CN113470921A - Double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet - Google Patents
Double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet Download PDFInfo
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- CN113470921A CN113470921A CN202110792795.4A CN202110792795A CN113470921A CN 113470921 A CN113470921 A CN 113470921A CN 202110792795 A CN202110792795 A CN 202110792795A CN 113470921 A CN113470921 A CN 113470921A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/006—Supplying energising or de-energising current; Flux pumps
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/04—Cooling
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Abstract
The invention discloses a double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet. The high-temperature superconducting magnet is manufactured by alternately stacking REBCO high-temperature superconducting sheets and insulating sheets after being manufactured into circular ring sheets with semicircular bulges and fixing the circular ring sheets by adopting a fixing device, wherein the magnet is excited by a magnetic flux pump consisting of a thermal switch and an excitation coil. The ring plate is provided with a big round hole and a small round hole, and the middle parts of the two round holes and the protruding part of the ring plate are called as a bridge. The thermal switch is formed by winding a heating coil on the bridge, and when the heating coil is electrified to heat, the thermal switch is disconnected, and after the heating is stopped, the thermal switch is closed. The excitation is carried out by controlling the current time sequence in the exciting coil and the heating coil, and a bridge at the periphery of the large circular hole and between the two circular holes forms an excited closed loop. The excitation method can gradually generate a stable magnetic field in space, and can realize the closed-loop operation of the high-temperature superconducting magnet without a current lead.
Description
Technical Field
The invention belongs to the field of high-temperature superconducting magnet application, and particularly provides a double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet.
Background
The ReBCO high-temperature superconducting material has high critical temperature, high critical magnetic field and high critical current density, still has higher current carrying capacity in a strong magnetic field environment, and has a prospect in the aspect of application of high-temperature superconducting magnets.
The superconducting magnet has great advantages compared with the conventional magnet, mainly including almost no joule heat consumption in operation and capability of generating a strong magnetic field beyond the reach of the conventional magnet. The superconducting magnet is mainly applied to various fields of particle accelerators, nuclear magnetic resonance, magnetic levitation trains and the like.
The excitation method for the superconducting magnet is mainly divided into two methods, one method is to directly pass current through a current lead to drive the superconducting magnet, and the other method is to carry out excitation through electromagnetic induction. However, compared with a Low Temperature Superconducting (LTS) magnet, due to the characteristics of the materials and the immaturity of the resistless welding technology, the high temperature superconducting magnet cannot realize closed-loop operation in cooperation with current leads and a power supply. Therefore, the most suitable excitation method for the high-temperature superconducting magnet at present is to perform excitation by using the electromagnetic induction principle, wherein the common excitation methods include: field cooling excitation, pulse field excitation and magnetic flux pump excitation.
Aiming at the problems, a preparation method and application of the REBCO circular ring piece high-temperature superconducting magnet excited by the double-thermal switch magnetic flux pump are provided. The REBCO circular ring piece high-temperature superconducting magnet has a stable structure, can output a stable high-intensity magnetic field, and does not need additional insulation treatment. The closed-loop operation of the high-temperature superconducting magnet without the current lead in the continuous current mode can be realized through a magnetic flux pump excitation mode matched with the thermal switch and the current source.
Disclosure of Invention
The invention aims to provide a double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet, which has the following specific technical scheme:
a double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet is characterized by comprising an REBCO annular sheet high-temperature superconducting magnet and a flux pump.
The REBCO annular sheet high-temperature superconducting magnet is formed by sequentially stacking REBCO circular annular sheets and insulating circular annular sheets, and the structure of the REBCO annular sheet high-temperature superconducting magnet is fixed by adding flange sheets above and below and matching with bolts and nuts.
The REBCO circular ring piece and the insulating circular ring piece are both circular ring pieces with semicircular bulges.
The outer contour of the circular ring piece with the semicircular bulges is the outer contour formed by intersecting two circles with different sizes, a large round hole and a small round hole are cut at the respective central positions of the large circle and the small circle, and the two round holes are not communicated.
Wherein, the shape and the size of the insulating circular ring sheet are the same as those of the REBCO circular ring sheet.
The REBCO circular ring sheet comprises a substrate, a buffer layer, a REBCO layer and a metal protection layer from bottom to top.
The substrate is usually made of hastelloy or stainless steel, the buffer layer is usually an insulating metal oxide, and the metal protective layer is usually made of silver and copper.
Wherein, the insulating sheet can be kraft paper, polypropylene laminated paper or epoxy sheet.
The flange plate is made of epoxy resin and epoxy glass reinforced plastic, and the bolt and the nut are made of nonmagnetic stainless steel.
Wherein, the magnetic flux pump is composed of a thermal switch and an excitation coil.
The thermal switch is composed of a bridge tightly wound with a heating coil, the heating coil can be formed by winding enamelled manganese copper wires, copper wires or aluminum wires, and the excitation coil can be formed by winding enamelled copper wires or aluminum wires.
Among them, a portion between a large circular hole at the center of the circular ring and a small circular hole on the protrusion is referred to as "bridge 1", and the protrusion portion is referred to as "bridge 2", and a heating coil 1 and a heating coil 2 are closely wound on the bridge 1 and the bridge 2, respectively, to constitute a thermal switch 1 and a thermal switch 2.
Wherein, the two ends of the heating coil of the thermal switch are respectively welded with current leads and connected to a power supply.
The bridge is heated to quench by electrifying the heating coil of the thermal switch so that the thermal switch is in an off state, and after heating is stopped, the bridge is recovered to a superconducting state in a low-temperature environment so that the thermal switch is in an on state.
And when the superconducting magnet runs, the superconducting magnet is cooled to a superconducting state in a liquid nitrogen soaking mode, and excitation is carried out by controlling current time sequences in the magnet exciting coil and the heating coil.
The specific process of controlling the current time sequence in the exciting coil and the heating coil to carry out excitation in a single period comprises the following steps:
(1) the magnet exciting coil is placed in the small round hole, the thermal switch 2 is switched off, and current is supplied to the magnet exciting coil.
(2) The thermal switch 2 is closed, the switch 1 is opened, and the current supply to the exciting coil is stopped.
(3) The thermal switch 1 is closed and the thermal switch 2 is opened.
(4) Closing the thermal switch 2 prepares to enter the next cycle.
Wherein, through excitation of a plurality of periods, the current can be accumulated to a desired value in a closed loop formed by the periphery of the large hole and the bridge 1, and a magnetic field with a desired size is generated in the space.
The invention has the beneficial effects that: according to the REBCO annular sheet high-temperature superconducting magnet, each REBCO annular sheet and each insulating annular sheet in the REBCO annular sheet high-temperature superconducting magnet are fixed in a non-welding mode, the structure is compact, the preparation process is simple, and the disassembly difficulty is small; the obtained high-temperature superconducting magnet is excited by a magnetic flux pump, and closed-loop operation in a continuous current mode can be realized without welding a current lead; in addition, the obtained high-temperature superconducting magnet can generate a magnetic field in a large space range, runs stably and has wide application prospect in the field of high-intensity magnetic fields.
Drawings
Fig. 1 is a schematic structural diagram of a REBCO circular ring plate with a dual thermal switch.
Fig. 2 is a schematic view of the structure of the insulating circular ring piece.
Fig. 3 is a schematic structural diagram of a high-temperature superconducting magnet formed by stacking REBCO circular ring sheets and insulating circular ring sheets.
Fig. 4 is a timing chart of the current in the heating coil 1 per cycle during excitation.
Fig. 5 is a timing chart of the current in the heating coil 2 every cycle during the excitation.
Fig. 6 is a timing diagram of the current in the field coil during each cycle of the excitation process.
Detailed Description
The invention provides a preparation method and application of a double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet. The present invention will be described in further detail below with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of REBCO circular ring plate. The REBCO circular ring sheet adopts the same substrate material as the second generation high temperature superconducting coating conductor to manufacture a circular substrate with a semicircular bulge; and cutting off two circular holes with one larger and one smaller according to the size of the original sheet-shaped substrate with the semicircular bulges to form a circular ring sheet with the semicircular bulges. Wherein the outer contour of the circular ring piece has a radius of R1Large circle and radius r1The distance between the circle centers of the outer contour of the intersected small circle and the circle center of the outer contour of the intersected small circle is l, and then the radius of the circle center of the outer contour of the intersected small circle and the circle center of the large circle is cut into R2The radius of the center of the big circular hole and the small circular hole is r2The substrate 1-1 is made into a circular ring sheet shape with a semicircular bulge. Then, a buffer layer 1-2 used by the current second generation high temperature superconducting coated conductor is adopted to deposit on the substrate 1-1. Then, a REBCO film 1-3 is plated on the buffer layer 1-2 by using the film coating technology used by the current second generation high temperature superconducting coated conductor. Finally, plating silver and copper films on the REBCO films 1-3 to serve as protective layers 1-4, and finally forming the REBCO circular ring sheet with the semicircular bulges. Winding heating coils on the bridges 1 and 2 of the REBCO circular ring sheet form the thermal switch 1 and the thermal switch 2, respectively.
Fig. 2 is a schematic structural diagram of an insulating circular ring piece. The shape of the insulating circular ring piece is the same as that of the REBCO circular ring piece, and the semicircular convex circular ring piece is formed by cutting a large circular hole and a small circular hole on a circular piece containing the semicircular convex. The shape and size of the insulating circular ring piece are the same as those of the REBCO circular ring piece.
The preparation method of the high-temperature superconducting magnet formed by stacking the REBCO circular ring sheets and the insulating circular ring sheets shown in the figure 3 comprises the following specific steps:
(1) a1 st insulating circular ring piece I is horizontally placed, a 1 st REBCO circular ring piece II is placed above the insulating circular ring piece I, a protective layer of the REBCO circular ring piece faces upwards, and the circle centers of the two holes are vertically aligned with the insulating circular wafer respectively.
(2) From the bottom up, pile up 2 insulating circular ring piece I, 2 circular ring piece II of REBCO, … …, the insulating circular ring piece I of Nth, the circular ring piece II of Nth REBCO, the insulating circular ring piece I of N +1 th in proper order. Wherein the protective layers of the N REBCO circular ring pieces II face upwards.
(3) After stacking is finished, the bridges 1 and 2 of all the annular sheets are respectively wound together by heating coils 3-1 and 3-2, then flange sheets 3-3 are added from top to bottom for fixing, 4 bolts 3-4 penetrate through positioning holes of the flange sheets and then are matched with nuts 3-5 for pressing and fixing REBCO circular ring sheets and insulating circular ring sheets to form the high-temperature superconducting magnet.
Fig. 4 shows a timing diagram of the currents in the field coil and the heating coil for each period of the excitation process, the excitation process being:
(1) connecting the magnet exciting coil 3-6 with the power supply 3-7, placing the magnet exciting coil in the small round hole, and starting to supply current to the magnet exciting coil 3-2 through the power supply 3-9 at 0 moment to disconnect the thermal switch 2, t1At that time, the current starts to flow into the exciting coil 3-6.
(2)t3The current supply to the heating coil 3-2 is stopped at any time, the current supply to the heating coil 3-1 is started through the power supply 3-8, the thermal switch 2 is closed after cooling, and the thermal switch 1 is disconnected. t is t5The current to the exciting coil 3-6 is stopped at all times.
(3)t6Stopping the current supply to the heating coil 3-1 at any time, cooling the thermal switch 1 and then closing t7At that time, the heating coil 3-2 is energized to turn off the thermal switch 2.
(4)t8And stopping supplying current to the heating coil 3-2 at any time, cooling the thermal switch 2, closing the thermal switch, and preparing to enter the next period.
By means of a plurality of periods of excitation, a current can be built up to a desired value in the closed circuit formed by the periphery of the large opening and the bridge 1, generating a magnetic field of a desired magnitude in space.
The above description is only an example of one embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions, such as changing the shape of the superconducting sheet or changing the waveform of the excitation current, which can be easily conceived by those skilled in the art within the technical scope of the present invention, should be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (6)
1. A double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet is characterized in that the device is composed of an REBCO circular annular sheet high-temperature superconducting magnet and a flux pump.
2. The REBCO ring piece high-temperature superconducting magnet as claimed in claim 1, wherein the main body is formed by alternately stacking REBCO superconducting pieces and insulating pieces which are made into a circular ring piece shape with semicircular protrusions, the top end and the bottom end are both insulating circular ring pieces, a flange piece with 4 positioning holes is respectively added on the upper and the lower of the main body, 4 non-magnetic insulating bolts pass through the positioning holes, and the magnet structure is fixed by matching nuts.
3. The flux pump according to claim 1, wherein the flux pump is comprised of two parts, a field coil and a thermal switch, the field coil being formed by winding an enameled copper wire or an enameled aluminum wire; the heating coil is tightly wound on the bridge to form a thermal switch, and the heating coil can be formed by winding enamelled manganese copper wires, copper wires or aluminum wires and the like.
4. The heat switch in the flux pump of claim 3, wherein two ends of the heating coil of the heat switch are connected to a power supply, when the heating coil is heated by current, the local temperature of the bridge on the high-temperature superconducting sheet exceeds the critical temperature, so that local quench is caused, and the heat switch is turned off.
5. The use of the REBCO ring piece high temperature superconducting magnet according to claim 1, wherein the magnet is operated in a liquid nitrogen immersion environment, and the excitation process is performed by controlling the timing of the current in the exciting coil and the heating coil; the bridge 1 and the bridge 2 are switched continuously to form a closed loop with the periphery of the large hole of the circular ring piece in sequence, so that magnetic flux induced by the excitation coil in each period is transferred to the closed loop formed by the bridge 1 and the periphery of the large hole and gradually accumulated until current in the loop is saturated.
6. Excitation process according to claim 5, characterized in that the specific operation process of a single cycle is: firstly, the magnet exciting coil is arranged in the small round hole, the thermal switch 2 is switched off, and current is supplied to the magnet exciting coil; then the thermal switch 2 is closed and the thermal switch 1 is opened, and the current is stopped flowing into the excitation coil; then the thermal switch 1 is closed, and the thermal switch 2 is opened; finally the thermal switch 2 is closed ready to enter the next cycle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110792795.4A CN113470921A (en) | 2021-07-14 | 2021-07-14 | Double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110792795.4A CN113470921A (en) | 2021-07-14 | 2021-07-14 | Double-thermal switch flux pump excited REBCO annular sheet high-temperature superconducting magnet |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1126966A (en) * | 1965-12-10 | 1968-09-11 | Gen Electric Co Ltd | Improvements in or relating to superconducting magnets |
| CN106872919A (en) * | 2015-12-14 | 2017-06-20 | 上海联影医疗科技有限公司 | The exciting method of superconducting magnet component and superconducting magnet, drop magnetism method |
| CN109273189A (en) * | 2018-09-29 | 2019-01-25 | 华北电力大学 | A kind of superconducting magnet based on high-temperature superconductor circle ring plate |
| CN110211763A (en) * | 2019-06-14 | 2019-09-06 | 华北电力大学 | A kind of superconducting magnet based on round ring plate |
-
2021
- 2021-07-14 CN CN202110792795.4A patent/CN113470921A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1126966A (en) * | 1965-12-10 | 1968-09-11 | Gen Electric Co Ltd | Improvements in or relating to superconducting magnets |
| CN106872919A (en) * | 2015-12-14 | 2017-06-20 | 上海联影医疗科技有限公司 | The exciting method of superconducting magnet component and superconducting magnet, drop magnetism method |
| CN109273189A (en) * | 2018-09-29 | 2019-01-25 | 华北电力大学 | A kind of superconducting magnet based on high-temperature superconductor circle ring plate |
| CN110211763A (en) * | 2019-06-14 | 2019-09-06 | 华北电力大学 | A kind of superconducting magnet based on round ring plate |
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