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

Abstract

The present invention discloses a high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions, which belongs to the field of superconducting magnet application technology. The high-temperature superconducting permanent magnet device includes a plurality of single-connected double-hole closed-loop superconducting sheet stacking units; wherein the single-connected double-hole closed-loop superconducting sheet stacking unit includes a plurality of stacked single-connected double-hole closed-loop superconducting sheets and a solenoid; a first circular hole and a second circular hole are opened on the single-connected double-hole closed-loop superconducting sheet, and a slit is provided between the first circular hole and the second circular hole; the single-connected double-hole closed-loop superconducting sheet is sleeved on the solenoid through the first circular hole; and a plurality of single-connected double-hole closed-loop superconducting sheet stacking units are evenly distributed in the circumferential direction with the second circular hole as the center. The present invention is composed of a full superconducting circuit, has a simple structure, can stably output the required strong magnetic field, and is widely used in steady-state strong magnetic field occasions.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting magnet applications, and in particular to a high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions. Background Art

[0002] Research into the generation and application of strong magnetic fields is of great significance to scientific facilities operating under extreme conditions, biomedical engineering, national defense special forces, and high-precision scientific instruments. Superconducting magnet technology is becoming increasingly mature in commercial applications, with widespread use in medical MRI and high-magnetic field applications.

[0003] Conventional high-temperature superconducting magnets are wound from superconducting tape, either in a double-pancake configuration or a layer-wound solenoid structure, and are excited by an external power supply. However, since high-temperature superconducting tape cannot be welded seamlessly, closed-loop operation of high-temperature superconducting magnets is impossible. Furthermore, due to the slow propagation of quench in high-temperature superconducting materials, quench heat is easily concentrated within the magnet, leading to excessively high localized temperature rises and, in severe cases, magnet burnout. Consequently, quench detection and protection for high-temperature superconducting magnets are extremely difficult. A high-temperature superconducting permanent magnet device with flux density amplification and flux accumulation capabilities is needed to address these issues. Summary of the Invention

[0004] The purpose of the present invention is to provide 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 double-hole closed-loop superconducting sheet stacking units; wherein the single-connected double-hole closed-loop superconducting sheet stacking unit includes a plurality of stacked single-connected double-hole closed-loop superconducting sheets and a solenoid; the single-connected double-hole closed-loop superconducting sheet is provided with a first circular hole and a second circular hole, and a slit is provided between the first circular hole and the second circular hole; the single-connected double-hole closed-loop superconducting sheet is sleeved on the solenoid through the first circular hole; and the plurality of single-connected double-hole closed-loop superconducting sheet stacking units are evenly distributed circumferentially with the second circular hole as the center.

[0005] The radius of the first circular hole is greater than the radius of the second circular hole.

[0006] The stacking manner of several single-connected double-hole closed-loop superconducting sheets is as follows: the first circular holes of each superconducting sheet overlap, and the second circular holes of each superconducting sheet also overlap.

[0007] The magnetic flux density of the second circular hole when the magnetic field is not saturated is:

[0008] B2=k*B1*(r4 / r3)

[0009] Wherein, B2 is the magnetic flux density of the second circular hole, k is the number of single-connected double-hole closed-loop superconducting sheet stacking units, B1 is the magnetic flux density of the first circular hole, r3 is the radius of the first circular hole, and r4 is the radius of the second circular hole.

[0010] A method for using a high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions is characterized in that different numbers of single-connected double-hole closed-loop superconducting sheet stacking units are evenly distributed in the circumferential direction with a second circular hole as the center, a conventional coil with an iron core wire is placed in the first circular hole to provide original magnetic flux, and the direction of the current I0 is designed using a field cooling excitation method to generate a constant current I1 that continuously flows around the periphery of the first circular hole, so that the magnetic flux density direction of all the single-connected double-hole closed-loop superconducting sheet stacking units is the same, thereby achieving magnetic flux accumulation of different numbers of single-connected double-hole closed-loop superconducting sheet stacking units in the second circular hole.

[0011] The beneficial effects of the present invention are:

[0012] 1. The present invention is made of stacked single-connected double-hole closed-loop superconducting sheets, without bending and winding links, and does not require welding and other processes. It can achieve unobstructed closed-loop operation by simply providing a superconducting state environment. It has a simple manufacturing process, no lead heat leakage, low operating cost, and has magnetic flux self-stabilization, self-protection and self-recovery functions, without the need for complex quench detection and protection measures.

[0013] 2. The present invention utilizes the flux conservation principle of a superconducting closed loop and the field-cooled excitation technology to provide magnetic flux density in a large hole using a conventional iron core coil, which can generate a larger magnetic flux density in a small hole, thus having a magnetic flux density amplification function.

[0014] 3. The device can be designed according to the needs to achieve the purpose of focusing the magnetic flux density in the central hole of the device by designing the size of the double holes of the stacked single-connected double-hole closed-loop superconducting sheets and the number of superconducting sheet stacking units; without the need for an external power supply, only the power supply that can keep the superconducting sheet in a superconducting state is needed to generate a high magnetic field on a small-sized superconducting sheet.

[0015] 4. The present invention is composed of a full superconducting circuit, has a simple structure, can stably output the required strong magnetic field, and is widely used in steady-state strong magnetic field occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of a single-connected double-hole closed-loop superconducting sheet;

[0017] Figure 2 This is a structural diagram of a single-connected double-hole closed-loop superconducting sheet stacking unit;

[0018] Figure 3 A high-temperature superconducting permanent magnet device assembled from four single-connected double-hole closed-loop superconducting sheet stacking units;

[0019] Figure 4 This is the timing diagram of the current being introduced into and removed from the excitation coil during the excitation process;

[0020] Figure 5Schematic diagram of the magnetic field and current of a high-temperature superconducting permanent magnet assembled from four single-connected double-hole closed-loop superconducting sheet stacking units after excitation is completed;

[0021] Figure 6 A high-temperature superconducting permanent magnet device is assembled from multiple single-connected double-hole closed-loop superconducting sheet stacking units.

[0022] In the figure: 101 - first circular hole; 102 - second circular hole; 103 - slit; 202 - solenoid. DETAILED DESCRIPTION

[0023] The present invention provides a high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions. The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] In order to intuitively depict the three-dimensional structure of the superconducting tape, the drawn scale is not the actual scale. The size can be designed according to the actual situation. Figure 1 This is a schematic diagram of the structure of a single-connected double-hole closed-loop superconducting sheet. The specific manufacturing method is as follows:

[0025] An "8"-shaped circular piece with radii r1 and r2 is cut from a second-generation high-temperature superconducting sheet, and the width of the line connecting the two centers is w1 and the length is l1; then, a first circular hole 101 with a radius r3 and a second circular hole 102 with a radius r4 are cut at a preferred center position inside the sheet, and r3 should be greater than r4 so that current can flow continuously around the periphery of the circular holes; at the same time, a slit 103 with a width w2 and a length l2 is cut at the line connecting the centers of the first circular hole 101 and the second circular hole 102 to connect the first circular hole 101 and the second circular hole 102.

[0026] Figure 2 The structure diagram of the stacked unit of single-connected double-hole closed-loop superconducting sheets is shown. Multiple single-connected double-hole superconducting sheets are aligned vertically and horizontally to form a stacked unit. A solenoid 202 is placed in the first circular hole 101 to form a part of the high-temperature superconducting permanent magnet.

[0027] Figure 3 The high-temperature superconducting permanent magnet device is assembled from four single-connected double-hole closed-loop superconducting sheet stacking units; its specific structure and working principle are as follows:

[0028] The single-connected double-hole closed-loop superconducting sheet stacking unit includes six stacked single-connected double-hole closed-loop superconducting sheets and a solenoid 202; the single-connected double-hole closed-loop superconducting sheet is sleeved on the solenoid 202 through the first circular hole 101; the four single-connected double-hole closed-loop superconducting sheet stacking units are evenly distributed in the circumferential direction with the second circular hole 102 as the center, and are completely aligned up and down and left and right.

[0029] The radius of the two circular holes, positioned apart, and the number of stacked units are designed based on the required magnetic flux density at the center. According to the Biot-Savart law, the magnetic field at the center of the ring is B = μ0*I / 2R (μ0 is the vacuum permeability, I is the current, and R is the ring radius). The smaller the hole diameter, the greater the magnetic flux density. Assuming the large hole diameter is R1 and the magnetic flux density is B1, and the small hole diameter is R2 and the magnetic flux density is B2, the final magnetic flux density in the small hole is:

[0030] B2=B1*(R1 / R2)

[0031] In this embodiment, the magnetic flux density of the second circular hole when the magnetic field is not saturated is:

[0032] B2=4*B1*(r4 / r3)

[0033] Wherein, B2 is the magnetic flux density of the second circular hole, B1 is the magnetic flux density of the first circular hole, r3 is the radius of the first circular hole, and r4 is the radius of the second circular hole.

[0034] 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:

[0035] (1) The excitation coils are placed in the first circular hole 101 respectively, and multiple excitation coils are energized at the same time under normal 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 has the same direction, so as to produce the effect of magnetic flux accumulation in the later stage;

[0036] (2) Lowering the ambient temperature to the critical temperature of the superconducting slices until all superconducting slices are completely in the superconducting state;

[0037] (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 double-hole superconducting sheet 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 both the first circular hole 101 and the second circular hole 102. According to Biot-Savart's law, a greater magnetic flux density is generated in the second circular hole 102 (achieving the function of magnetic flux density amplification).

[0038] (4) The combination of multiple stacked units will achieve the effect of magnetic flux accumulation in the second circular hole 102.

[0039] Depend on Figure 4 It can be seen that the excitation timing is as follows:

[0040] (1) At room temperature, connect the solenoid 202 to the power supply and Figure 3The direction shown is given by the current I0 during the period 0-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;

[0041] (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);

[0042] (3) Gradually reduce the current to 0 during the period t2-t3.

[0043] Figure 5 This is a schematic diagram of the magnetic field and current of a high-temperature superconducting permanent magnet assembled from four single-connected double-hole closed-loop superconducting sheet stacking units after the excitation is completed. According to the principle of flux conservation in a superconducting closed loop, a constant current I1 will be generated around the superconducting closed loop, as shown in Figure 2. Figure 5 As shown, because the outer periphery of the double-hole superconducting ring segment is connected, a current of the same magnitude and direction will flow around the second circular hole 102. Since the radius of the second circular hole 102 is smaller than the radius of the first circular hole 101, which houses the excitation coil, a greater magnetic flux density B2 will be generated in the second circular hole 102 than in the first circular hole 101, thereby achieving a magnetic flux density amplification function. Furthermore, because the superconducting magnet is composed of four stacked units, the magnetic field generated around the second circular hole 102 is four times that of a single double-hole superconducting stacked unit, thus achieving a cumulative magnetic flux density effect.

[0044] By adjusting the ratio of the radius of the two circular holes of the single-connected double-hole closed-loop superconducting sheet and the number of combined stacking units, the desired magnetic field can be generated in space, such as Figure 6 The figure shows a high-temperature superconducting permanent magnet device assembled from multiple single-connected double-hole closed-loop superconducting sheet stacking units.

[0045] The present invention features a simple manufacturing process, no lead heat leakage, low operating costs, and self-stabilizing, self-protective, and self-recovery magnetic flux, eliminating the need for complex quench detection and protection measures. Furthermore, it eliminates the need for an external power source, requiring only a source to maintain the superconducting state, enabling the generation of high magnetic fields on small superconducting sheets.

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 double-hole closed-loop superconducting sheet stacking units; wherein the single-connected double-hole closed-loop superconducting sheet stacking units include a plurality of stacked single-connected double-hole closed-loop superconducting sheets and a solenoid; the single-connected double-hole closed-loop superconducting sheet is provided with a first circular hole and a second circular hole, and a slit is provided between the first circular hole and the second circular hole; the single-connected double-hole closed-loop superconducting sheet is sleeved on the solenoid through the first circular hole; and the plurality of single-connected double-hole closed-loop superconducting sheet stacking units are evenly distributed circumferentially with the second circular hole as the center; The radius of the first circular hole is greater than the radius of the second circular hole; The stacking manner of several single-connected double-hole closed-loop superconducting sheets is as follows: the first circular holes of each superconducting sheet overlap, and the second circular holes of each superconducting sheet also overlap.

2. The high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions according to claim 1, characterized in that: The magnetic flux density of the second circular hole when the magnetic field is not saturated is: B2=k*B1*(r4 / r3) Wherein, B2 is the magnetic flux density of the second circular hole, k is the number of single-connected double-hole closed-loop superconducting sheet stacking units, B1 is the magnetic flux density of the first circular hole, r3 is the radius of the first circular hole, and r4 is the radius of the second circular hole.

3. A method for using the high-temperature superconducting permanent magnet device with magnetic flux density amplification and magnetic flux accumulation functions according to claim 1, characterized in that: Different numbers of single-connected double-hole closed-loop superconducting sheet stacking units are evenly distributed circumferentially with the second circular hole as the center. A conventional coil with an iron core wire is placed in the first circular hole to provide the original magnetic flux. The direction of the current I0 is designed using the field-cooling excitation method to generate a constant current I1 that continuously flows around the periphery of the first circular hole. This ensures that the magnetic flux density direction of all single-connected double-hole closed-loop superconducting sheet stacking units is the same, thereby achieving magnetic flux accumulation of different numbers of single-connected double-hole closed-loop superconducting sheet stacking units in the second circular hole.

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