High-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions

Abstract

The invention discloses a multi-ring high-temperature superconducting permanent magnet device. The device has magnetic flux density amplification and magnetic flux accumulation functions. The device comprises a plurality of single-communication four-hole closed-loop superconducting sheet stacking units, wherein the single-communication four-hole closed-loop superconducting sheet stacking unit comprises a plurality of stacked single-communication four-hole closed-loop superconducting sheets and solenoids; a first circular hole, a second circular hole, a third circular hole and a fourth circular hole are formed in the single-communication four-hole closed-loop superconducting sheet, and slits are formed between the first circular hole and the second circular hole, between the second circular hole and the third circular hole and between the third circular hole and the fourth circular hole; the two solenoids are sleeved with the single-communication four-hole closed-loop superconducting piece through the second round hole and the third round hole respectively. And the plurality of single-communication four-hole closed-loop superconducting sheet stacking units are uniformly distributed in the circumferential direction by taking the second circular hole and the third circular hole as centers. The device is composed of a full superconducting loop, is simple in structure, does not need welding, a power supply and a current lead, can stably output a required strong magnetic field, and can also be applied to occasions such as medium and large superconducting magnets.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of superconducting magnet applications, and particularly relates to a high-temperature superconducting permanent magnet device with double-amplification of magnetic flux density and accumulation of magnetic flux. BACKGROUND

[0002] Strong magnetic field technology has great significance in industrial production and daily life. Superconducting magnets are made of superconducting materials, have the advantages of low power consumption, small footprint, light weight, high stability, and no energy loss when generating strong magnetic fields, and their use can significantly promote the development of stable strong magnetic field technology.

[0003] With the continuous improvement of the performance of high-temperature superconducting wires, the research and development of high-temperature superconducting magnets is also steadily advancing. These magnets are usually wound from superconducting tapes, have various structural forms such as double-pie structure or layer-wound solenoid structure, and need external power for excitation. However, one challenge is that high-temperature superconducting tapes cannot achieve resistance-free welding, which results in the inability of the magnet to operate in a closed loop. In addition, due to the slow propagation speed of high-temperature superconducting material when it loses superconductivity, the heat generated when the magnet loses superconductivity is easy to accumulate locally, causing local overheating and possibly damaging the magnet in severe cases. Therefore, the detection and protection of high-temperature superconducting magnets when they lose superconductivity are extremely difficult.

[0004] In order to solve the above problems, it is necessary to develop a new type of high-temperature superconducting permanent magnet device that can amplify the magnetic flux density and accumulate the magnetic flux, thereby improving the performance and safety of the magnet. SUMMARY

[0005] The purpose of the present application is to provide a high-temperature superconducting permanent magnet device with double-amplification of magnetic flux density and accumulation of magnetic flux, characterized in that the high-temperature superconducting permanent magnet device comprises a plurality of stacked single-communication four-hole closed-loop superconducting sheets and solenoids; the single-communication double-hole closed-loop superconducting sheet has a first circular hole, a second circular hole, a third circular hole and a fourth circular hole, and a slit is provided between the first circular hole and the second circular hole, the second circular hole and the third circular hole, and the third circular hole and the fourth circular hole; the single-communication four-hole closed-loop superconducting sheet is sleeved on the solenoid through the second circular hole and the third circular hole; and the plurality of single-communication four-hole closed-loop superconducting sheets are stacked in the axial direction of the circular hole.

[0006] The radii of the second circular hole and the third circular hole are the same;

[0007] The radii of the second circular hole and the third circular hole are greater than the radii of the first circular hole and the fourth circular hole.

[0008] The stacking mode of the plurality of single-communication four-hole closed-loop superconducting sheets is that the first circular hole and the fourth circular hole of each superconducting sheet coincide.

[0009] When the magnetic field is not saturated, the magnetic flux density of the first circular hole and the fourth circular hole is:

[0010] B2 = 2 * k * B1 * (r4 / r3)

[0011] Wherein, B2 is the magnetic flux density of the first circular hole and the fourth circular hole, k is the number of single-connected four-hole closed-loop superconducting sheet stacking units, B1 is the magnetic flux density of the second circular hole and the third circular hole, r3 is the inner radius of the first circular hole and the fourth circular hole, and r4 is the inner radius of the second circular hole and the third circular hole.

[0012] A method for using a high-temperature superconducting permanent magnet device with magnetic flux density double amplification and magnetic flux accumulation functions, characterized in that different numbers of single-connected four-hole closed-loop superconducting sheet stacks are stacked, a conventional coil with a core is placed in the second circular hole and the third circular hole to provide original magnetic flux, the field-cooled excitation method is used to design the direction of the current I0, a constant current I1 continuously flowing outside the second circular hole and the third circular hole is generated, the magnetic flux density directions of all single-connected four-hole closed-loop superconducting sheet stacking units are the same, and the magnetic flux accumulation of different numbers of single-connected four-hole closed-loop superconducting sheet stacking units in the first circular hole and the fourth circular hole is realized. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a single-connected four-hole closed-loop superconducting sheet.

[0014] Figure 2 It is a structural diagram of a single-connected four-hole closed-loop superconducting sheet stacking unit.

[0015] Figure 3 It is a high-temperature superconducting permanent magnet device assembled by four single-connected four-hole closed-loop superconducting sheet stacking units.

[0016] Figure 4 It is a timing diagram of the current passing through and being removed from the excitation coil during the excitation process.

[0017] Figure 5 It is a flow schematic diagram of the high-temperature superconducting permanent magnet assembled by four single-connected four-hole closed-loop superconducting sheet stacking units after the excitation is completed.

[0018] In the figure: 101 - first circular hole; 102 - second circular hole; 103 - third circular hole; 104 - fourth circular hole; 105 - slit; 201 - solenoid; 202 - solenoid. DETAILED DESCRIPTION

[0019] In the following, the embodiments of the present application are explained with reference to the accompanying drawings:

[0020] The present application proposes a high-temperature superconducting permanent magnet device with magnetic flux density double amplification and magnetic flux accumulation functions, which will be further described in combination with the accompanying drawings and specific embodiments.

[0021] In order to intuitively depict the three-dimensional structure of the superconducting tape, the scale of the drawing is not the actual scale, and the size can be designed according to the actual situation. Figure 1 The figure is a schematic diagram of the structure of a single-communication four-hole closed loop superconducting sheet. The specific manufacturing method is as follows:

[0022] In the second generation of high temperature superconducting sheet, small-large-large-small circular sheets with radii of two r1 and two r2 are cut out, and r1 is smaller than r2. The centers of the four circles are on a line, forming four circular sheets. A first circular hole, a second circular hole, a third circular hole and a fourth circular hole concentric with each circular sheet are cut out inside the circular sheet, with radii of r3, r4, r4 and r3 respectively, wherein r4 is greater than r3. At the same time, three slits 105 with a width of w and a length of l are cut out at the center line of the first circular hole 101 and the second circular hole 102, the center line of the second circular hole 102 and the third circular hole 103, and the center line of the third circular hole 103 and the fourth circular hole 104, to connect the first circular hole 101 and the second circular hole 102, the second circular hole 102 and the third circular hole 103, and the third circular hole 103 and the fourth circular hole 104.

[0023] Figure 2 The figure is a structure diagram of a single-communication four-hole closed loop superconducting sheet stacking unit. A stacking unit formed by aligning a plurality of single-communication double-hole superconducting sheets up and down and left and right, and placing solenoids 201 and 202 in the second circular hole 102 and the third circular hole 103 respectively.

[0024] Figure 3 The figure is a high temperature superconducting permanent magnet device assembled by four single-communication four-hole closed loop superconducting sheet stacking units. The first circular hole 101 and the fourth circular hole 104 of the four single-communication four-hole closed loop superconducting sheet stacking units are stacked in pairs. The radii of the second circular hole and the third circular hole and the number of stacking units are designed according to the required magnetic flux density; according to the Biot-Savart law, the magnetic field B at the center of the circular ring is B = μ0*I / 2R (μ0 is the magnetic permeability of vacuum, I is the current, and R is the radius of the circular ring), the smaller the radius of the hole, the greater the magnetic flux density. Let the radius of the large hole be R1, the magnetic flux density be B1, the radius of the small hole be R2, and the magnetic flux density be B2, then the final magnetic flux density in the small hole is:

[0025] B2 = B1*(R2 / R1)

[0026] In this embodiment, the magnetic flux density of the first circular hole and the fourth circular hole when the magnetic field is not saturated is:

[0027] B2 = 2*B1*(r4 / r3)

[0028] Wherein, B2 is the magnetic flux density of the first circular hole and the fourth circular hole, B1 is the magnetic flux density of the second circular hole and the third circular hole, r4 is the inner diameter of the second circular hole and the third circular hole, and r3 is the inner diameter of the first circular hole and the fourth circular hole.

[0029] Figure 4 The following is a timing diagram of the current being introduced and removed from the excitation coil during the excitation process. The excitation method uses field-cooled excitation, and the specific operations are as follows:

[0030] (1) The excitation coils are placed in the second circular hole 102 and the third circular hole 103 respectively, and the two excitation coils are energized at the same time at room temperature, so as to generate a stable magnetic field in each superconducting ring. At the same time, it is necessary to ensure that the direction of the current flow is such that the magnetic field generated by all the excitation coils in the device is in the same direction, so as to produce the effect of magnetic flux accumulation in the later stage;

[0031] (2) Lowering the ambient temperature to the critical temperature of the superconducting slices until all superconducting slices are completely in the superconducting state;

[0032] (3) The current in the excitation coil is slowly reduced to zero. Based on the principle of flux conservation in a superconducting closed loop, an induced current is generated in each of the four-hole superconducting slices to maintain the total magnetic flux in the superconducting closed loop unchanged. As a result, a magnetic field generated by the induced current appears in the first circular hole 101, the second circular hole 102, the third circular hole 103, and the fourth circular hole 104. According to Biot-Savart's law, a greater magnetic flux density is generated in the first circular hole 101 and the fourth circular hole 104 (achieving the function of magnetic flux density amplification).

[0033] (4) The combination of multiple stacked units can achieve the effect of magnetic flux accumulation in the first circular hole 101 and the fourth circular hole 104.

[0034] Depend on Figure 4 It can be seen that the excitation timing is as follows:

[0035] (1) At room temperature, connect the solenoid 201 and the solenoid 202 to the power supply and Figure 4 The direction shown is given by the current I0 during the period t0-t1. The direction of current flow needs to make the magnetic field generated by all the excitation coils in the device have the same direction;

[0036] (2) placing the device in a coolant during the period t1-t2 to cool it sufficiently to a superconducting state (lowering the temperature below the critical temperature of the superconducting sheet);

[0037] (3) Gradually reduce the current to 0 during the period t2-t3.

[0038] Figure 5 The figure shows the magnetic field and current of a high-temperature superconducting permanent magnet assembled from a single-connected four-hole closed-loop superconducting sheet stack after excitation. According to the flux conservation principle of a superconducting closed loop, two cumulative constant currents I1 will be generated around the superconducting closed loop, such as Figure 5As shown, because the periphery of the four-hole superconducting ring is connected, the same size and direction current will flow around the first circular hole 101 and the fourth circular hole 104, and the radius of the first circular hole 101 and the fourth circular hole 104 is smaller than the radius of the second circular hole 102 and the third circular hole 103 where the excitation coil is placed, so that a larger magnetic flux density B2 will be generated in the first circular hole 101 and the fourth circular hole 104 than in the second circular hole 102 and the third circular hole 103, thereby realizing the function of double amplification and accumulation of the magnetic flux density. Because the superconducting magnet is stacked up and down to form a superconducting ring, the effect of accumulation of the magnetic flux density is realized.

[0039] By adjusting the ratio of the radius of the two circular holes of the single-communication four-hole closed-loop superconducting sheet and the number of stacked units, a magnetic field of a desired size can be generated in space.

[0040] The manufacturing process of the application is simple, has no lead heat leakage, and has low operating cost, has the functions of magnetic flux self-stabilization, self-protection and self-recovery, and does not need complex quench detection and protection measures. In addition, no external power supply is needed, only the superconducting sheet needs to be maintained in a superconducting state to generate a high magnetic field on a small-sized superconducting sheet.

Claims

1. A high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions, characterized in that: The high-temperature superconducting permanent magnet device includes a plurality of single-connected four-hole closed-loop superconducting sheet stacking units; wherein the single-connected four-hole closed-loop superconducting sheet stacking units include a plurality of stacked single-connected four-hole closed-loop superconducting sheets and solenoids; the single-connected four-hole closed-loop superconducting sheet is provided with a first circular hole, a second circular hole, a third circular hole and a fourth circular hole, and slits are provided between the first circular hole and the second circular hole, the second circular hole and the third circular hole, and the third circular hole and the fourth circular hole; the single-connected four-hole closed-loop superconducting sheet is respectively mounted on the two solenoids through the second circular hole and the third circular hole; and the plurality of single-connected four-hole closed-loop superconducting sheet stacking units are evenly distributed circumferentially with the second circular hole and the third circular hole as the center.

2. A high-temperature superconducting permanent magnet device with dual magnetic flux density amplification and magnetic flux accumulation functions according to claim 1, characterized in that: The radii of the second circular hole and the third circular hole are equal and larger than the radii of the first circular hole and the fourth circular hole.

3. The high-temperature superconducting permanent magnet device with the functions of dual magnetic flux density amplification and magnetic flux accumulation according to claim 1, characterized in that: The stacking manner of a plurality of single-connected four-hole closed-loop superconducting sheets is as follows: the first circular hole of each superconducting sheet coincides with the fourth circular hole of an adjacent superconducting sheet.

4. A high-temperature superconducting permanent magnet device with dual magnetic flux density amplification and magnetic flux accumulation functions according to claim 1, 2 or 3, characterized in that: When the magnetic field is not saturated, the magnetic flux density of the first and fourth circular holes is: B2=2*k*B1*(r4 / r3) Among them, B2 is the magnetic flux density of the first circular hole and the fourth circular hole, k is the number of single-connected four-hole closed-loop superconducting sheet stacking units, B1 is the magnetic flux density of the second circular hole and the third circular hole, r3 is the radius of the first circular hole and the fourth circular hole, and r4 is the radius of the second circular hole and the third circular hole.

5. A method for using the high-temperature superconducting permanent magnet device with dual magnetic flux density amplification and magnetic flux accumulation functions according to claim 1, characterized in that: Conventional coils with iron cores are placed in the second and third circular holes to provide the original magnetic flux. The direction of the current I0 is designed using the field-cooled excitation method to generate a constant current I1 that continuously flows around the second and third circular holes. This ensures that the magnetic flux density directions of all single-connected four-hole closed-loop superconducting sheet stacking units are the same, thereby achieving the accumulation of magnetic fluxes of different numbers of single-connected four-hole closed-loop superconducting sheet stacking units in the first and fourth circular holes.

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