JPH0467764B2 - - 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 Al, Nb ₃ AlGe, 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 M ₀ C, which are attracting attention as superconducting materials for magnets and the like 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
and/or a compound superconductor thin film is formed on a substrate made of a material with excellent electrical conductivity and thermal conductivity such as Cu, and the thin film is irradiated with a high-energy beam in a spiral shape to remove the compound superconductor in the irradiated area. The gist of this is to change it to a normal conductor. The high-energy beam used in the present invention includes laser beams,
It is a general term for electron beams, ion beams, etc., but below it will be represented by laser beams.

[Operation] In the present invention, first, a thin film made of the above-mentioned compound superconducting material is formed on a substrate such as Al and/or Cu. Although this thin film has superconducting properties as described above, since it is a mere thin film, it cannot exhibit the properties as a superconducting coil as it is. The present invention is characterized in that this superconducting thin film is processed into a coil shape using a special method, and specifically, as will be described in detail in Examples below, the thin film is irradiated with a laser beam in a spiral shape. do.
The compound superconductor existing in the area irradiated with the laser beam undergoes a structural change from crystalline to amorphous mixed crystal or supersaturated solid solution due to heating by the laser beam, and furthermore, some of the components evaporate. A change in the composition occurs, and the superconductor in the irradiated part transforms into a normal conducting material, and a spiral normal conducting part is formed in the superconducting thin film. The non-irradiated portion is separated from the irradiated portion while maintaining its superconducting properties, and is formed into a coiled spiral line.
In this way, a superconducting coil can be obtained without requiring any wire processing or the like.

All known compound superconducting materials can be used in the present invention, but the most preferred examples include Nb ₃ Sn, Nb ₃ Si,
Nb ₃ Al, Nb ₃ (Al・Ge), Nb ₃ Ge, Nb ₃ (Al・B・
Be), NbN, V ₃ Ga, V ₂ (Hf/Zr), etc. The method for forming these compound superconducting thin films is not particularly limited either. Common methods include sputtering, vapor deposition, and CVD. Although these compound thin films may exhibit superconducting properties by themselves, in some cases the internal structure of the thin film may be amorphous and the superconductivity may be insufficient. It is desirable to subject the thin film to a treatment such as annealing to promote crystallization and improve superconductivity.

In the present invention, Al 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, Al and Cu have excellent electrical 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 of quenching.

[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 1 indicates a substrate, and B indicates a compound superconducting thin film. In the present invention, after forming the compound superconducting thin film B on the substrate A by the method described above,
This is placed and fixed on the rotary disk 1. Then, while rotating the rotary disk 1 by the variable speed motor 2,
Laser beam L emitted from a laser beam generator
The compound superconducting thin film B is focused and irradiated 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 in the radial direction [arrow A direction] of the laser beam L 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 interval 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 superconducting thin film B, the irradiation temperature will decrease, and 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 (that is, the coil winding density) can be arbitrarily adjusted. By this laser beam irradiation, the compound superconducting material in the irradiated area B _L loses its superconductivity and changes to normal conductivity (in other words, the laser beam irradiation temperature is set such that it can change from superconductivity to normal conductivity) as described above. ). As a result, for example, Fig. 2 (top view) and Fig. 3 (cross-sectional view)
As shown in FIG. 2, a normal conductive laser beam irradiated part B _L is formed in a spiral shape in the compound superconducting thin film B layer, and a superconducting part B _s is formed in a coil shape in the thin film B layer. Therefore, for example, if electrode terminals Ta and Tb are connected to the outermost and innermost sides of the superconducting part _Bs as shown in Figure 3, current will flow only to the superconducting part _Bs in an extremely low temperature atmosphere. ,
This means that it can function as a superconducting coil.

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 compound 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 controlling the radial scanning speed v of the laser beam L as described above. ) The width of B _L itself can be changed arbitrarily by changing the magnification of the reduction optical system.

The present invention is carried out, for example, by the apparatus and method described above, but the structure of the apparatus itself does not limit the present invention in any way, and the point is that the compound superconducting thin film formed on the substrate is Any device may be used as long as it has the function of spirally irradiating the 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 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...Compound 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 compound superconductor thin film is formed on a substrate made of a material with excellent electrical and thermal conductivity, such as Al and/or Cu, and a high-energy beam is irradiated on the outer thin film in a spiral pattern to increase the compound superconductivity of the irradiated area. A method for manufacturing a superconducting coil characterized by changing the body into a normal conductor.