JPH05291036A - Quick disconnectable current lead - Google Patents

Abstract

PURPOSE:To diminish the calorie transmitted from a conductor to a superconducting magnet coil for reducing the thermal load upon a superconducting magnet. CONSTITUTION:Low temperature terminals 33 comprising a pair of mutually quick disconnectable terminals are arranged between a superconducting magnetic coil and a conductor 16 feeding a current exciting the coil. These low temperature terminals 33 are connected while the coil is being excited by an exciting power supply while disconnected when a permanent current switch is turned to the permanent current mode. Said low temperature terminals 33 forms a space encircled by specific members to be vacuumized when the low temperature terminal are disconnected. Accordingly, the thermal transmission by convection in the space can be avoided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to removable current leads.

[0002]

2. Description of the Related Art Conventionally, for example, in a superconducting motor,
The coil of the superconducting magnet is placed in a cryogenic state and a permanent current is passed through the coil to drive the coil.
In this case, the coil is housed in the system of the cryostat and is cooled to a cryogenic temperature by liquid helium.

FIG. 2 is a circuit diagram of a superconducting device. In the figure, 12 is an exciting power source, 13 is a coil of a superconducting magnet, and the exciting power source 12 supplies a current to the coil 13 of a superconducting magnet. Reference numeral 16 is a conductor wire made of copper, 17 is a superconducting wire connected to the conductor wire 16, and 18 is a superconducting wire 1
The coil 13 is branched at the intermediate contacts 21 and 22 of the coil 7.
Is a superconducting wire for a switch connected in parallel with.

The circular portion of the switch superconducting wire 18 is
The thermal or mechanical permanent current switch 23 is configured, and in the case of the thermal permanent current switch, a part of the switch superconducting wire 18 is usually surrounded by a heat insulating material such as FRP. The exciting power source 12 and the conducting wire 16 are placed in a normal conducting state, while the superconducting wire 17, the switch superconducting wire 18, the persistent current switch 23 and the superconducting magnet (including the coil 13) are indicated by a one-dot chain line cryostat 25. It is housed in the system, is usually cooled to a cryogenic temperature by a coolant such as liquid helium, and is placed in a superconducting state.

Then, the switch superconducting wire 18 is
For example, when heat is applied by heating with a heating element to raise the temperature above the critical temperature, the switch superconducting wire 18 momentarily enters the normal conducting state and can have a finite resistance.
When the heating is stopped and the switch superconducting wire 18 is cooled to a cryogenic temperature by the cryostat 25 and placed in a superconducting state, the resistance of the switch superconducting wire 18 becomes effectively zero. In this way, the permanent current switch 23
The switch superconducting wire 18 can be turned off by heating and turned on by cooling.

In the superconducting device having the above structure, first, when a current is supplied from the exciting power source 12 to the coil 13 of the superconducting magnet, the switch superconducting wire 18 is heated and placed in the normal conducting state, and the permanent current switch 23 is provided. Is off. Then, when the current supplied to the coil 13 reaches the set value, the heating of the switch superconducting wire 18 is stopped and the permanent current switch 23 is turned on. In this state, when the current from the exciting power source 12 is gradually reduced, the corresponding amount of current will flow through the switch superconducting wire 18.

When the supply of current from the exciting power source 12 is stopped, the switch superconducting wire 18 and the superconducting wire 1
The permanent current i _e continues to circulate in the closed loop circuit formed between the coil 7 and the coil 13, and the permanent current mode is set. By the way, in the permanent current mode, the contacts 21, 22, the superconducting wire 17, the switch superconducting wire 18, the permanent current switch 23 and the superconducting magnet are cooled to a cryogenic temperature and placed in the superconducting state. Since the conducting wire 16 is placed in the normal conducting state, heat may enter through the conducting wire 16 and cause a quench state to occur in the superconducting wire 17, the switch superconducting wire 18, the superconducting magnet, and the like. That is, for the superconducting magnet, the exciting power source 12 side from the contacts 21, 22 becomes a heat load.

Therefore, there is provided one in which the conducting wire 16 is completely taken out of the system of the cryostat 25 after the permanent current mode is set. However, in this case,
Although it is possible to prevent heat transfer from the conductor 16, it is necessary to attach and detach the conductor 16 and put it in and out of the system of the cryostat 25, and the work is very complicated and requires skill, Air, water, and the like often enter the system of the cryostat 25, causing troubles in the superconducting magnet.

Therefore, the conductor 16 is connected to the cryostat 25.
There is provided a detachable current lead in which the low temperature terminal is only electrically disconnected from the superconducting wire 17 without being taken out of the system. FIG. 3 is a schematic view of a conventional detachable current lead,
FIG. 4 is a sectional view of the conductor. In the figure, 16 is a lead wire,
Reference numeral 16a is an outer conductor tube, 16b is an inner conductor tube arranged concentrically inside the outer conductor tube 16a, and 17 is a superconducting wire connected to the coil 13 (FIG. 2). Further, 32 is a coil container for housing the coil 13 of the superconducting magnet, and 33 is a low temperature terminal for detachably connecting the conductor inner tube 16b of the conductor 16 and the superconducting wire 17. The low temperature terminal 33 comprises a male terminal 33a attached to the tip of the inner conductor tube 16b and a female terminal 33b attached to the coil container 32,
By moving the inner conductor tube 16b as shown by the arrow a, the male terminal 33a and the female terminal 33b can be selectively attached and detached. Incidentally, 34 is an electrically insulating material disposed between the female terminal 33b and the coil container 32.

In the detachable current lead having the above-mentioned structure, when a current is supplied from the exciting power source 12 to the coil 13 to excite the superconducting magnet, the current flows through the coil 13 to generate Joule heat, which causes the liquid to flow. Helium evaporates to low-temperature helium gas, which is released into the coil container 32. Therefore, the helium gas is used for cooling the conductor 16.

Therefore, the communication passage 36 is formed in the female terminal 33b.
And a space A formed between the conductor outer tube 16a and the conductor inner tube 16b via the communication passage 36,
It communicates with the space B in 2. Therefore, the coil container 32
The helium gas therein moves from the space B to the space A through the communication passage 36 as shown by the arrow b in FIG. 3, and through the helium gas inlet 38 as shown by the arrow c.
It flows in the conductor of 6b and cools the conducting wire 16.

After the current for exciting the coil 13 reaches a specified value and the permanent current switch 23 is turned on to set the permanent current mode, the inner wire tube 16b is pulled out to separate the male terminal 33a and the female terminal 33b. Then, the low temperature terminal 3
3 is cut off. Therefore, it is possible to prevent heat from entering the coil container 32 through the conductor 16.

[0013]

However, in the conventional detachable current lead described above, when the superconducting magnet is excited in the permanent current mode, the conducting wire 16 for supplying current to the superconducting magnet is separated from the superconducting wire 17. ,
Since the conductor 16 is cooled by the helium gas, the space A becomes a helium gas atmosphere and convection of the helium gas occurs. Therefore, due to this convection, heat from the conductive wire 16 is transferred to the coil 13 via the superconducting wire 17, and the conductive wire 16 becomes a heat load on the superconducting magnet.

The present invention solves the problems of the conventional detachable current lead, reduces the amount of heat transferred from the conductive wire to the coil of the superconducting magnet, and reduces the heat load on the superconducting magnet. It is an object to provide a detachable current lead.

[0015]

Therefore, in the detachable current lead of the present invention, a pair of terminals which are detachable from each other are provided between the coil of the superconducting magnet and the lead wire for supplying the current for exciting the coil. A low temperature terminal consisting of The low temperature terminal is surrounded by a predetermined member to form a space, and the space is evacuated when the low temperature terminal is separated.

[0016]

According to the present invention, as described above, the coil of the superconducting magnet and the low temperature terminal composed of a pair of detachable terminals are arranged between the wire for supplying the current for exciting the coil. .. The low temperature terminal is connected while the coil is excited by the exciting power supply, and is disconnected when the permanent current switch is turned on and the permanent current mode is set.

The low temperature terminal is surrounded by a predetermined member to form a space, and the space is evacuated when the low temperature terminal is separated. Therefore, heat transfer due to convection can be prevented in the space.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic view of a detachable current lead showing an embodiment of the present invention. In the figure, 16 is a conducting wire, 16a is a conducting wire outer tube, 16b is a conducting wire inner tube concentrically arranged inside the conducting wire outer tube 16a, and 17 is a coil 13.
It is a superconducting wire connected to (see FIG. 2). Also, 32
Is a coil container for housing the coil 13 of the superconducting magnet, 33
Is a low temperature terminal for detachably connecting the inner conductor tube 16b of the conductor 16 and the superconducting wire 17. The low temperature terminal 33 is
It consists of a pair of terminals, that is, a male terminal 33a attached to the tip of the inner conductor tube 16b and a female terminal 33b attached to the coil container 32. By moving the inner conductor tube 16b as shown by an arrow a, Terminal 3
3a and the female terminal 33b can be selectively attached and detached. Incidentally, 34 is an electrically insulating material disposed between the female terminal 33b and the coil container 32.

Further, an annular projection 51 protruding inward in the radial direction is formed in the vicinity of the low temperature terminal 33 on the inner circumference of the outer conductor tube 16a. The annular protrusion 51 may be formed integrally with the outer wire tube 16a, but it is preferably formed as a separate body with a material having a high heat insulating property. On the other hand, a flange 52 is formed at the tip of the inner conductor tube 16b, and a cylindrical bellows 53 is hermetically connected between the annular projection 51 and the flange 52.
As a result, the inside of the lead wire outer tube 16a is partitioned by the bellows 53, and the lead wire outer tube 16a, the lead wire inner tube 16b, and the bellows 53.
A space A ₁ surrounded by and a space A ₂ surrounding the low temperature terminal 33 are formed. Also, the coil container 3
A space B is formed in 2.

The space A ₂ is connected to a vacuum source via a vacuum exhaust pipe 55 and is also connected to the inside of the coil container 32 via a helium gas supply pipe (not shown). And
A switching valve (not shown) is provided in each of the vacuum exhaust pipe 55 and the helium gas supply pipe. By switching the switching valve by a control device (not shown), the space A ₂ is evacuated or filled with helium gas. You can do it. A hole 56 communicating with the vacuum exhaust pipe 55 and opening to the space A ₂ is formed in the flange 52.

When the current flowing through the coil 13 of the superconducting magnet reaches a specified value, the permanent current switch 23 is turned on to enter the permanent current mode, and the inner conductor tube 16b is moved to move the male terminal 33a and the female terminal. 33b is separated. At this time, the controller controls the space A through the vacuum exhaust pipe 55.
_{Since the} inside of ₂ is evacuated, heat transfer due to convection in the space A ₂ can be prevented. Therefore, the conductor 16
Does not become a heat load on the superconducting magnet.

On the other hand, when the coil 13 of the superconducting magnet is demagnetized and the conductor 16 and the superconducting wire 17 are connected,
First, helium gas is introduced into the space A ₂ , and then the inner conductor tube 16b is moved to couple the male terminal 33a with the female terminal 33b. By doing so, it is possible to prevent the seizure between the male terminal 33a and the female terminal 33b.
Further, the work of separating the low temperature terminal 33 is simplified, and air, water, etc. do not enter the system of the cryostat 25 during the work. Further, since the conductor 16 and the superconducting wire 17 can be automatically attached and detached, the conductor 16 and the superconducting wire 17 can be connected at high speed at the time of the occurrence of a quench, and the energy of the superconducting magnet can be released.

In the detachable current lead having the above-mentioned structure, when a current is supplied from the exciting power source 12 to the coil 13 to excite the superconducting magnet, the current flows through the coil 13 to generate Joule heat, which causes the liquid to flow. Helium evaporates to low-temperature helium gas, which is released into the coil container 32. Therefore, the helium gas is used for cooling the conductor 16.

Therefore, the coil container 32 is connected to the communication passage 5
7 communicates with each other, and the communication passage 57 and the space A ₁Tube with bellows 5 inside
8 communicate. And the space A₁Inside the conductor
In the vicinity of the flange 52 of the pipe 16b, the space A₁Against
An opening helium gas inlet 59 is formed. But
The helium gas in the coil container 32 is
As shown by the arrow d in the figure, the communication passage 57 and the pipe with bellows
Space A through 58₁Move in and as shown by arrow e
Conductor of inner tube 16b of the conductor through the helium gas inlet 59
It flows through and cools the conductor 16.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0026]

As described in detail above, according to the present invention, a low temperature composed of a coil of a superconducting magnet and a pair of terminals which are detachably attached to each other between a conductor for supplying a current for exciting the coil. Terminals are provided. The low temperature terminal is connected while the coil is excited by the exciting power supply, and is disconnected when the permanent current switch is turned on and the permanent current mode is set.

The low-temperature terminal is surrounded by a predetermined member to form a space, and the space is evacuated when the low-temperature terminal is cut off to prevent heat transfer due to convection in the space. Therefore, the thermal influence of the conductive wire on the superconducting magnet can be minimized, and the conductive wire does not become a heat load on the superconducting magnet. Further, the work of disconnecting the low temperature terminal is simplified, and air, water, etc. do not enter the system of the cryostat during the work.

Furthermore, since the conductor wire and the superconducting wire can be automatically attached and detached, the conductor wire and the superconducting wire can be connected at a high speed at the time of occurrence of a quench, and the energy of the superconducting magnet can be released.

[Brief description of drawings]

FIG. 1 is a schematic view of a detachable current lead according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a superconducting device.

FIG. 3 is a schematic view of a conventional removable current lead.

FIG. 4 is a cross-sectional view of a conductor wire.

[Explanation of symbols]

13 coil 16 conducting wire 16a conducting wire outer tube 16b conducting wire inner tube 17 superconducting wire 33 low temperature terminal 33a male terminal 33b female terminal A ₁ , A ₂ , B space

Claims (1)

[Claims] 1. (a) a coil of a superconducting magnet and a low temperature terminal, which is arranged between a lead wire for supplying a current for exciting the coil and is detachable from each other, (b)
A detachable current lead, comprising: a means for forming a space surrounding the low temperature terminal; and (c) means for evacuating the space when the low temperature terminal is separated.