JPH0332003A - High-magnetic-field magnet - Google Patents

Abstract

PURPOSE:To obtain a high-magnetic-field magnet having excellent characteristics by using an oxide superconductor having a specified C-axis orientation rate, the length of a crystal grain and a specific thickness as magnet wire, cooling the temperature of the wire to a specified temperature or below, and using the wire. CONSTITUTION:An oxide superconductor is used as a magnet wire, and a high- magnetic-field magnetic is formed. Said superconductor has a crystal structure wherein the C axis is oriented in the direction perpendicular to the current conducting direction. The length of the crystal grain in the current conducting direction is made to be 0.1mm or more. The thickness of the superconductor is made to be 0.5mm or less. The magnet is used at the temperature at 30K or below. The C-axis orientation rate is made to be 80% or more at a value F shown by the expression I (wherein F is the C-axis orientation rate, P0 is the X-ray diffraction intensity ratio at the side surface of the superconductor and P00 is the X-ray diffraction intensity ratio of uniformly mixed non-oriented oxide superconductor powder). Thus, the high-magnetic-field magnet which can generate the high magnetic field having excellent characteristics and has wide application fields can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnet that generates a high magnetic field of 2T (Tesler) or higher, especially IOT or higher, which cannot be generated industrially with normal conduction, and is suitable for scientific measurement, NMR spectroscopy, accelerators, fusion, magnetic levitation, generators, power storage (SM)
It relates to high-field magnets used in magnets that form the center of devices such as ES).

[Conventional technology]

A normal conducting magnet using a copper wire and an iron core can generate a magnetic field of up to 2T, but if a higher magnetic field is required, a composite magnet with Nb-T+ filament embedded in a conductive metal such as copper or aluminum can be used. A superconducting magnet made of multicore wires is used.

When using Nb-Ti as a conductor, these superconducting magnets have a limit of 7 to 8 T for liquid He at 4.2 K, and by supercooling to 1.8 K, it is possible to increase the magnetic field to around LOT. I can do it. In order to obtain an even higher magnetic field, A-15 type compounds such as NtzSn, V, and Ga are used as Nb-T.
Although it is used instead of i0, the generated magnetic field remains at 16-18T. The above-mentioned superconductors are often used as hybrid-noded magnets by disposing a superconductor such as Nb, Sn, V, or Ga inside and an Nb-Ti superconductor outside.

Further, superconducting magnets are used in coil forms such as solenoid, pancake, racetrack, and saddle shapes depending on the purpose.

By the way, as a matter of course, in these superconducting magnets, the larger the generated magnetic field, the greater the electromagnetic effect obtained, and therefore it is expected that the devices will be smaller and have higher performance.

For this reason, there is a desire to develop a magnet that can obtain a higher magnetic field, and in recent years, magnets with a liquid He temperature of 50T have been developed.
Chevrel phase compounds such as PbMo*S6, which can generate a critical magnetic field of has been done.

Under these circumstances, a copper-containing composite oxide was discovered that exhibits superconductivity at liquid nitrogen temperatures.

For example, this composite oxide has a critical temperature (T) of 90 to 95
YBaxCu307-6 or the above Y replaced with other rare earth elements, Bi with Tc of 90 to 110, 5r
zCaCu! Oa, BigSrtCazCu3(Lo,
T1. where T is 100 to 125. F3a.

CaCu,O,,TI! zBatca*cus○,. ,
TIBagCaiCusOs, s, etc., each of which is replaced with Pb, In, Sb, alkali metal, etc., for a part of the metal elements constituting the IJ(7) oxide superconductor,
Also included are those in which a part of O is replaced with F.

Although these composite oxides exhibit high superconducting properties as thin films, it has not been possible to obtain high properties as wires, and the development of high-field magnets has therefore stalled.

[Means to solve the problem]

The present invention was made as a result of intensive research in view of the above situation, and its purpose is to provide a high magnetic field magnet that can generate a magnetic field of 207 or more at 30°C.

That is, the present invention provides a high-field magnet using an oxide superconducting conductor as a magnet wire, wherein the crystal structure of the oxide superconducting conductor has an F value of 80% or more in the direction perpendicular to the direction of current flow as expressed by the following formula (1). It has a C-axis orientation ratio, the length of the crystal grain in the current direction is 0.1w or more, and the thickness of the conductor is 0.1w or more.
5 m or less, and the conductor is cooled to a temperature of 30 m or less.

F= (P, -P,.)/(1-P,.)...
(]) However, F... C-axis orientation rate Po... X-ray diffraction intensity ratio Po of the side surface of the oxide superconducting conductor. ... X-ray diffraction intensity ratio p 60r P e*=ΣI(OOIl)/ΣI (h
k f) Note that I (hkl) is (hM) The high-field magnet of the present invention uses an oxide superconductor for the magnet wire, and the crystal structure of the conductor is perpendicular to the current direction. C-axis oriented, the length of the crystal grain in the current direction is 0.1 m or more, and the conductor thickness is 0.5 m.
m or less, and the conductor is a magnet cooled to 30 m or less.

The magnet of the present invention can also be manufactured by creating an oxide superconductor having properties such as the crystal structure and shape described above and winding it into a coil (ReacL & Wind), but it is also possible to manufacture the magnet by using a precursor of the oxide superconductor. It is also possible to wind the oxide superconductor into a coil before it exhibits the above properties and then heat it to react to the superconductor and/or develop the above properties (Wind & Reac L). is a preferred method because it allows coiling without damaging the brittle oxide superconductor.

In addition to the method of coiling a flexible wire as described above, the magnet of the present invention can be produced by printing, coating, depositing, extruding, etc. a coiled circuit on a substrate such as a cylinder or disk. It can also be produced by heat treating this molded body. Furthermore, it is also possible to make a magnet by combining and connecting these cylinders and disks in multiple ways.

Since the magnet of the present invention is subjected to a large electromagnetic force (Lorentz force) during use, it is necessary to add reinforcement measures such as reinforcing the wire itself and the substrate, and firmly fixing the wires and the outer periphery of the coil with reinforcing material. It is necessary to suppress the movement of the conductor due to the Lorentz force, and to counter this, many techniques cultivated in the production of conventional superconducting magnets can be used. For example, tape-shaped oxide superconducting conductors and heat-resistant metals, Ni alloys such as Hastelloy and Fe such as SO3
There is a method of coiling an alloy, carbon fiber, ceramics such as Zr0z tape, etc. together.

In addition, as a method of insulating the conductor in coiling, for example, in the 1st & React method mentioned above, either the oxide superconductor or the reinforcing material is insulated by coating ceramics or heat-resistant glass in advance, or the above-mentioned ceramics are coated in advance. This is done by using a reinforcing material that also serves as insulation.

The most useful embodiment of the high magnetic field magnet of the present invention is when it is used as a high print magnet in combination with a metallic superconductor, and the magnet of the present invention shares the high magnetic field part that cannot be achieved with a metallic superconductor. A comprehensively high magnetic field can be generated.

That is, the above-mentioned hybrid magnet has the oxide superconducting conductor coil of the magnet of the present invention arranged inside and the metallic superconducting coil arranged outside, and both superconductors have the best characteristics at the liquid He temperature. If the same liquid He is used as a cooling medium, the FA construction of magnets will be greatly simplified.

As the oxide superconducting conductor used in the magnet of the present invention, a Bii-based oxide superconducting conductor such as a B1-3r-Ca-Cu-○ system is most preferable because it can provide a high Jc at the following temperatures. On the other hand, although Tc is high in Tl series, Tl
Since Y is toxic and volatile, heat treatment during wire rod processing is difficult, and Y-based materials have a low Tc, so they cannot be expected to improve the properties in the present invention as much as Bi-based materials.

[Effect]

The oxide superconducting conductor of the high magnetic field magnet of the present invention has a crystal structure in which the C-axis is oriented perpendicular to the direction of current flow, that is, the plane including the bc axis, through which superconducting current easily flows, is oriented parallel to the direction of current flow. A high J can be obtained, but the C
The axial orientation ratio is required to be 80% or more in F(I shown in formula (1)) in order to obtain the high JC value required in practice, and it is particularly preferable to set it to 90% or more.

Also, since grain boundaries become current-carrying resistance parts, it is important to reduce grain boundaries by forming crystal grains long in the current-carrying direction, and the length of the crystal grains in the current-carrying direction should be 0.1- or more. This is necessary in order to have a synergistic effect with the orientation.

In addition, the smaller the size of the oxide superconductor, the more favorable the C-axis orientation rate and the elongation of the crystal grains in the direction of current flow, and the better the quench resistance. It needs to be .5 or less, especially 0.3
It is preferable to set it to 0.03 m+.

The high magnetic field magnet of the present invention can generate a high magnetic field of 20 or more by cooling the oxide Mi conductor to a temperature of 30 or less, and even if the cooling temperature is lower than the oxide superconducting Even if the temperature is lower than the Tc of the conductor, liquid N
At a relatively high temperature such as 2 temperature, the above-mentioned high magnetic field cannot be obtained.The high magnetic field magnet of the present invention has characteristics that improve exponentially as the temperature decreases.
It is practically advantageous to use it after cooling it to below.

〔Example] The present invention will be explained in detail below using examples.

Example I

Claims (1)

[Claims] (1) A high-field magnet using an oxide superconductor as a magnet wire, wherein the crystal structure of the oxide superconductor has an F value of 8 in the direction perpendicular to the current direction according to the following formula (1).
It has a C-axis orientation rate of 0% or more, the length of the crystal grain in the current direction is 0.1 mm or more, and the thickness of the conductor is 0.5 mm.
A high magnetic field magnet as follows, and the conductor is cooled to a temperature of 30K or less. F=(P_0-P_0_0)/(1-P_0_0)...
(1) However, F...C-axis orientation rate P_0...X-ray diffraction intensity ratio of the side surface of the oxide superconducting conductor P_0_0...X-ray diffraction intensity ratio of uniformly mixed non-oriented oxide superconductor powder P_0orP_0_0=ΣI(00l)/ΣI( hkl
) Note that I(hkl) is the intensity of the (hkl) peak. High magnetic field magnet.