JPH1146022A - Persistent current switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device whose quenching current in a contact plane is large by a method, wherein the effects a self-generated magnetic field generated by a current applied to a conductor is prevented. SOLUTION: A permanent current switch has a 1st electrode 1a which has a superconducting metal member 2a on its contact part, a 2nd electrode 1c which has a superconducting metal member 2b on its contact part, is insulated from the 1st electrode 1a and is provided near the 1st electrode 1a, and a 3rd electrode 3 which is provided so as to face the 1st and 2nd electrodes and has a superconducting metal member 4 on its contact part. When the 1st and 2nd electrodes 1a and 1c and the 3rd electrode 3 are closed, the direction of a current flowing through the 1st electrode 1a and the metallic member 4 of the 3rd electrode 3 and the direction of a current flowing through the 2nd electrode 1c and the metal member 4 of the 3rd electrode 3 are opposite to each other so as to cancel a magnetic field in the neighborhood of the contact planes with self-generated magnetic fields which are generated by the current flowing through the 1st electrode 1a and the metallic member 4 of the 3rd electrode 3 and the current flowing through the 2nd electrode 1c and the metallic member 4 of the 3rd electrode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent current switch used for operating a superconducting coil with a permanent current.

[0002]

2. Description of the Related Art A permanent current switch for short-circuiting both ends of a superconducting coil is required to have an extremely small contact resistance value in a closed (closed) state. Therefore, there is known a vacuum-type permanent current switch in which an electrode is placed in a vacuum to prevent impurities and an oxide film from adhering to the contact surface and to obtain a clean contact surface to reduce the contact resistance.
(For example, Japanese Patent Publication No. 55-8826)

FIG. 10 is a diagram showing a configuration of a conventional vacuum permanent current switch described in Japanese Patent Publication No. 55-8826. In FIG. 10, reference numeral 101 denotes a movable electrode that is made of a high-purity metal member such as copper or silver and moves up and down. A superconducting metal member made of an alloy or the like, 103 is a fixed electrode made of a high-purity metal member such as copper or silver, and 104 is embedded in the central portion of the fixed electrode 103 along the direction in which a current flows when closed. It is a superconducting metal member made of a Ti alloy or the like.

[0005] Reference numeral 105 denotes a movable metal cover provided on the movable electrode 101 side, and 106 denotes a movable metal cylinder provided around the upper end of the movable electrode 101 so as to cover the movable electrode 101.
07 has a movable electrode 101 at one end and a movable metal cover 10 at the other end.
Bellows 108 fixed to the movable metal cylinder 1
06 and the insulating cylinder connected to the fixed-side metal cylinder 109, 1
09 is the fixed electrode 103 around the lower end on the fixed electrode 103 side.
The fixed-side metal tube 110 provided so as to cover the fixed-side metal cover is connected to the fixed electrode 103 and the fixed-side metal tube 109. The arrows shown in FIG. 10 indicate the direction in which the current flows when the electrodes are closed.

Next, the operation will be described. Movable electrode 10
Reference numeral 1 denotes a configuration in which a closing / opening operation is performed by a driving mechanism (not shown) so that the movable electrode 101 and the fixed electrode 103 can be closed. By moving the movable electrode 101 downward by such a driving mechanism, the superconducting metal member 102 provided on the movable electrode 101 is brought into contact with the superconducting metal member 104 provided on the fixed electrode 103, as shown in FIG. By forming a superconducting contact by making contact, current flows from the movable electrode 101 side to the fixed electrode 1.
It flows to the 03 side.

In the permanent current switch as shown in FIG. 10, the movable electrode 101 side is insulated by a bellows 107, a movable metal cover 105, and a movable metal cylinder 106.
And the fixed electrode 103 side is also fixed to the fixed metal cover 1.
10. Since the airtight container is airtightly fixed to the insulating tube 108 via the fixed side metal tube 109, an airtight container is formed and the inside is in a vacuum state. Further, the permanent current switch needs to be in an extremely low temperature state in order to maintain a superconducting state, and is cooled by liquid helium, a refrigerator, or the like (not shown).

FIG. 11 is a graph showing the characteristics of the current flowing when the electrodes are closed and the contact resistance in the conventional permanent current switch. It is assumed that the energizing current value is increased from I = 0 [A] to I = 1200 [A]. As shown in the figure, the switch is closed to form a superconducting contact, and the current I is gradually increased from 0 [A]. When such a switch is closed, it is in a superconducting state, so that the contact resistance value R maintains the state a of 2 × 10 ⁻⁹ [Ω].
= 600 [A], the quench of the superconducting contact (breaking of the superconducting state) occurs suddenly, and R = 2 × 10
^{Transits to} the state b of ^-5 [Ω].

The quench occurs because the critical current value of the superconducting material decreases due to the effect of the self-generated magnetic field due to the current flowing through the conductor, and quench occurs at the superconducting contact surface even at a low current value.

For example, for a conductor having a diameter d = 1 cm, I = 10
When a current of 00 [A] is passed, the magnetic field H near the surface of the conductor is H = I / (πd) = 1000 / (0.01π) = 10 ⁵
/ Π [A / m] The magnetic flux density B is as follows: B = μH = 4π × 10 ⁻⁷ × 10 ⁵ /π=0.04
[T].

However, when two cylindrical conductors are brought into contact, the contact area between the conductors on the contact surface is usually one.
Since the diameter of the conductor through which the current actually flows is 1/5 to 1/10 of d = 1 cm, that is, d
= 0.2 cm to 0.1 cm. The magnetic flux density B thus obtained is 0.2 to 0.2
0.4 [T]. This value is large enough to lower the critical current value of the superconducting material.

[0011]

Although the conventional permanent current switch can obtain a very small contact resistance value as described above, a quench at the contact surface occurs at a value lower than the planned current value. For this reason, 2
There is a problem that the device is complicated and large, such as connecting a plurality of permanent current switches in parallel, or using a permanent current switch having a conduction current value of I = 2000 [A] class.

The present invention has been made to solve the above problems, and provides an apparatus having a high quench current value at a contact surface by preventing the effect of a self-generated magnetic field due to a current flowing through a conductor. The purpose is to:

[0013]

According to the present invention, there is provided a permanent current switch having a superconducting metal member at a contact portion.
, A second electrode provided with a superconducting metal member at a contact portion, insulated from the first electrode, and provided near the first electrode, and opposed to the first and second electrodes. And a third electrode having a superconducting metal member at a contact portion, wherein the first electrode and the third electrode are closed when the first electrode, the second electrode, and the third electrode are closed. The current flowing between the electrodes and the current flowing between the second and third electrodes are in opposite directions.

Further, the first electrode and the second electrode are formed integrally. The first electrode and the second electrode are connected via a high-resistance member. Further, one of the first electrode and the second electrode is surrounded by the high resistance member, and the other surrounds the high resistance member. Furthermore, the first electrode and the second electrode have a target shape. In addition, a gap was provided between the contact portion of the third electrode with the first electrode and the contact portion of the second electrode.

Further, an insulating member is provided on the side opposite to the contact portion of the third electrode to insulate the container covering the contact portion from the third electrode. Further, the first electrode and the second electrode are covered with a high-resistance member, and the storage container covering the contact portion is insulated from the first and second electrodes.

A first electrode having a superconducting metal member at the contact portion, a superconducting metal member at the contact portion provided opposite to the first electrode, and a return path near the contact portion are provided. When the first electrode and the second electrode are closed, the current flowing in the reverse direction to the direction of the current flowing between the first electrode and the second electrode when the first electrode and the second electrode are closed is provided. Let it flow.

A first electrode having a superconducting metal member at a contact portion, a second electrode provided to face the first electrode and having a superconducting metal member at the contact portion, The first electrode and the second electrode are provided in the vicinity of the first electrode and the first electrode and the second electrode when the first electrode and the second electrode are closed. A conductor through which current flows in the opposite direction.

Further, the conductor portion may include the first electrode or the second electrode.
And the electrodes are integrally formed. Still further, the first electrode or the second electrode and the conductor are connected via a high-resistance member.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 The major difference between the present invention and the conventional example is that the conventional permanent current switch generates a magnetic field near the contact surface at the time of closing due to a self-generated magnetic field due to the current flowing at the time of closing, whereas the permanent current switch of the present embodiment In this case, a current reciprocating circuit is formed near the contact surface when the permanent current switch is closed, and the magnetic field near the contact surface is canceled by the self-generated magnetic field generated by the current flowing through the conductors.

FIG. 1 is a diagram showing the configuration of the permanent current switch according to the first embodiment. FIG. 1A is a sectional view of the permanent current switch, and FIG. 1B is a diagram shown in FIG. It is sectional drawing which looked at the cross section cut | disconnected by the dashed-dotted line XY cross section in a permanent current switch from the upper part.

In the drawing, reference numeral 1 denotes a movable electrode which moves up and down, a first metal member 1a having a cylindrical shape, and a high resistance member 1b provided so as to cover the first metal member 1a.
And a second metal member 1c provided so as to cover the high-resistance member 1b covering the first metal member 1a. The first and second metal members are, for example, high-purity metal members such as copper and silver, and it is desirable that the first metal member 1a and the second metal member 1c be the same metal member. The first metal member 1a and the second metal member 1c
Is provided through the high resistance member 1b, thereby maintaining an insulated state. The high-resistance member 1b is provided to maintain an insulation state between the first metal member 1a and the second metal member 1c, and has a higher resistance value than the first and second metal members 1a and 1c. A metal, an insulating member, or the like is used.

Reference numeral 2 denotes a superconducting metal member made of an Nb-Ti alloy or the like buried along the contact direction of the current when the movable electrode 1 is closed with a contact point of the first metal member 1a. The first superconducting metal member 2a provided and the second
And a second superconducting metal member 2b provided on the contact side of the metal member 1c. The high resistance member 1 is also provided between the first superconducting metal member 2a and the second superconducting metal member 2b.
b is provided, and the insulating state is maintained through the high resistance member 1b.

Reference numeral 3 denotes a fixed electrode made of a high-purity metal member such as copper or silver, and 4 denotes a Nb-Ti alloy or the like embedded at the contact side of the fixed electrode 3 along the direction of current flow when closed. A superconducting metal member, the first superconducting member 2 when closed
a and the second superconducting member 2b are provided so as to be in surface contact with each other, and the gap 11 is provided such that a portion that does not partially or completely contact the high-resistance member 1b when closed is formed. If the entire surface is not contacted, the effect of contact between the high resistance member 1b and the superconducting metal member 4 at the time of closing is eliminated, so that a permanent current switch can be more easily produced.

5 is a movable metal cover provided on the movable electrode 1 side, 6 is a movable metal cylinder provided around the upper end of the movable electrode 1 so as to cover the movable electrode 1, and 7 is one end of the movable electrode. 1
A bellows, the other end of which is fixed to the movable metal lid 5;
Is an insulating cylinder connected to the movable metal cylinder 6 and the fixed metal cylinder 9; 9 is a fixed metal cylinder provided around the lower end of the fixed electrode 3 so as to cover the fixed electrode 3; It is a fixed-side metal lid connected to the electrode 3 and the fixed-side metal cylinder 9.
The arrows shown in FIG. 1 indicate the direction in which the current flows when the electrodes are closed.

In the permanent current switch as shown in FIG. 1, the movable electrode 1 is hermetically fixed to the insulating cylinder 8 via the bellows 7, the movable metal cover 5, and the movable metal cylinder 6, and the fixed electrode 3 is fixed. The side is also hermetically fixed to the insulating tube 8 via the fixed-side metal cover 10 and the fixed-side metal tube 9, and the inside of the container forming the airtight container is in a vacuum state. Further, the permanent current switch needs to be in an extremely low temperature state in order to maintain a superconducting state, and is cooled by liquid helium, a refrigerator, or the like (not shown).

FIG. 1B is a cross-sectional view of the permanent current switch shown in FIG. 1A, taken along the dashed-dotted line XY section, as viewed from above. In the figure, 1a is the first
1b is a high resistance member, and 1c is a second metal member. As shown in FIG. 1B, the first metal member 1a
Is covered with a high-resistance member 1b.
Is covered by the second metal member 1c. Thus, the first metal member 1a and the second metal member 1c are separated by the high resistance member 1b, and are in an electrically insulated state.

Next, the operation of the permanent current switch according to this embodiment will be described. The movable electrode 1 is configured so that a closing / opening operation is performed by a driving mechanism (not shown) so that the movable electrode 1 and the fixed electrode 3 can be closed. The movable electrode 1 is moved downward by using such a driving mechanism, and the superconducting metal member 2 provided at the tip of the movable electrode 1 is attached to the tip of the fixed electrode 3 as shown in FIG. A superconducting contact is formed by bringing the superconducting metal members 4 provided into surface contact with each other.

At this time, the first superconducting metal member 2a and the superconducting metal member 4 provided at the tip of the first metal member 1a are in surface contact with each other and are provided at the tip of the second metal member 1c. The second superconducting metal member 2b and the superconducting metal member 4 come into surface contact. Therefore, the current flowing in the first metal member 1a of the movable electrode 1 flows from the upper part to the lower part (in the direction of the arrow) of the first metal member 1a as shown in FIG. It flows to the superconducting metal member 4 provided at the tip of the fixed electrode 3 via the fixed electrode 3.
(Hereinafter, this current is referred to as a forward path current.)

Further, at the time of closing, the superconducting metal member 4 provided at the tip of the fixed electrode 3 and the second metal member 1c
1A, the forward path current is applied to the second superconducting metal member 4b provided at the tip of the fixed electrode 3 as shown in FIG. (A U-turn in the superconducting metal member 4), flows from the superconducting metal member 4 to the superconducting metal member 2b via the contact point, and further from the lower part to the upper part of the second metal member 1c. (In the direction of the arrow). (Hereinafter, this current is referred to as return current)

As described above, at the time of closing, the contact surface between the first superconducting metal member 2a provided at the tip of the first metal member 1a and the superconducting metal member 4 provided at the tip of the fixed electrode 3 Forward current flowing through the second metal member 1
c, the return current flowing through the contact surface between the second superconducting metal member 2b provided at the tip of the fixed electrode 3 and the superconducting metal member 4 provided at the tip of the fixed electrode 3 are in opposite directions. The self-generated magnetic field generated by the outgoing current is canceled by the self-generated magnetic field generated by the return current near the contact surface. Therefore, on the contact surface,
The influence of the self-generated magnetic field is eliminated, and a decrease in the critical current value of the superconducting member caused by the self-generated magnetic field can be prevented.

Since the gap 11 is provided in the superconducting metal member 4 on the fixed electrode 3, the flow of the forward current and the return current on the superconducting contact surface can be made to be parallel in the vertical direction, and these self-generated The magnetic field can be canceled out better.

In the present embodiment, the gap is formed in the superconducting metal member provided on the fixed electrode. However, this is not particularly limited, and a high resistance member may be provided instead of the gap. Good. Further, in the present embodiment, a forward current flows to the superconducting member provided on the fixed electrode via the contact surface, from the upper part to the lower part of the first metal member, and from the superconducting member provided on the fixed electrode. The return current is caused to flow from the lower part to the upper part of the second metal member via the contact surface, but on the contrary, from the upper part to the lower part of the second metal member, and further on the fixed electrode via the contact surface. A current may flow through the superconducting member provided on the fixed electrode, and a current may flow from the lower portion to the upper portion of the first metal member via the contact surface from the superconducting member provided on the fixed electrode.

Further, in the present embodiment, a high resistance member is used to maintain the insulating state between the first metal member and the second metal member, but this is not particularly limited, and the first metal member is not limited to the first metal member. An insulating state may be maintained by providing a gap between the first metal member and the second metal member. Furthermore, if the cross-sectional area of the first metal member and the cross-sectional area of the second metal member are made equal, the current densities of the two become equal, which is more effective.

In this embodiment, the forward current flowing through the contact surface between the first superconducting metal member provided at the tip of the first metal member and the superconducting metal member provided at the tip of the fixed electrode, The second metal member is provided at the tip of the second metal member.
The return current flowing through the contact surface between the superconducting metal member and the superconducting metal member provided at the tip of the fixed electrode is in opposite directions, so the magnetic field near the contact surface is reduced by the self-generated magnetic field due to the forward current and the return current. It is possible to prevent the critical current value of the superconducting member from being reduced due to the cancellation and the self-generated magnetic field. In addition, since the outer periphery of the movable electrode is formed of the return conductor, weldability such as brazing to the bellows is good.

Embodiment 2 FIG. 2 is a diagram showing a configuration of the permanent current switch according to the second embodiment. FIG. 2A is a cross-sectional view of the permanent current switch, and FIG. 2B is a permanent current switch shown in FIG. FIG. 3 is a cross-sectional view of a cross section taken along a dashed-dotted line XY cross section in FIG. In the figure,
Reference numeral 1 denotes a movable electrode which moves up and down, and a first electrode having a semi-cylindrical shape.
The first metal member 1d, a plate-like high resistance member 1e, and a second metal member 1f having a semi-cylindrical shape whose cross-sectional shape is the same as the cross-sectional shape of the first metal member 1d.
The flat portion of the metal member 1d and the high-resistance member 1e are joined,
Similarly, the surface opposite to the surface connected to the first metal member 1d and the plane portion of the second metal member 1f are connected to each other. As the first and second metal members and the high resistance member, those described in Embodiment 1 may be used. Since the first metal member 1d and the second metal member 1f are provided via the high-resistance member 1e, the insulated state is maintained.

Reference numeral 2 denotes a superconducting metal member made of an Nb-Ti alloy or the like embedded in the direction of current flow when the metal electrode of the movable electrode 1 is closed, and is provided on the contact side of the first metal member 1d. The first superconducting metal member 2a provided and the second
And a second superconducting metal member 2b provided on the contact side of the metal member 1f. The high resistance member 1 is also provided between the first superconducting metal member 2a and the second superconducting metal member 2b.
e is provided, and the insulating state is maintained through the high resistance member 1e.

The other parts are the same as those described in the first embodiment, and a description thereof will be omitted. However, the gap 11 provided in the superconducting metal member 4 provided at the tip of the fixed electrode 3 has been changed to a shape corresponding to the change in the shape of the high-resistance member 1d of the movable electrode 1. This void 11
Like the first embodiment, is provided so that a portion that does not partially or completely contact the high-resistance member 1d at the time of closing is generated.

FIG. 2B is a cross-sectional view of the permanent current switch shown in FIG. 2A taken along the dashed-dotted line XY and viewed from above. In the figure, 1d is the first
1e is a high resistance member, and 1f is a second metal member. As shown in FIG. 2B, the first metal member 1d
Is joined to the high-resistance member 1e, and the surface of the high-resistance member 1e on the side not joined to the first metal member 1d is joined to the plane portion of the second metal member 1f. As described above, the first metal member 1d and the second metal member 1f are separated by the high-resistance member tube 1e, and are in an electrically insulated state.

Next, the operation of the permanent current switch according to this embodiment will be described. Except for the difference in the structure of the movable electrode 1 (the structure of the fixed electrode 3 associated therewith), the structure is the same as that of the first embodiment, and a detailed description is omitted. The movable electrode 1 is moved downward by using a driving mechanism (not shown), and the superconducting metal member 2 provided at the tip of the movable electrode 1 is fixed to the fixed electrode 3 as shown in FIG. The superconducting contact is formed by bringing the superconducting metal members 4 provided at the tips of the members into surface contact with each other.

At this time, the first superconducting metal member 2a and the superconducting metal member 4 come into surface contact, and the second superconducting metal member 2b and the superconducting metal member 4 come into surface contact. Therefore, the current flowing through the first metal member 1d of the movable electrode 1 is, as shown in FIG.
It flows from the upper part to the lower part of d (in the direction of the arrow), and flows to the superconducting metal member 4 provided at the tip of the fixed electrode 3 via the contact part. (Hereinafter, this current is referred to as a forward path current.)

Further, at the time of closing, since the superconducting metal member 4 and the second superconducting metal member 2b are also in contact with each other, this outward current flows through the superconducting metal member 4 as shown in FIG. (U-turn in the superconducting metal member 4), flows from the superconducting metal member 4 to the superconducting metal member 2b via the contact portion, and further, the second metal member 1
It flows from the lower part of f to the upper part (in the direction of the arrow).
(Hereinafter, this current is referred to as return current)

In this embodiment, the first metal member and the second metal member
Since the cross-sectional shapes of the metal members are equal, the current densities of the permanent current switches become equal when the permanent current switches are closed, and the self-generated magnetic fields generated by these currents can be equalized. Therefore, a decrease in the critical current value of the superconducting member caused by the self-generated magnetic field can be prevented more than in the permanent current switch described in the first embodiment. Further, since the movable electrode can be formed only by connecting a conductor having the same shape to the high-resistance member, the movable electrode can be easily formed.

Embodiment 3 In the present embodiment, the first and second embodiments have a configuration in which the current reciprocates on the movable electrode side. On the contrary, the first and second embodiments have a configuration in which the current reciprocates on the fixed electrode side. It is configured.

FIG. 3 is a diagram showing the configuration of the permanent current switch according to the third embodiment. FIG. 3A is a sectional view of the permanent current switch, and FIG. 3B is a diagram shown in FIG. It is sectional drawing which looked at the cross section cut | disconnected by the dashed-dotted line XY cross section in a permanent current switch from the upper part.

In the figure, 1 moves up and down, for example, copper,
The movable electrode 2 made of a high-purity metal member such as silver is a superconducting metal member made of an Nb-Ti alloy or the like which is buried in the contact side of the movable electrode 1 along the direction of current flow at the time of closing. The first superconducting metal member 4a and the second superconducting metal member 4b are provided so as to be in surface contact with each other, and the gap 11 is provided such that a portion that does not partially or completely contact the high resistance member 3b when closed is formed. Have been. If the contact is not made entirely, the effect of contact between the high resistance member 3b and the superconducting metal member 2 at the time of closing is eliminated, so that a permanent current switch can be more easily produced.

Reference numeral 3 denotes a fixed electrode, which is a cylindrical first metal member 3a, a high-resistance member 3b provided to cover the first metal member 3a, and a first metal member 3a.
And a second metal member 3c provided so as to cover the high-resistance member 3b covering the second metal member 3c. As the first and second metal members and the high resistance member, those described in the first embodiment may be used. Since the first metal member 3a and the second metal member 3c are provided via the high-resistance member 3b, an insulated state is maintained.

Reference numeral 4 denotes a superconducting metal member made of an Nb-Ti alloy or the like buried in the direction of current flow at the time of closing when it is closed on the contact side of the metal member of the fixed electrode 3, and on the contact side of the first metal member 3a. The first superconducting metal member 4a and the second
And a second superconducting metal member 4b provided on the contact side of the metal member 3c. The high resistance member 3 is also provided between the first superconducting metal member 4a and the second superconducting metal member 4b.
b is provided, and the insulating state is maintained through the high resistance member 3b. Reference numeral 12 denotes a drive shaft for driving the movable electrode 1. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

Next, the operation of the permanent current switch according to this embodiment will be described. Drive mechanism (not shown)
The movable electrode 1 is moved downward via the drive shaft 12 by the following procedure. As shown in FIG. 3A, the superconducting metal member 2 provided at the tip of the movable electrode 1 is provided at the tip of the fixed electrode 3. The superconducting metal members 4 are brought into surface contact with each other to form superconducting contacts.

At this time, the superconducting metal member 2 and the first superconducting metal member 4a provided at the front end of the first metal member 3a come into surface contact with each other, and the front end of the superconducting metal member 2 and the second metal member 3c. Is in surface contact with the second superconducting metal member 4b. Therefore, the current flowing through the first metal member 3a of the fixed electrode 3 flows from the lower part to the upper part (in the direction of the arrow) of the first metal member 3a as shown in FIG. It flows to the superconducting metal member 2 provided at the tip of the movable electrode 1 via the movable electrode 1.
(Hereinafter, this current is referred to as a forward path current.)

Further, at the time of closing, since the superconducting metal member 2 and the second superconducting metal member 4b provided at the tip of the second metal member 3c are in contact with each other, the forward current is reduced as shown in FIG. As shown in (1), via the superconducting metal member 2 provided at the tip of the movable electrode 1 (a U-turn in the superconducting metal member 2), the superconducting metal member 2 is connected to the superconducting metal member 4b via a contact. Flows further from the upper part to the lower part of the second metal member 3c (in the direction of the arrow). (Hereinafter, this current is referred to as return current)

Here, the superconducting metal member 2 on the movable electrode 1
Is provided with the air gap 11 so that the flow of current in the vertical direction on the superconducting contact surface can be made parallel.

As described above, at the time of closing, the contact surface between the first superconducting metal member 4a provided at the tip of the first metal member 3a and the superconducting metal member 2 provided at the tip of the movable electrode 1 Forward current flowing through the second metal member 3
c, the return current flowing through the contact surface between the second superconducting metal member 4b provided at the tip of the movable electrode 1 and the superconducting metal member 2 provided at the tip of the movable electrode 1 are in opposite directions. The self-generated magnetic field generated by the outgoing current is canceled by the self-generated magnetic field generated by the return current near the contact surface. Therefore, on the contact surface,
The influence of the self-generated magnetic field is eliminated, and a decrease in the critical current value of the superconducting member caused by the self-generated magnetic field can be prevented.

In the present embodiment, the cross-sectional shape of the fixed electrode is circular as shown in FIG. 3 (b), but this is not particularly limited, and it is not limited as shown in FIG. 2 (b). It may have a semicircular shape or the like. As described above, if the cross-sectional shape is as shown in FIG. 2B, the current density of the reciprocating currents becomes equal, so that the critical current value of the superconducting member caused by the self-generated magnetic field can be prevented from lowering. it can.

In this embodiment, the forward current flowing through the contact surface between the first superconducting metal member provided at the tip of the first metal member and the superconducting metal member provided at the tip of the movable electrode, The second metal member is provided at the tip of the second metal member.
The return current flowing through the contact surface between the superconducting metal member and the superconducting metal member provided at the tip of the movable electrode is in opposite directions, so the magnetic field near the contact surface is reduced by the self-generated magnetic field due to the forward current and the return current. It is possible to prevent the critical current value of the superconducting member from being reduced due to the cancellation and the self-generated magnetic field. In addition, since the outer periphery of the movable electrode is formed of the first metal member, the weldability with brazing to the bellows is good. Further, since the electric current reciprocates on the fixed electrode side, the movable electrode can be made very simple and compact.

Embodiment 4 FIG. 4 is a sectional view showing the configuration of the permanent current switch according to the fourth embodiment. In the drawing, reference numeral 1 denotes a movable electrode which moves up and down and is made of a high-purity metal member, and 2 denotes a superconducting metal made of an Nb-Ti alloy or the like which is embedded in the contact side of the movable electrode 1 in the direction of current flow when closed. The member is provided with a gap 11 such that a portion that does not partially or completely contact the high-resistance member 3b when closed is formed.

Reference numeral 3 denotes a cylindrical first metal member 3a.
And a high resistance member 3b provided to cover the first metal member 3a, and a second metal member 3c provided to cover the high resistance member 3b further covering the first metal member 3a. It is composed of The first and second metal members are high-purity metal members such as copper and silver. Since the first metal member 3a and the second metal member 3c are provided via the high-resistance member 3b, an insulated state is maintained.

Reference numeral 4 denotes a superconducting metal member made of Nb-Ti alloy or the like buried in the direction of current flow when the metal electrode of the fixed electrode 3 is closed along the contact direction of the first metal member 3a. The first superconducting metal member 4a and the second
And a second superconducting metal member 4b provided on the contact side of the metal member 3c. The high resistance member 3 is also provided between the first superconducting metal member 4a and the second superconducting metal member 4b.
b is provided, and the insulating state is maintained through the high resistance member 3b.

5 is a movable metal cover provided on the movable electrode 1 side, 7 is a bellows having one end fixed to the drive shaft 12 and the other end fixed to the movable metal cover 5, and 10 is a fixed electrode 3 and a metal cylinder 14. A fixed metal cover 12 is connected to a movable shaft 1 for driving the movable electrode 1 in the vertical direction. The drive shaft 12 is connected to a surface provided on the opposite side of the movable electrode 1 from the contact side. It is connected to the member 13 and to the bellows 7.

Numeral 13 denotes an insulating member provided between the movable electrode 1 and the drive shaft 12, and numeral 14 denotes a movable metal cover 5 and a fixed metal cover 1.
And a metal container provided so as to cover the movable electrode 1 and the fixed electrode 3. The container includes a movable metal cover 5, a bellows 7, a fixed metal cover 10, and a metal tube 14. The contact portion is vacuum-sealed by the electrode 3 and the drive shaft 12. At this time, the insulating member 13 also exists in the vacuum seal. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

Next, the operation of the permanent current switch according to this embodiment will be described. The movable electrode 1 is configured so that a closing / opening operation is performed by a driving mechanism (not shown) so that the movable electrode 1 and the fixed electrode 3 can be closed. At this time, the insulating member 13 provided on the surface of the movable electrode 1 on the side opposite to the contact side is always in a vacuum seal,
The insulating member 13 prevents a current from flowing between the movable electrode 1 and the bellows 7 at the time of closing.

The movable electrode 1 is moved downward by using such a driving mechanism, and as shown in FIG.
The superconducting metal member 2 provided at the tip of the
The superconducting contact is formed by bringing the superconducting metal members 4 provided at the tips of the members into surface contact with each other. The operation of the contact portion at the time of closing is the same as that of the third embodiment, and the description is omitted.

In the present embodiment, since the insulating member 13 is provided inside the airtight container, the cylinder covering the contact portion can be formed of metal or the like, and can be made of expensive ceramic such as the conventional device. No insulating cylinder is required. In addition, all the materials constituting the hermetic container can be made of a metal material, so that the weldability such as brazing is good, and the reliability of the hermetic container can be made extremely high.

FIG. 5 is a diagram showing the configuration of another permanent current switch according to the fourth embodiment. As compared to FIG.
3 except that the movable electrode 1 and the drive shaft 12 are directly coupled. Here, the drive shaft 12 uses a high-resistance member such as an insulating member. As described above, by using the insulating member for the drive shaft, the same effect as the permanent current switch shown in FIG. 4 can be obtained. Further, since the insulating member as shown in FIG. 4 is not required, the permanent current switch can be easily manufactured.

Embodiment 5 FIG. 6 is a sectional view showing the configuration of the permanent current switch according to the fifth embodiment. In the drawing, 5 is a movable metal cover provided on the movable electrode 1 side, 7 is a bellows having one end fixed to the movable electrode 1 and the other end fixed to the movable metal cover 5, and 10 is a metal tube 14 and an insulating plate 15. The fixed metal cover 14 is connected to the movable metal cover 5 and the fixed metal cover 10 and is a metal cylinder provided to cover the movable electrode 1 and the fixed electrode 3. The contact portion is vacuum-sealed by the movable electrode 1 and the housing composed of the bellows 7, the fixed metal cover 10, and the metal tube 14. Reference numeral 15 denotes an insulating plate provided on the fixed-side metal cover 10,
The opposite surface of the insulating plate 15 is connected to the fixed electrode 3. Other configurations are the same as those in the first embodiment, and a description thereof will not be repeated.

Next, the operation of the permanent current switch according to this embodiment will be described. The movable electrode 1 is configured so that a closing / opening operation is performed by a driving mechanism (not shown) so that the movable electrode 1 and the fixed electrode 3 can be closed. In the present embodiment, since the fixed electrode 3 and the fixed-side metal cover 10 are insulated by the insulating plate 15,
A current is prevented from flowing between the fixed electrode 3 and the fixed-side metal lid 10.

The movable electrode 1 is moved downward by using such a driving mechanism, and as shown in FIG.
The superconducting metal member 2 provided at the tip of the
The superconducting contact is formed by bringing the superconducting metal members 4 provided at the tips of the members into surface contact with each other. The operation of the contact portion at the time of closing is the same as that of the first embodiment, and therefore the description is omitted.

In this embodiment, since the insulating plate is provided between the fixed-side metal cover and the fixed electrode, the cylinder covering the contact portion can be formed of metal or the like, and is made of expensive ceramic such as a conventional device. No insulating cylinder is required. In addition, all the materials constituting the hermetic container can be made of a metal material, so that the weldability such as brazing is good, and the reliability of the hermetic container can be made extremely high.

FIG. 7 is a diagram showing the structure of another permanent current switch according to the fifth embodiment. As compared with FIG.
Except that the outer periphery of the movable electrode 1 is covered with a high-resistance member 1b. FIG. 7B is a cross-sectional view of the permanent current switch shown in FIG. 7A taken along the dashed-dotted line XY section, as viewed from above. In the figure, 1a is a first metal member, 1b is a high resistance member, and 1c is a second metal member. As shown in FIG. 7B, the first metal member 1
a is covered with the high-resistance member 1b.
b is covered with the second metal member 1c. Further, the second metal member 1c is covered with a high resistance member 1b. As described above, the first metal member 1a and the second metal member 1c are separated by the high resistance member 1b, and both the second metal member 1c and the bellows 7 are connected to the high resistance member 1c.
b and are electrically insulated.

As described above, by covering the movable electrode with the high resistance member, the same effect as the permanent current switch shown in FIG. 6 can be obtained. Further, since the high resistance member covering the outer periphery of the movable electrode can be formed in the same manner as forming the high resistance member provided between the first metal member and the second metal member, A permanent current switch can be easily created.

Embodiment 6 FIG. FIG. 8 is a sectional view showing the configuration of the permanent current switch according to the sixth embodiment. In the figure, 1 is a movable electrode which moves up and down and is made of a high-purity metal member. The metal member 3 is a fixed electrode made of a high-purity metal member such as copper, silver, or the like, and has a shape having a return path surrounding the contact portion. When closed, a current on the opposite side to the current flowing through the contact portion flows. Like that. Numeral 4 is buried in the vicinity of the contact portion of the fixed electrode 3 along the direction in which the current flows when closed.
A superconducting metal member made of a b-Ti alloy or the like, and is provided so as to be in surface contact with superconducting member 2 when closed.

Reference numeral 5 denotes a movable metal cover provided on the movable electrode 1 side, 6 denotes a movable metal cylinder provided around the upper end of the movable electrode 1 so as to cover the movable electrode 1, and 7 denotes one end of the movable electrode. A bellows having the other end fixed to the movable metal cover 5;
Is an insulating tube connected to the movable metal tube 6 and the fixed metal tube 9; 9 is a fixed metal tube provided at the lower end of the fixed electrode 3 so as to cover the fixed electrode 3; A fixed-side metal lid is connected to the side electrode 3 and the fixed-side metal cylinder 9.

Reference numeral 15 denotes an insulating plate provided on the fixed-side metal cover 10 so that the fixed electrode 3 and the fixed-side metal cover 10 are insulated from each other. Reference numeral 16 denotes a fixed electrode 4 surrounding the contact portion.
A current lead connected to the upper end portion of the return path of FIG. 1 leads to the outside via the fixed metal tube 9 or the fixed metal cover 10. At this time, the current lead 16 and the fixed-side metal tube 9 or the fixed-side metal cover 10 are kept insulated, and the current lead 16 and the fixed-side metal tube 9 or the fixed-side metal cover 10 are hermetically sealed. Shall be. The arrows shown in FIG. 8 indicate the direction in which the current flows when the electrodes are closed.

Next, the operation of the permanent current switch according to this embodiment will be described. The movable electrode 1 is moved downward using a driving mechanism (not shown), and the superconducting metal member 2 provided at the tip of the movable electrode 1 is attached to the tip of the fixed electrode 3 as shown in FIG. A superconducting contact is formed by bringing the superconducting metal members 4 provided into surface contact with each other.

At this time, superconducting metal member 2 provided on the tip of movable electrode 1 and superconducting metal member 4 provided on fixed electrode 4 come into surface contact. for that reason,
As shown in FIG. 8, the current flowing through the movable electrode 1 flows from the upper portion to the lower portion of the movable electrode 1 (in the direction of the arrow), and the superconducting metal member 4 provided on the fixed electrode 3 via the contact portion. It flows to. (Hereinafter, this current is referred to as a forward path current.)

Further, as shown in FIG. 8, this forward current flows from the superconducting metal member 4 through the tip of the fixed electrode 3 (the U.S.C.
Then, it flows to the upper part of the return path of the fixed electrode 3, and flows from the tip of the fixed electrode 3 to the current lead 16.

In the present embodiment, the return path of the fixed electrode surrounds the periphery of the contact point of the electrode, and this return path is connected to the current lead. Therefore, when the permanent current switch is closed, the return path is connected to the contact. Current flows in the opposite direction to the current flowing through the contact part, cancels the magnetic field near the contact surface by the self-generated magnetic field due to the current flowing in the return path and the current flowing in the contact part, and the critical current value of the superconducting member caused by the self-generated magnetic field Drop can be prevented. Furthermore, in the present embodiment, since there is only one contact portion between the movable electrode and the fixed electrode, the contact resistance can be further reduced.

In the present embodiment, the return path is formed so as to cover the contact portion, but this is not particularly limited, and the current flowing in the direction opposite to the current flowing through the contact portion near the contact portion at the time of closing is described. Any structure may be used as long as it can flow through the conductor, and a conductor provided in parallel with the contact or a plurality of these conductors may be provided.

Embodiment 7 FIG. FIG. 9 is a sectional view showing the configuration of the permanent current switch according to the seventh embodiment. In the drawing, reference numeral 1 denotes a movable electrode which moves up and down and is made of a high-purity metal member. The member 3 is a fixed electrode made of a high-purity metal member such as copper, silver or the like. The superconducting member 4 is buried in the contact side of the fixed electrode 3 along the direction of current flow when closed and is made of an Nb-Ti alloy or the like. The metal member is provided so as to be in surface contact with the superconducting metal member 2 when closed.

Reference numeral 5 denotes a movable metal cover provided on the movable electrode 1 side, 6 denotes a movable metal cylinder provided around the upper end of the movable electrode 1 so as to cover the movable electrode 1, and 7 denotes one end of the movable electrode. A bellows having the other end fixed to the movable metal cover 5;
Is an insulating cylinder connected to the movable metal cylinder 6 and the fixed metal cylinder 9; 9 is a fixed metal cylinder provided around the lower end of the fixed electrode 3 so as to cover the fixed electrode 3; It is a fixed-side metal lid connected to the fixed-side electrode 3 and the fixed-side metal cylinder 9.

Reference numeral 15 denotes an insulating plate provided on the fixed-side metal cover 10 so that the fixed electrode 3 and the conductor 17 are insulated from the fixed-side metal cover 10, and 16 is connected to the upper end of the conductor 17. And a current lead 16b connected to the lower end of the conductor portion 17 and reaches the outside via the fixed metal tube 9 or the fixed metal cover 10. At this time, the current lead 16 and the fixed-side metal tube 9 or the fixed-side metal cover 10 are kept insulated, and the current lead 16 and the fixed-side metal tube 9 or the fixed-side metal cover 10 are hermetically sealed. Shall be. Reference numeral 17 denotes a conductive portion provided on the insulating plate 15 so as to surround the contact portion. Both the movable electrode 1 and the fixed electrode 3 are in an insulated state.
At the time of closing, a current flows through the current lead 16. The arrows shown in FIG. 9 indicate the direction in which the current flows when the electrodes are closed.

Next, the operation of the permanent current switch according to this embodiment will be described. The movable electrode 1 is moved downward using a driving mechanism (not shown), and the superconducting metal member 2 provided at the tip of the movable electrode 1 is attached to the tip of the fixed electrode 3 as shown in FIG. A superconducting contact is formed by bringing the superconducting metal members 4 provided into surface contact with each other.

At this time, superconducting metal member 2 provided on the tip of movable electrode 1 and superconducting metal member 4 provided on fixed electrode 4 come into surface contact. for that reason,
As shown in FIG. 9, the current flowing through the movable electrode 1 flows from the upper portion to the lower portion of the movable electrode 1 (in the direction of the arrow), and flows to the superconducting metal member 4 provided on the fixed electrode 3 via the contact portion. And flows. As shown in FIG. 9, the operating current is transferred from the superconducting metal member 4 to the fixed electrodes 3 and 3.
It flows from the top to the bottom.

At the time of such closing, a current in the opposite direction to the current flowing through the contact portion flows through the conductor portion 17.
A current flows through the current lead 16. It is desirable that this current value be the same as the current value flowing through the contact portion at the time of closing. However, if the current value is further finely controlled in consideration of the distance between the contact portion and the conductor portion 17, the magnetic field near the contact surface can be canceled out more.

In the present embodiment, the insulating state is maintained by the gap between the fixed electrode 3 (superconducting metal member 4) and the conductor portion 17. However, this is not particularly limited. (Superconducting member 4) and conductor portion 17 may be coupled via a high-resistance member. If you do this,
Since the fixed electrode 3 and the conductor portion 17 can be integrally formed and coupled to the insulating plate 15, the production becomes easy. Further, the movable electrode 1 (superconducting metal member 2) and the conductor portion 17 may be connected to each other via a high-resistance member.

In this embodiment, since the conductor is provided in the vicinity of the contact, when the permanent current switch is closed, a current in the opposite direction to the current flowing through the contact can be passed through this conductor, and each other can flow. The magnetic field near the contact surface is canceled by the self-generated magnetic field due to the current flowing through the conductor, and the critical current value of the superconducting member caused by the self-generated magnetic field can be prevented from lowering. Further, since the current flowing through the conductor can be controlled, the magnetic field near the contact surface can be more appropriately canceled.

In the present embodiment, the conductor is formed so as to cover the contact. However, the shape is not particularly limited. When the conductor is closed, the current in the direction opposite to the current flowing through the contact near the contact is used. Any structure may be used as long as it can flow through the conductor, and a conductor provided in parallel with the contact or a plurality of these conductors may be provided.

[0087]

In the permanent current switch according to the present invention, the first electrode having the superconducting metal member at the contact portion and the superconducting metal member at the contact portion are insulated from the first electrode. A second electrode provided near the first electrode; and a third electrode provided to face the first and second electrodes and having a superconducting metal member at a contact portion. When the first electrode, the second electrode, and the third electrode are closed, the current flowing between the first electrode and the third electrode is opposite to the current flowing between the second electrode and the third electrode. Therefore, the first
Between the second electrode and the third electrode
The magnetic field near the contact surface can be canceled by the self-generated magnetic field due to the current flowing between the electrodes.

Further, since the first electrode and the second electrode are integrally formed, it is easy to form the first electrode and the second electrode so as to be in contact with the third electrode at the same time. It is easy to make a permanent current switch.

Since the first electrode and the second electrode are connected via a high-resistance member, the first metal and the second metal can be insulated from each other and the first metal member can be insulated. And the second metal member can be integrally formed.

One of the first electrode and the second electrode is surrounded by a high-resistance member, and the other surrounds the high-resistance member. And the reliability as an airtight container can be improved.

Since the first electrode and the second electrode have the target shapes, the currents flowing through the first electrode and the second electrode have the same density, and the effect of canceling the magnetic field near the contact surface is enhanced. .

Since a gap is provided between the contact portion of the third electrode with the first electrode and the contact portion of the second electrode,
The flow of the forward current and the return current at the superconducting contact surface can be made to be parallel in the vertical direction, and these self-generated magnetic fields can be more effectively canceled.

An insulating member is provided on the side opposite to the contact portion of the third electrode to insulate the third electrode from the storage container covering the contact portion, so that the storage container can be made of a metal member. An expensive ceramic insulating cylinder is not required, and a permanent current switch can be produced at low cost. Further, since all the materials constituting the hermetic container are metal members, the weldability such as brazing is good, and the reliability as the hermetic container can be extremely enhanced.

Since the first electrode and the second electrode are covered with a high-resistance member, and the first and second electrodes and the storage container covering the contact portion are insulated, the storage container is formed of a metal member. This eliminates the need for expensive ceramic insulating cylinders, and makes it possible to produce a permanent current switch at low cost. Further, since all the materials constituting the hermetic container are metal members, the weldability such as brazing is good, and the reliability as the hermetic container can be extremely enhanced.

The first having a superconducting metal member at the contact portion
And a second electrode provided opposite to the first electrode and having a superconducting metal member at the contact portion and having a return path portion covering the contact portion, wherein the first electrode and the second electrode are provided. When the electrodes are closed, the direction of the current flowing between the first electrode and the second electrode is opposite to the direction of the current flowing in the return path. Therefore, the number of contacts at the time of closing is one, and the contact resistance is reduced. Can be lower.

The first having a superconducting metal member at the contact portion
A second electrode having a superconducting metal member at a contact portion provided opposite to the first electrode, and a second electrode provided near the first electrode and the second electrode; When the first electrode and the second electrode are closed, there is provided a conductor portion through which a current flows in a direction opposite to a direction in which a current flows between the first electrode and the second electrode. In this case, the contact resistance can be reduced, and by controlling the current flowing through the conductor, the magnetic field near the contact surface can be more efficiently canceled by the self-generated magnetic field.

Since the conductor is formed integrally with the first electrode or the second electrode, it is easy to make a permanent current switch.

Since the first electrode or the second electrode and the conductor are connected via the high-resistance member, the first metal or the second metal and the conductor can be insulated from each other. , Can be integrally formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a permanent current switch according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a permanent current switch according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a permanent current switch according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a permanent current switch according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a permanent current switch according to a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of a permanent current switch according to a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a permanent current switch according to a fifth embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration of a permanent current switch according to a sixth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a permanent current switch according to a seventh embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional permanent current switch.

FIG. 11 is a view showing characteristics between electrodes of a conventional permanent current switch.

[Explanation of symbols]

1 movable electrode 1a, 1d, 3a
First metal member 1b, 1e, 3b High resistance member 1c, 1f, 3c
Second metal member 2 Superconducting metal member 2a, 4a First
Superconducting metal member 2b, 4b 2nd superconducting metal member 3 Superconducting metal member 4 Fixed electrode 5 Movable metal lid 6 Movable metal cylinder 7 Bellows 8 Insulation cylinder 9 Fixed metal cylinder 10 Fixed metal lid 11 Void 12 Drive shaft 13 High resistance member tube (plate) 14 Metal tube 15 Insulating plate 16 Current lead 101 Movable electrode 102, 104 Superconducting metal member 103 Fixed electrode 105 Movable metal cover 106 Movable metal tube 107 Bellows 108 Insulation tube 109 Fixed metal tube 110 Fixed metal lid

Claims (12)

[Claims] 1. A first electrode having a superconducting metal member at a contact portion, and a first electrode having a superconducting metal member at a contact portion, insulated from the first electrode and near the first electrode. A second electrode provided, and a third electrode provided to face the first and second electrodes and having a superconducting metal member at a contact portion, wherein the first electrode and the third electrode are provided. When the second electrode and the third electrode close, the current flowing between the first electrode and the third electrode is opposite to the current flowing between the second electrode and the third electrode. A permanent current switch characterized by a direction. 2. The permanent current switch according to claim 1, wherein the first electrode and the second electrode are formed integrally. 3. The permanent current switch according to claim 1, wherein the first electrode and the second electrode are connected via a high resistance member. 4. The permanent current according to claim 3, wherein one of the first electrode and the second electrode is surrounded by a high-resistance member, and the other surrounds the high-resistance member. switch. 5. The permanent current switch according to claim 3, wherein the first electrode and the second electrode have target shapes. 6. The air gap according to claim 1, wherein a gap is provided between a contact portion of the third electrode with the first electrode and a contact portion of the second electrode. Permanent current switch. 7. The third electrode according to claim 1, wherein an insulating member is provided on a side opposite to the contact portion of the third electrode, and the storage container covering the contact portion is insulated from the third electrode. 2. The permanent current switch according to claim 1. 8. The first electrode and the second electrode are covered with a high resistance member, and the container covering the contact portion is insulated from the first and second electrodes. 7. The permanent current switch according to claim 6. 9. A first electrode having a superconducting metal member at a contact portion, a superconducting metal member provided at the contact portion facing the first electrode, and a return path portion near the contact portion. A current flowing direction between the first electrode and the second electrode in the return path when the first electrode and the second electrode are closed. A permanent current switch characterized in that a current in the opposite direction flows. 10. A first electrode having a superconducting metal member at a contact portion, a second electrode provided opposite to the first electrode and having a superconducting metal member at a contact portion, It is provided in the vicinity of the first electrode and the second electrode, and flows between the first electrode and the second electrode when the first electrode and the second electrode are closed. A permanent current switch comprising: a conductor portion through which a current flows in a direction opposite to a direction in which the current flows. 11. The permanent current switch according to claim 10, wherein the conductor is formed integrally with the first electrode or the second electrode. 12. The permanent current switch according to claim 11, wherein the first electrode or the second electrode and the conductor are connected via a high resistance member.