JPH0464445B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a high-performance superconducting coil in a simple manner and with high productivity.

[Prior art] As electromagnetic application equipment such as electron microscopes and nuclear magnetic resonance measurement devices, and synchrotron orbital radiation devices become smaller, the performance required of the electromagnets used in these devices becomes increasingly strict. Compound superconducting materials are attracting attention as materials that can meet these demands. That is, examples of compound superconducting materials include Nb ₃ Sn, Nb ₃ Ge,
Nb ₃ Si, Nb ₃ Ga, Nb ₃ A1, Nb ₃ A1Ge, Nb ₃ SiGe,
V ₃ Ga, V ₃ Ge, V ₃ Si, V ₂ Zr, V ₂ Hf, NbN,
Examples include metal compounds such as NbNC and MoC, which are attracting attention as superconducting materials for magnets because of their high critical temperature (Tc) and high upper critical magnetic field (Hc ₂ ). However, since these compound superconducting materials are generally very hard and brittle, they cannot be processed into wires like alloy conductors, and special techniques are required to form them into coils. The wire rod manufacturing methods that have been researched or are beginning to be put into practical use include (1) diffusion methods (surface diffusion method, composite processing method, IN
(SITU method, powder method), (2) vapor deposition method (vacuum vapor deposition, sputtering, chemical vapor deposition), (3) precipitation method (precipitation from bcc phase, precipitation from amorphous phase), etc.

[Problems to be Solved by the Invention] However, the manufacturing process for compound superconducting wires as described above is generally extremely complicated, and it is difficult to ensure stable quality. It has to be wound into a shape, but the winding operation is extremely difficult, which is a major bottleneck in expanding demand for superconducting coils. Under these circumstances, the present invention aims to provide a technology that can produce a coil-shaped product made of a compound superconducting material with stable quality at a low cost by a simple method.

[Means for solving the problem] The method for manufacturing a superconducting coil according to the present invention includes A1
and/or consisting of a latent compound superconducting material such as amorphous, mixed crystal, or supersaturated solid solution that can exhibit superconductivity by irradiation with a high-energy beam on a substrate made of a material with excellent electrical conductivity and thermal conductivity such as Cu. The gist is that a thin film is formed and a high-energy beam is spirally irradiated onto the thin film to transform the irradiated portion into a crystalline superconducting film. The high-energy beam used in the present invention includes laser beams,
It is a general term for electron beams, ion beams, etc., but will be represented by laser beams below.

[Function] In the present invention, first, a thin film made of the above-mentioned compound superconducting material is formed on a substrate such as A1 and/or Cu. However, the constituent material of the thin film is a potentially superconducting thin film whose internal structure is amorphous, mixed crystal, or supersaturated solid solution, and does not have superconductivity by itself, but can only develop superconductivity when irradiated with a laser beam. form as. One way to obtain such a potential superconducting thin film is to sputter Nb ₃ Ge, V ₃ Si, Nb ₃ Si, etc. onto a low-temperature substrate.
Amorphous films can be easily obtained. Also, V ₃ Ge, Nb ₃
For A1, Nb ₃ (A1Ge), etc., supersaturated solid solutions can be obtained by the melt quenching method. Also, Nb ₃ Sn
Potential superconducting films such as
It can also be obtained by plating Sn.

A thin film is formed on the substrate using the method described above, and if necessary, Nb ₃ Ge, V ₃ Si, Nb ₃ Si, etc. can be subjected to treatments such as annealing to promote mixed crystallization. A potential superconducting thin film. Since this thin film only has latent superconductivity, not actual superconductivity, and is merely a thin film, it cannot exhibit the characteristics of a superconducting coil as it is. The present invention is characterized in that this potential superconducting thin film is processed into a coil-shaped superconducting film using a special method. Specifically, as will be described in detail in Examples below, the thin film is exposed to a laser beam. irradiates in a spiral pattern. The potential superconductor existing in the area irradiated by the laser beam is locally heated by the laser beam, and microcrystals grow in the amorphous structure, and the critical temperature (Tc), critical current (Ic) and critical magnetic field ( _Hc2 ) suddenly increases,
A spiral superconducting manifest portion is formed within the latent superconducting thin film. The non-irradiated portion is distinguished from the irradiated portion as a so-called normal conducting portion that remains latent without producing superconducting characteristics, and the superconducting portion is eventually formed in the form of a coil as a spiral line. In this way, a superconducting coil can be obtained without requiring any wire processing or the like.

In the present invention, A1 and/or Cu is selected as the substrate for the following reasons.

There is a phenomenon called quench in superconductors, which occurs when the superconductor undergoes mechanical strain due to the instability of the generated magnetic field or the Lorentz force generated by the magnetic field and current, causing heat generation and returning to a normal conducting state. This is a phenomenon that moves to When this phenomenon occurs in a superconducting coil, a large current flows through the high-resistance conductor that has become normal conductor, leading to catastrophic results such as burnout of the conductor.
Therefore, A1, Cu has excellent electrical conductivity and thermal conductivity.
It is necessary to provide a metal such as in close contact with the superconductor to prevent quenching by dissipating minute heat generation to the refrigerant, and to have the role of bypassing large currents in the event that quenching occurs.

[Example] Hereinafter, a method for manufacturing a superconducting coil according to the present invention will be explained with reference to the drawings of the example.

In FIG. 1, 1 is a rotary disk, 2 is a variable speed motor, 3 is an irradiation temperature/vortex spacing control device, 4 is an optical system scanning device, 5 is a laser beam generator, 6 is a reflecting mirror, 7 is a reduction optical system, A indicates a substrate, and B indicates a potential superconducting thin film. In the present invention, after the latent superconducting thin film B is formed on the substrate A by the method described above, it is placed and fixed on the rotary disk 1. While the rotary disk 1 is rotated by the variable speed motor 2, a laser beam L is emitted from the laser beam generator 5.
is focused and irradiated onto the potential superconducting thin film B from the reflecting mirror 6 through the reduction optical system 7, and at the same time, the irradiation direction of the laser beam L is gradually moved in the direction of arrow A by the optical system scanning device 4. Here, the rotational speed w of the variable speed motor 2 and the scanning speed v of the laser beam L in the radial direction [direction of arrow A] are determined by the irradiation temperature/vortex spacing control device 3.
By adjusting this, the temperature of the laser beam L irradiation part and the spiral spacing can be arbitrarily controlled. That is, if the rotational speed w of the motor 2 is increased to increase the scanning speed of the laser beam L in the circumferential direction on the potential superconducting thin film B, the irradiation temperature will decrease, and conversely, if the scanning speed is decreased, the irradiation temperature will increase. . Furthermore, if the radial scanning speed v of the laser beam L is increased, the spiral interval of the laser beam irradiating part B _L becomes wider, and on the other hand, if the same scanning speed v is decreased, the spiral interval of the laser beam irradiating part B _L becomes narrower.
Therefore, by appropriately controlling the above two scanning speeds w and v, the degree of heat treatment applied to the laser beam irradiation section B _L and the spiral spacing (i.e., the coil winding density) can be adjusted.
can be adjusted arbitrarily. As described above, this laser beam irradiation progresses the fine crystallization of the potential superconducting structure of the amorphous, mixed crystal, or supersaturated solid solution in the irradiated area B _L , and superconductivity is manifested (in other words, superconductivity is expressed). For example, as shown in Figure 2 (top view) and Figure 3 (cross-sectional view), the potential superconducting thin film B layer is irradiated with a superconducting laser beam. Department
B _L is formed in a spiral shape _, while the non-irradiated part B _O has latent superconductivity but still remains normal conductivity. It will be formed into a shape. Therefore, for example, as shown in FIG.
If electrode terminals Ta and Tb are connected to the outermost and innermost sides of B _L , current will flow only to the superconducting part B _L in an extremely low temperature atmosphere, and it can function as a superconducting coil. become.

In addition, if the motor 2 is always rotated at a constant speed in the above laser beam irradiation process, the circumferential speed on the outer circumferential side and the circumferential speed on the inner circumferential side will change continuously when the potential superconducting thin film B is irradiated with the laser beam L. As a result, the heat treatment temperature of the irradiated area becomes uneven. Therefore, when irradiating the laser beam, it is desirable to gradually increase the rotational speed w of the motor 2 as it moves from the outer circumferential side to the inner circumferential side, and to control the scanning speed of the laser beam to be constant. . Also, the laser beam irradiation part
The spiral gap (that is, the coil winding density) of B _L can be arbitrarily controlled by adjusting the radial scanning speed v of the laser beam L as described above, and the laser beam irradiation part (superconducting part) B The width of _L itself can be arbitrarily changed by changing the magnification of the reduction optical system.

The present invention is carried out by, for example, the above-described apparatus and method, but the structure of the apparatus itself does not limit the present invention in any way, and the point is that the potential superconducting thin film formed on the substrate Any device may be used as long as it has the function of spirally irradiating a high-energy beam. Furthermore, the superconducting coil obtained by the present invention may be used as a donut-shaped single piece, or a plurality of these may be stacked and each superconducting portion is connected in series via a through hole or a lead wire. Of course, it is also effective to increase the electromagnetic force.

[Effects of the Invention] The present invention is configured as described above, and can enjoy many effects as shown below.

(1) There is no need for wire drawing or tape processing, and it is extremely easy to apply to compound superconducting materials that are extremely difficult to mold. Moreover, since coiling processing is not required, manufacturing is simple and can be obtained at extremely low cost.

(2) Since this method uses a high-energy beam with extremely high convergence, it is possible to obtain superconducting coils with high processing accuracy and stable quality. Moreover, it is extremely easy to adjust the coil spacing and winding density, and it is possible to obtain the performance that meets your needs.

(3) Coils of any size (inner/outer diameter) can be easily manufactured.

(4) Unlike etching methods such as photolithography, it is not necessary to use an etching solution, so it is safe and does not cause secondary pollution.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of the present invention, and FIGS. 2 and 3 illustrate a superconducting coil obtained by the present invention. FIG. 2 is a plan view, and FIG. 3 is a sectional view. A...Substrate, B...Potential superconducting thin film, 1...
Rotary disk, 2...Variable speed motor, 5...Laser beam generator, 6...Reflector, 7...Reducing optical system.

Claims (1)

[Claims] 1. A thin film made of an amorphous latent compound superconducting material that can exhibit superconductivity by irradiation with a high-energy beam is formed on a substrate made of a material with good electrical and thermal conductivity such as A1 and/or Cu, and the thin film is A method for manufacturing a superconducting coil, which comprises irradiating a high-energy beam spirally onto the irradiated portion to transform the irradiated portion into a crystalline superconducting film.