JP3263764B2 - Superconducting magnet device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet device used in an environment where vibration occurs.

[0002]

2. Description of the Related Art A superconducting magnet device has a superconducting coil and an inner tank for storing liquid helium for cooling the superconducting coil. A radiation shield is provided so as to cover the inner tank to block radiant heat. Cooled with vaporized helium or liquid nitrogen. Further, a pipe through which a refrigerant for cooling the radiation shield passes is disposed in contact with the radiation shield. Further, an outer tank for accommodating the superconducting coil, the inner tank, and the radiation shield exists on the outer peripheral side of the radiation shield. For example, Japanese Patent Application Laid-Open No. 50-65185 is an example of the structure of such a superconducting magnet. The outer tub and the radiation shield have a function of reducing invasion heat, and also have a function of shielding a fluctuating magnetic flux from the outside since the outer tub and the radiation shield are made of a material having high electric conductivity.

In order to solve the problem that the radiation shield plate buckles or bends due to an attractive force with the superconducting coil when the current flowing through the superconducting coil changes suddenly,
That is, as a countermeasure against quenching, a structure in which a radiation shield plate is divided by a member having low conductivity is disclosed in Japanese Patent Application Laid-Open No. 2-9597.
No. 0 discloses this.

[0004]

In the prior art, the radiation shield is provided with a measure to shield the fluctuating magnetic flux without taking into account that the radiation shield relatively vibrates relative to the superconducting coil. The latter structure disclosed in Japanese Patent Application Laid-Open No. 2-95970 also considers a large induced current at the time of quenching, and does not consider a small induced current due to the relative vibration at all. For this reason, when a superconducting magnet is used in an environment such as a magnetic levitation train that is subject to vibration, relative vibration occurs between the radiation shield and the superconducting coil, and heat is generated by the mechanism shown below in the inner tank, causing a problem. Becomes That is, in the maglev train, the superconducting magnets on the upper side of the vehicle receive pulsating magnetic flux because the ground coils are discretely arranged. An eddy current flows through the radiation shield so as to cancel the time change of the pulsating magnetic flux. Further, the magnetic flux generated by the superconducting coil interacts with the eddy current, and an electromagnetic force acts on the radiation shield according to Fleming's left-hand rule, so that the radiation shield vibrates with respect to the superconducting coil.

Since the distance between the radiation shield and the superconducting coil is substantially the same as the size of the cross section of the superconducting coil, the spatial gradient of the magnetic flux density of the superconducting coil at the position of the radiation shield becomes large. Therefore, when the radiation shield relatively oscillates with respect to the superconducting coil, the magnetic flux linked to the radiation shield changes with time, and an induced current flows through the radiation shield. The induced current causes a change in magnetic flux in the inner tank containing the superconducting coil, and an eddy current flows in the inner tank so as to cancel the change in the magnetic flux, thereby generating heat in the inner tank. As a result, there is a problem that the amount of evaporation of the refrigerant increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problem. When a radiation shield vibrates relative to a superconducting coil, an eddy current is generated in the inner tank so as to cancel the change in the magnetic flux. It is an object of the present invention to provide a superconducting magnet device which can prevent the refrigerant from flowing and reduce the amount of evaporation of the refrigerant.

[0007]

In order to achieve the above object, the present invention provides an inner tank containing both a superconducting coil and a refrigerant;
In a superconducting magnet device comprising a radiation shield covering the periphery of the inner tank, a cooling pipe provided in contact with the radiation shield, and an outer tank covering the radiation shield, the radiation shield is a radiation shield. The cooling pipe is divided by a first divided member having a lower electric conductivity, the cooling pipe is divided in a pipe axis direction by a second divided member having a lower electric conductivity than the cooling pipe, and the second divided member is a first divided member. Is provided only in contact with

[0008] The present invention also provides an inner tank accommodating a superconducting coil and a refrigerant together, a radiation shield covering the periphery of the inner tank,
In a superconducting magnet device including a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield is an electric conduction device that reduces generation of eddy currents in the radiation shield. The cooling pipe is divided by a second divided member having a smaller electric conductivity than the cooling pipe in the pipe axis direction,
The second divided member is provided in contact with only the first divided member.

Further, the present invention provides an inner tank for accommodating both the superconducting coil and the refrigerant, a radiation shield covering the inner tank,
In a superconducting magnet device including a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield is electrically conductive so as to cut off an eddy current path generated in a translation mode. The cooling pipe is divided at least at one location in the circumferential direction by a first divided member having a small degree, the cooling pipe is divided by a second divided member having a smaller electric conductivity than the cooling pipe in the pipe axis direction, and the second divided member is formed by a second divided member. It is characterized in that it is provided in contact with only one divided member.

[0010] The present invention also provides an inner tank for accommodating a superconducting coil and a refrigerant together, a radiation shield covering the periphery of the inner tank,
In a superconducting magnet device including a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield may be in any of vibration modes of yawing, rolling, pitching, and bending modes. The cooling pipe is divided into at least two places by a first divided member having a small electric conductivity so as to cut off an eddy current path generated in the above, and the cooling pipe is divided by a second divided member having a smaller electric conductivity than the cooling pipe in a pipe axis direction. In addition, the second divided member is provided in contact with only the first divided member.

[0011] The present invention also provides an inner tank for accommodating both a superconducting coil and a refrigerant, a radiation shield covering the inner tank,
In a superconducting magnet apparatus including a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield is configured to cut off an eddy current path generated in a torsional vibration mode. First with low conductivity
The cooling pipe is divided into at least four places by a dividing member, and the cooling pipe is divided in the pipe axis direction by a second dividing member having a smaller electric conductivity than the cooling pipe, and the second dividing member comes into contact only with the first dividing member. It is characterized by being provided.

Further, the present invention provides an inner tank for accommodating a superconducting coil and a refrigerant together, a radiation shield covering the inner tank,
In a superconducting magnet device including a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield includes translation, yawing,
Rolling, pitching, bending mode, divided into at least six places by a first divided member having a small electric conductivity so as to cut off eddy current paths generated in all vibration modes of torsion,
The cooling pipe is divided in a pipe axis direction by a second divided member having a lower electric conductivity than the cooling pipe, and the second divided member is provided in contact only with the first divided member. Things.

[0013] The present invention also provides an inner tank for accommodating both a superconducting coil and a refrigerant, a radiation shield for covering the periphery of the inner tank,
In a superconducting magnet device provided with a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield has two layers of a member layer having a large electric conductivity and a member layer having a small electric conductivity. And a slit for electrically separating a member layer having a large electric conductivity is provided. The cooling pipe is divided by a second divided member having a smaller electric conductivity than the cooling pipe in a pipe axis direction. The dividing member is provided only at the position of the slit.

Further, the present invention provides an inner tank for accommodating both a superconducting coil and a refrigerant, a radiation shield for covering the periphery of the inner tank,
In a superconducting magnet device including a cooling pipe provided in contact with the radiation shield and an outer bath covering the radiation shield, the radiation shield includes a member layer having a large electric conductivity, a member layer having a small electric conductivity, and a large member. Each of the layers has at least three or more layers, and a slit for electrically separating a member layer having high electric conductivity is provided in each layer, and the slits are shifted from each other in a longitudinal direction, and the cooling pipe is arranged in a pipe axis direction. The cooling pipe is divided by a second divided member having lower electric conductivity than the cooling pipe, and the second divided member is provided only at the position of the slit.

In any of the superconducting magnet devices described above,
It is preferable that the radiation shield has a bridging portion, and the bridging portion is divided by the member having a small electric conductivity.

[0016]

FIG. 2 shows an eddy current diagram in the radiation shield at the time of yawing vibration which rotates around the z-axis, which is one of the main vibration modes. Transfer portions 3a, 3 of radiation shield 1
b, a semilunar eddy current path 12 flowing in the arc portion is formed. Two eddy current paths 12 are formed on the left and right, and the directions of the eddy currents are opposite to each other. Therefore, in order to suppress the eddy current, the eddy current path can be cut off by arranging the first divided member made of a material having lower electric conductivity than the radiation shield 1 at the transfer portions 3a and 3b. Since the eddy current is suppressed as described above, heat generated in the inner tank can be reduced.

As a vibration mode similar to this, there is a bending vibration mode, and an eddy current diagram at that time is shown in FIG.
The bending mode is a mode in which the radiation shield 1 vibrates so as to bend around the z-axis. An eddy current path 13 substantially similar to the yawing vibration is formed, but the left and right eddy currents flow in the same direction. Therefore, the eddy current path 13 can be cut off by arranging the first divided members in the transfer portions 3a and 3b as in the case of the yawing vibration. Since the eddy current is suppressed as described above, heat generated in the inner tank can be reduced.

FIG. 4 shows an eddy current diagram at the time of rolling vibration that rotates and vibrates about the x-axis, which is another main vibration mode.
Shown in Eddy current paths 14 in which the directions of the eddy currents are opposite to each other are formed in upper and lower portions of the radiation shield 1. Therefore, the eddy current path 14 can be cut off by disposing the first divided member at the center of the linear portion of the radiation shield 1.

FIG. 5 shows an eddy current diagram during torsional vibration. The torsional vibration is a mode in which the upper right and lower right portions vibrate in opposite directions, and the upper right and upper left portions vibrate in opposite directions. Therefore, the eddy current path 1
5 results. The radiation shield 1 is configured by arranging two or more first division members in one arc part, that is, four or more parts in the entire race track so as to block the center of the eddy current path 15. By doing so, the eddy current generated by the torsional vibration can be suppressed, so that the heat generated in the inner tank can be reduced.

FIG. 6 shows an eddy current diagram in the case where the radiation shield performs pitching vibration that rotates and vibrates about the y-axis. Since four eddy current paths 16 are generated similarly to the torsional vibration, the eddy current paths can be cut off by arranging at least two or more first divided members in one circular arc portion, that is, four or more in the entire race track. .

FIG. 7 shows an eddy current diagram when the radiation shield oscillates in the translation mode in the y direction with respect to the superconducting coil. An eddy current path 17 is formed in the circumferential direction of the race track.
Therefore, by arranging one first divided member arbitrarily on the race track, the eddy current generated in the translation mode can be suppressed.

Therefore, when the radiation shield is divided by the first division member having a small electric conductivity so as to cut off the eddy current path generated in the above-described vibration mode, heat generation due to the eddy current is reduced.

Since the radiation shield usually has a cooling pipe, the cooling pipe is also divided into a second divided member having a small electric conductivity, and the second divided member is disposed so as to be in contact only with the first divided member. By this, without electrically shorting the area that is electrically isolated between the radiation shields,
The above-described object of reducing the eddy current loss is achieved.

[0024]

FIG. 1 is a plan view of a radiation shield according to an embodiment of the present invention. In this embodiment, an example of a race track type radiation shield is shown. The radiation shield 1 is shaped so as to cover an inner tank (not shown) in order to block radiant heat, and the inner tank is provided with a transfer section (not shown) for holding electromagnetic force.
Having. Therefore, the radiation shield has a structure that bridges the linear portion so that the transfer portions 3a and 3b cover the transfer portion of the inner tank in order to block radiant heat. The entire radiation shield 1
It is made of a material having high electric conductivity such as copper or aluminum so as to prevent a temporal change of the external magnetic flux. At a temperature of liquid nitrogen, the electrical conductivity of copper is ^{5 × 10 8 Ω ~ 1 m} ~
^1. The electrical conductivity of aluminum is 2 × 10 ⁸ Ω to ¹ m to ¹ . The radiation shield 1 is provided with a cooling pipe 9 for cooling. The cooling pipe 9 is also made of a material such as copper or aluminum.

As described above, when the radiation shield 1 performs yawing vibration or bending vibration, an eddy current path 12 as shown in FIG. 2 or 3 is generated. Therefore, as shown in FIG. 1, any one of the first divided members 2b, 2c, 2d and 2h, 2f, 2c made of a member having a small electric conductivity such as stainless steel or an insulator is provided on the transfer portions 3a, 3b or the arc portions. By interposing any one of 2g, the eddy current flowing through the bridges 3a, 3b is cut off. Under the temperature of liquid nitrogen, the electrical conductivity of stainless steel is 1.8 × 10 ⁶ Ω to ¹ m- ¹ .
As described above, it is desirable that the difference in electrical conductivity between the constituent member of the radiation shield and the first divided member be approximately two digits or more. Similarly, the cooling pipe 9 is also divided by a second divided member made of a member having low electric conductivity such as stainless steel or an insulator. This second divided member cannot cut off the induced current when it is in contact with the main body of the radiation shield 1. Therefore, a second divided member is provided at a position corresponding to the first divided member, and the second divided member is formed so as to be in contact only with the first divided member. If it explains according to FIG. 1, it will be any part of 1st division | segmentation member 2c, 2d and any part of 2f, 2g. In other words, the second divided members 10a or 10b and 10b correspond to the portions where the first divided members are provided (any of 2c and 2d and any of 2f and 2g).
d or 10d is provided. Therefore, the occurrence of yawing vibration can be suppressed, the heat generated in the inner tank can be reduced, and the amount of refrigerant evaporated can be reduced.

Similarly, at the time of the rolling vibration shown in FIG. 4, the first divided members 2a and 2e are interposed at the center of the linear portion of the race track as shown in FIG. Then, a second divided member 10c is provided at a position corresponding to the first divided member 2e of the cooling pipe 9. As a result, the eddy current path is interrupted at the center of the linear portion, so that eddy current during rolling vibration can be suppressed.

At the time of the torsional vibration shown in FIG. 5 and the pitching vibration shown in FIG. 6, in order to cut off the central part of the four eddy current paths, as shown in FIG. The division members 2c, 2d, 2f, and 2g are interposed. And 4
The second divided members 10a, 10b, 10 of the cooling pipe 9 are set to respective values corresponding to the first divided members 2c, 2d, 2f, 2g.
d and 10e are provided. On the other hand, during vibration in the translation mode,
Since an eddy current path is generated so as to go around the race track, any one of the first divided members 2c, 2d, 2e, 2f, and 2g and the second divided member 1 provided corresponding thereto are provided.
The eddy current path can be interrupted by any of Oa, 10b, 10c, and 10d.

According to this embodiment, even if the radiation shield 1 oscillates relative to the superconducting coil in the main vibration mode,
The eddy current can be suppressed, and the amount of evaporation of the refrigerant can be reduced.

FIG. 8 is a perspective sectional view of a radiation shield according to another embodiment. In this embodiment, the member 4 having a large electric conductivity is used.
This is an example in which a two-layer structure of a, 4b and a substance 6 having a small electric conductivity is used. The structure has a structure in which eddy current paths generated in the vibration mode are cut off by cutting the materials 4a and 4b having high electric conductivity with the slits 5. There are two methods for manufacturing a two-layer structure.
A desired portion may be cut out by bonding different kinds of materials or etching a member having a large electric conductivity. As shown in FIG. 9, the second divided member 1 of the cooling pipe 9
0 a is provided at a position corresponding to the slit 5. Reference numerals 11a and 11b denote members having a large electric conductivity serving as a main body of the cooling pipe. According to this embodiment, there is an effect that the radiation shield 1 can be further strengthened. The same effect can be obtained even if the slit 5 is made of a member having a small electric conductivity.

FIG. 10 is a perspective sectional view of another embodiment.
In this embodiment, the members 4a, 4b and 7 having a large electric conductivity are used.
In FIGS. 7A and 7B, a member 6 having a small electric conductivity is formed into a three-layer structure by scissors. Members 4a, 4 having large electric conductivity
b is divided by a slit 5, and members 7 a and 7 b having high electric conductivity are divided by a slit 8. Further, the positions of the vertical sections of the slit 5 and the slit 8 are arranged so as to be shifted from each other. Further, the multilayer structure may be employed only in the vicinity of the slit, not in the entire surface of the radiation shield.
Although not shown, the second divided member of the cooling pipe is provided at a position corresponding to the slit 5. According to this embodiment, in addition to the above-described embodiment, there is an effect that a change in external magnetic flux can be more effectively shielded.

According to this embodiment, the radiation shield can be efficiently cooled, and the eddy current generated by the vibration can be suppressed without forming the eddy current path by the cooling pipe. An embodiment combining the above embodiments is also possible.

[0032]

According to the present invention, since the radiation shield is divided by a substance having a small electric conductivity, the eddy current generated in the radiation shield can be suppressed, whereby the heat generation in the inner tank can be reduced. Therefore, there is an effect of reducing the amount of evaporation of the refrigerant.

[Brief description of the drawings]

FIG. 1 is a plan view of a radiation shield according to an embodiment of the present invention.

FIG. 2 is an eddy current diagram during yawing vibration.

FIG. 3 is an eddy current diagram during bending vibration.

FIG. 4 is an eddy current diagram during rolling vibration.

FIG. 5 is an eddy current diagram during torsional vibration.

FIG. 6 is an eddy current diagram during pitching vibration.

FIG. 7 is an eddy current diagram during translational oscillation.

FIG. 8 is a perspective view of a main part of a radiation shield according to another embodiment of the present invention.

FIG. 9 is a perspective view of a main part of a radiation shield according to another embodiment of the present invention.

FIG. 10 is a perspective view of a main part of a radiation shield according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radiation shield 2a-2h 1st division member 3a, 3b Transfer part 4a, 4b Member with large electric conductivity 5 Slit 6 Member with small electric conductivity 7a, 7b Member with large electric conductivity 8 Slit 9 Cooling pipe 10a-10e Second divided member 11a, 11b Member having large electric conductivity of cooling pipe

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Shibata 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Within Hitachi, Ltd.Hitachi Research Laboratory (72) Inventor Noriaki Hino 4026 Kuji-machi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Inside the laboratory (72) Inventor Ken Yoshioka 1168 Moriyama-cho, Hitachi City, Ibaraki Prefecture Inside Energy Research Laboratory, Hitachi, Ltd. (72) Inventor Yoko Kameoka 1168 Moriyama-cho, Hitachi City, Ibaraki Prefecture Energy Research Laboratory, Hitachi, Ltd. (56) Reference Document JP-A-60-217611 (JP, A) JP-A-64-30206 (JP, A) JP-A-62-194171 (JP, A) JP-A-6-69551 (JP, A) 166169 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 39/04 H01F 6/00

Claims (5)

(57) [Claims] 1. An inner tank containing both a superconducting coil and a refrigerant, a radiation shield covering the periphery of the inner tank, a cooling pipe provided in contact with the radiation shield, and an outer cover covering the radiation shield. In the superconducting magnet device provided with a tank, the radiation shield is divided by a first divided member having a smaller electric conductivity than the radiation shield, and the cooling pipe has a second electric conductivity smaller than the cooling pipe in a pipe axis direction. The superconducting magnet device is divided by a dividing member, and the second dividing member is provided in contact with only the first dividing member. 2. An inner tank for accommodating both the superconducting coil and the refrigerant, a radiation shield covering the inner tank, a cooling pipe provided in contact with the radiation shield, and an outer cover for covering the radiation shield. In the superconducting magnet device having a tank, the radiation shield is circumferentially divided by a first divided member having a small electric conductivity so as to cut off an eddy current path generated in a translation mode, and the cooling pipe is a pipe. A superconducting magnet device, which is divided in an axial direction by a second divided member having lower electric conductivity than the cooling pipe, and the second divided member is provided in contact only with the first divided member. 3. An inner tank for accommodating both the superconducting coil and the refrigerant, a radiation shield covering the periphery of the inner tank, a cooling pipe provided along and in contact with the radiation shield, and an outer cover for covering the radiation shield. In a superconducting magnet device having a tank, the radiation shield is composed of two layers, a member layer having a large electric conductivity and a member layer having a small electric conductivity, and a slit for electrically separating the member layer having a large electric conductivity is provided. A superconducting magnet device, wherein the cooling pipe is divided in the pipe axis direction by a second divided member having lower electric conductivity than the cooling pipe, and the second divided member is provided only at the position of the slit. 4. An inner tank for accommodating a superconducting coil and a refrigerant together, a radiation shield covering the periphery of the inner tank, a cooling pipe provided in contact with the radiation shield, and an outer cover for covering the radiation shield. In the superconducting magnet device provided with a tank, the radiation shield includes at least three or more layers of a member layer having a large electric conductivity, a member layer having a small electric conductivity, and a member layer having a large electric conductivity, and electrically separates the member layer having a large electric conductivity. Slits are provided in each layer, and the slits are shifted from each other in the longitudinal direction. The cooling pipe is divided in the pipe axis direction by a second dividing member having smaller electric conductivity than the cooling pipe, and A superconducting magnet device, wherein the dividing member is provided only at the position of the slit. 5. The superconducting magnet apparatus according to any one of claims 1-4, the radiation shield has a pass portion, smaller該渡and unit electrical conductivity according to any one of claims 1-4 A superconducting magnet device characterized by being divided by members.