JP7145791B2 - Superconducting magnet device - Google Patents

Description

An embodiment of the present invention relates to a superconducting magnet apparatus that conductively cools a superconducting coil with a refrigerator.

In general, superconducting magnet devices require superconducting coils to be cooled to extremely low temperatures using liquid helium or the like. In recent years, a method using a cryogenic refrigerator capable of cooling down to the temperature of liquid helium has also become popular.

In the refrigerator cooling system, as shown in FIG. 4, which is a longitudinal sectional view showing a conventional example of a superconducting magnet device 6, a superconducting coil 1 and a refrigerator 2 placed in an adiabatic vacuum 5 are connected by a high-purity metal heat transfer plate 3. Connect to form a thermal link for conduction cooling. Both ends of the high-purity metal heat transfer plate 3 on the side of the superconducting coil 1 and on the side of the refrigerator 2 have a temperature difference that is proportional to the amount of heat transfer and length, and inversely proportional to the thermal conductivity and cross-sectional area. In order to minimize this temperature difference, high-purity aluminum, high-purity copper, or the like is used as a material with high thermal conductivity.

JP 2013-207088 A JP 2015-179791 A

AIP Conference Proceedings 1435, 140 (2012)

The above-mentioned high-purity aluminum, high-purity copper, etc. are thermally heated in a magnetic field, as shown in the characteristic diagrams showing the relationship between the magnetic field and thermal conductivity of high-purity metals shown in FIGS. A phenomenon in which conductivity decreases is known. Therefore, it is necessary to increase the cross-sectional area of the high-purity metal heat transfer plate in consideration of this decrease in thermal conductivity. On the other hand, high-purity aluminum and the like are expensive, and it is desired to reduce the amount used in order to reduce costs.

The present invention has been made to solve the above-described problems, and the heat transfer direction of the high-purity metal heat transfer plate is set parallel to the magnetic field, or the width direction of the heat transfer plate is set radially with respect to the axis of the magnetic field. An object of the present invention is to obtain a superconducting magnet device capable of achieving the same temperature difference with a small amount of high-purity aluminum by arranging them.

A superconducting magnet apparatus according to the above embodiment includes a superconducting coil, a refrigerator that conductively cools the superconducting coil, and a high-purity metal heat transfer plate that thermally connects the superconducting coil and the refrigerator. In the device, the cross-sectional area on the side of the superconducting coil, which is a portion where the longitudinal direction of the high-purity metal heat transfer plate intersects with the magnetic field generated by the superconducting coil, is such that the longitudinal direction of the high-purity metal heat transfer plate is the magnetic field. It is characterized by being larger than the cross-sectional area on the side of the refrigerator, which is the parallel portion.

According to the embodiment of the present invention, the amount of the high-purity metal heat transfer plate that thermally connects the superconducting coil and the refrigerator is reduced, and the temperature difference between both ends of the high-purity metal heat transfer plate is reduced. be able to.

1 is a longitudinal sectional view of a superconducting magnet device according to Embodiment 1 of the present invention; FIG. The superconducting magnet device concerning Example 2 of this invention is shown, (a) is a longitudinal cross-sectional view, (b) is a front view. It is a diagram schematically showing the relationship between the arrangement of the high-purity metal heat transfer plate and the magnetic field, (a) is a side view in which the high-purity metal heat transfer plate is arranged obliquely with respect to the longitudinal direction, (b) is a ), (c) is a side view when the high-purity metal heat transfer plates are arranged radially with respect to the axis of the magnetic field, and (d) is a front view of (c). FIG. 2 is a vertical cross-sectional view showing a conventional example of a superconducting magnet device. FIG. 4 is a characteristic diagram showing the relationship between magnetic field and thermal conductivity when the direction of heat flow in high-purity metal is perpendicular to the magnetic field. FIG. 4 is a characteristic diagram showing the relationship between magnetic field and thermal conductivity when the direction of heat flow in high-purity metal is parallel to the magnetic field.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a superconducting magnet device according to the present invention will be described with reference to the drawings.

(Example 1)
First, Example 1 will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of a superconducting magnet device according to Embodiment 1 of the present invention. In FIG. 1, the same parts as those in FIG. 4 are given the same reference numerals for explanation.

1, a superconducting magnet apparatus 10 according to the first embodiment includes a superconducting coil 1, a refrigerator 2 for conducting conduction cooling of the superconducting coil 1, and a high-purity metal conductor for thermally connecting the superconducting coil 1 and the refrigerator 2. It is composed of a hot plate 3 and a reinforcing member 4 attached to the high-purity metal heat transfer plate 3 . High-purity aluminum or high-purity copper is used for the high-purity metal heat transfer plate 3 as a material with high thermal conductivity.

Here, in the superconducting coil 1, a pair of superconducting coils 1a and 1b are arranged in a Helmholtz-type coil arrangement that generates a magnetic field along the same horizontal direction. The hot plate 3 is arranged so as to be substantially parallel to the magnetic field A. As shown in FIG.

The heat flow direction B is from the superconducting coil 1 to the refrigerator 2 as indicated by the arrow. In the conventional example shown in FIG. 4, part of the heat flow direction B is perpendicular to the magnetic field A. In FIG. 5 and 6, when the direction of the heat flow is perpendicular to the magnetic field, the thermal conductivity decreases to about 1/2 of that when the direction is parallel to the magnetic field, so the temperature difference increases.

On the other hand, in Example 1 of FIG. 1, the heat flow direction B is generally parallel to the magnetic field A, and the decrease in thermal conductivity is suppressed, so the temperature difference is kept small. Conversely, the cross-sectional area of the heat transfer plate required to obtain the same temperature difference as in FIG. 4 is reduced, and the required amount of high-purity aluminum can be reduced.

However, in FIG. 1, since the high-purity metal heat transfer plate 3 near the superconducting coil 1 is not arranged parallel to the magnetic field, the thermal conductivity is lower than that of other portions. Therefore, the thickness t1 of the high-purity metal heat transfer plate 3 at the portion not parallel to the magnetic field near the superconducting coil 1, for example, the connection portion with the superconducting coil 1 on the side of the superconducting coil 1, is increased to increase the cross-sectional area. By increasing the size and decreasing the cross-sectional area of the other portion (refrigerating machine 2 side) t2, the heat resistance per unit length is made substantially the same. By doing so, it is possible to reduce the amount of high-purity aluminum or high-purity copper required for the high-purity metal heat transfer plate 3 in order to equalize the temperature difference.

In addition, the length of the portion where the longitudinal direction of the high-purity metal heat transfer plate 3 is substantially parallel to the magnetic field A is longer than the length of the portion intersecting the magnetic field A, so that the high-purity metal heat transfer plate 3 requires more It is possible to reduce the amount of high-purity aluminum or high-purity copper used.

Moreover, in FIG. 1, the high-purity metal heat transfer plate 3 is arranged in the air. Therefore, when the magnetic field A fluctuates, an eddy current is induced in the high-purity metal heat transfer plate 3, an electromagnetic force is applied to the high-purity metal heat transfer plate 3, and the high-purity metal heat transfer plate 3 is destroyed. there is a possibility. For this reason, the reinforcing member 4 functions to receive this electromagnetic force, and is configured to prevent the breakage of the heat transfer plate 3 . Moreover, since the above electromagnetic force works in opposite directions when the magnetic field increases and when the magnetic field decreases, the reinforcing material 4 is attached to both upper and lower surfaces of the high-purity metal heat transfer plate 3 . From the viewpoint of excellent corrosion resistance and heat resistance, the reinforcing material 4 is preferably made of Ni-based alloys such as Hastelloy (registered trademark) and Inconel (registered trademark), Fe-based alloys such as stainless steel, and aluminum alloys. . Furthermore, fiber reinforced plastics (FRP) or glass fiber reinforced plastics (GFRP) can be adopted.

Although FIG. 1 shows that the high-purity metal heat transfer plate 3 is arranged only in the superconducting coil 1a, the high-purity metal heat transfer plate 3 and the reinforcing material are also arranged in mirror-symmetrical positions in the superconducting coil 1b. 4 are placed.

(Example 2)
Next, Embodiment 2 of the superconducting magnet device according to the present invention will be described with reference to FIGS. Embodiment 2 FIG. 2 shows a superconducting magnet apparatus according to Embodiment 2 of the present invention, where (a) is a longitudinal sectional view and (b) is a front view.

In addition, the same code|symbol is attached|subjected to the structure same as Example 1, and the overlapping description is abbreviate|omitted. This embodiment also employs a Helmholtz-type coil arrangement that generates a magnetic field along the same horizontal direction, and the superconducting magnet on one side is omitted.

In FIG. 2, the superconducting magnet device 11 is arranged high in the axial direction of the refrigerator 2, and when the superconducting coil 1 and the refrigerator 2 are linearly connected thermally by the high-purity metal heat transfer plate 3, heat flows in the direction B and the direction of the magnetic field A intersect without being parallel. Therefore, as shown in FIG. are placed in

The effect of this arrangement will be described with reference to FIG. (a) of FIG. 3 is a side view when the high-purity metal heat transfer plate 3 is arranged obliquely with respect to the longitudinal direction, (b) is a front view of (a), and (c) is a high-purity metal heat transfer plate. 3 are arranged radially with respect to the axis of the magnetic field A, and (d) is a front view of (c).

In FIG. 3, the heat flow direction B is divided into a component perpendicular to the magnetic field A and a parallel component, and attention is focused on the component perpendicular to the magnetic field.

In (a) and (b), the heat transfer area is the product t×w of thickness t and width w, but in (c) and (d) it is the product t×l of thickness t and length l. Here, if w<<l, (c) and (d) have a larger heat transfer area and a smaller temperature difference in the component perpendicular to the magnetic field, so that the temperature difference as a whole can be reduced. Conversely, the cross-sectional area of the high-purity metal heat transfer plate 3 required to make the temperature difference in (c) and (d) the same as in (a) and (b) becomes smaller, and the required amount of high-purity aluminum becomes smaller. As a result, the cost can be reduced.

In the first and second embodiments, the high-purity metal heat transfer plate 3 has been described as a single plate. However, although not shown, it may have a structure in which thin plates are laminated so as to be highly flexible. Of course.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention.

These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention.

These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

REFERENCE SIGNS LIST 1 Superconducting coil 2 Refrigerator 3 High-purity metal heat transfer plate 4 Reinforcing material 5 Insulated vacuum 6, 10, 11 Superconducting magnet device A Magnetic field B Heat flow direction
t, t1, t2...thickness
w…Width
l…Length

Claims (9)

a superconducting coil;
a refrigerator for conducting conduction cooling of the superconducting coil;
a high-purity metal heat transfer plate that thermally connects the superconducting coil and the refrigerator;
In a superconducting magnet device comprising
The cross-sectional area on the side of the superconducting coil, which is a portion where the longitudinal direction of the high-purity metal heat transfer plate crosses the magnetic field generated by the superconducting coil, is such that the longitudinal direction of the high-purity metal heat transfer plate is parallel to the magnetic field. A superconducting magnet device, characterized in that the cross-sectional area is larger than that of the refrigerator side, which is a part of the superconducting magnet device. 2. A superconducting magnet apparatus according to claim 1, wherein the length of the portion of the high-purity metal heat transfer plate that is parallel to the magnetic field is longer than the length of the portion that intersects with the magnetic field. 3. A superconducting magnet apparatus according to claim 1 , wherein said high-purity metal heat transfer plate is pasted with a reinforcing material. 4. The superconducting magnet apparatus according to claim 3 , wherein the reinforcing members are arranged so as to sandwich the high-purity metal heat transfer plate in the thickness direction. 5. A superconducting magnet apparatus according to claim 3 , wherein said reinforcing material is made of Ni-based alloy, stainless steel, aluminum alloy, fiber-reinforced plastic, or glass-fiber-reinforced plastic. . 6. The superconducting device according to any one of claims 1 to 5 , characterized in that said high-purity metal heat conducting plate is arranged in a direction perpendicular to the axis of the magnetic field generated by said superconducting coil. magnet device. 7. The superconducting magnet apparatus according to any one of claims 1 to 6 , wherein the width direction of the high-purity metal heat transfer plate is arranged radially with respect to the axis of the magnetic field generated by the superconducting coil. . 8. The superconducting magnet device according to claim 1 , wherein the high-purity metal heat transfer plate is made of high-purity aluminum or high-purity copper. 9. A superconducting magnet apparatus according to claim 1 , wherein said high-purity metal heat transfer plate has a structure in which thin plates are laminated.

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