JPH0461207A - Conductor for electric-current lead use - Google Patents

Abstract

PURPOSE:To reduce the evaporation of liquid He or the like for cooling a superconducting magnet or the like by a method wherein ceramic superconductor layer is formed continuously in the lengthwise direction on the inner or/ and the outer circumferential face of a metal pipe on which fins have been formed on the inner circumferential face or/and the outer circumferential face. CONSTITUTION:A metal pipe 1 on which fins 3 have been installed rectlinearly on the outer circumferential face is filled with a ceramic super-conductor layer 2. A conductor for electric-current lead use is formed in such a way that a metal hollow body is filled with a raw material substance which can be changed to a ceramic superconductor. The conductor is extended and worked; after that, a prescribed heat treatment is executed; the raw-material substance is reacted with the ceramic superconductor. The fins are manufactured by being welded onto the metal pipe. As a method to continuously form the ceramic superconductor layers in the lengthwise direction on the inner circumferential face or/and the outer circumferential face of the metal pipe on which the fins have been formed on the inner circumferential face or/and the outer circumferential face, a tapelike ceramic superconducting wire material manufactured by metal-sheathing the ceramic superconductor layer is soldered to the inner circumferential face or the outer circumferential face of said metal pipe.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method for supplying a current from a current supply source placed at room temperature to a superconducting device or device such as a magnet or current limiter cooled with liquid He or the like. Concerning the conductor for the IT current lead used for supplying it.

(Conventional technology) Magnet, power transmission cable or 5QL using superconductivity
Electronic equipment, etc. incorporating IID, Jimachi Sefson elements, etc. are cooled with liquid He, etc., and the current supply to these electronic equipment, etc. is carried out from an external source at the start of operation or during operation. It is done through flowing - de.

By the way, steel has conventionally been used for current lead conductors, but since superconducting magnets and the like require an electric current, the current lead conductors are made thicker to reduce Joule heat generation and reduce overflow. Measures are taken to prevent fusing. However, when the current lead conductor is made thicker, the amount of heat flowing in from the outside increases, causing the problem that (1) the amount of evaporation of the refrigerant, such as 0, increases and the cooling cost increases.

For this reason, in recent years, ceramic superconductors that exhibit superconductivity at liquid N1 temperature have been combined with metals that are good electrical conductors.
iA conductor for current leads was proposed.

In this current lead conductor, current is supplied mainly through the ceramic superconductor on the superconducting element side cooled with liquid He, etc., and through the metal coating layer on the current supply source side at room temperature. Superconductor is liquid He
On the superconducting element side, which is cooled by It has the following.

[Problem 8 to be solved by the invention] However, the current lead conductor made of ceramic superconductor as described above is not cooled by He vapor emitted from liquid He used for cooling superconducting equipment. If the cooling effect is insufficient, the superconductor layer may quench and burn out, or heat from the outside may be transmitted through the current lead conductor, causing liquid He to evaporate multiple times. There was a problem.

[Means for Solving the Problems] The present invention was made as a result of intensive research in view of the above situation, and its purpose is to reduce the amount of evaporation of liquid He, etc. used for cooling superconducting magnets, etc. L2 An object of the present invention is to provide a conductor for a current lead.

That is, the present invention is characterized in that a ceramic superconductor layer is continuously provided in the longitudinal direction on the inner circumferential surface and/or outer circumferential surface of a metal pipe having fins on the inner circumferential surface and/or outer circumferential surface. That is.

Hereinafter, the present invention will be specifically explained with reference to the following sections.

FIGS. 1 to 3 are cross-sectional views showing embodiments of the tYk lead conductor of the present invention, and FIG. 4 is a partially cutaway perspective view of the same.

In the current lead conductor shown in FIG. 1, a metal pipe 1 in which twins 3 are arranged linearly on the circumference is filled with a Yaraminox superconductor layer 2.

This current lead conductor is made by filling a metal hollow body with a raw material that can be made into a ceramic superconductor (7), and then subjecting it to a pre-elongation process (I) and then subjecting it to a predetermined heat treatment to convert the raw material into a ceramic superconductor (Q). After that, the fins are welded to the metal vig 19 shown in F. A tape-shaped ceramic superconducting wire 4 made by sheathing a ceramic superconductor layer 2 with metal is soldered to the inner peripheral surface of the pipe.

Further, the conductor for t flowing to 't' shown in FIG.
The tape-shaped ceramic superconducting wire 4 described above is soldered to the II 11, and a cold-insulating metal tube 5 is further placed on the outer periphery thereof.

The itit-lead body shown in FIG. 4 is made by forming the tape-shaped ceramic superconducting wire 4 in a spiral shape on the outer peripheral surface of a metal pipe l having spiral fins 3 on the outer peripheral surface. It is soldered and furthermore, a cold insulation metal tube 5 is arranged around it.

The above-mentioned cold insulation metal pipe is a material that prevents dissipation of He vapor and increases cooling efficiency by placing the superconductor layer around the outer circumference of the metal pipe. is Cerami・1. Plastics such as plastics and FRP can also be applied.

In the present invention, the ceramic superconductor includes Y-Ba
-Cu-0 system, B1-3r-Ca-Cu-○ system, Tl-
Any ceramic super IIs such as Ba-Ca-Cu-0 series
The body is used.

In the present invention, a method of continuously providing a ceramic superconductor layer in the longitudinal direction on the inner circumferential surface and/or outer circumferential surface of a metal vibrator having fins on the inner circumferential surface and/or outer circumferential surface is as follows: In addition to the method described above in which a tape-shaped ceramic superconducting wire made by sheathing a ceramic superconductor layer with a metal sheath is soldered to the inner peripheral surface or outer surface of the metal pipe, ceramic superconducting powder can be used. A method is used in which the base material is kneaded with a binder to form a base material, and this is applied onto the inner peripheral surface and/or outer peripheral surface of the finned metal pipe.

The above-mentioned arc-shaped ceramic conductive wire can be made into, for example, a ceramic superconductor by: 1- filling the hollow body of a metal mold with the raw material to be obtained; It is manufactured by subjecting a predetermined heat treatment to reacting the raw material with the ceramic superconductor.

In J-, the shape of the elongated material is not limited to a tape shape, but any cross-sectional shape such as a circle, ellipse, polygon, etc. can be applied, but the contact area M with the surface of the gold S pipe should be made large. A tape-shaped material is particularly preferred.

In the present invention, Ag, Cu, Affi, alloys thereof, etc., which have excellent thermal conductivity, are suitable for the material of the metal pipe having fins. Further, the shape of the fins is not particularly limited, and any shape can be applied.

[Effect]

Since the IT lead thick conductor and ceramic superconductor layer of the present invention are provided in close contact with the circumferential surface of a metal pipe having fins, the metal pipe is efficiently cooled by a refrigerant such as He vapor, and as a result, The ceramic superconductor layer provided on the circumferential surface of the metal pipe is cooled in one minute, and the superconducting state of the ceramic superconductor layer is stably maintained, and external heat is transferred through the metal pipe. is also cooled and removed by the heat dissipation effect of the fins.

(Example〕 The present invention will be explained in detail below using examples.

Example 1 B 1zOs, S r CO3, as starting materials
Using powders of CaCOa and CuO, they were mixed into Bi:Sr:
The atomic ratio of Ca:Cu is 2:2:1. : 2 and mix to make a mixed powder, then this mixed powder is pre-calcined in the atmosphere at 800°C for 20 hours, this is pulverized and classified to make a pre-sintered powder, then this pre-sintered powder is After filling the fired powder into an Ag pipe with an outer diameter of 25 m and an inner diameter of 15 mm, it was subjected to swaging processing and groove rolling to become a wire rod with an outer diameter of 5 mm.
'CX heat-treated for 50 hours to react the calcined powder of the inner layer into a superconductor to form a ceramic superconducting wire, and after that, this ceramic superconducting wire was made into a ceramic superconducting wire with a thickness of 0.
A copper ribbon with a width of 10 cm was bent into an L shape, and the bent cheeks were welded in a straight line to the surface of the wire to form 11 straight fins with a height of 8 mm at equal intervals. The structure was as shown in the figure, and three of these were connected in parallel to form a current lead conductor.

Example 2 The wire rod with an outer diameter of 5 mm produced in Example g41 was further drawn and rolled without being subjected to heat treatment to react and zeify it into a superconductor, to form a tape wire rod with a thickness of 0.3 mm and a width of 5 mm. After that, this tape wire was heat-treated in the air at 850°C for 50 hours in the same manner as in Example 1 to obtain a tape-shaped ceramic superconducting wire, and then this tape-shaped wire was made into a copper wire with inner peripheral surface fins. 1 along the fins on the inner circumference of the pipe
A thick conductor for an IT lead having the structure shown in FIG. 2 was manufactured by soldering six wires.

] - The copper pipe with inner circumference fins has an outer diameter of 31 m and a wall thickness of 1 inch, and a thickness of 0.1 w and a height of 8 mm on the inner circumference of the pipe.
16 copper fins are arranged in a straight line at equal intervals.

Example 3 A copper pipe with an outer diameter of 31 cm and a wall thickness of 1 cm has 16 copper fins of 0.1 cm thick and 8 cm in height arranged in a straight line at equal intervals on the inner and outer peripheral surfaces of the pipe. On the outer circumferential surface of the copper pipe, 16 wire tapes similar to those used in Example 2 were soldered along the fins to serve as current lead conductors, and the wires shown in Figure 3 were soldered around the outer circumference of the copper pipe. As shown, the inner diameter is 48
A copper cold storage tube with a wall thickness of 1 inch was placed. The improved recording tube was placed to prevent HefQ air from escaping outward within the tube.

Example 4 Thickness O on the outer peripheral surface of a copper pipe with an outer diameter of 31W+ and a wall thickness of l
,Iam, 74,216 copper rods of 8 heights were placed at equal intervals, 5
16 ceramic superconducting wires, the same as those used in Example 2, were soldered along the fins to the outer circumferential surface of this finned copper pipe in a pinched spiral shape to serve as a current lead conductor. Furthermore, a copper cold storage tube was placed around it as shown in FIG.

Comparative Example 1 Three 5 m ceramic superconducting wires produced in Example 1 were connected in parallel without welding fins to form a current lead conductor.

Comparative Example 2 Ceramic superconducting wires with a thickness of 0.3 cm and a width of 5 cm produced in Example 2 were placed at equal intervals on the inner peripheral surface of a copper pipe without fins with an outer diameter of 31 cm and a wall thickness of 1 cm. 16 wires were lined up in a straight line and soldered, and the periphery was covered with a copper tube having an inner diameter of 48 cm and a wall thickness of 1 mm to form a current lead conductor.

For each current lead conductor thus obtained, one end was connected to a Nb-Ti electromotive magnet cooled in liquid He, and the other end was connected to a copper busbar at room temperature. ,,,The entire conductor for the first current lead is maintained at a temperature of 77 degrees Fahrenheit by He vapor emitted from the liquid He, and a current of 6T and 800A is applied to the magnet 7 to remove the liquid He. The amount per shot was measured. In addition, before starting current supply, the temperature of the end of the current lead conductor on the copper bus bar side was measured to investigate the cooling state of each current lead conductor.

Also, for each current lead conductor, 77K and 30K
The critical current (IC) was measured to check the current carrying capacity of each current lead conductor.

The results are shown in Table 1. Note that the evaporation amount of liquid He is the value obtained by subtracting the evaporation amount when no current is applied.

As is clear from Table 1, the products of the present invention (Nos. 1 to 4) had a high cooling capacity and therefore had a small amount of evaporation cap of i(e).

In particular, floor 4 has long spiral fins, so cooling by He vapor is effective and the He evaporation cover is minimized. In addition, problem 1 is difficult to cool because the ceramic superconductor layer has a circular cross-section and a small surface ratio, so the He evaporation lid is the largest among the inventions.

In addition, in Section 3.4, the ceramic superconducting layer was provided on the outer peripheral surface of the finned metal pipe, so it was easier to solder the ceramic superconducting wire, and the copper tube was placed on the outside. I was also able to prevent my mind from escaping.

On the other hand, Comparative Example Product No. 5 had a small surface ratio of the ceramic superconductor layer and no fin was attached to the metal pipe, so the ceramic superconductor layer was quenched and burned out. Since no fins were attached to the copper pipe, the cooling capacity was poor, and a large amount of He would evaporate.However, there is no significant difference in the critical IT residue (1,,) at 77K and 30K for each current lead conductor. On the other hand, the room temperature side temperature of the current lead conductor when no current is applied varies greatly depending on whether or not the conductor has fins, and in 1, a correlation is recognized between the temperature and the amount of evaporation of liquid He. The effect of fins on the evaporation of liquid He has been demonstrated.

In addition, when a conventional current lead conductor made of 10 bundled 1.2wφ copper wires was used under the same conditions as above, the evaporation cap of He was measured.2. It was Oj2/H.

Although the case where the ceramic superconductor layer is provided only on either the inner circumferential surface or the outer circumferential surface of a copper pipe having fins has been described above, it goes without saying that the same effect can be obtained when the ceramic superconductor layer is provided on the inner circumferential surface. stomach.

[Effects] As mentioned above, the current lead conductor of the present invention has a rich cooling capacity, and can reduce the amount of evaporation of a refrigerant such as liquid (1e) for cooling superconducting equipment to 4 times the width. Ding-1: Demonstrates remarkable efficacy 8

[Brief explanation of the drawing]

1-3 are cross-sectional views showing embodiments of the current lead conductor of the present invention, and FIG. 4 is a cut-away perspective view of the same. DESCRIPTION OF SYMBOLS 1... Metal pipe, 2... Ceramic superconductor layer, 3... Fin, 4... Ceramic superconducting wire, 5... Metal tube for cold storage.

Claims (1)

[Claims] A conductor for a current lead, characterized in that a ceramic superconductor layer is continuously provided in the longitudinal direction on the inner circumferential surface and/or outer circumferential surface of a metal pipe having fins on the inner circumferential surface and/or outer circumferential surface.