Superconducting magnet excitation and back field testing device and method

Abstract

The invention discloses a superconducting magnet excitation and back field testing device and method, and relates to the technical field of superconducting magnet excitation and test.The superconducting magnet excitation and back field testing device comprises a supporting structure and a coil, the supporting structure is internally provided with an excitation cavity and a detection cavity, the excitation cavity is used for arranging a superconducting magnet, and the detection cavity is used for detecting the superconducting magnet; a detection device can be arranged in the detection cavity, the coil is wound outside the supporting structure and surrounds the excitation cavity, the coil can be electrified, and the detection device can detect the intensity of a magnetic field generated by the excited superconducting magnet. And the magnetic field of the superconducting magnet can be detected in a background magnetic field.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting magnet excitation and testing, and in particular to a superconducting magnet excitation and back field testing device and method. Background Art

[0002] The second generation of high temperature superconductor REBCO (REBa2Cu3O 7-x , RE refers to rare earth elements such as Y and Gd) magnets are widely used in strong magnetic field equipment, such as magnetic resonance imaging (MRI), nuclear magnetic resonance spectrometers (NMR), and magnetohydrodynamic power generation. The second generation of high-temperature superconducting magnets generally requires a test current lead to be directly connected to the superconducting second high-temperature magnet to energize for excitation. In order to improve the stability during the excitation process, a superconducting switch needs to be installed on the superconducting magnet during the excitation process, and the excitation process is inconvenient. In addition, under the background magnetic field (the magnetic field outside the superconducting magnet itself), the stability and performance of the magnetic field of the superconducting magnet also need to be studied. Therefore, there is an urgent need for a superconducting magnet excitation and back field testing device and method that is simpler to excite and can detect the magnetic field of the superconducting magnet under the background magnetic field. Summary of the invention

[0003] The purpose of the present invention is to provide a superconducting magnet excitation and back field testing device and method to solve the problems existing in the above-mentioned prior art, make superconducting magnet excitation simpler, and be able to detect the magnetic field of the superconducting magnet under the background magnetic field.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a superconducting magnet excitation and back field testing device, comprising: a supporting structure and a coil, wherein the supporting structure is provided with an excitation cavity and a detection cavity, wherein the excitation cavity is used to arrange a superconducting magnet, wherein a detection device can be arranged in the detection cavity, wherein the coil is wound around the supporting structure and surrounds the excitation cavity, wherein the coil can be energized, and wherein the detection device can detect the intensity of the magnetic field generated by the superconducting magnet.

[0006] In some embodiments, the supporting structure includes a base plate, an outer cylinder and an inner cylinder, both ends of the outer cylinder and the inner cylinder are open, both the outer cylinder and the inner cylinder are detachably fixedly connected to the base plate, the inner cylinder is arranged in the outer cylinder, the inner cylinder is parallel to the axis of the outer cylinder, the annular space between the inner cylinder and the outer cylinder forms the excitation cavity, the space in the inner cylinder forms the detection cavity, and the coil is wound around the outer cylinder.

[0007] In some embodiments, it also includes an upper fixing ring, a lower fixing ring and a plurality of first fixing screws, the axis of the outer cylinder is perpendicular to the bottom plate, the lower fixing ring is fixedly connected to the bottom plate, a first limiting groove matching the shape of the bottom end of the outer cylinder is arranged in the lower fixing ring, the lower end of the outer cylinder can be stuck in the first limiting groove, the upper fixing ring is arranged at the top of the outer cylinder, a second limiting groove matching the top end of the outer cylinder is arranged in the upper fixing ring, the top end of the outer cylinder can be stuck in the second limiting groove, a plurality of upper through holes are arranged on the upper fixing ring, a plurality of lower through holes are arranged on the lower fixing ring, a plurality of first screw holes are arranged on the bottom plate, the upper through holes, the lower through holes and the first screw holes correspond one to one, and the first fixing screw can pass through an upper through hole and a lower through hole at the same time and be threadedly connected in the first screw hole.

[0008] In some embodiments, it also includes a cover plate and a second fixing screw, the axis of the inner cylinder is perpendicular to the bottom plate, the cover plate is arranged on the top of the inner cylinder, a first mounting groove matching the shape of the top end of the inner cylinder is arranged on one side of the cover plate, the top end of the inner cylinder can be stuck in the first mounting groove, a second mounting groove matching the shape of the bottom end of the inner cylinder is arranged on one side of the bottom plate, the bottom end of the inner cylinder can be stuck in the second mounting groove, a plurality of fixing through holes are arranged on the cover plate, and a plurality of second screw holes are also arranged on the bottom plate, the fixing through holes correspond to the second screw holes one by one, and the second fixing screw can pass through the fixing through holes and be threadedly connected in the second screw holes.

[0009] In some embodiments, two fixing members and two electrodes are further included, the two fixing members are fixedly connected to the upper side of the upper fixing ring, the two electrodes are respectively connected to the first fixing member and the second fixing member by bolts, the upper fixing ring is provided with two mounting holes connecting the two sides of the fixing ring at positions corresponding to the two electrodes, the two electrodes each have a first end and a second end, the two first ends respectively pass through the corresponding mounting holes and extend from the lower side of the upper fixing ring, the first ends of the two electrodes can be respectively connected to the positive terminal and the negative terminal of the coil, and the second ends of the two electrodes are used to be connected to the positive and negative electrodes of an external power supply.

[0010] In some embodiments, the cover plate is further provided with a detection hole connecting the inner cylinder with the outside.

[0011] The present invention also provides a zero-field cold excitation method, comprising the following steps: placing a superconducting magnet in the excitation cavity and cooling the superconducting magnet to allow the superconducting magnet to enter a superconducting state, then energizing the coil and detecting the magnetic field strength through a detection device, and when the magnetic field strength reaches a predetermined magnetic field strength, reducing the current on the coil until the current is zero.

[0012] The present invention also provides a field-cooled excitation method, comprising the following steps: at room temperature, a superconducting magnet is placed in the excitation cavity, power is supplied to the coil, and the magnetic field strength is detected by a detection device, and then the superconducting magnet is cooled, and after the superconducting magnet enters a superconducting state, the current on the coil is reduced until the current is zero.

[0013] The present invention also provides a back field test method, comprising the following steps: placing the excited superconducting magnet in the excitation cavity, and cooling the superconducting magnet to allow the superconducting magnet to enter a superconducting state, then energizing the coil, and detecting the magnetic field strength after coupling of the magnetic field on the superconducting magnet and the magnetic field of the coil by a detection device, and keeping the current in the coil unchanged when the magnetic field strength reaches a predetermined magnetic field strength, and calculating the magnetic field attenuation rate based on the detection data of the detection device after a period of time.

[0014] In some embodiments, when the excited superconducting magnet is arranged in front of the excitation cavity and no superconducting magnet is arranged in the excitation cavity, the following steps are also included: energizing the coil to the preset current intensity, and detecting the magnetic field generated on the coil by a detection device.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The superconducting magnet excitation and back field test device provided in this embodiment can first energize the coil, then set the superconducting magnet in the excitation cavity, and then reduce the temperature of the superconducting magnet to perform field-cooled excitation; it can also first set the superconducting magnet in the excitation cavity and reduce the temperature of the superconducting magnet, then energize the coil and perform zero-field cold excitation. Since both field-cooled excitation and zero-field cold excitation are to excite the superconducting magnet indirectly through the magnetic field generated by the coil, this avoids setting a superconducting switch on the superconducting magnet and operating the superconducting switch, making the excitation process simpler. In addition, the excited superconducting magnet can also be set in the excitation cavity and cooled to make the superconducting magnet reach a superconducting state, and at the same time, the coil is energized to generate a background magnetic field, and at the same time, the magnetic field after the coupling of the coil magnetic field and the superconducting magnet magnetic field is detected by the detection device, and the magnetic field attenuation rate is calculated, and then the stability of the superconducting magnet under the background magnetic field is evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1It is a three-dimensional structural diagram of a superconducting magnet excitation and back field testing device in some embodiments of the present invention;

[0019] Figure 2 A three-dimensional structural diagram of an upper fixing ring in some embodiments of the present invention;

[0020] Figure 3 A three-dimensional structural diagram of a lower fixing ring in some embodiments of the present invention;

[0021] Figure 4 A three-dimensional structural diagram of a bottom plate in some embodiments of the present invention;

[0022] Figure 5 A three-dimensional structural diagram of a cover plate in some embodiments of the present invention;

[0023] In the figure: 1. coil; 2. excitation cavity; 3. detection cavity; 4. bottom plate; 41. second mounting groove; 42. first screw hole; 43. second screw hole; 5. outer cylinder; 6. inner cylinder; 7. upper fixing ring; 71. fixing piece; 72. electrode; 73. second limiting groove; 74. upper through hole; 75. mounting hole; 8. lower fixing ring; 81. first limiting groove; 82. lower through hole; 9. cover plate; 91. detection hole; 92. first mounting groove; 93. fixing through hole. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The purpose of the present invention is to provide a superconducting magnet excitation and back field testing device and method to solve the problems existing in the above-mentioned prior art, make the excitation of the superconducting magnet simpler, and be able to detect the magnetic field of the superconducting magnet under the background magnetic field.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Embodiment 1

[0028] This embodiment provides a superconducting magnet excitation and back field testing device, such as Figure 1-5As shown, it includes: a support structure and a coil 1, the support structure is provided with an excitation cavity 2 and a detection cavity 3, the excitation cavity 2 is used to set a superconducting magnet, the detection cavity 3 can be provided with a detection device, the coil 1 is wound around the support structure and surrounds the excitation cavity 2, the coil 1 can be energized, and the detection device can detect the strength of the magnetic field generated by the superconducting magnet.

[0029] The superconducting magnet excitation and back field test device provided in the present embodiment can firstly energize the coil 1, then set the superconducting magnet in the excitation cavity 2, and then reduce the temperature of the superconducting magnet so that the superconducting magnet in the superconducting state has a magnetic field, and perform field-cooled excitation; or firstly set the superconducting magnet in the excitation cavity 2 and reduce the temperature of the superconducting magnet, and then energize the coil 1 so that the superconducting magnet in the superconducting state has a magnetic field, and perform zero-field cold excitation. Since both field-cooled excitation and zero-field cold excitation indirectly excite the superconducting magnet through the magnetic field generated by the coil 1, this avoids setting a superconducting switch on the superconducting magnet and operating the superconducting switch, making the excitation process simpler. In addition, the excited superconducting magnet can be placed in the excitation cavity 2 and cooled to make the superconducting magnet reach the superconducting state, and the coil 1 is energized to generate a background magnetic field, and the magnetic field after the magnetic field of the coil 1 and the magnetic field of the superconducting magnet are coupled by the detection device, and the magnetic field attenuation rate (unit: ppm / h) is calculated, so as to evaluate the stability of the superconducting magnet under the background magnetic field. The coil 1 is preferably wound by enameled wire; the detection device is preferably a Hall sensor.

[0030] In one implementation of this embodiment, the support structure includes a bottom plate 4, an outer cylinder 5 and an inner cylinder 6, both of which are open at both ends, and both of which are detachably fixedly connected to the bottom plate 4, the inner cylinder 6 is arranged in the outer cylinder 5, the inner cylinder 6 is parallel to the axis of the outer cylinder 5, the annular space between the inner cylinder 6 and the outer cylinder 5 forms an excitation cavity 2, the space in the inner cylinder 6 forms a detection cavity 3, and the coil 1 is wound outside the outer cylinder 5. By forming an annular excitation cavity 2 between the outer cylinder 5 and the inner cylinder 6, and winding the coil 1 outside the outer cylinder 5 to generate a magnetic field, the magnetic field generated by the coil 1 can be uniformly transmitted to the superconducting magnet in the excitation cavity 2, so that the excitation effect is better.

[0031] In one implementation mode of the present embodiment, the superconducting magnet excitation and back field test device provided in the present embodiment further includes an upper fixing ring 7, a lower fixing ring 8 and a plurality of first fixing screws, the axis of the outer cylinder 5 is perpendicular to the bottom plate 4, the lower fixing ring 8 is fixedly connected to the bottom plate 4, a first limiting groove 81 matching the shape of the bottom end of the outer cylinder 5 is arranged in the lower fixing ring 8, the lower end of the outer cylinder 5 can be clamped in the first limiting groove 81, the upper fixing ring 7 is arranged at the top of the outer cylinder 5, a second limiting groove 73 matching the top end of the outer cylinder 5 is arranged in the upper fixing ring 7, the top end of the outer cylinder 5 can be clamped in the second limiting groove 73, a plurality of upper through holes 74 are arranged on the upper fixing ring 7, a plurality of lower through holes 82 are arranged on the lower fixing ring 8, a plurality of first screw holes 42 are arranged on the bottom plate 4, the upper through holes 74, the lower through holes 82 and the first screw holes 42 correspond one to one, and the first fixing screw can simultaneously pass through an upper through hole 74 and a lower through hole 82 and be threadedly connected in the first screw hole 42. The first limiting groove 81 and the second limiting groove 73 can limit the outer cylinder 5 , and the first fixing screw can connect the upper fixing ring 7 and the lower fixing ring 8 together, and at the same time firmly fix the outer cylinder 5 on the bottom plate 4 .

[0032] In one implementation of the present embodiment, the superconducting magnet excitation and back field test device provided in the present embodiment further includes a cover plate 9 and a second fixing screw, the axis of the inner cylinder 6 is perpendicular to the bottom plate 4, the cover plate 9 is arranged at the top of the inner cylinder 6, a first mounting groove 92 matching the shape of the top end of the inner cylinder 6 is arranged on one side of the cover plate 9, the top end of the inner cylinder 6 can be stuck in the first mounting groove 92, a second mounting groove 41 matching the shape of the bottom end of the inner cylinder 6 is arranged on one side of the bottom plate 4, the bottom end of the inner cylinder 6 can be stuck in the second mounting groove 41, a plurality of fixing through holes 93 are arranged on the cover plate 9, and a plurality of second screw holes 43 are also arranged on the bottom plate 4, the fixing through holes 93 correspond to the second screw holes 43 one by one, and the second fixing screw can pass through the fixing through holes 93 and be threadedly connected in the second screw holes 43. The inner cylinder 6 can be limited by the first mounting groove 92 and the second mounting groove 41, and the second fixing bolt can fix the cover plate 9 and the bottom plate 4 together, and at the same time, the inner cylinder 6 is firmly fixed on the bottom plate 4.

[0033] Specifically, the bottom plate 4, the upper fixing ring 7, the lower fixing ring 8, the outer tube 5, the inner tube 6 and the cover plate 9 are all made of low-temperature resistant materials, such as glass fiber board or stainless steel plate coated with PTFE; the tops of the first fixing screw and the second fixing screw can be screwed into nuts to fix the upper fixing ring 7 and the cover plate 9.

[0034] In one implementation of this embodiment, the superconducting magnet excitation and back field test device provided in this embodiment also includes two fixing members 71 and two electrodes 72. Both fixing members 71 are fixedly connected to the upper side of the upper fixing ring 7. The two electrodes 72 are respectively connected to the first fixing member 71 and the second fixing member 71 by bolts. The upper fixing ring 7 is provided with two mounting holes 75 that communicate with both sides of the fixing ring at positions corresponding to the two electrodes 72. Both electrodes 72 have a first end and a second end. The two first ends pass through the respective corresponding mounting holes 75 and extend from the lower side of the upper fixing ring 7. The first ends of the two electrodes 72 can be respectively connected to the positive terminal and the negative terminal of the coil 1. The second ends of the two electrodes 72 are used to be connected to the positive and negative poles of the external power supply. By bolting the electrodes 72 and the fixing members 71, the removal and replacement of the electrodes 72 can be facilitated. The first ends of the two electrodes 72 extend from the corresponding mounting holes 75, so that the electrodes 72 are close to the coil 1 and the connection between the coil 1 and the electrodes 72 is facilitated. Among them, the electrodes 72 are preferably copper electrodes 72.

[0035] In one embodiment of the present invention, a detection hole 91 is also provided on the cover plate 9 to connect the inner cylinder 6 with the outside world. The detection hole 91 can facilitate the insertion and removal of the detection device into and out of the detection cavity 3, thereby improving the convenience of the device when used.

[0036] Embodiment 2

[0037] The present embodiment provides a zero-field cold excitation method, comprising the following steps: placing a superconducting magnet in an excitation cavity 2, and cooling the superconducting magnet to put the superconducting magnet into a superconducting state, then energizing the coil 1, and detecting the magnetic field strength through a detection device, and when the magnetic field strength reaches a predetermined magnetic field strength, reducing the current on the coil 1 until the current is zero.

[0038] The zero-field cold excitation method provided in this embodiment uses the superconducting magnet excitation and back field testing device in the first embodiment, and can perform zero-field cold excitation without setting a superconducting switch, making the excitation process more convenient.

[0039] Embodiment 3

[0040] The present embodiment provides a field-cooled excitation method, comprising the following steps: at room temperature, a superconducting magnet is disposed in an excitation cavity 2, power is supplied to the coil 1, and the magnetic field strength is detected by a detection device, and then the superconducting magnet is cooled, and after the superconducting magnet enters a superconducting state, the current on the coil 1 is reduced until the current is zero.

[0041] The zero-field cold excitation method provided in this embodiment uses the superconducting magnet excitation and back field test device in the first embodiment, and can perform field-cooled excitation without setting a superconducting switch, making the excitation process more convenient.

[0042] Embodiment 4

[0043] The present embodiment provides a back field test method, comprising the following steps: placing the excited superconducting magnet in the excitation cavity 2, and cooling the superconducting magnet to put the superconducting magnet into a superconducting state, then energizing the coil 1 to a preset current intensity, and detecting the magnetic field intensity after coupling between the magnetic field on the superconducting magnet and the magnetic field of the coil 1 by a detection device, and keeping the current in the coil 1 unchanged when the magnetic field intensity reaches the predetermined magnetic field intensity, and calculating the magnetic field attenuation rate according to the detection data of the detection device after a period of time.

[0044] The back field test method provided in this embodiment can detect the magnetic field after the magnetic field of the superconducting magnet and the magnetic field of the coil 1 are coupled under the background magnetic field, and then evaluate the stability of the magnetic field of the superconducting magnet under the background magnetic field after excitation. Among them, the detection device directly detects the magnetic field strength after the magnetic field of the superconducting magnet and the magnetic field of the coil 1 are coupled. Since the current on the coil 1 is constant, the magnetic field generated on the coil 1 is constant, and the magnetic field attenuation rate of the magnetic field of the coupled magnetic field can be directly calculated, and the stability of the magnetic field on the superconducting magnet can be evaluated based on the magnetic field attenuation rate of the coupled magnetic field.

[0045] In one implementation of this embodiment, before the superconducting magnet after excitation is set in the excitation cavity 2, when no superconducting magnet is set in the excitation cavity 2, the following steps are also included: energize the coil 1 to a preset current intensity, and detect the magnetic field generated on the coil 1 by a detection device. When the superconducting magnet is not set, first energize the coil 1 to a preset current intensity, and detect the magnetic field intensity generated by the coil 1 at this time by a detection device and calculate it as the field strength of the coil 1, then put the superconducting magnet into the excitation cavity 2, cool the superconducting magnet, and then detect the magnetic field intensity after coupling between the magnetic field of the coil 1 and the magnetic field of the superconducting magnet by a detection device, and then subtract the magnetic field intensity of the coil 1 measured at the preset current intensity from the magnetic field intensity after coupling to directly evaluate the magnetic field intensity of the superconducting magnet. Wherein:

[0046] The magnetic field strength on the superconducting magnet = coupling magnetic field strength - coil magnetic field strength.

[0047] Specifically, in Embodiment 2, Embodiment 3 and Embodiment 4, the superconducting magnet is preferably a high-temperature superconducting magnet; the method for cooling the superconducting magnet is: immersing the superconducting magnet excitation and back field test device and the superconducting magnet arranged in the excitation cavity together in liquid nitrogen for cooling.

[0048] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A superconducting magnet excitation and back field testing device, characterized in that: include: A support structure and a coil, wherein the support structure has an excitation cavity and a detection cavity, the excitation cavity is used to set a superconducting magnet, and the detection cavity can be set with a detection device, the coil is wound around the support structure and surrounds the excitation cavity, the coil can be energized, and the detection device can detect the strength of the magnetic field generated by the superconducting magnet.

2. The superconducting magnet excitation and back field testing device according to claim 1, characterized in that: The supporting structure comprises a bottom plate, an outer cylinder and an inner cylinder, both ends of the outer cylinder and the inner cylinder are open, both the outer cylinder and the inner cylinder are detachably fixedly connected to the bottom plate, the inner cylinder is arranged in the outer cylinder, the inner cylinder is parallel to the axis of the outer cylinder, the annular space between the inner cylinder and the outer cylinder forms the excitation cavity, the space in the inner cylinder forms the detection cavity, and the coil is wound outside the outer cylinder.

3. The superconducting magnet excitation and back field testing device according to claim 2, characterized in that: The cam is secured to the bottom of the housing, wherein the first and second fixing portions are engaged with the first and second fixing portions, respectively.

4. The superconducting magnet excitation and back field testing device according to claim 2, characterized in that: The cover plate also includes a second fixing screw, the axis of the inner cylinder is perpendicular to the bottom plate, the cover plate is arranged on the top of the inner cylinder, a first mounting groove matching the shape of the top end of the inner cylinder is arranged on one side of the cover plate, the top end of the inner cylinder can be stuck in the first mounting groove, a second mounting groove matching the shape of the bottom end of the inner cylinder is arranged on one side of the bottom plate, the bottom end of the inner cylinder can be stuck in the second mounting groove, a plurality of fixing through holes are arranged on the cover plate, a plurality of second screw holes are also arranged on the bottom plate, the fixing through holes correspond to the second screw holes one by one, and the second fixing screw can pass through the fixing through holes and be threadedly connected in the second screw holes.

5. The superconducting magnet excitation and back field testing device according to claim 3, characterized in that: It also includes two fixing members and two electrodes, the two fixing members are fixedly connected to the upper side of the upper fixing ring, the two electrodes are respectively connected to the first fixing member and the second fixing member by bolts, the upper fixing ring is provided with two mounting holes connecting the two sides of the fixing ring at positions corresponding to the two electrodes, the two electrodes have a first end and a second end, the two first ends respectively pass through the corresponding mounting holes and extend from the lower side of the upper fixing ring, the first ends of the two electrodes can be respectively connected to the positive terminal and the negative terminal of the coil, and the second ends of the two electrodes are used to be connected to the positive and negative electrodes of an external power supply.

6. The superconducting magnet excitation and back field testing device according to claim 4, characterized in that: The cover plate is also provided with a detection hole connecting the inner cylinder and the outside.

7. A zero-field cold excitation method, characterized in that: The following steps are involved: A superconducting magnet is arranged in the excitation cavity and cooled to make the superconducting magnet enter a superconducting state. Then, power is supplied to the coil and the magnetic field strength is detected by a detection device. When the magnetic field strength reaches a predetermined magnetic field strength, the current on the coil is reduced until the current is zero.

8. A field cooling excitation method, characterized in that: The method comprises the following steps: at room temperature, placing a superconducting magnet in the excitation cavity, supplying power to the coil, detecting the magnetic field strength by a detection device, cooling the superconducting magnet, and after the superconducting magnet enters a superconducting state, reducing the current on the coil until the current is zero.

9. A back field testing method, characterized in that: The method comprises the following steps: placing the excited superconducting magnet in the excitation cavity, cooling the superconducting magnet to make the superconducting magnet enter a superconducting state, then energizing the coil to a preset current intensity, and detecting the magnetic field intensity after coupling of the magnetic field on the superconducting magnet and the magnetic field of the coil by a detection device, keeping the current in the coil unchanged when the magnetic field intensity reaches the preset magnetic field intensity, and calculating the magnetic field attenuation rate according to the detection data of the detection device after a period of time.

10. The superconducting magnet excitation and back field testing device according to claim 9, characterized in that: When the excited superconducting magnet is arranged in front of the excitation cavity and no superconducting magnet is arranged in the excitation cavity, the method further includes the following steps: energizing the coil to the preset current intensity and detecting the magnetic field generated on the coil by a detection device.

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