A Bitter-type FeSeTe superconducting magnet system

Abstract

The present invention discloses a Bitter-type FeSeTe superconducting magnet system, which includes two parts: an exciting cryogenic superconducting coil and a FeSeTe high-temperature superconducting coil. The FeSeTe high-temperature superconducting coil includes a FeSeTe Bitter wafer, an insulating sheet, a cover plate, a pull rod, and a heater. The FeSeTe Bitter wafer is prepared by growing a buffer layer and a FeSeTe superconducting layer on a Hastelloy wafer. Then, the FeSeTe Bitter wafers and the insulating sheets are stacked alternately, and pull rods and nuts are passed through the middle small holes of the FeSeTe Bitter wafers and the insulating sheets to align the small holes on both of them. Then, the device is fixed by the cover plate and the pull rod, and both the upper and lower cover plates are in contact with the insulating sheet. Finally, the heater is fixed on the cover plate. Placing the FeSeTe high-temperature superconducting coil at the center of the exciting cryogenic superconducting coil completes the preparation of the entire magnet.

Description

Technical Field

[0001] The present invention belongs to the field of superconducting magnet preparation, and particularly relates to a Bitter-type FeSeTe superconducting magnet system Background Art

[0002] Superconducting magnets have the advantages of high stability, low loss, long life, and low operating cost, and are ideal devices for providing a magnetic field environment. Superconducting magnet technology is an indispensable key technology in the fields of future nuclear fusion reactors, high-energy particle accelerators, nuclear magnetic resonance imaging, spallation neutron sources, etc. Due to the limitation of its field strength, low-temperature superconducting materials (LTS) cannot operate in an ultra-high field environment. High-temperature superconducting materials (HTS) have broad application prospects in the field of high-field magnets due to their advantages such as high critical temperature, high critical magnetic field, and high current-carrying capacity. However, the development cost of all-HTS high-field magnets is very high, the strain on the materials is huge, and the failure risk is high. Therefore, the HTS-LTS hybrid magnet scheme is a particularly effective method for achieving high magnetic fields by superconducting magnets at present. A large-aperture low-temperature superconducting magnet is used as the back-field magnet to provide a uniform magnetic field environment, and the high-temperature superconducting magnet is inserted into the low-temperature back-field magnet

[0003] The existing inserted high-temperature superconducting magnets mainly include solenoid superconducting magnets and Bitter-type superconducting magnets. The Bitter-type superconducting magnet proposed in the present invention is an improvement based on the Bitter-type superconducting magnet. Compared with the solenoid superconducting magnet, it does not need to prepare joints, reducing the resistance of the joints; it has more holes inside, with faster heat dissipation; it does not need to wind the tape, and is directly stacked by Bitter plates; it does not need to bend and twist the tape, reducing the damage to the tape performance; it does not need to be connected to the current through current leads, improving the stability of the magnetic field; the layered stacked structure limits the action of the circumferential force; under the action of the axial compression force, the acting surface is the circular surface of the Bitter plate, with a large acting area and little damage to the performance. The Bitter plates will compress each other, improving the stability of the structure. Since the Bitter-type superconducting magnet has no external joints, the quench method is to heat the magnet to exceed the critical transition temperature to cause the magnet to quench. The critical transition temperature of the FeSeTe high-temperature superconducting material is relatively low, usually only about 10K under normal preparation methods, much lower than high-temperature superconducting materials such as YBCO, making it easier to control the operation of the device Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a Bitter-type FeSeTe superconducting magnet system. By alternately stacking FeSeTe Bitter discs and insulating sheets, a pull rod and a nut are passed through the middle small holes of the FeSeTe Bitter discs and the insulating sheets to align the small holes on both of them, and then the device is fixed by a cover plate and a pull rod. Finally, a heater is fixed on the cover plate. The FeSeTe high-temperature superconducting coil is excited by an excitation cryogenic superconducting coil to achieve stable operation of the magnetic field environment in the FeSeTe Bitter coil.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A Bitter-type FeSeTe superconducting magnet system, characterized in that it includes two parts: an excitation cryogenic superconducting coil and a FeSeTe high-temperature superconducting coil. Among them,

[0007] The excitation cryogenic superconducting coil is composed of NbTi and Nb3Sn superconducting coils;

[0008] The FeSeTe high-temperature superconducting coil includes FeSeTe Bitter discs, insulating sheets, cover plates, small-hole pull rods and heaters; the FeSeTe Bitter discs and the insulating sheets are alternately stacked, and a small-hole pull rod and a nut are passed through the middle small holes of the FeSeTe Bitter discs and the insulating sheets to align the small holes on both of them; then they are fixed by a cover plate and a pull rod, and the upper and lower cover plates are in contact with the insulating sheets; finally, the heater is fixed on the cover plate;

[0009] The FeSeTe high-temperature superconducting coil is placed at the center of the excitation cryogenic superconducting coil.

[0010] Further, the FeSeTe Bitter disc is prepared by growing a buffer layer and a FeSeTe superconducting layer on a Hastelloy disc.

[0011] Further, there are several small holes on the FeSeTe Bitter disc, which play a role in rapid heat dissipation and changing the current distribution.

[0012] Further, the insulating sheet is made of AlN and plays an insulating role between the FeSeTe Bitter discs.

[0013] Further, the FeSeTe high-temperature superconducting coil has no internal joints, external joints and current leads, reducing the heat leakage during the operation of the magnet and improving the stability of the magnetic field.

[0014] Further, the heater is made of manganese copper wire, and one is arranged on each of the upper and lower cover plates. By heating the manganese copper wire, the ambient temperature of the inserted magnet is increased, thereby controlling the operation of the inserted magnet.

[0015] The beneficial effects of the present invention compared with the prior art are as follows:

[0016] In the magnet system of the present invention, the inserted coil does not require joints and current leads, reducing the magnet resistance, reducing the heat leakage during the operation of the magnet, and improving the system stability; in the magnet system of the present invention, the superconducting material of the inserted coil does not need to be twisted and bent, preventing damage to the properties of the tape.

[0017] The superconducting material of the inserted coil in the magnet system of the present invention is a layered stacked structure, which can effectively reduce the action of the circumferential force, and under the action of the axial compressive force, the damage to the properties of the tape is small, and the Bitter plates will compress each other, improving the structural stability.

[0018] The inserted coil in the magnet system of the present invention has a porous structure, with fast heat dissipation and can achieve current redistribution.

[0019] The critical temperature of the inserted coil in the magnet system of the present invention is relatively low, and the operation of the system can be better controlled by the heater. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the FeSeTe Bitter wafer structure in the present invention;

[0021] Figure 2 It is a schematic diagram of the FeSeTe high-temperature superconducting coil structure in the present invention. In the figure: 1 - cover plate, 2 - small hole pull rod, 3 - heater, 4 - pull rod, 5 - alternately stacked FeSeTe Bitter wafers and insulating sheets;

[0022] Figure 3 It is a schematic diagram of the structure of the Bitter-type FeSeTe superconducting magnet system in the present invention. In the figure: 6 - excitation low-temperature superconducting coil, 7 - FeSeTe high-temperature superconducting coil, 8 - insulating sheet, 9 - FeSeTe Bitter wafer. Detailed Embodiments

[0023] In order to more clearly illustrate the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the prior art and the embodiments.

[0024] The present invention discloses a Bitter - type FeSeTe superconducting magnet system, which includes two parts: an excitation cryogenic superconducting coil 6 and a FeSeTe high - temperature superconducting coil 7. Among them, the FeSeTe high - temperature superconducting coil 7 is the core part. The excitation cryogenic superconducting coil 6 is composed of NbTi and Nb3Sn superconducting coils. The FeSeTe high - temperature superconducting coil 7 has no internal joints, external joints and current leads, which reduces the heat leakage during the operation of the magnet and improves the stability of the magnetic field.

[0025] As Figure 1 , Figure 3 shown, the FeSeTe Bitter disk 9 has a porous structure. The FeSeTe Bitter disk 9 is prepared by growing a buffer layer and a FeSeTe superconducting layer on a Hastelloy disk with a porous structure. The porous structure can play a role in rapid heat dissipation and changing the current distribution.

[0026] As Figure 2 , Figure 3 shown, the FeSeTe high - temperature superconducting coil 7 includes a FeSeTe Bitter disk 9, an insulating sheet 8, a cover plate 1, a small - hole pull rod 2 and a heater 3. The FeSeTe Bitter disks 9 and the insulating sheets 8 are stacked alternately. The small - hole pull rod 2 and nuts pass through the middle small holes of the FeSeTe Bitter disks 9 and the insulating sheets 8 to align the small holes on both of them, thus forming an alternately stacked structure of FeSeTe Bitter disks and insulating sheets 5. Then the device is fixed by the cover plate 1 and the pull rod 4, and both the upper and lower cover plates 1 are in contact with the insulating sheet 8. Finally, the heater 3 is fixed on the cover plate 1.

[0027] The layered stacking structure between the FeSeTe Bitter disks 9 and the insulating sheets 8 can effectively reduce the effect of the circumferential force. And under the action of the axial compressive force, the performance damage of the tape is small, and the Bitter disks will compress each other, improving the stability of the structure. The insulating sheet 8 is made of AlN and plays an insulating role between the FeSeTe Bitter disks 9. And AlN has good thermal conductivity and a small thermal expansion coefficient, and is a good heat - resistant shock material, which can better conduct the heat generated during the operation of the FeSeTe Bitter disks 9 in the middle of the magnet. The heater 3 is wound with manganin wire, and one is arranged on each of the upper and lower cover plates 1. By heating the manganin wire, the ambient temperature of the inserted magnet is increased, so as to control the operation of the inserted magnet. Since the heater 3 is immersed in liquid helium, the temperature rise generated by it is limited. Therefore, the high - temperature superconducting tape with a higher critical temperature cannot be quenched due to this temperature rise, while the critical temperature of FeSeTe is lower, and the operation of the system can be better controlled through the heater 3.

[0028] As Figure 3As shown, the high-temperature superconducting coil 7 of FeSeTe is placed at the center of the excitation low-temperature superconducting coil 6, and the whole system is placed in liquid helium to keep the magnet in a low-temperature and safe operating environment. First, an electric current is passed through the excitation low-temperature superconducting coil 6, which will generate an induced current in the high-temperature superconducting coil 7 of FeSeTe. Then, the heater 3 is powered on to make the high-temperature superconducting coil 7 of FeSeTe quench, and then the heater 3 is turned off. Finally, the current in the excitation low-temperature superconducting coil 6 is reduced to zero, and a current will be induced in the high-temperature superconducting coil 7 of FeSeTe, thereby obtaining a stable magnetic field. In addition, a high magnetic field can also be obtained by superimposing the magnetic fields generated by the excitation low-temperature superconducting coil 6 and the high-temperature superconducting coil 7 of FeSeTe.

[0029] Although the above description of the illustrative specific embodiments of the present invention is provided for the understanding of those skilled in the art of the present technology, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

Claims

1. A Bitter-type FeSeTe superconducting magnet system, characterized in that: It consists of two parts: the excitation low-temperature superconducting coil and the FeSeTe high-temperature superconducting coil. The excitation low-temperature superconducting coil is composed of NbTi and Nb3Sn superconducting coils; The FeSeTe high-temperature superconducting coil includes a FeSeTe Bitter disc, an insulating sheet, a cover plate, a small hole tie rod, and a heater. The FeSeTe Bitter discs and the insulating sheet are stacked alternately, and a small hole tie rod and a nut are passed through the middle small holes of the FeSeTe Bitter disc and the insulating sheet to align the small holes on the two. The cover plate and the tie rod are then used to fix them, and both the upper and lower cover plates are in contact with the insulating sheet. Finally, the heater is fixed on the cover plate. The FeSeTe high temperature superconducting coil is placed at the center of the excitation low temperature superconducting coil; The superconducting material of the inserted coil in the magnet system has a layered stacked structure, which effectively reduces the effect of the hoop force. Under the action of axial compression force, the performance of the strip is less damaged. The FeSeTe Bitter discs are compressed against each other, which improves the stability of the structure.

2. The Bitter-type FeSeTe superconducting magnet system according to claim 1, characterized in that: The FeSeTe Bitter wafer is prepared by growing a buffer layer and a FeSeTe superconducting layer on a Hastelloy wafer.

3. The Bitter-type FeSeTe superconducting magnet system according to claim 1, characterized in that: The FeSeTe Bitter disc has a number of small holes on it, which play the role of rapid heat dissipation and changing the current distribution.

4. The Bitter-type FeSeTe superconducting magnet system according to claim 1, characterized in that: The insulating sheet is made of AlN and serves as insulation between the FeSeTe Bitter discs.

5. The Bitter-type FeSeTe superconducting magnet system according to claim 1, characterized in that: The FeSeTe high-temperature superconducting coil has no internal joints, external joints or current leads, thereby reducing heat leakage of the magnet during operation and improving the stability of the magnetic field.

6. The Bitter-type FeSeTe superconducting magnet system according to claim 1, characterized in that: The heater is made of wound manganese copper wire and is arranged one on each of the upper and lower cover plates; by heating the manganese copper wire, the ambient temperature of the inserted magnet is increased, thereby controlling the operation of the inserted magnet.

Images