Superconducting diode

Abstract

The present technology relates to an electrical device including a length of superconducting material in which a critical current when current flows in one direction is different from a critical current of the length of the superconducting material when current flows in the opposite direction through the length of the superconducting material. The electrical device may further include a magnetic field generating device including two permanent magnets disposed on the same side of the length of the superconducting material and disposed substantially antiparallel to each other. The polar axes of the two permanent magnets may be oriented substantially perpendicular to the plane of the length of the superconducting material.

Description

Technical Field

[0001] 1. Field of the Invention The present technology relates to superconducting power supplies. In particular, the present technology relates to electrical devices including components formed from superconducting materials, particularly high-temperature superconducting materials. In particular, the present technology relates to electrical devices that operate as diodes or similar to diodes. 2.

Background Art

[0002] Superconducting circuits are used in a wide range of applications. Examples of applications of systems including superconducting circuits include, but are not limited to, superconducting magnets, flux pumps, fault current limiters, magnetic energy storage systems, space propulsion, nuclear fusion, nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), levitation, water purification, induction heating, and the like.

[0003] In many applications involving superconducting circuits, a low-voltage high-current power supply is required, such as a powerful high-temperature superconducting (HTS) magnet for applications such as nuclear fusion. To meet these requirements, conventional power supply devices require a large amount of space, posing a major challenge to the infrastructure. Also, when connecting a normal conducting circuit to a superconducting circuit housed in a cryostat, a large heat load is generated in the cryostat through physical contact, making cooling difficult. This requires advanced thermal design and imposes a significant thermal penalty on the cryostat and the cooling system. Also, a large voltage drop occurs across the entire normal conducting circuit component, requiring a power supply that is significantly higher than that required only to supply power to the superconducting coil.

[0004] Superconducting power supplies contribute to the solution of these problems. When the current density is high, the power supply device can be made more compact, and since an HTS flux pump can magnetically couple an alternating current (AC) circuit without physical contact, the cooling problem can be avoided. However, to supply power to an HTS magnet, a large direct current (DC) is required, and rectification is needed to convert AC (a current whose direction periodically reverses) to DC (a current that flows only in one direction). In other applications of superconducting circuits, current rectification is also required or merits can be obtained through rectification.

[0005] Semiconductor diodes can be used to rectify AC to DC. A diode is a component that can conduct current with low resistance in one direction but provides a relatively high resistance in the opposite direction. However, existing semiconductor diodes cause large losses when used with the high currents required for superconducting power supplies.

[0006] Rectification can also be achieved using switches such as superconducting switches instead. However, superconducting switches usually require a separate independent power supply and feedthrough, which increases complexity and cost. Also, when the switch is placed inside a cryostat, heat is dissipated in the cold environment, which can have an adverse effect on efficiency.

[0007] Therefore, a diode formed from a superconducting material is desirable. However, previous designs of superconducting diodes have had significant drawbacks. In some devices, the difference between the forward bias current and the reverse bias current can only be made very small, which is insufficient for the above high-power applications. Other existing superconducting diodes do not have a critical current high enough to be used in power applications. Other existing superconducting diodes require advanced manufacturing techniques for production, are costly, and are complex.

[0008] 3. Objectives of the Invention The object of the present invention is to provide an improved superconducting diode. Alternatively, it is an object of this technology to provide an improved electrical device for rectifying an alternating current using a superconducting material. Alternatively, it is an object of this technology to provide at least a useful option for the general public. 4.

Summary of the Invention

[0009] Aspects of this technology relate to an electrical device including a length of a superconducting material, wherein the critical current of the length of the superconducting material when current flows in one direction through the entire length of the superconducting material is different from the critical current of the length of the superconducting material when current flows in the opposite direction through the entire length of the superconducting material.

[0010] In one aspect of this technology, a rectifier including a length of a superconducting material is provided, wherein the critical current of the length of the superconducting material when current flows in one direction through the entire length of the superconducting material is different from the critical current of the length of the superconducting material when current flows in the opposite direction through the entire length of the superconducting material.

[0011] In one aspect of this technology, a superconducting diode is provided. The superconducting diode includes a length of a superconducting material, and the critical current of the length of the superconducting material when current flows in one direction through the entire length of the superconducting material may be different from the critical current of the length of the superconducting material when current flows in the opposite direction through the entire length of the superconducting material.

[0012] According to one aspect of this technology, an electrical device including a length of a superconducting material is provided, and the superconducting material is affected by a plurality of magnetic fields. The influence exerted by the plurality of magnetic fields on the length of the superconducting material is different when current flows in one direction through the entire length of the superconducting material and when current flows in the opposite direction through the entire length of the superconducting material. In some forms, the plurality of magnetic fields includes a self-magnetic field generated by the length of the superconducting material when current flows and an applied magnetic field generated by a magnetic field generating device. In other forms, the plurality of magnetic fields includes a first applied magnetic field generated by a first magnetic field generating device and a second applied magnetic field generated by a second magnetic field generating device.

[0013] According to certain aspects of this technology, an electrical device is provided that includes a length of superconducting material and a magnetic field generating device configured and arranged to apply an applied magnetic field to the length of the superconducting material. The length of the superconducting material can generate a self-magnetic field when a current flows through the entire length of the superconducting material, and a net magnetic field is generated by the self-magnetic field and the applied magnetic field. The magnetic field generating device can be configured and arranged such that when a first current flows through the length of the superconducting material in a first direction, the magnitude of the net magnetic field is substantially lower compared to when a second current flows through the length of the superconducting material in a second direction. The magnitudes of the first current and the second current can be equal or similar. The magnetic field generating device can be configured and arranged such that when a current flows through the length of the superconducting material in a first direction, the applied magnetic field is similar to the self-magnetic field.

[0014] According to one aspect of the present invention, an electrical device is provided. The electrical device can include a length of superconducting material. The electrical device is configured and arranged to apply an applied magnetic field to the length of the superconducting material such that when a first current flows through the length of the superconducting material in a first direction, a first critical current occurs in the length of the superconducting material, and when a second current flows through the length of the superconducting material in a second direction, where the second direction is opposite to the first direction, a second critical current occurs in the length of the superconducting material, and the first critical current is substantially greater than the second critical current.

[0015] In examples, the length of the superconducting material can generate a self-magnetic field when a current flows through the entire length of the superconducting material. The self-magnetic field and the applied magnetic field can generate a net magnetic field. The magnetic field generating device can be configured and arranged such that when a first current flows through the length of the superconducting material in a first direction, the magnitude of the net magnetic field is substantially lower compared to when a second current flows through the length of the superconducting material in a second direction.

[0016] In examples, the magnetic field generating device can be configured and arranged such that when a current flows through the length of the superconducting material in a first direction, the applied magnetic field is similar to the self-magnetic field.

[0017] In various examples, the length of the superconducting material is the length of the first superconducting material, and the magnetic field generating device may include the length of the second superconducting material disposed close to the length of the first superconducting material. An applied magnetic field may be generated when an electric current flows through the length of the second superconducting material.

[0018] In various examples, when the direction of the electric current flowing through the length of the second superconducting material is changed to the opposite direction, the first direction and the second direction of the electric current flowing through the length of the first superconducting material may be interchanged.

[0019] In various examples, the magnetic field generating device may include a permanent magnet disposed near the length of the superconducting material.

[0020] In various examples, the magnetic field generating device may include two permanent magnets disposed on the same side of the length of the superconducting material. The polar axes of the two permanent magnets may be disposed substantially antiparallel to each other. The polar axes of the two permanent magnets may be oriented substantially perpendicular to the plane of the length of the superconducting material facing the magnets.

[0021] According to one aspect of the present invention, an electrical device is provided. The electrical device may include the length of a superconducting material including two substantially parallel opposing surfaces. The electrical device may further include a magnetic field generating device including two permanent magnets disposed on the same side of the length of the superconducting material. The polar axes of the two permanent magnets may be disposed substantially antiparallel to each other. The polar axes of the two permanent magnets may be oriented substantially perpendicular to the plane of the length of the superconducting material. The magnetic field generating device may be configured and arranged to apply a magnetic field to the length of the superconducting material such that when a first electric current flows in a first direction through the length of the superconducting material, a first critical current is generated in the length of the superconducting material, and when a second electric current flows in a second direction through the length of the superconducting material, the second direction being opposite to the first direction, a second critical current is generated in the length of the superconducting material, and the first critical current is substantially greater than the second critical current.

[0022] In various examples, the length of the superconducting material can generate a self - magnetic field when a current flows through the entire length of the superconducting material. The self - magnetic field and the applied magnetic field can generate a net magnetic field. The magnetic field generating device can be configured and arranged such that when a first current flows in a first direction through the length of the superconducting material, the magnitude of the net magnetic field is substantially lower compared to when a second current flows in a second direction through the length of the superconducting material.

[0023] In various examples, the magnetic field generating device can be configured and arranged such that when a current flows in a first direction through the length of the superconducting material, the applied magnetic field is the same as the self - magnetic field.

[0024] In various examples, two permanent magnets can be disposed at an equal distance from the length of the superconducting material.

[0025] In various examples, the length of the superconducting material can include a length, a width, and a depth. The depth is the distance between two substantially parallel opposing surfaces. The length can be significantly larger than the width. The width can be significantly larger than the depth.

[0026] In various examples, two permanent magnets can be disposed substantially aligned along the length of the superconducting material.

[0027] In various examples, both permanent magnets can be displaced by substantially the same distance from the length of the superconducting material in a direction perpendicular to the plane of the length of the superconducting material.

[0028] In various examples, two permanent magnets can be separated with a gap in a direction parallel to the width of the length of the superconducting material. The gap can be larger than the width of the length of the superconducting material.

[0029] In various examples, the magnetic field generating device can include a third permanent magnet and a fourth permanent magnet disposed on the length of the superconducting material on the side opposite to the two permanent magnets.

[0030] According to one aspect of the present invention, an electrical device is provided. The electrical device may include a length of superconducting material. The electrical device may further include a first magnetic field generating device configured and arranged to apply a first applied magnetic field to the length of the superconducting material. The electrical device may include a second magnetic field generating device configured and arranged to apply a second applied magnetic field to the length of the superconducting material. The first applied magnetic field and the second applied magnetic field generate a net magnetic field. The first magnetic field generating device and the second magnetic field generating device are such that when a first current flows in a first direction through the length of the superconducting material, the net magnetic field has a first magnitude, a first critical current flows through the length of the superconducting material, a second current flows in a second direction through the length of the superconducting material, and the second direction is opposite to the first direction, the net magnetic field has a second magnitude and a second critical current flows through the length of the superconducting material, and may be configured and arranged. The first magnitude may be substantially lower than the second magnitude, and the first critical current may be substantially larger than the second critical current.

[0031] In some examples, the magnetic field generating device may include a magnetic core formed of a material having a high magnetic permeability. The magnetic core may be arranged to direct the applied magnetic field to the length of the superconducting material.

[0032] In some examples, the magnetic core may include a gap, and the length of the superconducting material may be disposed within the gap.

[0033] In some examples, the magnetic field generating device may be the first magnetic field generating device, and the applied magnetic field may be the first applied magnetic field. The electrical device may further include a second magnetic field generating device configured and arranged to apply a second applied magnetic field to the length of the superconducting material. The first magnetic field and the second applied magnetic field generate a net magnetic field. The first magnetic field generating device and the second magnetic field generating device may be configured and arranged such that when a first current flows in a first direction through the length of the superconducting material, the magnitude of the net magnetic field is substantially lower compared to when a second current flows in a second direction through the length of the superconducting material.

[0034] In various examples, the length of the superconducting material can be the length of the first superconducting material, the electrical device can further include the length of a second superconducting material, and the length of the second superconducting material is coupled in series with the length of the first superconducting material. The second magnetic field generating device can include the length of the second superconducting material such that a second applied magnetic field is generated by the length of the second superconducting material.

[0035] In various examples, the length of the second superconducting material can be disposed within the coil. The length of the first superconducting material can be disposed within the coil.

[0036] In various examples, the cross-sectional area of the length of the first superconducting material can be made smaller than the cross-sectional area of the length of the second superconducting material.

[0037] In one aspect of this technology, a rectifier is provided that includes an electrical device according to any one or more of the other aspects of this technology.

[0038] A further aspect of this technology should be considered in all its novel aspects and will become apparent to those skilled in the art upon reading the following description which illustrates at least one example of the practical application of this technology. 5.

Brief Description of the Drawings

[0039] In the following, one or more embodiments of the present invention will be described by way of example only and not with the intention of being limiting, with reference to the drawings.

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Embodiments for Carrying Out the Invention

[0040] 6. 6.1. Superconductivity

[0041] A superconductor is a substance whose electrical resistance becomes zero below a specific temperature called the critical temperature T c This lack of resistance is the result of a phenomenon called the Meissner effect, in which all magnetic fields are completely excluded from the superconductor. A superconductor is a perfect diamagnet up to a specific magnetic field strength called the critical magnetic field B c At this point, the superconductor can no longer block the magnetic field, and therefore the superconducting phenomenon is destroyed. This critical magnetic field also means that there is a limit to the current that can flow through the superconductor, which is called the critical current I c

[0042] There are two types of superconductors: type I and type II. Type I superconductors are usually pure metals and operate as described above. Type II superconductors behave differently. In type II superconductors, a certain amount of magnetic field can penetrate up to the critical magnetic field H c1 <H c without transitioning from the superconducting state. For this reason, type II superconductors can carry more current. Because it has superior characteristics to type I superconductors, it is useful for practical applications.

[0043] ​The critical temperature of a superconductor is usually defined as the temperature below which the resistivity of the superconductor becomes zero or nearly zero. In other words, when the temperature of the superconductor is lower than the critical temperature, the superconductor is said to be in the superconducting state, and when the temperature is higher than the critical temperature, the superconductor is said to be in the non-superconducting state. Many superconductors have critical temperatures close to absolute zero. For example, it is known that the critical temperature of mercury is 4.1 K. However, it is also known that some materials may have much higher critical temperatures, such as 30 K to 125 K. For example, the critical temperature of magnesium diboride is about 39 K, while the critical temperature of yttrium barium copper oxide (YBCO) is about 92 K. These superconductors are generally called high-temperature superconductors (HTS). 6.1.1. Critical Current

[0044] The critical current of a high-temperature superconducting wire or tape is usually defined as the current flowing through the superconducting wire / tape at which an electric field drop of 100 μV / m (= 1 μV / cm) occurs along the wire. The critical current is a function of both the superconducting material used and the physical arrangement of the superconducting material. For example, a wide tape / wire can have a higher critical current than a thin tape / wire made of the same material. However, for the sake of simplicity, throughout this specification, reference is made to the critical current of the superconductor / superconducting material.

[0045] In a superconductor / superconducting material, when the current I is approximately equal to the critical current tI c the resistance of the superconductor is not zero but small. However, when I is much larger than the critical current I c the resistance of the superconductor becomes large enough to cause heat dissipation, heating the superconductor to a temperature above the critical temperature, and as a result, it ceases to be superconducting. This state is sometimes called a "quench" and may damage the superconductor itself.

[0046] Figure 1 is an exemplary graph showing the curve of the internal electric field and current of a high-temperature superconductor. The electric field shown in this graph is related to the resistance by the following equation.

[0047]

Number

[0048] Therefore, the graph in Figure 1 is related to the resistance per unit length of the superconductor, and since the drawn curve is non-linear, the resulting resistance of the superconductor becomes non-linear with respect to the current.

[0049] In Figure 1, it was found that the electric field strength in the superconductor is substantially zero below the critical current I of the superconductor. As the current in the superconductor approaches the critical current, the electric field in the superconductor begins to increase. At the critical current, the electric field in the superconductor becomes 100 μV / m. When the current in the superconductor is further increased above the critical current, the electric field strength in the conductor increases rapidly.

[0050] As shown in Figure 1, the transition from the superconducting state to the normal conducting state in the HTS material can be explained by an empirical law called the E-J power law.

[0051]

Number

[0052] Throughout this specification, reference may be made to the relative resistance of superconducting materials and the components that make up the superconducting materials. More specifically, this specification refers to a superconducting material in a low-resistance state or a high-resistance state. When in the superconducting state, a superconducting material can have zero or substantially zero resistance, and thus it is understood that these resistances are often represented by the electric field present throughout the superconducting material for a given current. However, throughout this specification, for the sake of simplicity of discussion, reference is made to relative resistances, such as the low-resistance state and the high-resistance state of a superconducting material.

[0053] The term "low-resistance state" may refer to a case where a superconducting material has a resistance that is approximately zero or substantially zero in the superconducting state, or where the material is partially in the superconducting state and has a low resistance. The term "high-resistance state" refers to a state where a superconducting material has a resistance that is substantially greater than the resistance in the low-resistance state, such as a resistance that is not substantially zero, or a resistance that is close to zero but substantially greater than the resistance in the low-resistance state. To avoid ambiguity, the high-resistance state referred to in this specification may include the superconducting state unless otherwise clearly stated in the context.

[0054] Similarly, in this specification, when it is mentioned that a superconducting material is in a high-resistance state as a result of the current carried by the superconductor exceeding the critical current, it should be understood that the high-resistance state may also be achieved when the current carried by the superconductor approaches or is substantially equal to the critical current, unless the context clearly indicates otherwise.

[0055] In the description of the technology of this specification, materials and the components that make up the materials are referred to as "superconducting". This term is commonly used in the art for such materials and does not mean that the related materials are always in the superconducting state. Under certain conditions, materials and the components that make up the materials may not be in the superconducting state. That is, this material can be described as having superconductivity but not being superconducting. 6.1.2. Superconducting Materials

[0056] Certain forms of the present technology may include various types of superconducting materials. For example, forms of this technology may include high-temperature superconducting (HTS) materials. Exemplary HTS materials suitable for use in the described forms of the technology include cuprate superconductors, such as rare-earth barium copper oxides (ReBCO) like yttrium barium copper oxide, gadolinium barium copper oxide, or bismuth strontium calcium copper oxide (BSCCO) superconductors, and iron-based superconductors. BSCCO superconductors typically have a strong interdependence between the critical current and the applied magnetic field, and thus may be particularly suitable for some forms of the present technology. Other types of superconductors may be used in other forms of the technology.

[0057] Although this form of the technology is described in relation to high-temperature superconductors, it is necessary to understand that in other forms of this technology, other types of superconductors, such as low-temperature superconductors, may be used instead. 6.1.3. Influence of Magnetic Field on Superconductors

[0058] The critical current of a superconductor depends on the external magnetic field applied to the superconductor. More specifically, as a higher external magnetic field is applied to the superconductor, the critical current decreases to the value of the critical magnetic field, and beyond that, the superconductor no longer remains in the superconducting (low-resistance) state. This relationship is shown in Figure 2. Figure 2 is a graph showing the relationship between the electric field and current of a superconducting material when three different magnitudes of external magnetic fields are applied. The maximum value B of the external magnetic field 印加1 lowers the critical current value I c1 to the lowest. In some forms, the external magnetic field for achieving this effect may be applied perpendicular to the length of the superconductor where the critical current is reduced or suppressed. The applied magnetic field is in only one direction and can be called a direct current magnetic field, while a magnetic field that changes with time, for example, circulates in a sinusoidal shape in direction, can be called an alternating current magnetic field.

[0059] In all superconductors, the critical current drops rapidly with the application of a small magnetic field. This means that a small change in the applied magnetic field can result in a large change in the critical current. This relationship depends on the superconducting material and the method of manufacturing the length of the superconducting material through which the current flows.

[0060] Note that this mechanism of reducing or suppressing the critical current by applying an external magnetic field (e.g., a DC magnetic field) is different from the phenomenon of dynamic resistance. This occurs when a superconductor is exposed to a magnetic field that changes over time while carrying a DC transport current. As a result, a DC electrical resistance is generated within the superconductor, and when this resistance becomes large enough, the superconductor can switch to a higher resistance state. 6.2. Superconducting Diode

[0061] 6.2.1. Operating Principle

[0062] The forms of technology described in this specification are electrical devices that may also be referred to as "superconducting diodes." In this specification, the term "diode" is used to refer to an electrical device that exhibits different resistance characteristics (or equivalent conductivity) when current flows through the device in one direction and when current flows through the device in the opposite direction. In the case of a conventional semiconductor diode, when current flows in one direction, the resistance of the diode is low (ideally zero), and when current flows in the opposite direction, the resistance is high (ideally infinite). The forms of technology described in this specification are electrical devices that include the length of a superconducting material, and the critical current of the length of the superconducting material when current flows through the entire length of the superconducting material in one direction is different from the critical current of the length of the superconducting material when current flows through the length of the superconducting material in the opposite direction. Such an electrical device uses the term "diode" because the resistance characteristics of the device change according to the direction of the current flowing through the device. In the forward bias direction of such a diode, no resistance occurs because a relatively large current flows when the diode is in a lower resistance (e.g., superconducting) state. In the reverse bias direction, the diode can be configured such that the same magnitude of current flowing in the opposite direction experiences a higher level of resistance (e.g., because the current approaches the critical current, is of the same order as the critical current, or exceeds the critical current). When the current value is low, the resistance state of the diode can be low in the reverse bias direction. The superconducting diodes described in this specification can be considered to be the electromagnetic dual of semiconductor diodes.

[0063] The general principle of the operation of an electrical device in a specific technical form, also called a superconducting diode, is that the length of a superconducting material exhibiting the diode effect is affected by multiple magnetic fields (e.g., two magnetic fields), and when a current flows in one direction along the length of the superconducting material and when a current (e.g., of the same or similar magnitude) flows in the other opposite direction along the length of the superconducting material, there is a difference in the effect of the combined magnetic field. The combination of multiple magnetic fields can be called the net magnetic field. Due to this asymmetry, the critical current varies according to the length of the superconducting material depending on the direction in which the current flows along the length of the superconducting material, and the diode effect occurs.

[0064] In some forms of this technology, the multiple magnetic fields include the self - magnetic field generated by the length of the superconducting material when a current flows and the applied magnetic field generated by a magnetic - field generating device. In other forms, the multiple magnetic fields include a first applied magnetic field generated by a first magnetic - field generating device and a second applied magnetic field generated by a second magnetic - field generating device. In some of the latter forms, the self - magnetic field from the length of the superconducting material may be negligibly small compared to the applied magnetic field.

[0065] In some forms of this technology, the self - magnetic field contributes to the net magnetic field, and the strength of the self - magnetic field depends on the magnitude of the current flowing along the entire length of the superconducting material. Furthermore, the critical current of the length of the superconducting material depends on the net magnetic field applied to the length of the superconducting material. This form of technology relates to an electrical device in which the length of the superconducting material has a first critical current when a first current of a certain magnitude flows in one direction along the entire length of the superconducting material and has a second critical current when a second current flows in the opposite direction to the first current along the entire length of the superconducting material. The difference in the critical current when currents of the same magnitude but opposite directions flow along the length of the superconducting material is the asymmetry that produces the diode effect in a specific form of technology.

[0066] During operation, the current flowing through the form of the superconducting diode described herein may be significantly lower than, approaching, substantially equal to, and / or significantly greater than the critical current of the length of the superconducting material exhibiting the diode effect. In the forward bias configuration of a superconducting diode with a relatively high critical current, the diode can conduct a current significantly less than the critical current, and as a result, it is clear that the length of the superconducting material becomes superconducting. In the reverse bias configuration with a relatively low critical current, the diode can conduct a current significantly lower than, approaching, substantially equal to, and / or significantly greater than the critical current of the length of the superconducting material. In some forms, in the reverse bias configuration, the magnitude of the current is such that the length of the superconducting material remains in the superconducting state, but has a resistance significantly greater than the resistance of the length of the superconducting material in the forward bias configuration with a current of a similar magnitude. For a particular form of diode, the appropriate magnitude of the current to enable the diode to operate in the desired state can be readily determined through experimentation.

[0067] In certain forms, for example, when the diode is used as a rectifier or is included as part of a rectifier, it is understood that an alternating current (AC) is provided to the diode. 6.2.2. Diodeicity

[0068] An electrical device that operates in the described manner and may also be called a superconducting diode can include a property called "diodeicity". Diodeicity is a measure of the diode effect generated by the electrical device, that is, the degree to which the critical current of the length of the superconducting material differs when the current flows in one direction and when it flows in the other direction.

[0069] In certain forms, the diodeicity D is defined as follows.

[0070]

Equation

[0071] A particular form of this technology relates to an electrical device 100 that includes a length 200 of a superconducting material. The length 200 of the superconducting material is the portion of the superconductor where the diode effect is generated. The length 200 of the superconducting material can be formed from any superconducting material including any of the examples described above. In a particular form of the technology, the length 200 of the superconducting material may be formed from an HTS material. In a particular form, the length 200 of the superconducting material where the diode effect is generated is a single strand of the superconducting material, and for example, there may be no loops or branches in the length 200 of the superconducting material. 6.2.3.1. Superconducting tape

[0072] In a particular form of this technology, the length 200 of the superconducting material can take the form of a tape, i.e., a length of material that is significantly larger in length than its width and depth and significantly larger in width than its depth. The tape has two substantially parallel opposing surfaces that are separated by the depth of the tape.

[0073] An example of an electrical device 100 including a length 200 of a tape-shaped superconducting material is shown in FIG. 3. FIG. 3 is a view seen from the end of the tape, meaning that the length of the tape extends into and out of the page. When current flows through the entire tape, the current flows along the length of the tape, that is, depending on the direction of the current, it flows inside or outside the page. The width of the tape extends across the page in the direction of arrow X in FIG. 3. Unless otherwise specified, in this specification, when explaining the direction regarding the length 200 of the tape-shaped superconducting material, the following coordinate rules are used. The x-direction is the direction across the width of the tape (i.e., the left-right direction of the page in FIG. 3), the y-direction is the direction perpendicular to the opposite surface of the tape (i.e., the up-down direction of the page in FIG. 3), and the z-direction is the length direction of the tape (i.e., the inside-outside direction of the page in FIG. 3).

[0074] In other forms of this technology, the length 200 of the superconducting material can take other forms, such as a wire including a wire with a substantially circular cross-sectional shape, or the length of a superconducting material having other cross-sectional shapes. 6.2.3.2. Self-magnetic field of the length of the superconductor

[0075] Moving charges generate a magnetic field. As a result, when current flows through the entire length 200 of the superconducting material, a magnetic field is generated. In this specification, the magnetic field generated when current flows through the entire length 200 of the superconducting material is called the self-magnetic field. The magnetic field lines of the self-magnetic field are around the length 200 of the superconducting material in a direction according to the "right-hand rule". In some forms of this technology, as will be described later, the self-magnetic field interacts with another magnetic field applied to the length 200 of the superconducting material to produce a diode effect. 6.2.4. Cryostat

[0076] Even if not explicitly stated for a particular form, forms of this technology include an electrical device 100 that includes a cryostat for housing the length 200 of the superconducting material and maintaining a temperature suitable for the superconducting material to be in a superconducting state. An appropriate form of cryostat or cooling mechanism can be used. 6.2.5. Magnetic field generating device

[0077] This form of technology is related to an electrical device including a magnetic field generating device 300. Specific examples of magnetic field generating devices will be described, but this term can refer to any component or assembly that generates a magnetic field. Examples of magnetic field generating devices include magnets (e.g., permanent magnets and electromagnets) and conductors through which an electric current flows (e.g., the length of a superconducting material through which an electric current flows).

[0078] In a specific form, the magnetic field generating device 300 may include a magnetic core 340 formed of a material having a high magnetic permeability such as iron or ferrite. The magnetic core 340 can be disposed relative to the magnet to direct the applied magnetic field generated by the magnetic field generating device 300 to the length 200 of the superconducting material. For example, a permanent magnet can be disposed immediately adjacent to the magnetic core 340, for example, sandwiched between two portions of the magnetic core 340. In another form, a conductor can be wound around a part of the magnetic core 340, and an electromagnet can be formed by passing an electric current through the entire conductor to generate a magnetic field throughout the magnetic core 340. In a specific form, the magnetic core 340 includes a gap 350, and the length 200 of the superconducting material can be disposed within the gap 350.

[0079] The magnetic core 340 can be configured in any shape or form suitable for concentrating magnetic field lines on the length 200 of the superconducting material. For example, the magnetic core 340 can include one or more tapered ends adjacent to the length 200 of the superconducting material. In other forms, the magnetic core 340 can include a plurality of teeth adjacent to the length 200 of the superconducting material. 6.2.6. Types of Superconducting Diodes

[0080] In the following description, various types of electrical devices considered to be superconducting diodes will be described. In one type of such a device, since the net effect of the self - magnetic field generated by the length 200 of the superconducting material and the applied magnetic field generated by the magnetic field generator 300 is different, different net magnetic fields can be generated when the current flows in one direction through the entire length 200 of the superconducting material and when the current flows in the opposite direction through the length 200 of the superconducting material. In another type, the different net magnetic fields generated when the current flows in different directions can be caused by the difference in the net magnetic fields generated by two (or more) magnetic field generators.

[0081] Furthermore, as another classification of the technical forms described in this specification, there are active devices and passive devices. In the technical form that can be described as a passive device, no additional power source is required to generate the diode effect other than the current flowing through the entire length 200 of the superconducting material that generates the diode effect. In the technical form called an active device, an additional power source is used to produce the diode effect.

[0082] These different types of devices will be described in more detail in relation to exemplary forms of the technology. One or more of the described exemplary electrical devices can be incorporated into a rectifier for rectifying an alternating current in some forms of the technology. 6.2.6.1. Self - magnetic field and applied magnetic field

[0083] In certain forms of the technology, due to the different net effects of the self - magnetic field generated by the length 200 of the superconducting material and the applied magnetic field generated by the magnetic field generating device 300, when a current flows in one direction through the entire length 200 of the superconducting material and when a current flows in the opposite direction through the length 200 of the superconducting material, different net magnetic fields can be generated in the length 200 of the superconducting material. For example, the magnetic field generating device 300 can be configured and arranged such that the magnitude of the net magnetic field is substantially lower when a current flows in one direction through the length of the superconducting material compared to when a current (e.g., a current of the same magnitude) flows in the opposite direction through the length of the superconducting material. In some forms, this can be achieved by configuring and arranging the magnetic field generating device such that the applied magnetic field is similar to the self - magnetic field when the current flows through the entire length of the superconducting material in a first direction. This similarity of the magnetic fields results in an additional effect on the net magnetic field with respect to the length 200 of the superconducting material. When the current flows in the opposite direction through the entire length of the superconducting material, the magnetic fields are similar but opposite, resulting in a canceling effect, and as a result, the net magnetic field at the length 200 of the superconducting material is relatively low. The critical current of the length 200 of the superconducting material depends on the magnetic field it experiences, and the critical current decreases as a higher magnetic field is applied. Therefore, when the self - magnetic field and the applied magnetic field of the length 200 of the superconducting material at least partially cancel each other out, the critical current of the length 200 of the superconducting material increases.

[0084] In certain embodiments, the applied magnetic field can be similar to the self - magnetic field of the length 200 of the superconducting material in terms of how at least one of its magnitude or direction changes in a region proximate to the length 200 of the superconducting material. In certain embodiments, the applied magnetic field can be similar to the self - magnetic field of the length 200 of the superconducting material in terms of how both its magnitude and direction change in a region proximate to the length 200 of the superconducting material. In certain embodiments, the applied magnetic field can be similar to the self - magnetic field of the length 200 of the superconducting material with respect to the magnitude of the component of the magnetic field in a direction perpendicular to the surface of the length 200 of the superconducting material (e.g., the y - direction in FIG. 3), and the change in its magnitude along the width of the length 200 of the superconducting material (i.e., the x - direction in FIG. 3). In certain embodiments, when a desired level of diodicity is obtained, the applied magnetic field can be considered to be sufficiently similar to the self - magnetic field. In certain embodiments, in a region close to the length 200 of the superconducting material, the level of diodicity can be higher to the extent that the magnitude and / or direction of the applied magnetic field is similar to the self - magnetic field. 6.2.6.1.1. Permanent Magnet

[0085] In some forms of this technology, the electrical device 100 includes a magnetic - field - generating device 300 that includes one or more magnets for generating an applied magnetic field. Some such exemplary forms are shown in FIGS. 3, 8, 10A, and 10B. In these examples, the electrical device 100 includes the length 200 of the superconducting material and two permanent magnets 310a and 310b disposed near the length 200 of the superconducting material. The proximity of the permanent magnets 310a and 310b to the length 200 of the superconducting material can depend on the selection of the permanent magnets, e.g., the strength of the magnets, but can be such proximity as to obtain the effects described in the following explanation. In certain embodiments, the proximity is such that the strength of the magnetic field applied by the permanent magnets to the length 200 of the superconducting material is similar to the strength of the self - magnetic field generated by the length 200 of the superconducting material when an operating current of typical magnitude flows through the length 200 of the superconducting material, e.g., of the same order of magnitude.

[0086] The permanent magnets are arranged to generate an applied magnetic field having a similar shape and / or intensity to the self-magnetic field generated by the length 200 of the superconducting material when a current flows. Exemplary arrangements of the two permanent magnets 310a and 310b are shown in FIGS. 3, 8, 10A, and 10B. In these configurations, both the permanent magnets 310a and 310b are arranged on the same side of the length 200 of the superconducting material. The permanent magnets 310a and 310b are disposed equidistant from the length 200 of the superconducting material. The permanent magnets 310a and 310b are displaced in the y-direction (i.e., perpendicular to the tape surface) from the length 200 of the superconducting material. Both magnets can be moved by substantially the same distance in this direction. The permanent magnets 310a and 310b in these configurations are oriented such that the polar axes of the magnets are substantially anti-parallel (i.e., in opposite directions). Further, the polar axes of the magnets can be arranged substantially perpendicular to the tape surface forming the length 200 of the superconducting material. That is, the polar axes are oriented substantially parallel to the y-direction. In the configurations of FIGS. 8, 10A, and 10B, the spacing between the permanent magnets 310a and 310b in the x-direction (i.e., the width in the direction of the length 200 of the superconducting material) is greater than the width in the direction of the length 200 of the superconducting material.

[0087] This arrangement of the permanent magnets 310a and 310b is useful for generating an applied magnetic field having a magnetic field strength profile similar to the self - magnetic field of the length 200 of the superconducting material across the width of the length 200 of the superconducting material. FIGS. 4A and 4B are graphs showing the variation of the magnetic field strength with respect to the length 200 of the superconducting material of FIG. 3. The magnetic field strength indicated by the vertical axis is the magnetic field strength in the direction perpendicular to the plane in the direction of the length 200 of the superconducting material of FIG. 3, that is, the magnetic field strength in the y - direction. The horizontal axes of FIGS. 4A and 4B are the distances along the width of the length 200 of the superconducting material, that is, the distances in the x - direction. In each graph, the line 410 shows the profile of the self - magnetic field generated by the length 200 of the superconducting material when current flows. The line 420 shows the profile of the applied magnetic field generated by the permanent magnets 310a and 310b. The line 430 is the net magnetic field generated by the combination of the self - magnetic field generated by the length 200 of the superconducting material and the applied magnetic field of the permanent magnets 310a and 310b, that is, the sum of the lines 410 and 420. From FIG. 4B, it was found that when the current flows in one direction along the length 200 of the superconducting material, the self - magnetic field has a profile similar to the applied magnetic field, that is, the shapes of the lines 410 and 420 are similar.

[0088] The magnetic field state shown in FIG. 4A is the "forward - bias" state of the electrical device 100. In this state, the current flows in one direction throughout the length 200 of the superconducting material, and the self - magnetic field generated by the length 200 of the superconducting material has the same intensity but the opposite direction to the applied magnetic field of the permanent magnets 310a and 310b at each point along the width of the length 200 of the superconducting material. As a result, the magnetic fields at least partially cancel each other out or negatively interfere, and the net magnetic field (shown by the line 430) is relatively low across the entire width of the length 200 of the superconducting material. The relatively low net magnetic field strength means that the suppression of the critical current of the length 200 of the superconducting material is relatively small. For example, the suppression of the critical current of the length 200 of the superconducting material is less than when the length 200 of the superconducting material is only under the applied magnetic field of the permanent magnets 310a and 310b, that is, when no current is flowing through the entire length 200 of the superconducting material. As a result, the critical current I of the length 200 of the superconducting material in the forward - bias statec,順方向 is greater than the critical current I of the length 200 of the superconducting material when no current is flowing, that is, |I c,0 | > |I c,順方向 |. c,0

[0089] The magnetic field state shown in FIG. 4B is the "reverse bias" state of the electrical device 100. In this state, the current flows through the entire length 200 of the superconducting material in a direction opposite to the direction in which the current flows in the forward bias state. Therefore, the self-magnetic field generated by the length 200 of the superconducting material is in the same direction as and can have the same intensity as the applied magnetic fields of the permanent magnets 310a and 310b at each point along the width of the length 200 of the superconducting material. As a result, the magnetic fields interfere positively, and the pure magnetic field (shown by line 430) becomes relatively high in a specific region across the width of the length 200 of the superconducting material. The relatively high net magnetic field intensity in these regions (compared to the forward bias state) means that there is a relatively high suppression of the critical current of the length 200 of the superconducting material in these regions. For example, the suppression of the critical current of the length 200 of the superconducting material is greater than when the length 200 of the superconducting material is only subjected to the applied magnetic fields of the permanent magnets 310a and 310b, that is, when no current is flowing through the length 200 of the superconducting material. As a result, the critical current I of the length 200 of the superconducting material in the reverse bias state c,逆方向 is less than the critical current I of the length 200 of the superconducting material when no current is flowing. That is, |I c,0 | < |I c,逆方向 |. As a result, |I c,0 | < |I c,逆方向 |. This results in a diodicity and a diode effect in the length 200 of the superconducting material. c,順方向

[0090] ​​In the technical configuration shown in FIG. 3, the diode effect is mainly realized in the edge region of the length 200 of the superconducting material. This is shown by the fact that in the forward bias configuration of FIG. 4A, the net magnetic field changes relatively greatly in the region where the absolute value of x is large, as compared with the reverse bias configuration of FIG. 4B. When x = 0, and for low values of x corresponding to the central region of the length 200 of the superconducting material, the net magnetic field strength is similarly low in both the forward bias configuration and the reverse bias configuration. As a result, the diodicity of the end region of the length 200 of the superconducting material becomes greater than the diodicity of the central region of the length 200 of the superconducting material.

[0091] In other configurations of this technology, the electrical device 100 may include a magnetic field generating device 300 that includes a different number of magnets and / or other magnet arrangements. For example, in one alternative configuration, the magnetic field generating device 300 includes a single permanent magnet 310 disposed on one side of the length 200 of the superconducting material (i.e., spaced in the y direction from the length 200 of the superconducting material and on the opposite side of the plane of the length 200 of the superconducting material), and the polar axis of the magnet 310 is substantially parallel to the width of the length 200 of the superconducting material, i.e., the polar axis is substantially parallel to the x direction.

[0092] In other configurations, the magnetic field generating device 300 may be the same as the arrangement of FIG. 3, but include three, four, or more permanent magnets disposed on one side of the length 200 of the superconducting material, with an even greater number of magnets. The magnets may be arranged such that the polar axes of the alternately arranged magnets are anti-parallel to each other. The magnets may be arranged, for example, in a straight line or other arrangement.

[0093] In yet another form, the magnetic field generating device 300 may include one or more magnets (i.e., disposed at positive y-direction coordinates) on one side of the length 200 of the superconducting material, and may include one or more magnets (i.e., disposed at negative y-direction coordinates) on the opposite side of the length 200 of the superconducting material. For example, in one form, the magnetic field generating device 300 includes two permanent magnets 310a and 310b arranged in the manner shown in FIG. 3 (and the manner described above), and two additional permanent magnets arranged on the opposite side of the length 200 of the superconducting material (i.e., the lower side of the length 200 of the superconducting material as shown in FIG. 3). The two additional permanent magnets may be arranged such that their polar axes are substantially anti-parallel to each other and are substantially parallel to the y-direction.

[0094] The form of the technology in which the applied magnetic field is generated by permanent magnets can be considered a passive electrical device because the electrical device 100 does not include an additional power source for generating the diode effect other than the current flowing through the entire length 200 of the superconducting material where the diode effect is generated.

[0095] In other forms of this technology, the magnetic field generating device 300 may include other types of magnets, such as electromagnets. The electromagnets can be arranged in the same positions and directions as those described in the form of the technology using permanent magnets. The form of the technology in which the applied magnetic field is generated by an electromagnet can be considered an active electrical device because, in addition to the current flowing along the length 200 of the superconducting material where the diode effect is generated, the electromagnet can use a power source to supply current to the electromagnet and generate the diode effect. 6.2.6.1.2. Experimental Results / Simulations - Permanent Magnets

[0096] Figure 5 is a schematic diagram of an electrical device 100 according to one form of a technique similar to the arrangement of Figure 3. This setup was used to experimentally test the electrical device. The electrical device 100 in Figure 5 (referred to as a diode in the following description) includes two opposing neodymium bar magnets 310a, 310b to generate a static applied magnetic field in a length 200 of superconducting material in the form of an HTS tape. The magnets are attached to a G10 base 320. The purpose of this experiment is to find the optimal position of the magnets to maximize the diodicity. To facilitate this, the apparatus shown in Figure 5 was designed and manufactured to allow for a reasonable degree of freedom in the placement of the magnets in both the x - direction and the y - direction. The position of the magnets can be selected by inserting a 1.5 - mm - thick G10 spacer at a specific location. To adjust the horizontal position, spacers were placed between the magnet holder and the aluminum end stops. The vertical position was changed by placing a spacer under the magnet within the holder. Alternatively, thinner spacers could also be used.

[0097] For the purposes of the experiment, the sample HTS tape was etched, and the critical current of the HTS tape in a specific region decreased. Normally, when a magnetic field is applied to a specific region, the critical current in that region decreases and etching becomes unnecessary. However, in the forward - bias direction, the critical current can increase beyond the rest of the tape, which means that a quench could occur somewhere else. Therefore, etching was used to prevent such a situation. The electric field of the tape was measured using voltage taps placed on both sides of the etched region. These voltage taps were connected to a nanovoltmeter that could be monitored and sampled using a LabVIEW program.

[0098] The diode was subjected to a plurality of complete forward and reverse bias cycles to test whether it affects the diode characteristics.

[0099] The experimental results are shown in Figure 6. This is a graph showing the forward and reverse critical currents and the diodeicity of the diode arrangement of Figure 5. The current was passed through the diode five times until the results shown in the figure were obtained. The average silicon dioxide content was 11.31 ± 0.03%.

[0100] The results of another experimental test of the prototype constructed based on the arrangement shown in Figure 3 are shown in Figure 7. In this version, the diodeicity of silicon dioxide was calculated to be 0.266 (or 26.6%).

[0101] The positions of the permanent magnets 310a and 310b can be moved to change the performance of the diode. For example, to optimize the diodeicity of the diode, the desired positions of the magnets can be selected through trial and error or by analyzing the positions of the magnets that optimize the diodeicity by simulating the arrangement. Figure 8 shows a schematic diagram of the modeling geometry according to one form of this technique. The arrangement of the items of the electrical device 100 composed of the length 200 of the superconducting material and the two permanent magnets 310a and 310b modeled in the analysis is the same as the arrangement shown in Figure 3. The x and y variables are the distances from the center of one of the permanent magnets to the center of the length 200 of the superconducting material in the x - direction and y - direction, respectively. The center of the other magnet is arranged at (-x,y).

[0102] The results of an example of the simulation are shown in Figure 9. In Figure 9, the normalized bipolarity is shown on the scale on the right side of the figure. This simulation shows that the number of dipoles increases with the decrease of x and the increase of y, but when the value of x is low, the number of dipoles decreases when y increases beyond the optimal value. Other simulations have shown that relatively high bipolarity can be achieved when the value of x is relatively low regardless of the value of y. These results indicate that the closer the permanent magnets 310a and 310b are, the more likely it is to achieve a higher diodeicity, but there may be an optimal separation distance between the permanent magnets for any value of y. In some forms, these distances can be determined experimentally.

[0103] In the simulations performed, it has been shown that diode reversals occur at specific positions of the permanent magnets 310a and 310b in the arrangements as shown in FIGS. 3 and 8. This is represented by the negative value of the number of dipoles at the lower right of the graph in FIG. 9. That is, when the value of x is relatively high and / or when the value of y is relatively low, the bias of the diode can be reversed. This bias reversal can occur for a predetermined distance from the y-direction length of the superconducting material 200 to the magnet when the magnets are arranged at a distance greater than the threshold distance.

[0104] This bias reversal is shown by FIGS. 10A and 10B, which are magnetic field line plots of two exemplary arrangements of the permanent magnets 310a and 310b compared to the length 200 of the superconducting material in the arrangements of FIGS. 3 and 8. In these figures, the positive and negative signs indicate the direction of the net magnetic field in the y-direction, i.e., the up and down of the page, at the relevant points, and the density of the signs roughly indicates the strength of the magnetic field in the relevant region. The field within the ellipse around the length 200 of the superconducting material is amplified to show more clearly the nature of the field within this region. It has been found that the direction of the net magnetic field at each end of the length 200 of the superconducting material in FIG. 10A is opposite to that in FIG. 10B. The diode arrangement in FIG. 10A has a bias opposite to that of the diode arrangement in FIG. 10B, and the permanent magnets 310a and 310b are arranged further apart (i.e., the x value is large) and closer to the plane of the length 200 of the superconducting material (i.e., the y value is small). The y-component of the applied magnetic field generated by the permanent magnet points in the opposite direction in the manner of the magnet compared to the magnetic field of the pole. This means that when the magnet is arranged at a relatively high position compared to the length 200 of the superconducting material, the magnetic field in the length 200 of the superconducting material mainly originates from the poles of the magnet. When the magnet is lowered so as to be located on almost both sides of the length 200 of the superconducting material, the magnetic field in the manner of the magnet becomes dominant, and the y-component of the magnetic field in the tape is reversed. This reverses the polarity of the diode, and negative diode characteristics are observed in the arrangement of FIG. 10B compared to the arrangement of FIG. 10A.

[0105] In one form of this technology, the electrical device 100 may include a magnet position mechanism configured to controllably move the positions of the permanent magnets 310a and 310b to select a desired orientation in the forward bias direction and the reverse bias direction. 6.2.6.1.3. Additional Superconductors

[0106] In another form of this technology, the electrical device 100 includes a magnetic field generating device 300 that includes a length 330 of a second superconducting material for generating an applied magnetic field. The length 330 of the second superconducting material generates a magnetic field when current flows through it. This is the same as what occurs when a conductor carries a current, as previously explained.

[0107] In an exemplary form, the length 330 of the second superconducting material is disposed near the length 200 of the first superconducting material. The length 330 of the second superconducting material may be disposed such that the length 200 of the first superconducting material receives an applied magnetic field of a strength similar to, for example, the same magnitude as, the self - magnetic field generated by the length 200 of the first superconducting material when current flows through it. In these forms, the length of the first superconducting material and the length of the second superconducting material are electrically separated from each other.

[0108] Exemplary forms of the electrical device 100 with this type of arrangement are shown in FIGS. 11 and 12, which are a perspective view and an end cross - sectional view of the electrical device 100, respectively. In the examples of FIGS. 11 and 12, the length 330 of the second superconducting material is oriented substantially parallel to the length 200 of the first superconducting material. For example, the lengths of both superconducting materials are in the form of tapes (e.g., HTS tapes), and the faces of the two tapes are parallel to each other. Further, the lengths of the tapes may be arranged parallel to each other. The two tapes may be disposed close to each other such that, for example, the distance between the tape faces is significantly smaller than the width of either tape.

[0109] FIG. 12 shows a Hall probe array disposed under a length 330 of a second superconducting material, which shows an exemplary arrangement that can be used for experimentally verifying the operation of the electrical device 100, and the array can be omitted from the electrical device 100 in normal operation.

[0110] In one experiment using the exemplary forms shown in FIGS. 11 and 12, a diode characteristic of 10.85 ± 0.04% was achieved with a forward bias current on the order of several hundred amperes. During the experiment, the behavior of the magnetic field was analyzed and found to be consistent with the aforementioned theory. Due to continuing problems with the power supply and Hall probe array, the quality of the results deteriorated and the amplitude of the obtained diodes decreased, but the data still showed a strong tendency to support the functionality of the device.

[0111] Another exemplary form of this technique is shown in FIG. 13. In this form, the electrical device 100 includes a magnetic field generating device 300 that includes two superconducting materials 330, such as HTS tapes. One of the tapes is disposed on one side of a length 200 of the superconducting material where the diode effect occurs, similar to that described with respect to the forms of FIGS. 11 and 12, and the other tape is disposed in the vicinity and on the opposite side of the length 200 of the superconducting material, but is electrically insulated. The two tapes can be arranged substantially parallel to each other and / or to the length 200 of the superconducting material.

[0112] In use, a current is passed through the entire length of each HTS tape, each tape generates a magnetic field, and the combination of these two magnetic fields becomes the applied magnetic field of the magnetic field generating device 300. In a particular form, a DC current is passed in the same direction across the entire length of each HTS tape, for example, in the direction indicated by arrow I in FIG. 13. ゲート The magnetic field strength profiles of the applied magnetic fields in the forward and reverse bias configurations of the magnetic field generating device 300 in the form shown in FIG. 13 are similar to those shown in FIGS. 4A and 4B.

[0113] In an experiment using the electric device 100 equipped with such a magnetic field generating device 300, it has been suggested that with this configuration, there is a possibility of achieving a higher degree of diodicity than in a form where the magnetic field generating device 300 includes a single HTS tape close to the length 200 of the superconducting material. For example, as an example of such a device, a diodicity of 15.6% was recorded.

[0114] The electric device 100 according to the technical form shown in FIGS. 11 to 13 is considered to be an active device because an additional power source is used to supply current to the length 330 of the second superconducting material (that is, in addition to supplying current to the length 200 of the superconducting material). In a specific form, power may be supplied from a DC power source to the length of the superconducting material 330 (for example, to rectify alternating current), and alternating current may be supplied to the length 200 of the superconducting material. The direction of the bias of the diode effect in the electric device 100 can be adjusted by controlling the direction of the current flowing through the entire length 330 of one or more second superconducting materials. When the direction of the current flowing through the entire length 330 of the second superconducting material is changed to the opposite direction, the direction of the current flowing through the entire length 200 of the superconducting material corresponding to the forward bias direction and the reverse bias direction is switched. This effect can be utilized in some forms of the technology. For example, the electric device 100 may include a current control mechanism configured to selectively control the direction of the current flowing through one or more superconducting materials 330. Any suitable current control mechanism may be used. In addition, the current control mechanism may be configured to selectively stop supplying current to the length 330 of one or more superconducting materials. In these forms, the diode effect of the electric device 100 can be selectively turned off and on, and when turned on, the direction of the bias can be controlled, that is, the electric device 100 can function as a controllable direction-reversible diode. The electric device 100 in these forms can be considered to operate as a transistor or similarly to a transistor. 6.2.6.2. Second Magnetic Field Generating Device

[0115] In certain forms of the technology, the electrical device 100 includes a second magnetic field generating device 500 in addition to the magnetic field generating device 300, which may be referred to as the first magnetic field generating device 300 to distinguish the two magnetic field generating devices. In use, each of the first magnetic field generating device 300 and the second magnetic field generating device 500 is configured and arranged to apply a magnetic field to the length 200 of the superconducting material. The magnetic fields generated by the first and second magnetic field generating devices may be referred to as the first magnetic field and the second magnetic field, respectively.

[0116] In these forms of the technology, a diode effect can occur in the length 200 of the superconducting material. This is because the combined effect of the two magnetic fields when the current flows in one direction through the entire length 200 of the superconducting material is different from the combined effect of the two magnetic fields when the current flows in the opposite direction through the entire length 200 of the superconducting material.

[0117] Examples of such forms of the technology are described below. In these forms, in addition to the magnetic fields generated by the first and second magnetic field generating devices, it is necessary to understand that the length 200 of the superconducting material itself also generates a self-magnetic field, as described previously for other forms of the technology. In some cases, the magnitude and effect of this self-magnetic field may be negligibly small compared to the magnitude and effect of each magnetic field generated by the first and second magnetic field generating devices. As a result, in some forms of the technology where there are two other magnetic fields that interact to generate a net magnetic field acting on the length 200 of the superconducting material, the self-magnetic field may be almost negligible.

[0118] FIG. 14A is a schematic diagram of an electrical device 100 according to one form of the technology of the present invention. The electrical device 100 shown in FIG. 14A includes a length 200 of a superconducting material that may be in the form of an HTS tape. The length 200 of the superconducting material extends in and out of the page. In use, a current can flow in either direction along the length 200 of the superconducting material.

[0119] The electrical device 100 of FIG. 14A includes a first magnetic field generating device 300. The first magnetic field generating device 300 includes a permanent magnet 310 disposed at a position where the generated first magnetic field is applied to the length 200 of the superconducting material. In the exemplary form of FIG. 14A, this is achieved, for example, by using a magnetic core 340 in any of the forms of the magnetic core 340 described above. The magnetic core 340 guides the first magnetic field to the length 200 of the superconducting material. For example, the magnetic core 340 may include one or more magnetic core portions arranged to form a gap 350 between two ends of the magnetic core portion. The length 200 of the superconducting material may be disposed within the gap 350. This arrangement may have the effect of generating a substantially uniform first magnetic field between the ends of the magnetic core portion. The x-direction change in the strength of the first magnetic field in the length 200 of the superconducting material (the distance along the width of the length 200 of the superconducting material, i.e., the left-right direction in FIG. 14A) is shown by line 420 in FIGS. 15A and 15B. The magnitude of the magnetic field is substantially the same for all x over the entire width of the length 200 of the superconducting material. The direction of the first magnetic field depends on the polarity of the permanent magnet 310, but is shown as positive in FIGS. 15A and 15B.

[0120] In the illustrated form, the magnetic core 340 is formed from two parts, one end of each magnetic core part forms the edge of the gap 540, and the other end of each magnetic core part abuts against the permanent magnet 310. The magnetic core part can be, for example, substantially U-shaped or C-shaped. In other forms, the magnetic core 340 can have a different shape, and other examples of suitable magnetic cores are described above.

[0121] In an alternative form, the first magnetic field generating device 300 may include a different form of magnetic field generating device, such as an electromagnet. For example, a coil of conductor (e.g., superconductor) can be wound around the magnetic core 340 to induce a first magnetic field in the core when an electric current flows through the conductor. In some alternative forms, the first magnetic field generating device 300 may not include the magnetic core 340.

[0122] The form of the electrical device 100 shown in FIG. 14A also includes a second magnetic field generating device 500. The second magnetic field generating device 500 is also disposed at a position where the magnetic field it generates, i.e., the second magnetic field, is applied to the length 200 of the superconducting material. The second magnetic field generating device 500 includes a coil 510 of a conductor through which a current can flow. When a current flows through the coil 510 as described above, a second magnetic field is generated. The length 200 of the superconducting material can be arranged with respect to the coil 510 such that the second magnetic field is applied. For example, the length 200 of the superconducting material can be disposed within the coil 510. In the form of the electrical device 100 shown in FIG. 14A, the coil 510 is disposed around a gap 350 defined by a magnetic core 340. In some forms, at least a part of the coil 510 is wound around the magnetic core 340, and all of the coil 510 can be wound around the magnetic core 340. By disposing the coil 510 in this way, the second magnetic field also becomes substantially uniform over the width of the length 200 of the superconducting material. The magnetic field lines of the second magnetic field can be substantially parallel to the magnetic field lines of the first magnetic field. The direction (i.e., polarity) of the second magnetic field can be determined by the direction of the current flowing through the entire coil 510.

[0123] As shown in the circuit diagram of FIG. 14B, an electrical device 100 in the same form as shown in FIG. 14A is schematically shown connected to an AC power supply 700, and the conductor forming the coil 510 can be a length of conductor, such as a length of superconducting material, connected in series to the length 200 of the superconducting material where the diode effect is generated. As a result, the direction of the current flowing through the entire length 200 of the superconducting material where the diode effect is generated is linked to the direction of the current flowing through the entire coil 510, and consequently linked to the direction of the second magnetic field acting on the length 200 of the superconducting material. This link is used to create an asymmetry in the net magnetic field along the entire length 200 of the superconducting material according to the direction of the current flowing through the entire length 200 of the superconducting material. Also, since the current flowing through the coil 510 that generates the second magnetic field is the same as the current flowing through the length of the conductive material 200 that undergoes the diode effect, no additional power source for generating the diode effect is required other than the current flowing through the length 200 of the superconducting material where the diode effect is generated, and the technology in this form can be regarded as a passive device.

[0124] FIG. 15A is a graph showing the change in the magnetic field strength in the length 200 of the superconducting material when the current flows in one direction through the entire length 200 of the superconducting material of FIGS. 14A and 14B. In this graph, line 420 is the first magnetic field applied by the first magnetic field generating device 300 (i.e., the permanent magnet 310 of FIGS. 14A and 14B), line 440 is the second magnetic field applied by the second magnetic field generating device 500 (i.e., the coil 510 through which the current flows), and line 430 is the net magnetic field (i.e., the sum of the first magnetic field and the second magnetic field). FIG. 15B shows the same magnetic field strength when the current flows in the opposite direction through the entire length 200 of the superconducting material.

[0125] The situation shown in FIG. 15A is the forward bias configuration of the electrical device 100. In this configuration, the first magnetic field and the second magnetic field act in opposite directions. As a result, when they combine to generate a net magnetic field, their magnitudes cancel each other out, and the magnitude of the net magnetic field becomes relatively low. For example, if the absolute magnitudes of the first magnetic field and the second magnetic field are equal, the net magnetic field can be close to zero or substantially zero. In this configuration, the suppression of the critical current of the length 200 of the superconducting material by the applied net magnetic field is relatively small. As a result, the critical current of the length 200 of the superconducting material becomes relatively high.

[0126] The situation shown in FIG. 15B is the reverse bias configuration of the electrical device 100. In this configuration, the current flowing through the coil 510 is in the opposite direction to that during forward bias verification, and the first magnetic field and the second magnetic field act in the same direction. As a result, when they combine to generate a net magnetic field, their magnitudes are added together, and the magnitude of the net magnetic field becomes relatively high. In this configuration, the critical current of the length 200 of the superconducting material is more significantly suppressed by the applied net magnetic field. As a result, the critical current of the length 200 of the superconducting material becomes relatively low compared to the case of the forward bias configuration.

[0127] This difference between the critical current of the length 200 of the superconducting material and the forward bias configuration and the reverse bias configuration depends on the direction of the current flowing through the entire length 200 of the superconducting material, and generates the diode effect in the length 200 of the superconducting material and the value of the diodicity defined above.

[0128] When configuring the appropriate electrical device 100 to operate in the manner described herein, it is understood that various parameters of the device that affect the strength and direction of the magnetic field can be selected to achieve relative first and second magnetic field strengths similar to those shown in FIGS. 14A and 14B. Further, the parameters can be selected such that the magnitude of the net magnetic field applied to the length 200 of the superconducting material maintains the length 200 of the superconducting material in the superconducting state at least in the forward bias configuration and, in some forms, also maintains an operating current of a desired magnitude in the reverse bias configuration. In some forms, the electrical device 100 is configured such that the net magnetic field strength applied to the length 200 of the superconducting material in the forward bias configuration (as shown in FIG. 15A) is substantially zero, i.e., the magnitudes of the first and second magnetic fields are equal but they act in opposite directions.

[0129] In certain forms of the technology, the length 200 of the superconducting material in which the diode effect is generated may have a lower critical current than the adjacent portions of the superconducting material coupled in series with the length 200 of the superconducting material, which includes the length of the superconducting material 330 forming the coil 510 in the exemplary form of FIG. 14A. As the current density approaches, equals, or exceeds the critical current density, the superconductor transitions to a higher resistance state. For example, when the current density exceeds the critical current density, the superconductor becomes a non-superconducting state. When operating the electrical device 100 as a diode, it is desirable for only the length 200 portion of the superconducting material where the diode effect occurs to approach, substantially equal, or exceed the critical current density, and it may be desirable for this not to be the case in other portions of the superconducting circuit. In certain forms, this effect can be achieved, for example, by the length 200 of the superconducting material in which the diode effect is generated having a smaller cross-sectional area than the adjacent portions of the superconducting material coupled in series with the length 200 of the superconducting material. The current density flowing through the entire length of the superconducting material depends on the magnitude of the current flowing through the material and the cross-sectional area of the length of the superconducting material. When the length 200 of the superconducting material has a smaller cross-sectional area than other portions of the superconducting circuit (for example, when the width is narrow in the case of an HTS tape), the critical current density is achieved in the length 200 of the superconducting material before other portions of the circuit. The difference in cross-sectional area between adjacent portions of the superconducting material can be a useful way to achieve a difference in critical current between these portions when the portions are formed from a single length of superconducting material. In other forms, differences can be achieved by other methods, such as using different superconducting materials for two portions, for example.

[0130] FIG. 16 is a graph showing current versus electric field for the length 200 of the conductor superconducting material coated with the rare earth element BaCuO by computer modeling of the form of the technology shown in FIG. 14A. In the exemplary modeling, the critical current in the forward bias configuration is 233.5 A and the critical current in the reverse bias configuration is 55.7 A. This means that the silicon dioxide content is 76.1%.

[0131] The length 200 of the superconducting material within the electrical device 100 of FIG. 14A can be affected by the change in the net magnetic field over its entire width between the forward bias configuration and the reverse bias configuration. This can result in diode characteristics that are greater than those of other forms of technology, such as the electrical device of FIG. 3, which experiences a change in the net magnetic field only in the regions at the ends of the length of the superconducting material.

[0132] In some forms, the coil 510 in the form of the electrical device 100 shown in FIG. 14A can have an inductance sufficient to affect the operation of the device. This can, for example, affect the frequency response of the electrical device 100.

[0133] By selecting specific parameters of the electrical device 100 according to the form of the technology shown in FIG. 14A, the generated diodicity can be changed. In some forms, it may also be possible to adjust these parameters to increase the diodicity and, in some cases, optimize it significantly. FIG. 17 is a graph showing the relationship between specific parameters within the electrical device 100 according to the form of the technology shown in FIG. 14A. The line 610 represents the critical current of an exemplary superconducting material that can be used to form the length 200 of the superconducting material with respect to the applied external perpendicular magnetic field. This line shows that the critical current is suppressed as the absolute value of the applied magnetic field increases. The line 620 shows the saturation magnetic field of the material used to form the magnetic core. For example, the saturation magnetic field of iron is approximately 1.2 T.

[0134] Line 630 indicates the change in the transport current flowing through the entire length of the superconducting material 200 and the coil 510 (vertical axis) in accordance with the value of the second magnetic field generated by the second magnetic field generating device 500, for example, the coil 510 made of a superconducting material. Line 630 is a straight line, and in the case of the second magnetic field generating device 500 including the coil 510, its gradient is a function of the number of turns of the superconductor in the coil 510. When no current is flowing through the coil 510, the second magnetic field does not exist. Thus, the intersection of line 630 and the horizontal axis (indicating the value of the net applied magnetic field) represents the magnitude of the first magnetic field generated by the first magnetic field generating device 300, that is, the permanent magnet 310 and the magnetic core 340 in the exemplary form of FIG. 14A.

[0135] When the electrical device 100 is biased in the forward direction, a current flows through the coil 510 in a direction opposite to the first magnetic field generated by the permanent magnet 310 due to the second magnetic field generated by the coil 510. This state is represented by the value of the critical current indicated by the intersection of line 630 and the upper part of line 610, that is, line 640. When the electrical device 100 is reverse-biased, the current flows through the coil 510 in the opposite direction, and the second magnetic field generated by the coil 510 is added to the first magnetic field generated by the permanent magnet 310. This state is represented by the value of the critical current indicated by the intersection of line 630 and the lower part of line 610, that is, line 650. In the technical form where the electrical device 100 includes the magnetic core 340, the intersection of line 630 and the lower part of line 610 occurs at the saturation magnetic field of the magnetic core, because line 630 becomes non-linear for higher magnetic field strengths. This limitation does not apply to certain specific forms of technology where the electrical device does not include the magnetic core 340.

[0136] The diodeicity of the electrical device 100 is based on the relative difference between the forward bias critical current and the reverse bias critical current according to the above formula. The parameters of the electrical device 100 can be selected to generate a desired diodeicity. In particular, the electrical device 100 may be designed to maximize the diodeicity using the information shown in FIG. 17. For example, the coil 510 can be designed to have an appropriate number of coils, so that the difference between the upper intersection and the lower intersection is maximized by the gradient of the line 630, and the diodeicity of the electrical device 100 is maximized. In a specific form, it has been found that maximum (or nearly maximum) diode characteristics occur when the electrical device 100 is configured such that the line 630 substantially touches the line 610. Since the line 610 represents the critical current of the length 200 of the superconducting material, bringing the line 630 into contact with the line 610 represents making the configuration of the electrical device 100 the maximum possible current without losing the superconducting state beyond the critical current.

[0137] Another design consideration is the trade-off between the self-inductance of the coil 510 and the diodeicity. It may be desirable to reduce the self-inductance of the coil 510, but doing so may also reduce the diodeicity of the electrical device 100. The desired balance can be determined through experiments on the given parameters and varies depending on the application of the electrical device 100. 6.3. Other Considerations

[0138] Unless the context clearly dictates otherwise, throughout the description and claims, words such as "comprise", "comprising", etc. shall be construed in an inclusive sense, i.e., in the sense of "including, but not limited to", rather than in an exclusive or exhaustive sense.

[0139] The entire disclosure contents of all applications, patents, and publications cited above and below are incorporated herein by reference.

[0140] A reference to prior art in this specification does not admit, suggest, or should be construed to admit or suggest that such prior art forms part of the common general knowledge in the art in any country in the world.

[0141] Broadly speaking, the technology may be constituted by the parts, elements, and features described or shown in the specification of the application, individually or in combination, either singly or in any or all combinations of two or more of said parts, elements or features.

[0142] In the above description, where integers or their equivalents are referred to known components, these integers are incorporated as if individually described.

[0143] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the technology and without diminishing the attendant advantages. Accordingly, such changes and modifications are intended to be included within the scope of this technology.

Claims

1. An electrical device, comprising: a length of superconducting material including two substantially parallel opposing surfaces; and a magnetic field generating device including two permanent magnets disposed on the same side of the length of the superconducting material, wherein the polar axes of the two permanent magnets are arranged substantially antiparallel to each other, and the polar axes of the two permanent magnets are oriented substantially perpendicular to the plane of the length of the superconducting material. The magnetic field generating device is configured and arranged to apply a magnetic field to the length of the superconducting material. When a first current flows in a first direction through the length of the superconducting material, a first critical current is generated in the length of the superconducting material. When a second current flows in a second direction through the length of the superconducting material, and the second direction is opposite to the first direction, a second critical current is generated in the length of the superconducting material. The first critical current is substantially greater than the second critical current.

2. When the current flows through the entire length of the superconducting material, the length of the superconducting material generates a self-magnetic field, and the self-magnetic field and the applied magnetic field generate a net magnetic field. The magnetic field generating device is configured and arranged such that when the first current flows in the first direction through the length of the superconducting material, the magnitude of the net magnetic field is substantially smaller than when the second current flows in the second direction through the length of the superconducting material. The electrical device according to claim 1.

3. The magnetic field generating device is configured and arranged such that when the current flows in the first direction through the entire length of the superconducting material, the applied magnetic field is the same as the self-magnetic field. The electrical device according to claim 2.

4. The two permanent magnets are disposed at an equal distance from the length of the superconducting material. The electrical device according to any one of claims 1 to 3.

5. The length of the superconducting material includes a length, a width, and a depth. The depth is the distance between two substantially parallel opposing surfaces. The length is significantly greater than the width, and the width is significantly greater than the depth. The electrical device according to any one of claims 1 to 4.

6. The two permanent magnets are disposed substantially aligned along the length of the superconducting material. The electrical device according to any one of claims 1 to 5.

7. Both permanent magnets are offset from the length of the superconducting material by substantially the same distance in a direction perpendicular to the plane of the length of the superconducting material. The electrical device according to any one of claims 1 to 6.

8. The two permanent magnets are separated from each other at intervals in a direction parallel to the width of the length of the superconducting material, and the interval is larger than the width of the length of the superconducting material. The electrical device according to any one of claims 1 to 7.

9. The magnetic field generating device includes a third permanent magnet and a fourth permanent magnet disposed on the length of the superconducting material on the side opposite to the two permanent magnets. The electrical device according to any one of claims 1 to 8.

10. An electrical device, a length of superconducting material, a first magnetic field generating device configured and arranged to apply a first applied magnetic field to the length of the superconducting material, a second magnetic field generating device configured and arranged to apply a second applied magnetic field to the length of the superconducting material, and the first applied magnetic field and the second applied magnetic field generate a net magnetic field, the first magnetic field generating device and the second magnetic field generating device are such that when the first current flows in the first direction through the length of the superconducting material, the net magnetic field has a first magnitude, the length of the superconducting material has a first critical current, and when the second current flows in a second direction opposite to the first direction, the net magnetic field has a second magnitude, and the length of the superconducting material has a second critical current, and are configured and arranged accordingly, the first magnitude is substantially lower than the second magnitude, and the first critical current is substantially larger than the second critical current. The electrical device.

11. The first magnetic field generating device includes a magnetic core formed of a material having a high magnetic permeability, and the magnetic core is disposed so as to guide the applied magnetic field to the length of the superconducting material. The electrical device according to claim 10.

12. The magnetic core includes a gap, and the length of the superconducting material is disposed within the gap. The electrical device according to claim 11.

13. The length of the superconducting material is the length of a first superconducting material, the electrical device further includes the length of a second superconducting material, the length of the second superconducting material is coupled in series to the length of the first superconducting material, the second magnetic field generating device includes the length of the second superconducting material, and the second applied magnetic field is generated by the length of the second superconducting material. The electrical device according to any one of claims 10 to 12.

14. The length of the second superconducting material is arranged in a coil shape. The electrical device according to claim 13.

15. The length of the first superconducting material is the electrical device according to claim 14, which is disposed inside the coil.

16. The length of the second superconducting material has a critical current higher than that of the length of the first superconducting material, and the electrical device according to any one of claims 13 to 15.

17. The cross-sectional area of the length of the first superconducting material is smaller than the cross-sectional area of the length of the second superconducting material, and the electrical device according to claim 16.

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