JPH04352373A - High-temperature superconducting switching element - Google Patents

Abstract

PURPOSE:To make the title device compact and to make its power loss very small. CONSTITUTION:An electric current is made to flow to a direction perpendicular to the bonding face of a high-temperature superconductor 2 in which high- temperature superconductor layers 4, 4,..., 4 and insulator layers 5, 5,..., 5 have been Josephson-bonded in a multilayer manner; a magnetic field is applied or cut in a direction parallel to the bonding face. Thereby, the electric field is switching-controlled.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to switching elements used in various electrical and electronic devices. More specifically, the present invention relates to a high temperature superconducting switching element suitable for use in power storage systems, motors, etc. using superconductivity, which are expected to be put to practical use in the future.

0002

[Prior Art] Conventionally, AC/DC converters, motors, large electrical appliances,
Typical high-power switching elements used in electronic equipment include thyristors, triacs, power transistors, and power FETs. These conventional switching elements are compact and very easy to control.

0003

[Problems to be Solved by the Invention] However, conventional switching elements have a large power loss, and when large currents are controlled by these switching elements, the amount of heat generated is also extremely large, and heat dissipation measures are also required. was. Therefore, even if the switching element itself is small, a relatively large space is required for heat dissipation.

[0004] Furthermore, since these switching elements are manufactured on the assumption that they will operate at room temperature, when used in equipment that uses superconductivity, a large temperature difference will occur between the switching element and the main body of the equipment that uses superconductivity. , heat penetration loss in the equipment body is also large. Furthermore, as electronic devices using superconductivity, superconducting digital devices that aim to save power and significantly increase processing speed are currently under research and development, but there are no power switching devices for large-capacity power.

An object of the present invention is to provide a high temperature superconducting switching element with extremely low power loss.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the high temperature superconducting switching element of the present invention comprises Josephson bonding of high temperature superconductors in a multi-layered manner, and a current flow in a direction perpendicular to the bonding surface of the high temperature superconductors. The switching control of the current is carried out by applying and cutting off a magnetic field from a direction parallel to the junction surface.

[0007]

[Operation] Therefore, when a magnetic field is applied, the Josephson coupling between the high temperature superconductor layers is broken, creating a high resistance and blocking the flow of current. Furthermore, when no magnetic field is applied, each layer of the high temperature superconductor is Josephson coupled and a Josephson current flows, so the resistance value becomes 0. Therefore, the switching of the current flowing in the direction perpendicular to the junction surface of the high temperature superconductor is controlled by turning the magnetic field ON and OFF.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained in detail below based on embodiments shown in the drawings.

FIG. 2 schematically shows an embodiment of the high temperature superconducting switching element of the present invention. In this high-temperature superconducting switching element, a high-temperature superconductor 2 with current leads 3, 3 fixed to both sides thereof is arranged in a magnetic field, for example, inside a coil 1.
By energizing the coil 1, a magnetic field generated within the coil 1 is applied to the high temperature superconductor 2. As shown in the detailed view of FIG. 1, the superconductor portion 2 is formed into a multilayered structure in which high-temperature superconductor layers 4 and insulator layers 5 are alternately laminated. Current leads 3, 3 made of high temperature superconductor are fixed. The insulator layers 5, 5, ..., 5 are formed to have a thickness of, for example, several angstroms to several tens of angstroms, and the high temperature superconductor layers 4,
4,...,4 are Josephson-combined. Therefore, when a magnetic field is not applied in a direction parallel to the bonding surface of this high temperature superconductor layer 4, a Josephson current is generated in the superconductor portion 2 due to the Josephson effect, and both current leads of this superconductor portion 2 are generated. The resistance in three directions becomes zero. In other words, when a current is passed between both current leads 3, the power loss in the superconductor portion 2 becomes zero. When a magnetic field of several hundred Gauss is applied in a direction parallel to the bonding surface of the superconductor portion 2, the Josephson coupling occurring in the high temperature superconductor layers 4, 4,..., 4 is interrupted, and the superconductor portion 2
becomes high resistance and turns off the current. As a switching element, it is desirable to increase this resistance value to prevent leakage current, so as in this embodiment, insulating layers 5, 5, ...,
It is desirable to have a multilayer structure in which a large number of 5s are present. The high-temperature conductor layers 4, 4,..., 4 and the insulator layers 5, 5,..., 5 need to be aligned extremely smoothly within a few angstroms, so this embodiment is not particularly limited. In this case, they are made by alternating epitaxial growth. Therefore, it is necessary to match the crystal structures and lattice constants of the materials constituting the high temperature superconductor layers 4, 4, . . . , 4 and the insulator layers 5, 5, . For example, in this example,
Yttrium-barium-based Y-Ba2-Cu3-Ox is applied to the high-temperature superconductor layers 4, 4,..., 4, and the insulator layers 5, 5
,...,5 is praseodymium barium-based Pr-Ba2 −
The superconductor portion 2 is made by alternate epitaxial growth using Cu3-Ox.

Since the device is constructed as described above, it operates as a switching element in the following manner. By passing a current through the coil 1, a magnetic field of an appropriate strength, for example, several hundred Gauss, is generated in a direction parallel to the bonding surfaces of the layered high temperature superconductors 4, 4, ..., 4 constituting the high temperature superconductor portion 2. When applied, the Josephson coupling of each high temperature superconductor layer 4, 4, . On the other hand, when the current supply to the coil 1 is stopped and the magnetic field is removed, the high temperature superconductor layers 4, 4, . . . , 4 are Josephson-coupled and a Josephson current flows. That is, it is turned on in a non-excited state and turned off in an excited state.

[0011] The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in this embodiment, a case has been described in which the superconductor portion 2 is made of an yttrium-barium-based high-temperature superconductor and a praseodymium-barium-based insulator, but the superconductor portion 2 is not particularly limited to this, and other high-temperature superconductors may be used. Needless to say, it is possible to use other materials such as or insulators. Further, it is possible to eliminate power loss in the coil 1 by forming the coil 1 itself with a superconductor, but if the power loss is ignored, there is no need to form the coil with a superconductor. Further, in this embodiment, the magnetic field is controlled by a coil, but the system is not limited to this method, and any method that can control the magnetic field with a predetermined Gauss number may be used.

0012

[Effects of the Invention] As is clear from the above explanation, the high temperature superconducting switching element of the present invention has a structure in which a Josephson current flows, so that the power loss when the switching element is turned on and off can be ignored. Can be done. Therefore, there is no need to take measures to dissipate heat from the switching elements, and the entire device can be made smaller.

Furthermore, in the high temperature superconducting switching element of the present invention, a layered structure with a large area can be easily formed, so that large current control can be easily performed.

Furthermore, when superconducting devices such as superconducting power storage systems and superconducting motors are put into practical use in the future, the entire system can be made superconducting by using this element, preventing heat from entering from the outside. can do.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a superconductor portion of a high temperature superconducting switching element of the present invention.

FIG. 2 is an explanatory diagram showing one embodiment of the high temperature superconducting switching element of the present invention.

[Explanation of symbols]

1 Coil that generates a magnetic field 2 Superconductor part 4 High temperature superconductor layer 5 Insulator layer

Claims (1)

[Claims] 1. High-temperature superconductors are Josephson-coupled in a multilayered manner, a current is passed in a direction perpendicular to the bonding surface of the high-temperature superconductors, and a magnetic field is applied or cut in a direction parallel to the bonding surface. A high-temperature superconducting switching element characterized in that the current is controlled by switching.