JPH088166B2 - Current lead - Google Patents

Description

The present invention relates to a current lead for supplying a current to a superconducting element such as a superconducting magnet.

<Prior Art> Conventionally, as a current lead used for supplying a current to a superconducting magnet or the like, in particular, a detachable current lead having a socket and a plug, as shown in FIG. A plug (21) made of a copper body is provided on a high temperature side connection terminal portion (24) connected to the main body through a normal conductor current lead (23) made of a rod-shaped, pipe-shaped or busbar-shaped copper body, and a superconducting magnet. It is known that a socket (22) is provided in the low temperature side connection terminal part (26) connected to the like and the plug (21) is attached to and detached from the socket (22) to maintain or cut off the energized state. . The socket (22) is made of brass or copper, and one or a plurality of beryllium-copper multifaceted contacts (25) are attached to the inside of the socket (22) by utilizing the spring characteristic. The contact resistance can be minimized.

<Problems to be solved by the invention> However, in the above conventional detachable current lead, since the socket and the plug are normal conductors, moreover, copper conductors, brass, etc. which are good heat conductors are used, Joule loss occurs due to the voltage drop when the member itself is energized and the voltage drop due to the contact resistance between the socket and the plug, and this heat generation penetrates into the refrigerant such as liquid helium and liquid nitrogen in which the superconducting magnet is immersed, There is a problem that the refrigerant evaporates due to the conduction heat.

In addition, it is necessary to secure the cross-sectional area of the normal conductor necessary to secure the current capacity, so that the amount of heat transferred to the refrigerant from the high temperature part is large, and to minimize the heat transferred to this refrigerant, Various test studies have been conducted. However, although it is only about the voltage drop between the plug and socket, at the present time, for example, when the energization amount is 1800 A,
A voltage drop of 3 mV is unavoidable, and in this case, if the current lead is a plus / minus pair, it will be 1800A x 0.013V x 2 = 46.8W. For example, if the refrigerant is liquid helium, 1.4l / hr per 1W heat conduction Therefore, the evaporation of 65.52 l / hr caused a problem. The same problem has occurred not only with the above-mentioned detachable type, but also with one non-detachable current lead formed of a normal conductor.

<Purpose of the Invention> The present invention has been made in view of the problems of the conventional current lead described above, there is almost no Joule loss due to energization, and the current that can suppress the evaporation amount of the refrigerant such as liquid helium and liquid nitrogen to be low. Intended to provide leads.

<Means for Solving Problems> A structure of the present invention for achieving the above object is a current lead for supplying a current to a superconducting element, which is composed of a ceramics superconductor and a good electric conductor. It exists in a current mode formed by a complex with a support.

<Operation> The present invention uses a current lead as a ceramic superconductor,
Since it is formed of a composite with a support made of a good electrical conductor, it does not generate heat due to energization when used below the critical temperature, and heat transfer from the high temperature part to the refrigerant can be reduced, The evaporation amount of refrigerants such as liquid helium and liquid nitrogen can be reduced.

<Embodiment> An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

 FIG. 1 is a sectional view showing a current lead of the present invention.

The current lead is detachably formed by the plug (1) and the socket (2), of which the plug (1)
Is constituted as a composite body in which a superconductor (1a) made of oxide ceramics is filled in a support (1b) made of a pipe-shaped good electrical conductor made of copper, aluminum or the like. The plug (1) is a pipe-shaped support (1
After filling the superconductor (1a) in b), it is swaged or stretched after swaging to form a desired length.

The socket (2) corresponding to this is pressed and bonded with powder of the ceramic superconductor (2a) on the outer surface of the support (2b) made of a pipe-shaped good electrical conductor made of copper, aluminum or the like. It is a composite and integrated by a method such as extrusion, electrodeposition or the like. Also, inside the support (2b) made of a pipe-shaped good electrical conductor, a suitable number of beryllium-copper multifaceted contacts (3) are attached according to the current capacity of the lead (two in the figure). The contact resistance can be kept to a minimum by utilizing the spring characteristics (installed).

Further, the low temperature side connection terminal portion (5) is integrally connected to the support (2b) made of a good electric conductor, and the surface of the low temperature side connection terminal portion (5) is also a powder of the superconductor (2a). Are composite-integrated by methods such as powder compaction, adhesion, extrusion, and electrodeposition.

The ceramic superconductors (1a) and (2a) are manufactured by sintering a ceramic superconductor raw material,
As the raw material, any form of a simple substance or a compound may be used as long as it contains an element constituting a superconductor. Examples of the above-mentioned elements include I, II and III of the periodic table.
Examples of the group element include oxygen and fluorine.

More specifically, among the group I elements of the periodic table, examples of the group Ia elements include Li, Na, K, Rb, and Cs, and the group Ib elements include Cu, Ag, and Au. Also, the periodic table
Of the II group elements, the IIa group elements include Be, Mg, Ca, S
r, Ba, and Ra, and the IIb group elements include ZN and Cd.
Etc. Of the III group elements of the periodic table, IIIa group elements include Sc, Y and lanthanoid series elements such as La and C.
Actinides such as e, Gd, Lu, etc. Ac, Th, Pa, C
f and the like. Further, as the group IIIb element, Al, G
a, In, Tl and the like.

Of the above elements, a ceramic superconductor composed of an element selected from the group Ib, particularly an element selected from the group IIa composed of oxides, a group IIIa and a lanthanoid series element, and an element selected from oxygen and fluorine. (1a)
(2a) is preferred. Note that Cu and Ag are preferable as the Group Ib element.

In addition, the support (1) made of a pipe-shaped good electrical conductor formed of copper, aluminum or the like in the plug (1)
b) and a support (2b) made of a good electrical conductor in the form of a pipe made of copper, aluminum or the like for the socket (2)
It is preferable that each of them has a cross-sectional area as small as possible to facilitate transfer of current between the superconductors (1a) and (2a) when fitted together.

The supports (1b) and (2b) made of a good electrical conductor are made of a normally conductive metal body, but the current does not flow through the metal body like the conventional ones, and the stabilizing material is used. , To serve as a support. Therefore, it is not necessary to increase the cross-sectional area and the like to secure the current capacity unlike the conventional one, and the amount of heat conduction can be greatly reduced.

Further, in the conventional detachable current lead, the socket and the plug are made of a normal conductor, and are made of a copper conductor, brass, etc. which are good conductors of heat. , Joule loss occurs due to voltage drop due to contact resistance between the socket and the plug, and this heat generation is conducted to the refrigerant such as liquid helium and liquid nitrogen in which the superconducting magnet is immersed, and this conduction heat evaporates the refrigerant. However, in the case of the above-mentioned embodiment, since the current lead is formed by the composite body of the ceramics superconductor and the support made of the good electrical conductor, the voltage drop due to the contact resistance between the socket and the plug is caused. Can almost eliminate the Joule loss.

Further, instead of the detachable type as described above, one current lead can be implemented in the same manner as the detachable type.

<Effects of the Invention> As described above, according to the present invention, since the current lead is formed of the composite body of the ceramic superconductor and the support made of the good electrical conductor, it is possible to apply the current to the superconducting magnet or the like. The Joule loss can be almost eliminated, and since the good electric conductor only functions as a support and a stabilizing material and does not need to secure the current capacity as a current-carrying member, its cross-sectional area is made extremely small. It is possible to significantly reduce the heat conduction amount due to the heat transfer from the high temperature part to the refrigerant such as liquid helium, and to minimize the evaporation amount of the refrigerant. It is not necessary to form a large refrigerant storage tank in anticipation of the evaporation amount of the refrigerant, and the current lead can be formed with a compact structure such as a compact structure. Produce the effect of.

[Brief description of drawings]

FIG. 1 is a sectional view showing one embodiment of a current lead of the present invention, and FIG. 2 is a sectional view showing a conventional current lead. (1) …… Plug, (2) …… Socket, (1a) (2a)
…… Superconductor, (1b) (2b) …… Good electrical conductor,

Claims (1)

[Claims] 1. A current lead for supplying a current to a superconducting element, which is formed of a composite of a ceramics superconductor and a support made of a good electrical conductor.