JP7290006B2 - High frequency superconducting laminate - Google Patents

Description

The present invention relates to superconductors, and in particular to high frequency superconductor laminates comprising a spiral superconductor coil sandwiched between dielectric supports.

Resonators used in high-frequency bands (several KHz to several 100 MHz) include detection coils (resonators) for receiving resonance signals from MRI and NMR equipment using nuclear magnetic resonance, and nuclear quadrupolar resonance (NQR). detection coils (resonators) for explosives and illicit drug detection devices, and power transmission/reception coils (resonators) used in wireless power transmission (WPT), which has been attracting attention in recent years.

The most basic way to improve the performance (eg sensitivity and transmission efficiency) of these devices is to use high Q (low conductor loss) coils.

However, these coils are usually made of copper wire, and the conductor loss cannot be reduced any further. Therefore, a high Q value cannot be achieved, and performance improvements in MRI, NMR, NQR, and WPT are reaching their limits.

One of the methods that can solve this problem is the use of "superconductors".

Superconductors are lossless in the case of direct current, and are expected to have a conductor loss that is three orders of magnitude lower than that of copper in the high frequency band. Therefore, by using a superconductor as a coil, a dramatically high Q value can be realized, and performance improvement of various devices can be expected.

However, the rare-earth superconducting wire developed for direct current applications currently in practical use has no loss in direct current, but the conductor loss does not become so small in the high frequency band. A high Q value could not be achieved. Moreover, the superconducting thin film substrate has a planar structure, and it is difficult to increase the area.

Therefore, the application of superconducting materials in the high frequency band has not yet been explored. Non-Patent Document 1 proposes a new structure of a superconducting wire (superconducting wire for high frequencies) to solve the above problem.

N. Sekiya, Y. Monjugawa, "A novel REBCO wire structure that improves coil quality factor in MHz range and its effect on wireless power transfer systems," IEEE Trans. Appl. Supercond. vol. 27, 6602005, 2017-6

However, Non-Patent Document 1 describes (1) a superconducting wire bonding method, (2) a structure for supporting the superconducting wire, and (3) a thin protective film. There were problems to be solved in order to realize

The inventors attempted to solve the above problems by using a spiral superconducting coil manufactured from a superconducting bulk. However, since it is technically difficult to increase the diameter of the superconducting bulk, it is not easy to increase the number of turns of the spiral superconducting coil simply by increasing the diameter of the coil. In order to lower the resonance frequency of the spiral superconducting coil, it is preferable to increase the number of turns of the spiral superconducting coil. Therefore, it was investigated to increase the number of turns by narrowing the line-to-line distance and line width of the spiral superconductor coil, but it was found that narrowing the line-to-line distance and line width would reduce the Q value. That is, there is a limit to lowering the resonance frequency of the spiral superconductor coil while maintaining a high Q value.

As a result of intensive research, the inventors of the present invention have found that all of the above problems can be solved by using a superconducting laminate in which a spiral superconducting coil is sandwiched between dielectric supports.

The present invention
at least one spiral superconductor coil;
at least two dielectric supports;
The spiral superconductor is sandwiched between the dielectric supports,
The dielectric loss of the dielectric support is 7.0×10 ⁻⁵ or less.
This is a superconducting laminate for high frequencies.

Such a superconducting laminate (1) does not require bonding of superconducting wires, (2) does not require a structure for maintaining the shape of the coil, Therefore, it has the advantage that the thickness of the protective film can be easily reduced.

FIG. 1 shows a developed view of a high-frequency superconducting laminate having a structure in which two dielectric supports 20 sandwich one spiral superconducting coil. FIG. 2 shows a perspective cross-sectional view of a high-frequency superconducting laminate in which two dielectric supports 20 sandwich one spiral superconducting coil. FIG. 3 shows an exploded view of a high frequency superconducting stack comprising two spiral superconducting coils and three dielectric supports. FIG. 4 is a graph showing simulation results of changes in the Q value depending on the line-to-line distance g and the line width w of the spiral superconducting coil in the high-frequency superconducting laminate. FIG. 5 is a graph showing simulation results of the relationship between the dielectric loss of the dielectric support and the Q value in the high frequency superconducting laminate. FIG. 6 is a graph showing a simulation result of the relationship between the dielectric constant of the dielectric support and the resonance frequency in the high-frequency superconducting laminate. FIG. 7 is a graph showing a simulation result of the relationship between the thickness of the dielectric support and the resonance frequency in the high frequency superconducting laminate. FIG. 8 is a graph showing simulation results of changes in the Q value depending on the line-to-line distance g and the line width w of the first spiral superconductor coil and the second spiral superconductor coil in a high-frequency superconducting laminate. .

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural references.

Although the numerical ranges and parameters set forth herein are approximations, the numerical values set forth in the specific examples are described as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Also, as used herein, the term "about" generally means within 10%, 5%, 1% or 0.5% of a given value or range. Alternatively, the term "about" means within an acceptable standard error, as considered by one of ordinary skill in the art.

First Embodiment A high-frequency superconducting laminate according to the present embodiment includes one spiral superconductor coil and two dielectric supports, and the spiral superconductor includes the dielectric support The dielectric loss of the dielectric support is 7.0×10 ⁻⁵ or less.

1. High Frequency Superconducting Laminate FIG. 1 shows one spiral superconducting coil 10 according to this embodiment and two dielectric supports 20 (a first dielectric support 21 and a second dielectric support 22). 1 shows a developed view of a high-frequency superconducting laminate 1 having a structure sandwiched by . FIG. 2 shows a state in which one spiral superconductor coil 10 is sandwiched between two dielectric supports 20 (a first dielectric support 21 and a second dielectric support 22) according to this embodiment. The perspective sectional view of the superconducting laminated body 1 for high frequencies is shown. As shown in FIG. 2, when the high-frequency superconducting laminate 1 is used, the spiral superconducting coil 10 is sandwiched between a first dielectric support 20a and a second dielectric support 20b. That is, when the high-frequency superconducting laminate 1 is used, the first dielectric support 20a is in contact with one surface of the spiral superconductor coil 10, and the second dielectric support 20b is in a spiral shape. It is in contact with the other surface of the superconductor coil 10 . The one side and the other side of the spiral superconductor coil 10 refer to the planes through which the central axis of the spiral superconductor coil 10 passes perpendicularly, and are opposite to each other. The Q value of the spiral superconducting coil 10 in the high-frequency superconducting laminate 1 is preferably 10,000 or more, more preferably 18,000 or more, and even more preferably 20,000 or more.

Spiral Superconductor Coil The spiral superconductor coil 10 is a superconductor coil having a planar spiral shape. The diameter of the spiral superconductor coil 10 is not particularly limited, but may be substantially the same as the diameter of the superconducting bulk used when manufacturing the spiral superconductor coil 10 . The thickness of the spiral superconductor coil 10 may be determined based on the actual implementation environment, for example any of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 mm. The thickness may be within the range between two points of , or the thickness may exceed 10 mm.

The superconducting material of the spiral superconductor coil 10 is selected from, but not limited to, the group consisting of alloy-based materials, copper-based oxide superconductor materials, and iron-based superconductors. The alloy-based material is selected from, but not limited to, the group consisting of NbTi, _Nb3Sn , _MgB2 and NbN. _{The copper} - _based oxide _{superconductor} material _is selected from the _{group consisting of Bi2Sr2CaCu2O8 , Bi2Sr2Ca2Cu3O10 , YBa2Cu3O7 and REBa2Cu3O7} (However, RE (rare earth element) is selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu).

The spiral superconducting coil 10 is formed by, for example, a method of processing a superconducting bulk obtained by crystallizing a superconducting material into a coil shape (GF method), or a precursor made of superconducting material components. can be produced by a method (FG method) in which the is processed into a coil shape and then crystallized.

The superconducting bulk may be produced by a melt crystallization method in which the crystal is grown on slow cooling from a partially molten state. The superconducting bulk is desirably monocrystalline. Here, the term "single crystal" may mean a perfect single crystal, or may mean a single crystal having defects (such as low-angle grain boundaries) that do not interfere with practical use.

Spiral superconductor coil 10 may be manufactured by forming spiral grooves in a superconducting bulk. The manufacturing method includes, for example, (1) slicing a superconducting bulk to a predetermined thickness and processing it into a disk shape, and (2) forming spiral grooves in the sliced superconducting bulk. For slicing, cutting with a blade or the like embedded with diamond powder is suitable. Spiraling can be done with small diamond points or sandblasting.

The line-to-line distance g of the spiral superconducting coil 10 is not particularly limited as long as the Q value of the spiral superconducting coil 10 is 10000 or more, but is 0.2 mm or more. is preferably 0.2, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 and Within the range between any two points within 5.0mm.

The line width w of the spiral superconducting coil 10 is not particularly limited as long as the Q value of the spiral superconducting coil 10 is 10000 or more. It is preferably within the range between any two points of 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 and 2.5 mm.

As long as the Q value of the spiral superconductor coil 10 can be 10000 or more, the spiral superconductor coil 10 may be provided with any protective layer or protective film. , a protective layer or film is not essential. Preferably, the spiral superconductor coil 10 has no artificial layers or films on its surface. As long as the Q value of the spiral superconducting coil 10 is 10000 or more, the space between the wires of the spiral superconducting coil 10 may be filled with any material. It does not need to be filled with material. The space between the wires of the spiral superconductor coil 10 is preferably filled with air, more preferably a vacuum. When the space between the wires of the spiral superconducting coil 10 is evacuated, the high-frequency superconducting laminate 1 may have a closed structure that can be evacuated inside. It may be a closed structure capable of evacuating the inside of the device covering the laminate 1 .

Dielectric Support The dimensions of the dielectric support 20 are such that the spiral superconductor coil 10 is covered when the spiral superconductor coil 10 is sandwiched therebetween. The shape of the dielectric support 20 may be a disk shape or a square plate shape. Alternatively, a shape in which a part of the spiral superconductor coil 10 is not covered, such as a cross shape, may be used. The dimensions of the first dielectric support 21 may be the same as those of the second dielectric support 22, or may be different from each other.

The dielectric loss of the dielectric support 20 is not particularly limited as long as the Q value of the spiral superconductor coil 10 can be 10000 or more, but is preferably 7.0×. It is 10 ⁻⁵ or less, more preferably 1.0×10 ⁻⁵ or less, and still more preferably 1.0×10 ⁻⁶ or less. The dielectric support may be made of MgO or _{Al2O3 (} sapphire), preferably _Al2O3 ( _sapphire ). Since Al ₂ O ₃ (sapphire) has a high thermal conductivity, the spiral superconducting coil can be cooled by heat conduction from the cold head of the refrigerator when the refrigerator is cooled. That is, the spiral superconductor coil 10 can be cooled while maintaining the Q value of the spiral superconductor coil 10 at a high value.

The thickness of the dielectric support 20 can vary depending on the desired resonant frequency and can be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 mm. The thickness may be within the range between any two points of , and the thickness may exceed 10 mm based on the actual implementation environment.

Second Embodiment FIG. 3 shows two spiral superconductor coils 100 (first spiral superconductor coil 101, second spiral superconductor coil 102) and three dielectric coils according to this embodiment. 1 shows a developed view of a high-frequency superconducting laminate 2 including supports 200 (a first dielectric support 201, a second dielectric support 202, and a third dielectric support 203). A first spiral superconductor coil 101 is sandwiched between a first dielectric support 201 and a second dielectric support 202 . A second spiral superconductor coil 102 is sandwiched between a second dielectric support 202 and a third dielectric support 203 . Various conditions and parameters of the spiral superconducting coil 10 and the dielectric support 20 in the high-frequency superconducting laminate 1 are the same as those of the spiral superconducting coil 100 and the dielectric support in the high-frequency superconducting laminate 2. Various conditions, parameters, etc. of the body 200 also apply.

The central axis of the first spiral superconductor coil 101 is on the same straight line as the central axis of the second spiral superconductor coil 102 . The spiral direction of the first spiral superconductor coil 101 is opposite to the spiral direction of the second spiral superconductor coil 102 . It is important that the resonance frequencies of the two facing coils match. By coupling coils with the same resonance frequency, the resonance frequency is split into two. By using the resonance frequency on the low frequency side, it is possible to lower the resonance frequency to a low frequency while using a coil of the same size as when using a single coil. Therefore, it is preferable to prepare two coils of the same shape, but even if the shapes are different, if the resonance frequencies of the two coils match, the two coils can be coupled to lower the frequency. That is, the number of turns of the first spiral superconductor coil 101 may be the same as or different from the number of turns of the second spiral superconductor coil 102 as long as the resonance frequencies match. . Also, the diameter of the first spiral superconductor coil 101 may be the same as or different from the diameter of the second spiral superconductor coil 102 .

If the two facing coils have the same size and shape, the spiral direction of the first spiral superconductor coil 101 may be the same as the spiral direction of the second spiral superconductor coil 102 . In this case, the resonance frequency of the coupled coil does not decrease, but the thickness of the coupled coil is equal to the sum of the thicknesses of the two facing coils, so the thickness of the single coil is can be applied if there are manufacturing constraints on , but it is desired to use a thicker coil.

Simulation 1
FIG. 4 is a graph showing simulation results of changes in the Q value depending on the line-to-line distance (gap) g and line width w of the spiral superconducting coil 10 in the high-frequency superconducting laminate 1 according to this embodiment. A three-dimensional electromagnetic field simulator (CST Studio Suite) was used for the simulation. The electrical conductivity of the spiral superconductor coil 10 is 9×10 ¹¹ S/m, the diameter of the spiral superconductor coil 10 is 65 mm, the thickness of the spiral superconductor coil 10 is 1 mm, and the spiral superconductor coil When the line width w of 10 is between 1.5 mm, 2.0 mm and 2.5 mm, a Q value of 10000 or more is realized by setting the line-to-line distance g of the spiral superconducting coil 10 from 0.2 mm to 5.0 mm. It became clear that it is possible.

FIG. 5 is a graph showing simulation results of the relationship between the dielectric loss (loss tangent) of the dielectric support and the Q value in the high-frequency superconducting laminate 1 according to this embodiment. The electrical conductivity of the spiral superconductor coil 10 is 9×10 ¹¹ S/m, the diameter of the spiral superconductor coil 10 is 65 mm, the thickness of the spiral superconductor coil 10 is 1 mm, and the spiral superconductor coil Dielectric loss of 7.0×10 ^-5 or less when the line width w of 10 is 1.5 mm, the line-to-line distance g of the spiral superconducting coil 10 is 0.95 mm, and the relative permittivity e of the dielectric support is 9.9. It has been clarified that a Q value of 10000 or more can be achieved by using a dielectric support having a

FIG. 6 is a graph showing simulation results of the relationship between the relative dielectric constant of the dielectric support and the resonance frequency (MHz) in the high-frequency superconducting laminate 1 according to the present embodiment. be. The electrical conductivity of the spiral superconductor coil 10 is 9×10 ¹¹ S/m, the diameter of the spiral superconductor coil 10 is 65 mm, the thickness of the spiral superconductor coil 10 is 1 mm, and the spiral superconductor coil The line width w of 10 was set to 1.5 mm, the line-to-line distance g of the spiral superconductor coil 10 was set to 0.95 mm, and the dielectric loss of the dielectric support was set to 1.0×10 ^-7 . As shown in FIG. 6, it was found that the resonance frequency decreased as the dielectric constant of the dielectric support increased.

FIG. 7 is a graph showing simulation results of the relationship between the thickness of the dielectric support and the resonance frequency in the high-frequency superconducting laminate 1 according to this embodiment. The electrical conductivity of the spiral superconductor coil 10 is 9×10 ¹¹ S/m, the diameter of the spiral superconductor coil 10 is 65 mm, the thickness of the spiral superconductor coil 10 is 1 mm, and the spiral superconductor coil The line width w of 10 was 1.5 mm, the line-to-line distance g of the spiral superconducting coil 10 was 0.95 mm, and the dielectric support was made of sapphire. As shown in FIG. 7, it was found that the resonance frequency decreased as the thickness of the dielectric support increased.

From the above simulation results, it can be seen that by using a dielectric support with a dielectric loss of 7.0×10 ^-5 or less, the line width w can be reduced to 1.5 mm and 2.0 mm without changing the diameter of the spiral superconducting coil. and 2.5 mm, a high Q value can be achieved by setting the line-to-line distance g of the spiral superconductor coil 10 between 0.2 mm and 5.0 mm. Also, by increasing the dielectric constant or increasing the thickness of the dielectric support, it has become possible to lower the resonance frequency of the spiral superconducting coil while maintaining a high Q value.

Simulation 2
FIG. 8 shows the line distance (gap) g between the first spiral superconductor coil 101 and the second spiral superconductor coil 102 in the high-frequency superconducting laminate 2 according to the present embodiment, and Q by the line width w. It is a graph which shows the simulation result of the change of a value. When the conductivity, diameter, thickness and line width w of the first spiral superconductor coil 101 and the second spiral superconductor coil 102 are respectively 9×10 ¹¹ S/m, 65 mm, 1 mm and 1.5 mm, It has been clarified that a Q value of 10,000 or more can be achieved by setting the line-to-line distance g of the spiral superconductor coil 10 from 0.4 mm to 3.9 mm. It was also found that when the line width w is 2.0 mm, a Q value of 10,000 or more can be achieved by setting the line-to-line distance g of the spiral superconducting coil 10 from 0.3 mm to 3.5 mm. rice field.

A spiral superconducting coil 10 (single, without dielectric support), a high frequency superconducting laminate 1 (single sand), a first spiral superconducting coil 101 and a second spiral superconducting coil 102 (double , no dielectric support) and the high-frequency superconducting laminate 2 (double sand). Table 1 shows the results.

In Table 1, the reason why the resonance frequency of Single sand is lower than that of Single sand is that the capacitance component of LC resonance is increased by the dielectric. The reason why the resonance frequency of Double and Double sand is lower than that of Single is due to the coupling between the coils. The double sand resonance frequency is lower than the double resonance frequency. because it will increase.

As shown in Table 1, the resonance frequency decreases from single to double sand. That is, it has been clarified that the resonance frequency decreases as the number of spiral superconducting coils and dielectric supports sandwiching them increases.

From the results of the second embodiment and simulation 2, the following can be said. That is, the resonance frequency can be shifted to a lower frequency by coupling the two coils. Also, the resonance frequency is determined by the magnitude of the coupling between the two coils. Therefore, the smaller the distance between the two coils, the greater the coupling, and the frequency shifts to lower frequencies. By facing the two coils, the stray capacitance can be confined between the coils. This reduces the effect of dielectric proximity. In particular, the effect of confining the stray capacitance is greater when the coil is sandwiched between dielectrics.

INDUSTRIAL APPLICABILITY The high-frequency superconducting laminate according to the present invention can dramatically improve transmission efficiency by using it in a power transmission/reception coil for wireless power transmission. Also, by using the high-frequency superconducting laminate according to the present invention for coils of various analyzers (NMR, MRI, NQR, etc.), the sensitivity of the analyzers can be dramatically improved. Furthermore, the high-frequency superconducting laminate according to the present invention can be used for high-sensitivity high-frequency antennas and high-frequency low-loss filters.

1 high-frequency superconducting laminate 2 high-frequency superconducting laminate 10 spiral superconductor coil 100 spiral superconductor coil 101 first spiral superconductor coil 102 second spiral superconductor coil 20 dielectric support body 200 dielectric support 21 first dielectric support 22 second dielectric support 201 first dielectric support 202 second dielectric support 203 third dielectric support g wire of spiral superconductor coil Inter-distance w Line width of spiral superconducting coil

Claims (6)

a spiral superconductor coil;
two dielectric supports;
The spiral superconductor coil is sandwiched between the dielectric supports,
The dielectric loss of the dielectric support is 7.0×10 ⁻⁵ or less,
the spiral superconductor coil has a line-to-line distance of 0.5 mm to 2.5 mm;
The spiral superconductor coil has a line width of 1.5 to 2.5 mm,
The Q value of the spiral superconductor coil is 18000 or more,
High frequency superconducting laminate. 2. The high-frequency superconducting laminate according to claim 1, wherein the dielectric loss of said dielectric support is 1.0×10 ⁻⁵ or less. 3. The high frequency superconducting laminate according to _claim 2, wherein said dielectric support is made of MgO or _Al2O3 . 4. The high-frequency superconducting material according to claim 1, wherein said spiral superconductor coil is manufactured by forming spiral grooves in a superconducting bulk and has a thickness of 1 mm or more. laminate. two spiral superconductor coils;
three dielectric supports;
The spiral superconductor coil is sandwiched between the dielectric supports,
The dielectric loss of the dielectric support is 7.0×10 ⁻⁵ or less,
The spiral superconductor coil has a line-to-line distance of 1.0 mm to 3.0 mm,
The spiral superconductor coil has a line width of 1.5 to 2.0 mm,
The Q value of the spiral superconductor coil is 18000 or more,
A high-frequency superconducting laminate, wherein the central axes of the spiral superconducting coils are on the same straight line. 6. The high frequency superconducting laminate according to claim 5, wherein spiral directions of spiral superconductor coils adjacent to each other via said dielectric support are opposite to each other.

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