WO2024078439A1

WO2024078439A1 - Structure and method for excitation across dewar wall, and magnetically conductive middleware

Info

Publication number: WO2024078439A1
Application number: PCT/CN2023/123503
Authority: WO
Inventors: 王为; 龙润; 吴成怀; 熊晨凌; 李洪
Original assignee: 四川大学
Priority date: 2022-10-11
Filing date: 2023-10-09
Publication date: 2024-04-18
Also published as: CN115662722A; CN115662722B

Abstract

The present invention relates to the technical field of superconducting excitation, and in particular to a structure and method for excitation across a Dewar wall, and a magnetically conductive middleware. The structure for excitation across a Dewar wall comprises a flux pump, a superconducting stator, a magnetic yoke and a superconducting load. The flux pump is arranged outside a Dewar. The superconducting stator the superconducting load are connected to each other so as to form a closed loop, and are arranged in the Dewar along with the magnetic yoke. The magnetic yoke and the flux pump are closely adjacent to the same Dewar wall area, and the superconducting stator is located in an air gap between the magnetic yoke and the flux pump. The magnetically conductive middleware comprises a carrier and a magnetically conductive element embedded in the carrier, the carrier being made of a non-ferromagnetic material. The method for excitation across a Dewar wall comprises: generating an alternating traveling wave magnetic field by means of a flux pump arranged outside a Dewar; the alternating traveling wave magnetic field being transmitted into the Dewar; and exciting a superconducting stator by means of the alternating traveling wave magnetic field. In the present invention, the flux pump is arranged outside the cryogenic vacuum Dewar, such that the flux pump has more heat dissipation mode options, and the size limit of the flux pump can also be ameliorated.

Description

Dewar wall excitation structure, method and magnetic conductive middleware

Technical Field

The present invention relates to the technical field of superconducting excitation, and in particular to a Dewar wall excitation structure, method and magnetic conductive intermediate piece.

Background technique

High-temperature superconducting technology is becoming more and more mature and is gradually being put into more and more practical application fields. At present, in practical application fields, it is usually necessary to place high-temperature superconducting magnets in low-temperature vacuum dewars. When we use flux pumps to excite high-temperature superconducting magnets, due to the limited cooling power of the refrigerator, the heat generated by the flux pump in the low-temperature dewar is difficult to be effectively removed, making it difficult to control the temperature of the flux pump, which seriously affects its operating efficiency and creates a serious burden on the cryogenic system, thereby seriously limiting the practical application of flux pump technology and high-temperature superconducting technology. This application aims to propose a technical solution to solve the above-mentioned defects.

Summary of the invention

The purpose of the present invention is to provide a dewar wall excitation structure, method and magnetic conductive intermediate piece, which can solve the technical problem in the practical application field of high-temperature superconducting technology that due to the limited refrigeration power of the low-temperature dewar, it is difficult to effectively remove the heat generated by the flux pump out of the dewar, which makes the temperature of the flux pump difficult to control and has a serious impact on the low-temperature system.

The embodiments of the present invention are implemented by the following technical solutions:

In a first aspect, a dewar wall excitation structure is provided, comprising a flux pump, a superconducting stator, a yoke and a superconducting load, wherein the flux pump is arranged outside the dewar, the superconducting stator and the superconducting load are connected to form a closed loop and are both arranged inside the dewar, and the yoke is also arranged inside the dewar; the yoke and the flux pump are adjacent to the same dewar wall area, and the superconducting stator is located in the air gap between the yoke and the flux pump.

In a second aspect, a magnetic conductive intermediate piece is provided, comprising a carrier and a magnetic conductive element embedded in the carrier, wherein the carrier is made of non-ferromagnetic material.

Furthermore, the carrier is provided with a plurality of through channels, and the magnetic conductive elements are embedded in each of the through channels.

Furthermore, the through channel includes at least one of an axial cross-sectional dimension and/or a cross-sectional shape.

Furthermore, the through channels with the same cross-sectional size or shape are arranged at equal intervals.

Furthermore, the length of the magnetic conductive element is greater than or equal to the axial length of the through channel.

Furthermore, the carrier is a Dewar wall.

Furthermore, the carrier is a flange plate, and the flange plate is used to connect to a flange interface on the Dewar wall.

On the third aspect, a method for excitation through a dewar wall is provided, wherein a flux pump disposed outside the dewar generates an alternating traveling wave magnetic field, the alternating traveling wave magnetic field is transmitted through the dewar wall to the inside of the dewar, and then the superconducting stator is excited by the alternating traveling wave magnetic field.

Furthermore, a magnetic conductive intermediate piece is provided on the wall of the dewar, and the alternating traveling wave magnetic field is transmitted to the interior of the dewar through the magnetic conductive intermediate piece.

The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

The present invention places the magnetic flux pump outside the cryogenic vacuum dewar, so that the magnetic flux pump does not need to be installed in the cryogenic dewar with poor heat dissipation conditions; outside the dewar, the magnetic flux pump has more heat dissipation options, and the size limit of the magnetic flux pump can also be improved, that is, a larger magnetic flux pump can be used to achieve higher performance, and it can achieve heat dissipation through a larger heat dissipation area and a more effective heat dissipation method;

At the same time, a magnetic conductive intermediate piece is added to the wall of the dewar, so that the alternating traveling wave magnetic field generated by the flux pump outside the dewar can be efficiently transmitted to the inside of the dewar, thereby ensuring the excitation effect of the flux pump on the superconducting stator inside the dewar;

In addition, the magnetic conductive intermediate piece can be arranged on the flange and connected to the dewar wall through the flange, which can make installation and replacement more convenient and flexible. As a result, when the dewar wall is excited using the solution of the present invention, more magnetic flux pump component solutions and structures can be selected, thereby improving the practical value of the dewar wall excitation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a dewar wall excitation structure without a magnetic conductive intermediate member provided by the present invention;

FIG2 is a cross-sectional view of a magnetic conductive intermediate member provided by the present invention;

FIG3 is a schematic structural diagram A of a magnetic conductive intermediate member provided by the present invention;

FIG4 is a schematic structural diagram B of a magnetic conductive intermediate member provided by the present invention;

FIG5 is a schematic structural diagram C of a magnetic conductive intermediate member provided by the present invention;

FIG6 is a schematic structural diagram D of a magnetic conductive intermediate member provided by the present invention;

FIG7 is a schematic structural diagram E of a magnetic conductive intermediate member provided by the present invention;

FIG8 is a schematic diagram of the structure of a carrier provided by the present invention as a Dewar wall;

FIG9 is an enlarged view of point A in FIG8 ;

10 is a cross-sectional view of a Dewar wall excitation structure in which a carrier provided by the present invention is a Dewar wall;

FIG11 is a cross-sectional view of another Dewar wall excitation structure in which the carrier is a Dewar wall provided by the present invention;

12 is a cross-sectional view of the structure of a magnetic conductive intermediate member provided by the present invention, wherein the carrier is a flange;

13 is a cross-sectional view of a dewar wall excitation structure in which a carrier is a flange provided by the present invention;

FIG14 is a cross-sectional view of another dewar wall excitation structure in which the carrier is a flange provided by the present invention;

FIG15 is a schematic diagram of a flange with a magnetic conductive element and a corresponding dewar structure provided by the present invention;

FIG16 is an embodiment of the Dewar wall excitation method provided by the present invention;

FIG. 17 is another embodiment of the Dewar wall excitation method provided by the present invention.

In the figure, 1-flux pump, 2-superconducting stator, 3-superconducting load, 4-Dewar, 5-magnetic element, 6-flange, 7-flange interface, 8-sealant, 9-carrier, 10-threaded hole, 11-yoke.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

When the flux pump is operated in a low-temperature dewar, it is difficult to control the temperature of the flux pump at an ideal working value for a long time due to the limitations of the refrigerator power and heat conduction efficiency. The temperature of the flux pump often rises after working for a period of time, which in turn affects the excitation effect of the flux pump. Therefore, how to solve the problem of heating and heat dissipation of the flux pump in actual use has become the focus of technical breakthroughs.

Example 1

In actual use, we need a dewar 4 to provide a low-temperature environment for the superconducting system. At present, the mainstream superconducting systems all place the flux pump 1 in the dewar 4. The present invention takes the linear motor type flux pump 1 as an example. The AC winding and the DC winding in the linear motor type flux pump 1 will quickly generate a large amount of heat when working; and because the dewar 4 needs to provide a vacuum-tight and low-temperature environment, the size of the dewar 4 is generally not too large, which will limit the selection of the size of the flux pump 1 and the use of higher-performance flux pumps 1; secondly, because the dewar 4 is in a vacuum-tight state during operation and lacks a heat transfer medium, the flux pump 1 can only use a solid heat conductive sheet to conduct heat to the cold head of the refrigerator, and its cooling power and heat conduction effect are very limited; it can be seen that the flux pump 1 is placed in the dewar 4 as a whole, and its heat-generating components are difficult to dissipate heat, thereby affecting its operating performance. Other flux pump 1 structures with electric coils also have the above problems, which limits their further industrial applications.

Therefore, the present invention proposes a dewar wall excitation structure, as shown in FIG1, including a flux pump 1, a superconducting stator 2, a yoke 11 and a superconducting load 3. In order to keep the temperature in the low-temperature dewar 4 stable, the present invention sets the flux pump 1 outside the dewar 4; it can be understood that the flux pump 1 set outside the dewar 4 can be supported by a workbench, a bracket, etc., and the flux pump 1 is close to the outer wall of the dewar 4. The superconducting stator 2 and the superconducting load 3 are connected to form a closed loop and are both set in the dewar 4. The yoke 11 is also set in the dewar 4, and the superconducting stator 2 is located between the yoke 11 and the magnetic load 3. The yoke 11 is in the air gap between the flux pump 1 and the dewar 4; it can be understood that the yoke 11 is also close to the inner wall of the dewar 4. The yoke 11 and the flux pump 1 are close to the inside and outside of the same dewar wall area, so that the alternating traveling wave magnetic field generated by the flux pump 1 is effectively transmitted to the area where the superconducting stator 2 is located inside the low-temperature dewar 4; the purpose of the yoke 11 and the flux pump 1 being close to the dewar wall is to reduce the air gap between the yoke 11 and the flux pump 1, so as to maintain a good excitation effect on the superconducting stator 2.

The mainstream magnetic flux pumps 1 except the rotating permanent magnet magnetic flux pump 1 all have electric coils that will generate heat load during operation; therefore, in the above scheme, we set the magnetic flux pump 1 that is easy to generate heat outside the dewar 4, which does not need to rely on the limited refrigeration capacity inside the dewar 4, and because it is set outside the dewar 4, it has a large space for heat dissipation and will not cause heat accumulation; at the same time, the magnetic flux pump 1 set outside the dewar 4 will have more diverse cooling methods. For example, air cooling can be used to achieve cooling by configuring a cooling fan for the magnetic flux pump 1; liquid cooling can also be used, such as configuring a cooling pipeline for the magnetic flux pump 1, and accurately achieving heat dissipation of the seriously heated parts of the magnetic flux pump 1 through the arrangement of the cooling pipeline.

When the rotating permanent magnetic flux pump 1 is placed in the low-temperature dewar 4, the lubricant in the bearing will solidify and cannot rotate due to the low temperature. Therefore, when it is used in conjunction with the dewar 4, a low-temperature resistant lubricant needs to be used, and the temperature in the dewar 4 should not be too low. In view of this, the rotating permanent magnetic flux pump 1 can also be arranged outside the dewar 4, so that a non-low-temperature resistant lubricant can be used, and the inside of the dewar 4 is kept at a low temperature that is compatible with the superconducting stator 2, thereby achieving a better excitation effect.

When we place the flux pump 1 outside the dewar 4 for excitation, the air gap between the flux pump 1 and the yoke 11 in the dewar 4 should be minimized as much as possible. As shown in FIG1 , the flux pump 1 and the yoke 11 are both close to the dewar wall, so as to achieve a better excitation effect on the superconducting stator 2. That is, the preferred way is to make the flux pump 1 and the yoke 11 close to the same dewar wall area as much as possible.

It should be noted that in order to better excite the superconducting stator 2, a number of magnetic conductive teeth corresponding to the iron teeth of the main body of the AC winding of the flux pump 1 are provided between the yoke 11 and the inner wall of the outer layer of the dewar 4, as shown in Figure 1; it can be understood that in order to achieve a better excitation effect, the end of the magnetic conductive teeth away from the inner wall of the outer layer of the dewar 4 is gathered.

It is also necessary to further explain that in all the schemes of the present application, one of the embodiments is shown in Figure 1, the dewar 4 has an outer layer and an inner layer, wherein the magnetic flux pump 1 and the yoke 11 are adjacent to the outer layer of the dewar 4; and the superconducting load 3 and the superconducting stator 2 are both in the space wrapped by the inner layer of the dewar 4, and the wall of the inner layer has a through hole for part of the yoke 11 and part of the magnetic conductive teeth to pass through the through hole to excite the superconducting stator 2.

Example 2

In Example 1, although the heat generation problem caused by the magnetic flux pump 1 being placed in the low-temperature Dewar 4 is solved, the excitation effect is ensured by making the magnetic flux pump 1 and the magnetic yoke 11 adjacent to the same Dewar wall area; however, when the magnetic flux pump 1 of the same size or performance parameters is used, the excitation effect is still different from that of the magnetic flux pump 1 and the magnetic yoke 11 without the Dewar wall. Although this difference can be accepted in some scenarios, the present application also hopes to propose a Dewar wall-separated excitation structure that can achieve the same excitation effect as that without the Dewar wall.

Therefore, based on the first embodiment, this embodiment adds a magnetic conductive intermediate piece in the Dewar wall between the magnetic flux pump 1 and the magnetic yoke 11. In the absence of the magnetic conductive intermediate piece, the magnetic flux pump 1 and the magnetic yoke 11 are separated by the Dewar wall, so the air gap between the magnetic flux pump 1 and the magnetic yoke 11 will be larger, and the Dewar wall has no function of transmitting the magnetic field, so it is conceivable that its excitation effect will be somewhat discounted.

As the name implies, the magnetic conductive middle piece is a workpiece that has the ability to transmit magnetic fields and is placed between the magnetic flux pump 1 and the magnetic yoke 11. In this embodiment, there is no specific restriction on the structural setting of the magnetic conductive middle piece; but it can be understood that the magnetic conductive middle piece has related components for transmitting magnetic fields. The magnetic conductive middle piece will replace the dewar wall as the interval between the magnetic flux pump 1 and the magnetic yoke 11. Although the air gap between the magnetic flux pump 1 and the magnetic yoke 11 is still large, due to the magnetic field transmission effect of the magnetic conductive middle piece, the alternating traveling wave magnetic field can be transmitted from the outside of the dewar 4 to the inside of the dewar 4 as if there is no gap, thereby realizing efficient excitation of the superconducting stator 2.

In order to achieve the best excitation effect, it is known that the magnetic flux pump 1 and the magnetic yoke 11 are placed as close as possible to or even in contact with the magnetic conductive intermediate component that transmits the magnetic field. Although the contact between the magnetic flux pump 1 and the magnetic conductive intermediate component may cause the heat generated by the magnetic flux pump 1 to be transferred to the dewar 4, since the magnetic flux pump 1 is placed outside the dewar 4, its cooling and heat dissipation method is more efficient and has a better selection surface. Therefore, targeted cooling and heat dissipation can be performed on the contact part between it and the magnetic conductive intermediate component, thereby avoiding heat transfer to the dewar 4 and affecting the working temperature of the superconducting stator 2.

By adding a magnetic conductive intermediate piece, the alternating traveling wave magnetic field generated by the magnetic flux pump 1 outside the dewar 4 can be efficiently transmitted to the inside of the dewar 4, ensuring that the excitation effect of the dewar wall is optimal, and thus the structure can be suitable for more practical application scenarios.

It should be noted that the magnetic conductive intermediate piece in this embodiment can be realized by improving a preset area in the Dewar wall, or it can be a dedicated other workpiece that matches the structure of Dewar 4, and the workpiece and Dewar 4 can be connected. Disassembly, such as flanges or covers, this kind of detachable workpiece will greatly increase the flexibility of the equipment and improve its practical value.

Example 3

In this embodiment, the magnetic conductive middle piece is shown in FIG. 2 , and mainly includes a carrier 9 and a magnetic conductive element 5 embedded in the carrier 9, wherein the magnetic conductive element 5 is used to transfer the magnetic field, so that the alternating traveling wave magnetic field can be transferred from the outside of the dewar 4 to the inside of the dewar 4 without a gap; in order to avoid other effects on the magnetic field, the carrier 9 needs to be made of non-ferromagnetic materials, such as G10 materials. In this embodiment, we do not limit the specific shape of the carrier 9, as long as it has a magnetic conductive element 5, and the magnetic conductive element 5 can transfer the magnetic field outside the dewar 4 to the inside of the dewar 4.

It is understandable that there are more than one magnetic conductive elements 5 embedded in the carrier 9, and accordingly, it is necessary to open through channels in the carrier 9 that are equal to the number of magnetic conductive elements 5, and then embed the magnetic conductive elements 5 in the through channels. It should be noted that the length of the magnetic conductive element 5 should be greater than or equal to the axial length of the through channel; because the carrier 9 is located on the wall of the dewar, it is necessary to ensure the airtightness of the through channel in which the magnetic conductive element 5 is embedded, and then ensure the airtightness of the vacuum dewar 4. It is understandable that the structure of the magnetic conductive element 5 should match the cross-sectional shape and size of the through channel in the axial direction, so as to ensure the stability of the embedding and facilitate the implementation of sealing measures.

The cross-sectional shape and size of the through-channel in the axial direction can be set according to different practical needs. In one embodiment, the cross-sectional shape can include at least one of square, rectangular and circular shapes. As shown in FIG3, an embodiment is provided in which the cross-sectional or end face shape of the magnetic conductive element 5 is rectangular, FIG4 is provided in which the cross-sectional or end face shape of the magnetic conductive element 5 is circular, FIG5 is provided in which the cross-sectional or end face shape of the magnetic conductive element 5 is square, FIG6 is provided in which the cross-sectional or end face shape of the magnetic conductive element 5 includes circular and rectangular, and FIG7 is provided in which the cross-sectional or end face shape of the magnetic conductive element 5 includes circular and square; it can be understood that the shape of the cross-sectional or end face is not limited to the embodiments shown in the above figures, and the shape of the cross-sectional or end face can also be other special shapes, and can be a combination of any two or more shapes.

When the cross section or end face of the magnetic conductive element 5 is circular, it is not necessarily a cylinder, but may also be a truncated cone structure; as shown in FIG2 , an embodiment is provided in which the magnetic conductive element 5 is a truncated cone structure, such as the cross section of the magnetic conductive intermediate piece shown in the figure, in which the cross section of the magnetic conductive element 5 is a trapezoid.

Generally, the length of the magnetic conductive element 5 is slightly larger than the axial length of the through channel, mainly for the convenience of Installation and sealing considerations. When it is necessary to implement sealing measures, such as applying sealant 8, then when the length of the magnetic conductive element 5 is slightly larger than the axial length of the through-channel, it is easier to apply sealant 8 to the edge of the magnetic conductive element 5 that contacts the carrier 9, as shown in FIG9 . It can be seen that applying sealant 8 is only one of the common sealing implementation methods. Similarly, a better sealing effect can be achieved by wrapping a sealing material in the magnetic conductive element 5, such as wrapping a raw tape, and then embedding the magnetic conductive element 5 into the through-channel.

In addition, when the length of the magnetic conductive element 5 is slightly larger than the axial length of the through-channel, it is more conducive to the contact requirements between the magnetic flux pump 1 and the magnetic conductive element 5, and in the case of contact, this setting is also more conducive to the heat dissipation of the contact surface, avoiding heat transfer to the inside of the Dewar 4.

Since there are more than one magnetic conductive elements 5 embedded on the carrier 9, when there are multiple magnetic conductive elements 5, the arrangement of the magnetic conductive elements will also affect the excitation effect. In practical applications, through-channels with the same cross-sectional size or shape are generally opened at equal intervals, so as to achieve equal-interval embedding of the magnetic conductive elements 5. The implementations shown in Figures 3 to 7 are all implementations in which the through-channels are opened at equal intervals. Of course, in some application scenarios, it is also allowed to open the through-channels at non-equal intervals; therefore, whether to open them at equal intervals can be selected according to actual conditions. In this embodiment, opening the through-channels at equal intervals is a recommended method.

It should be noted that the carrier 9 of the magnetic conductive intermediate piece can be a Dewar wall, as shown in FIG8 , that is, a through channel is opened in a certain preset area of the Dewar wall, and the magnetic conductive element 5 is embedded in the through channel arranged on the Dewar wall, thereby realizing the transmission of the alternating traveling wave magnetic field inside and outside the Dewar 4. As shown in FIG10 , an implementation method is provided in which the magnetic flux pump 1 contacts the magnetic conductive element 5 when the carrier 9 is a Dewar wall; FIG11 provides an implementation method in which the magnetic flux pump 1 is adjacent to the magnetic conductive element 5 when the carrier 9 is a Dewar wall.

In another specific embodiment, the carrier 9 of the magnetic conductive intermediate piece can also be a flange 6, as shown in FIG12, that is, a corresponding through channel is opened on the flange 6, and the magnetic conductive element 5 is embedded in the through channel on the flange 6, thereby realizing the transmission of the alternating traveling wave magnetic field inside and outside the dewar 4. It can be understood that this method requires a matching flange interface 7 on the dewar wall. As shown in FIG13, an embodiment is provided in which the magnetic flux pump 1 contacts the magnetic conductive element 5 when the carrier 9 is a flange 6; FIG14 provides an embodiment in which the magnetic flux pump 1 is adjacent to the magnetic conductive element 5 when the carrier 9 is a flange 6.

When the carrier 9 is a flange 6, when the Dewar wall is excited, the arrangement of the magnetic element 5 and the magnetic element The size selection of 5 will be more flexible, that is, excitation can be achieved by replacing different carriers 9 with the magnetic conductive middleware of the flange 6; this feature can mainly meet different excitation requirements and when using different magnetic flux pumps 1 for excitation, a more matching magnetic conductive middleware can be selected; compared with the method in which the carrier 9 is a Dewar wall, its flexibility and practical value are higher, and only one set of equipment is needed to match a variety of scenarios or a variety of equipment; in actual use, a flexible solution means that the cost expenditure in the corresponding scenario can be reduced.

As shown in Figure 15, when the carrier 9 is a flange 6, the outer wall of the dewar 4 is equipped with a flange interface 7, and correspondingly, a threaded hole 10 is provided on the flange interface 7; correspondingly, a threaded hole 10 is also provided on the flange 6; it should be understood that since the dewar 4 requires a sealed environment, a sealing gasket can be installed between the flange interface 7 and the flange 6 to increase its sealing performance.

Example 4

This embodiment provides a method for excitation through a dewar wall, as shown in FIG16 , comprising the following steps:

An alternating traveling wave magnetic field is generated by a magnetic flux pump disposed outside the dewar;

The alternating traveling wave magnetic field is transmitted to the interior of the Dewar through the Dewar wall, so that the superconducting stator is in the alternating traveling wave magnetic field generated by the flux pump;

Finally, the superconducting stator is excited by an alternating traveling wave magnetic field, so that current is generated in the superconducting stator and pumped to the superconducting load.

For the method in this embodiment, the order of transmitting the alternating traveling wave magnetic field is the same as the traditional method. Its main feature is that in this excitation method, the alternating traveling wave magnetic field is generated by a flux pump outside the Dewar, and transmitted to the inside of the Dewar through the Dewar wall, thereby making the superconducting stator in the Dewar be in the alternating traveling wave magnetic field and generating current.

The method described in this embodiment is generated from the needs of practical application. In actual use, we need a dewar to provide a low-temperature environment for the superconducting system. At present, the mainstream superconducting systems all place the flux pump in the dewar. Taking the linear motor type flux pump as an example, the AC winding and DC winding in the linear motor type flux pump will quickly generate a lot of heat when working; and because the dewar needs to provide a vacuum-tight and low-temperature environment, the size of the dewar is generally not too large, which will limit the selection of the size of the flux pump and limit the use of higher performance flux pumps; secondly, because the dewar is at work, The dewar is in a vacuum-sealed state and lacks heat transfer medium. Therefore, the magnetic flux pump can only use solid heat conductive sheets to transfer heat to the cold head of the refrigerator. Its cooling power and thermal conductivity are very limited. It can be seen that when the magnetic flux pump is placed in the dewar as a whole, its heat-generating components are difficult to dissipate heat, thus affecting its operating performance.

Therefore, through the method in this embodiment, in a superconducting scenario where a dewar is required, the flux pump is placed outside the cryogenic vacuum dewar, so that the flux pump does not need to be installed in a cryogenic dewar with poor heat dissipation conditions; outside the dewar, the flux pump has more heat dissipation options, and the size limit of the flux pump can also be improved, that is, a larger size flux pump can be used to achieve higher performance, and it can achieve efficient heat dissipation through a larger heat dissipation area and a more effective heat dissipation method, so that it can continue to be excited for a long time and produce a better excitation effect.

Example 5

Since the air gap between the flux pump and the magnetic yoke is larger when separated by a dewar wall, when using a flux pump of the same size or performance parameters, the excitation effect brought about by the flux pump and the magnetic yoke when separated by the dewar wall is still different from that brought about by the flux pump and the magnetic yoke when not separated by the dewar wall. Therefore, this embodiment will also provide an implementation method to overcome the difference in excitation performance caused by the dewar wall.

As shown in FIG. 17 , the method steps of this embodiment are as follows:

The alternating traveling wave magnetic field is transmitted to the interior of the dewar through the magnetic conductive intermediate piece on the dewar wall, so that the superconducting stator is in the alternating traveling wave magnetic field generated by the flux pump;

The magnetic conductive intermediate piece is a workpiece that has the ability to transmit magnetic fields and is placed between the magnetic flux pump and the magnetic yoke. The magnetic conductive intermediate piece can make the alternating traveling wave magnetic field more effectively transmitted to the dewar, thereby achieving the same excitation effect as the magnetic flux pump and the magnetic yoke without the dewar wall. It should be noted that the magnetic conductive intermediate piece in this embodiment is the magnetic conductive intermediate piece in Embodiment 2 or 3.

In the method of this embodiment, the alternating traveling wave magnetic field is transmitted to the Dewar through the magnetic conductive intermediate piece, thereby ensuring The effect of the flux pump on the excitation of the superconducting stator inside the Dewar.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

The dewar wall excitation structure is characterized in that it comprises a flux pump (1), a superconducting stator (2), a yoke (11) and a superconducting load (3), wherein the flux pump (1) is arranged outside the dewar (4), the superconducting stator (2) and the superconducting load (3) are connected to form a closed loop and are both arranged inside the dewar (4), and the yoke (11) is also arranged inside the dewar (4); the yoke (11) and the flux pump (1) are adjacent to the same dewar wall area, and the superconducting stator (2) is located in the air gap between the yoke (11) and the flux pump (1).
A magnetic conductive intermediate piece, applied to the dewar wall excitation structure in claim 1, characterized in that it comprises a carrier (9) and a magnetic conductive element (5) embedded in the carrier (9), wherein the carrier (9) is made of non-ferromagnetic material.
The magnetic conductive intermediate piece according to claim 2 is characterized in that a plurality of through channels are provided on the carrier (9), and the magnetic conductive elements (5) are embedded in each of the through channels.
The magnetic conductive intermediate piece as described in claim 3 is characterized in that the through channel includes at least one axial cross-sectional size and/or cross-sectional shape.
The magnetic conductive intermediate piece as described in claim 4 is characterized in that the through channels with the same cross-sectional size or shape are arranged at equal intervals.
The magnetic conductive intermediate piece according to any one of claims 3 to 5 is characterized in that the length of the magnetic conductive element (5) is greater than or equal to the axial length of the through-channel.
The magnetic conductive intermediate piece according to any one of claims 3 to 5, characterized in that the carrier (9) is a Dewar wall.
The magnetic conductive intermediate piece according to any one of claims 3 to 5 is characterized in that the carrier (9) is a flange (6), and the flange (6) is used to connect to the flange interface (7) on the Dewar wall.
The method of excitation through the dewar wall is characterized in that an alternating traveling wave magnetic field is generated by a magnetic flux pump arranged outside the dewar;

The alternating traveling wave magnetic field is transmitted to the interior of the Dewar through the Dewar wall;

The superconducting stator is then excited by the alternating traveling wave magnetic field.
According to the dewar wall excitation method of claim 9, a magnetic conductive intermediate piece is also provided on the dewar wall, and the alternating traveling wave magnetic field is transmitted to the inside of the dewar through the magnetic conductive intermediate piece.