JPH0828532B2 - Current leads for superconducting electromagnet devices - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a lead body of a current lead for a superconducting electromagnet device for supplying electric power from an external power source to a superconducting electromagnet in a cryogenic container.

[Prior art and its problems]

Since the superconducting electromagnet is generally cooled by a cryogenic refrigerant such as liquid helium, it is housed inside a container insulated by a liquid nitrogen shield or a vacuum tube. The current lead supplies electric power to the superconducting electromagnet, which is maintained at a cryogenic temperature, from the room temperature part, and the Joule heat generated in the conductor of the current lead and the heat entering from the outside room temperature part to the inside cryogenic part by conduction. In order to reduce the amount, a method of cooling by using low-temperature helium gas in which liquid helium is evaporated is adopted. Therefore, if the invasion heat is too large, not only the amount of expensive liquid helium consumed will be large, but also the characteristics of the superconducting electromagnet may be adversely affected.

A general structure of the superconducting electromagnet device will be described with reference to the sectional view of FIG. Liquid helium He is contained in the cryogenic container 1, and the superconducting electromagnet 2 is immersed in the liquid.
The current lead 3 is attached through the flange 5 provided on the upper lid 4 of the cryocontainer 1, and the lower end of the lead body 12 inside the cryocontainer 1 is connected to the superconducting electromagnet 2 via the connecting lead 6. . A liquid nitrogen shield N is arranged outside the liquid helium He storage tank in order to block heat entering from the outside. Also, the low temperature container 1 of the current lead 3
A bus bar 7 for connecting to an external power source (not shown) is installed at the upper end of the outside. In such a configuration, the helium gas evaporated in the cryogenic container 1 is guided to the internal gap of the current lead 3 to cause heat exchange inside the current lead 3 to reduce heat entering the cryogenic portion.

FIG. 10 shows the lead body 12 of the current lead 3 shown in FIG.
A cross section of a portion is shown, and a gap 10 formed by inserting a plurality of conductors 9 into a hollow lead pipe 8 is used as a flow path of helium gas. The outer circumference of the lead pipe 8 is surrounded by an insulator 11 to insulate the lead body 12. According to this configuration, by dividing the conductor for energization into a plurality of conductors, the cooling surface area of the conductor is increased and the cooling efficiency is improved. However, when the current lead with this configuration is used for a long and large current, the number of conductors becomes large (for example, several hundreds), which causes the workability of inserting into a hollow lead pipe. There is a drawback in that the diameter of the conductor is limited by itself, the cooling effect of the conductor is lowered, the heat of penetration from the room temperature portion to the cryogenic portion is increased, and the consumption amount of liquid helium is increased.

[Object of the Invention]

In view of the above-mentioned circumstances, an object of the present invention is to improve the lead body so that the housing work is easy when a large number of thin conductors are housed in a lead pipe for use with a long type large current. To do.

[Main points of the invention]

In the present invention, in order to achieve the above object, the structure of the lead body is as follows. That is, a plurality of thin conductors were housed in a case that was divided into two in the longitudinal direction, external pressure was applied thereto, and then the case that was divided into two was airtightly joined.

Example of Invention

FIG. 1 is a transverse cross-sectional view of a current lead body showing a first embodiment of the present invention. The parts having the same functions as those of the conventional structure are designated by the same reference numerals and the description thereof will be omitted. The case corresponding to the lead pipe having the helium gas passage is formed by combining the U-shaped pipes (or U-shaped pipes) 13a and 13b. 2 to 4, the assembling method of the first embodiment will be described. First, a plurality of conductors 9 are provided in a U-shaped tube (or U-shaped tube) 13a made of a material (for example, stainless steel) having sufficient strength at extremely low temperatures and having low thermal conductivity.
Is arranged, and the bottom of the U-shaped tube (or U-shaped tube) 13b is inserted from the upper side of the conductor 9 along the inner side surface from the opening of the U-shaped tube 13a. At this time, the bottom portion of the U-shaped pipe 13b is pushed in the direction of the arrow by the external force F, and the U-shaped pipes 13a and 13b are hermetically joined by welding or the like at the P portions near the opening side portions, respectively. A required helium gas flow area can be obtained in the gap 10 formed between the pipe 13a and each conductor 9. An insulator 11 is provided on the outer circumference of the lead case formed by the U-shaped tubes (or U-shaped tubes) 13a and 13b.

FIG. 5 is a cross-sectional view of a current lead body showing a second embodiment of the present invention. As a lead case, the opening of a U-shaped tube (or U-shaped tube) 13a is closed by a flat lid 13c. It was formed by. FIG. 6 is a cross-sectional view of a current lead body showing a third embodiment of the present invention.
It is formed by closing the opening of the character tube (or semicircular tube) 13d with a flat plate-like lid 13c. FIG. 7 is a cross-sectional view of a current lead body showing a fourth embodiment of the present invention, in which two U-shaped tubes (or U-shaped tubes) 13a are formed as lead cases by joining them at their openings. It was done. FIG. 8 is a cross-sectional view of a current lead body showing a fifth embodiment of the present invention. As a lead case, two C-shaped tubes (or semi-circular tubes) 13d are joined at their openings. It was done.

〔The invention's effect〕

In the present invention, since the case formed by dividing the case into two in the longitudinal direction is joined at the opening as the structure of the lead case, it becomes easy to accommodate a large number of long and thin conductors in the lead pipe, and the cooling surface area of the conductor is reduced. The cooling efficiency can be improved because the cooling efficiency can be increased. As a result, heat to the cryogenic portion can be reduced, and an economical current lead can be provided which can reduce the consumption of expensive liquid helium.

[Brief description of drawings]

FIG. 1 is a transverse sectional view of a lead body of a current lead according to a first embodiment of the present invention, FIGS. 2 to 4 are transverse sectional views showing an assembling order of the lead body, and FIG. Second
FIG. 6 is a cross sectional view of a lead body of a current lead which is an embodiment of the present invention, FIG. 6 is a cross sectional view of a lead body of a current lead which is a third embodiment of the present invention, and FIG. 7 is a fourth embodiment of the present invention. FIG. 8 is a transverse sectional view of a lead body of a current lead as an example, FIG. 8 is a transverse sectional view of a lead body of a current lead as a fifth embodiment of the present invention, and FIG. 9 is a longitudinal sectional view of a superconducting electromagnet device. FIG. 10 is a cross-sectional view of a lead body of a current lead for a superconducting electromagnet device according to a conventional configuration. 1: low temperature container, 8: lead piping, 9: conductor, 10: gap, 13a, 13
b: Case.

Claims (2)

[Claims] 1. A plurality of conductors are housed in a lead pipe for supplying electric power from an external power source to a superconducting electromagnet which is kept in a cryogenic state in a cryogenic container, and the conductor is cooled in a gap in the lead pipe. In the current lead in which the helium gas is circulated, the lead body is formed by housing a plurality of thin conductors in a case made of a material having a small thermal conductivity divided into two parts in the longitudinal direction and applying external pressure, and then forming the thin conductor. A current lead for a superconducting electromagnet device, characterized in that a case divided into two parts is hermetically joined. 2. The current lead for a superconducting electromagnet device according to claim 1, wherein the case made of a material having a small thermal conductivity is made of stainless steel.