switch, turn off the superconducting switch heater to complete the magnetic field loading.

[0015] Optionally, the formula for calculating the magnitude of the magnetic field in step 2 is:

[0016] B(z)=B*cos(θ)

[0017]

[0018] Optionally, the formula for calculating the current in step 4 is:

[0019] I(z)=Fz*B*cos(θ)

[0020]

[0021] The present application provides a superconducting magnet device, which adopts the following technical solution:

[0022] Optionally, it includes a vacuum container and a superconducting magnet mechanism installed on the vacuum container, the superconducting magnet mechanism includes a superconducting coil, and the superconducting coil generates a three-dimensional vector magnetic field.

[0023] Optionally, the superconducting magnet mechanism also includes a pulse tube refrigerator, which is fixedly mounted on the upper surface of the vacuum container, a cold shield is provided inside the vacuum container, one end of the pulse tube refrigerator is fixedly mounted on the outer surface of the cold shield, and the other end of the pulse tube refrigerator is fixedly mounted with a hot and cold conductive connector.

[0024] Optionally, a fixed cold plate is fixedly mounted on one end of the heat and cold conductive connector, a coil frame is fixedly mounted on the outer surface of the fixed cold plate, and the X coil, the Y coil and the Z coil are all wound on the outer surface of the coil frame.

[0025] Optionally, the Z coil is an inner coil in the shape of a spiral tube coil, the X coil is an intermediate coil in the shape of a saddle coil, and the Y coil 2 is an outer coil in the shape of a saddle coil.

[0026] Optionally, a room temperature hole is opened inside the vacuum container, the gap between the temperature-controlled inner wall and the cold screen is the cold screen internal control, and the inner wall of the cold screen inner cylinder is fixedly bonded with an insulation layer, and the material of the insulation layer is a double-sided aluminum-plated film.

[0027] Optionally, a vacuum electrical connector is fixedly mounted on the upper surface of the vacuum container, and one end of the vacuum electrical connector is electrically connected to the X coil, the Y coil and the Z coil respectively.

[0028] Optionally, a vacuum port with a high vacuum function is fixedly mounted on the upper surface of the vacuum container, and a signal line interface is fixedly mounted on the upper surface of the vacuum container.

[0029] In summary, the present application includes at least one of the following beneficial technical effects:

[0030] By setting up a superconducting magnet device, a compact superconducting coil structure is adopted, the Z coil is the inner coil in the form of a solenoid, and the X coil and the Y coil are saddle-shaped coils. Under the same working magnetic field, the structural space is smaller and the magnetic field utilization rate is higher, which can significantly reduce the production cost. At the same time, the magnetic field provided by the X and Y coils is more uniform, and has ultra-low vibration performance under high magnetic fields, which can meet the measurement requirements of optics or magnetism with high vibration requirements. Flexible conductive cooling tapes are used to cool the superconducting coils, which can effectively reduce the vibration of the superconducting coils and improve the vibration stability of the magnetic field. When the magnetic field is loaded, the current is overshot by about 0.5% to 1%, and then the current is adjusted to the target magnetic field, which can be conducive to quickly stabilizing the magnetic field and reducing the magnetic field drift, solving the problems of large superconducting coil volume, low magnetic field utilization rate and high cost in the existing three-axis vector superconducting magnets, and the technical problem of low uniformity due to the distance between X and Y and the center of the magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a superconducting magnet device and a vector magnetic field loading method proposed by the present invention;

[0032] Figure 2 A three-dimensional diagram of a vacuum container structure of a superconducting magnet device and a vector magnetic field loading method proposed by the present invention;

[0033] Figure 3 A three-dimensional diagram of a pulse tube refrigerator structure of a superconducting magnet device and a vector magnetic field loading method proposed by the present invention;

[0034] Figure 4 A three-dimensional diagram of a superconducting coil structure of a superconducting magnet device and a vector magnetic field loading method proposed by the present invention;

[0035] Figure 5 A three-dimensional diagram of a Y-coil structure of a superconducting magnet device and a vector magnetic field loading method proposed by the present invention;

[0036] Figure 6 A three-dimensional diagram of a fixed cold plate structure of a superconducting magnet device and a vector magnetic field loading method proposed by the present invention;

[0037] Figure 7 A three-dimensional diagram of a vacuum port structure of a superconducting magnet device and a vector magnetic field loading method proposed in the present invention.

[0038] In the figure: 1. vacuum container; 2. pulse tube refrigerator; 21. cold shield; 22. hot and cold connecting parts; 23. fixed cold plate; 3. superconducting coil; 31. coil frame; 32. X coil; 33. Y coil; 34. Z coil; 4. room temperature hole; 41. cold shield inner tube; 42. insulation layer; 5. vacuum electrical connector; 51. vacuum extraction port; 52. signal line interface. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-Figure 7 This application is described in further detail.

[0040] Reference Figure 1 , a vector magnetic field loading method, comprising: step 1: determining the magnitude and direction of the vector magnetic field.

[0041] Step 2: Perform orthogonal decomposition of the magnetic field to determine the magnetic field size required in the X, Y, and Z directions.

[0042] The formula for calculating the magnitude of the magnetic field is:

[0043] B(z)=B*cos(θ)

[0044]

[0045] Step 3: Calculate the ratio of magnetic field to current using the coil size.

[0046] Step 4: Calculate the magnitude of the current applied in the X, Y, and Z directions based on the proportional relationship of the magnetic field.

[0047] The formula for calculating the current is:

[0048] I(z)=Fz*B*cos(θ)

[0049]

[0050] Step 5: Determine the superconducting magnet device without a superconducting switch based on the design input.

[0051] Step 6: Use the excitation power supply to load current to the X, Y, and Z coils, and adjust the current to reach the target current.

[0052] Step 7: When there is a superconducting switch, it is necessary to turn on the superconducting switch heater and wait for 30 or 60 seconds to put the superconducting switch in a non-superconducting state. Use the excitation power supply to load current to the X, Y, and Z coils, and overshoot about 0.5% to 1% of the current before entering step 6.

[0053] Step 8: Detect the magnetic field to determine whether the magnetic field is reached. If the corresponding magnetic field is not reached, fine-tune each group of currents again until the target magnetic field and target magnetic field direction are reached.

[0054] Step 9: If the superconducting magnet system is equipped with a superconducting switch, turn off the superconducting switch heater to complete the magnetic field loading.

[0055] like Figure 2-Figure 7 As shown, a superconducting magnet device includes a vacuum container 1 and a superconducting magnet mechanism installed in the vacuum container 1. The superconducting magnet mechanism includes a superconducting coil 3. The superconducting coil 3 generates a three-dimensional vector magnetic field.

[0056] Specifically, in order to cool the superconducting coil 3 and the cold shield 21, the superconducting magnet mechanism also includes a pulse tube refrigerator 2. The pulse tube refrigerator 2 is a two-stage refrigerator, including a refrigerator stage 1 and a refrigerator stage 2. The pulse tube refrigerator 2 is fixedly installed on the upper surface of the vacuum container 1. A cold shield 21 is provided inside the vacuum container 1. The refrigerator stage 1 of the pulse tube refrigerator 2 is fixedly installed on the outer surface of the cold shield 21. The cold shield 21 can usually be cooled to about 40K, thereby providing a low heat leakage vacuum radiation environment for the superconducting coil 3.

[0057] The second stage of the pulse tube refrigerator 2 is fixedly installed with a hot and cold connecting piece 22 for cooling the superconducting coil 3. The superconducting coil 3 can be cooled to an ultra-low temperature state, usually below 5K, thereby ensuring that the superconducting coil 3 is in a superconducting state, so that it has a high current carrying capacity and a high magnetic field performance. The flexible hot and cold connecting piece 22 cools the superconducting coil 3, which can effectively reduce the vibration of the superconducting coil 3 and improve the vibration stability of the magnetic field. The material of the flexible hot and cold connecting piece 22 is oxygen-free copper, or other materials with good thermal conductivity. The hot and cold connecting piece 22 is made of soft braided wire, or it can be made of copper stranded wire or copper sheet, but it will sacrifice the softness. The rotary valve of the pulse tube refrigerator 2 is fixed separately from the superconducting magnet to reduce the vibration of the superconducting coil 3, and can also be fixed integrally with the superconducting magnet.

[0058] Specifically, in order to install the superconducting coil 3, a fixed cold plate 23 is fixedly installed at one end of the hot and cold connecting piece 22. The fixed cold plate 23 is made of oxygen-free copper or aluminum alloy to ensure good thermal contact and a certain fixing ability. The superconducting coil 3 includes a coil skeleton 31, an X coil 32, a Y coil 33 and a Z coil 34. The outer surface of the fixed cold plate 23 is fixedly installed with the outer surface of the coil skeleton 31. The coil skeleton 31 is divided into three groups of skeletons, and the material is an aluminum alloy skeleton. The aluminum alloy skeleton shown is a paramagnetic material. Compared with other skeleton materials such as stainless steel, it has the advantages of light weight and no residual magnetism. The X coil 32, the Y coil 33 and the Z coil 34 are all wound on the outer surface of the coil skeleton 31; the three groups of coils are wound on the coil skeleton 31 to increase cooling and reduce a certain amount of eddy current heating.

[0059] Specifically, in order to reduce the volume of the superconducting coil 3, the Z coil 34 is an inner coil in the shape of a spiral tube coil, the X coil 32 is an intermediate coil in the shape of a saddle coil, and the Y coil 33 is an outer coil in the shape of a saddle coil. A compact structure is adopted, the Z coil 34 is an inner coil in the form of a solenoid, and the X coil 32 and the Y coil 33 are saddle coils. Under the same working magnetic field, the structural space is smaller and the magnetic field utilization rate is higher, which can significantly reduce the manufacturing cost. At the same time, the magnetic field uniformity provided by the X coil 32 and the Y coil 33 is higher, and a compensation coil or a shim coil can be added on this basis to correct the magnetic field. The X coil 32 and the Y coil 33 can also be coils of other shapes, such as a solenoid shape or a CCT or DCT shape.

[0060] Specifically, in order to facilitate the measurement of the superconducting coil 3, a room temperature hole 4 is opened inside the vacuum container 1, which can provide a large-diameter cylindrical space at room temperature for inserting other scientific measurement equipment, providing installation and testing space for scientific measurement equipment. In order to reduce radiation heat leakage, a cold shield inner cylinder 41 is arranged between the room temperature hole 4 and the superconducting coil 3. The inner wall of the cold shield inner cylinder 41 is fixedly bonded with an insulating layer 42. The material of the insulating layer 42 is a double-sided aluminum-plated film, and the number of layers is 40.

[0061] Specifically, in order to provide power to the superconducting coil 3, a vacuum electrical connector 5 is fixedly installed on the upper surface of the vacuum container 1, and one end of the vacuum electrical connector 5 is electrically connected to the X coil 32, the Y coil 33 and the Z coil 34 respectively; it includes three sets of current lead vacuum electrical connectors 51, which are used to separately power the X coil 32, the Y coil 33 and the Z coil 34.

[0062] Specifically, in order to evacuate the superconducting magnet device, a vacuum outlet 51 with a high vacuum angle valve is fixedly installed on the upper surface of the vacuum container 1, which is used to evacuate the superconducting magnet device so that a high vacuum is obtained inside the superconducting magnet device, so as to reduce heat leakage caused by gas heat exchange inside the superconducting magnet, so that the pulse tube refrigerator 2 can use sufficient residual cooling capacity to cool the superconducting coil 3 to an ultra-low temperature. A signal line interface 52 is fixedly installed on the upper surface of the vacuum container 1. Several signal line interfaces 52 use vacuum wall penetration parts to isolate the vacuum inside the superconducting magnet, and provide interfaces for detecting detection signals such as temperature and quench pressure drop.

[0063] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A vector magnetic field loading method, characterized in that: include: Step 1: Determine the magnitude and direction of the vector magnetic field; Step 2: Perform orthogonal decomposition of the magnetic field to determine the magnetic field size required in the X, Y, and Z directions; Step 3: Calculate the ratio of magnetic field to current by coil size; Step 4: Calculate the magnitude of the current applied in the three directions of X, Y, and Z according to the proportional relationship of the magnetic field; Step 5: Determine the superconducting magnet device without a superconducting switch according to the design input; Step 6: Use the excitation power supply to load current to the X, Y, and Z coils, and adjust the current to reach the target current; Step 7: When there is a superconducting switch, it is necessary to turn on the superconducting switch heater, wait for 30 or 60 seconds to put the superconducting switch in a non-superconducting state, use the excitation power supply to load current to the X, Y, and Z coils, and overshoot about 0.5% to 1% of the current before entering step 6; Step 8: Detect the magnetic field to determine whether the magnetic field is reached. If the corresponding magnetic field is not reached, fine-tune each group of currents again until the target magnetic field and target magnetic field direction are reached; Step 9: If the superconducting magnet system is equipped with a superconducting switch, turn off the superconducting switch heater to complete the magnetic field loading.

2. A vector magnetic field loading method according to claim 1, characterized in that: The formula for calculating the magnetic field magnitude in step 2 is: B(z)=B*cos(θ) 3. A vector magnetic field loading method according to claim 2, characterized in that: The formula for calculating the current in step 4 is: I(z)=Fz*B*cos(θ) 4. A superconducting magnet device, comprising a vector magnetic field loading method according to any one of claims 1 to 3, characterized in that: It comprises a vacuum container (1) and a superconducting magnet mechanism installed in the vacuum container (1), wherein the superconducting magnet mechanism comprises a superconducting coil (3), and the superconducting coil (3) generates a three-dimensional vector magnetic field.

5. A superconducting magnet device according to claim 4, characterized in that: The superconducting magnet mechanism further comprises a pulse tube refrigerator (2), the pulse tube refrigerator (2) being fixedly mounted on the upper surface of the vacuum container (1), a cold shield (21) being arranged inside the vacuum container (1), a cold end of the pulse tube refrigerator (2) being fixedly mounted on the outer surface of the cold shield (21), and a hot and cold conductive connector (22) being fixedly mounted on the other cold end of the pulse tube refrigerator (2).

6. A superconducting magnet device according to claim 5, characterized in that: A fixed cold plate (23) is fixedly mounted on one end of the hot and cold conductive connecting piece (22); the superconducting coil (3) comprises a coil frame (31), an X coil (32), a Y coil (33) and a Z coil (34); the outer surface of the fixed cold plate (23) is fixedly mounted on the outer surface of the coil frame (31); the X coil (32), the Y coil (33) and the Z coil (34) are all wound on the outer surface of the coil frame (31).

7. A superconducting magnet device according to claim 6, characterized in that: The Z coil (34) is an inner coil and is in the shape of a spiral tube coil, the X coil (32) is an intermediate coil and is in the shape of a saddle coil, and the Y coil (33) is an outer coil and is in the shape of a saddle coil.

8. A superconducting magnet device according to claim 7, characterized in that: A room temperature hole (4) is provided inside the vacuum container (1); a gap between the inner wall of the room temperature hole (4) and the cold screen (21) is a cold screen inner tube (41); an insulation layer (42) is fixedly bonded to the inner wall of the cold screen inner tube (41); and the insulation layer (42) is made of a double-sided aluminum-plated film.

9. A superconducting magnet device according to claim 8, characterized in that: A vacuum electrical connector (5) is fixedly mounted on the upper surface of the vacuum container (1), and one end of the vacuum electrical connector (5) is electrically connected to the X coil (32), the Y coil (33) and the Z coil (34) respectively.

10. A superconducting magnet device according to claim 4, characterized in that: A vacuum extraction port (51) with a high vacuum angle valve is fixedly mounted on the upper surface of the vacuum container (1), and a signal line interface (52) is fixedly mounted on the upper surface of the vacuum container (1).

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