JPH01162178A - Superconductive magnetism detector - Google Patents

Abstract

PURPOSE:To give an output corresponding to the size of magnetic field, by arranging the sectional area of a superconductive member not to be uniform in a flowing direction of current. CONSTITUTION:The sectional area of a superconductive member 2 is made ununiform in a flowing direction of current, thereby to make different the current density in each section of the member. Accordingly, the size of a critical magnetic field is varied along the flowing direction of the current. Thus, a superconductive magnetism detector is constructed. The length of a section which is transformed to a paraconductive state is changed corresponding to the size of the magnetic field, so that the magnetism detector can be obtained in a simple construction which can measure the size of the magnetic field, with having an output characteristic corresponding to the size of the magnetic field. By changing the applying manner of the sectional area of the superconductive member 2 along the flowing direction of the current, various kinds of characteristics can be added.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic detector that utilizes the transition of a superconductor into a superconducting state and a normal conducting state with a critical magnetic field as the boundary.

[Conventional technology]

Even if a superconductor is in a state below the transition temperature where it exhibits superconductivity, it will transition to a normal conduction state if the magnetic field applied to it exceeds a magnitude unique to the superconductor called the critical magnetic field. On the other hand, when the magnetic field decreases below the #-critical magnetic field, most high-temperature superconductors, which have been rapidly developed in recent years, show a transition in the opposite direction to the above, and exhibit high resistance values in the normal conduction state. Magnetic detectors have been proposed that utilize large changes in resistance near a magnetic field.

This detector is designed to detect step-like changes in the magnetic field in the vicinity of the critical magnetic field by utilizing the above-mentioned large changes in the resistance value of the superconductor when a current is passed through it, and is used as a magnetic detection switch. Ru.

[Problem that the invention seeks to solve]

A magnetic detector such as this magnetic detection switch detects a binary change in resistance value due to a relatively large change in the magnetic field near the critical magnetic field, and provides it as a binary output of voltage, so the magnitude of the magnetic field I couldn't get the corresponding output.

This invention solves the above-mentioned drawbacks of superconducting magnetic detectors, and
An object of the present invention is to provide a superconducting magnetic detector capable of providing an output corresponding to the magnitude of a magnetic field.

Means for Solving Problem C] This invention focuses on the fact that the magnitude of the critical magnetic field of a superconductor depends on the current density of the current flowing through the superconductor. The current is non-uniform in the direction of flow.

[Effect]

If the cross-sectional area of a superconductor is non-uniform in the direction of current flow, the current density at each part along the current direction will also be non-uniform, and the length of the part transitioning from the superconducting state to the normal conducting state will vary accordingly. The magnetic field changes depending on the magnitude of the magnetic field. This makes it possible to obtain a resistance value that corresponds to the magnitude of the magnetic field, so it is possible to apply a constant current and obtain an output voltage that corresponds to the magnetic field.

〔Example〕

FIG. 1 is a plan view of an embodiment of a superconducting magnetic detector according to the present invention.A superconductor 1p142 of constant thickness is formed on a substrate l serving as an insulator, and ordinary metal thin film electrodes are formed on both ends of the superconductor 1p142. 3 is provided. The metal thin film electrode 3 has wire bonding pads 4.5 formed at the corners of the substrate l;
A constant current is applied to the superconductor WtWA via external electrodes (not shown) connected to these, and the voltage generated between the metal thin film electrodes is measured.

The width of the superconductor thin film 2 changes linearly in the direction of current flow, and the cross-sectional area in the above direction is non-uniform, and since the thickness of the film is constant, the width changes linearly in the direction of current flow. For this reason, the superconductor WiM via the metal thin film electrode 3
When a current is passed through 42, the current density differs in each part along the direction of flow.

When a magnetic field is applied to the superconductor thin film 2 in this state, the critical magnetic field is small in the narrow section where the cross-sectional area is small and the current density is high, i.e., the narrow section transitions to the normal conduction state. do. The area that has transitioned to the normal conduction state is
It depends on the strength of the applied magnetic field and the magnitude of the current flowing. Ultra low conductivity 1! As mentioned above, the resistance value of the entire 2 changes depending on the width of the part that has transitioned to the normal conduction state, so if a constant current is applied to the ultra-low conductivity thin M42, the resistance value between the electrodes 3 corresponds to the magnitude of the magnetic field. produces an output voltage that can be measured to determine the magnitude of the magnetic field.

This makes it possible to measure continuous changes in the magnetic field, since the above-mentioned transitions behave in opposite directions with respect to increases and decreases in the magnetic field.

The relationship between the output voltage of the magnetic detector and the strength of the magnetic field according to this embodiment is approximately linear as shown in FIG.

One of the major advantages of the magnetic detector according to the present invention is that the shape of the superconductor can be changed to provide arbitrary output characteristics.

FIG. 3 shows a second embodiment of the present invention, in which a step-like ultra-low conductivity thin film 115!6 is formed with the same configuration as the embodiment shown in FIG. Corresponding to the shape of , it has a step-like shape as shown in FIG. Furthermore, in the third embodiment shown in FIG. 5, a superconductor thin film 7 having the shape shown is formed, and as shown in FIG. 6, an output characteristic in which the detection sensitivity varies depending on the strength of the magnetic field is obtained. .

FIG. 7 is an outline drawing of a fourth embodiment of the present invention. In this embodiment, a superconductor thin film 12 of a certain thickness is formed on a truncated cone-shaped insulator ll, and normal conductor metal thin film electrodes 13 and 14 are provided at both ends, respectively, and lead wires 1 are connected to these.
5.1 (i is joined.Superconductor 1a film 12
The area changes along the direction of current flow, and the current density also changes accordingly, exhibiting output characteristics in accordance with this change.

With this type, arbitrary output characteristics can be obtained by changing the shape of the insulator.

In addition, a structure in which the above-mentioned insulator is not used, the superconductor itself has a shape similar to that shown in FIG. 7, and metal thin film electrodes and lead wires are provided at both ends of the superconductor can also produce similar effects.

〔Effect of the invention〕

According to this invention, the cross-sectional area of the superconductor is made non-uniform in the direction of current flow, and by making the current density different in each part, the magnitude of the critical magnetic field changes depending on the direction in which the current flows. Super low N1. It constitutes a magnetic detector. For this reason, the length of the part that transitions to the normal conduction state changes depending on the magnitude of the magnetic field, making it a simple magnetic detector that can measure the magnitude of the magnetic field and has output characteristics according to the magnitude of the magnetic field. is obtained.

It is possible to provide various characteristics depending on how the cross-sectional area of the superconductor is given along the direction of current flow.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an embodiment of a superconducting magnetic detector according to the present invention, Fig. 2 is a graph showing the output characteristics of the embodiment, and Figs. 3, 4, 5, and 6 are respectively A plan view of the second and third embodiments of the invention and a graph showing their characteristics, and FIG. 7 is an outline diagram of the fourth embodiment of the invention. 1...Substrate (insulator), 2,6.7.12...Superconductor thin film, 11...Insulator. Man 1 Illustration 2 Comments

Claims (1)

[Claims] 1) In a magnetic detector that utilizes the fact that a superconductor transitions into a superconducting state and a normal conducting state with a critical magnetic field as the boundary, the cross-sectional area of the superconductor is aligned in the direction of current flow. A superconducting magnetic detector characterized by non-uniformity. 2) A superconducting magnetic detector according to claim 1, wherein the superconductor is a thin film provided on an insulator.