JP5161744B2 - Superconducting coil - Google Patents

Description

  The present invention relates to a superconducting coil.

  Conventionally, a winding frame including a body part and a pair of flange parts extending radially outward from both ends in the axial direction of the body part, and a solenoid wound around the body part in an area sandwiched between the pair of flange parts. 2. Description of the Related Art A superconducting coil including a coil portion made of a rotated superconducting wire is known.

  In this superconducting coil, the coil is impregnated with an impregnating material after winding, and the members are bonded to each other, thereby suppressing the minute displacement of the superconducting wire during excitation operation and preventing the occurrence of quenching due to the minute displacement. ing.

  By the way, as a cause of quenching in the above-described impregnation type superconducting coil, peeling during excitation of members bonded with an impregnating material can be cited. This peeling occurs when the surface pressure (contact pressure) between the winding frame and the coil portion is lowered by the electromagnetic force acting on the excited coil portion, and the impregnating material between the two is cracked.

Therefore, Patent Document 1 includes a winding frame that is configured to be disassembled into a body portion and a flange portion, and disassembles the winding frame and removes it from the coil before excitation, so that the contact between the winding frame and the coil portion is achieved. There is disclosed a superconducting magnet that eliminates the problem. In this superconducting magnet, separation between the winding frame and the coil portion does not occur, and quenching due to this separation is prevented.
JP-A-2-134802

  However, in the magnet of Patent Document 1, it is necessary to disassemble and remove the winding frame before excitation and to attach another support for supporting the coil portion. There is a problem that the assembly of the magnet becomes complicated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a superconducting coil that can be easily assembled and can suppress quenching.

  The inventor of the present application, in the case of a superconducting coil impregnated with an impregnating material, when the coil is peeled off during the operation in a high magnetic field state in which the coil is completely excited, high energy is generated by the peeling. While quenching occurs easily because of the release, if the magnetic field is in the initial stage of excitation even during excitation, the critical temperature for quenching is high and the margin is large. It was thought that the occurrence of quenching could be sufficiently suppressed by separating the winding frame and the coil portion by the initial stage of excitation. As a means for promoting the above-described peeling, it is conceivable to reduce the surface pressure (contact pressure) acting between the winding frame and the coil portion while the coil is cooled to the operating temperature. It is conceivable to make the linear expansion coefficient of the winding frame larger than the linear expansion coefficient of the coil portion. However, in that case, the surface pressure between the flange portions and the coil portions at both ends in the axial direction of the winding frame increases. For this reason, the inventor of the present application can reduce both the radial surface pressure and the axial surface pressure acting between the winding frame and the coil portion while cooling the coil to the operating temperature. A superconducting coil is proposed.

  Accordingly, a superconducting coil according to claim 1 of the present invention includes a winding frame including a body portion and a pair of flange portions extending radially outward from both axial ends of the body portion and facing each other, and the pair of flanges. A superconducting coil that is impregnated with an impregnating material in a winding state, the coil portion comprising a coil made of a superconducting wire wound in a solenoid shape around the body in a region sandwiched between parts, Is formed in a cylindrical shape and adjacent to the inner periphery of the coil part, and is provided with a radial gap on the radially inner side of the outer trunk part, and extends in the axial direction to extend the pair. The outer body is made of a material having a linear expansion coefficient larger than the linear expansion coefficient of the coil part, and is cooled to a predetermined operating temperature. It shrinks in the radial direction within the gap. Arranged so as to contract in the axial direction independently of the inner body part, the inner body part is made of a material having a linear expansion coefficient smaller than the linear expansion coefficient of the coil part, and reaches the operating temperature. Regardless of the contraction of the outer body portion in the axial direction due to cooling, the distance between the pair of flange portions is kept larger than the dimension in the axial direction of the coil portion.

  According to the superconducting coil of the first aspect, both the radial surface pressure and the axial surface pressure acting between the winding frame and the coil portion are lowered while the coil is cooled to the operating temperature. That is, in this superconducting coil, as described above, the body portion of the winding frame has an outer body portion adjacent to the inner periphery of the coil portion, and a pair of flange portions extending in the axial direction radially inward of the outer body portion. And an inner body part connected to the body. Since the outer body portion is made of a material having a linear expansion coefficient larger than the linear expansion coefficient of the coil portion, the amount of heat shrinkage in the radially inward direction of the outer body portion due to cooling is reduced by the heat shrinkage in the radially inward direction of the coil portion. The surface pressure in the radial direction acting between the outer body portion and the coil portion is reduced by cooling the coil to the operating temperature. Further, since the inner body portion is made of a material having a linear expansion coefficient smaller than that of the coil portion, the amount of thermal contraction in the axial direction of the coil portion is larger than the amount of heat shrinkage in the axial direction of the inner body portion due to cooling. Thus, the axial surface pressure acting between each flange portion and the coil portion is reduced by cooling the coil to the operating temperature. As a result, the winding frame and the coil part easily peel off at the initial stage of excitation of a relatively low magnetic field during cooling to the operating temperature or after completion of cooling. And since the impregnated material once cracked does not re-adhere, it is possible to prevent the reel and coil part from peeling off during operation in a high magnetic field state where the coil is completely excited. Generation | occurrence | production of the quench resulting from can be suppressed.

  Moreover, in the superconducting coil according to claim 1 of the present invention, an effect of quench suppression can be obtained by cooling and exciting the coil portion supported by the winding frame having the above configuration. Therefore, it is easier to assemble the coil as compared with the conventional case where a work such as removal of the winding frame is involved.

  The superconducting coil according to claim 2 is the superconducting coil according to claim 1, wherein the superconducting wire of the coil part is made of NbTi, the outer body part is made of aluminum, and the inner body part is made of stainless steel. It is characterized by that.

  If each part of the superconducting coil is made of the material as described above, both the radial surface pressure and the axial surface pressure acting between the winding frame and the coil portion cool the coil to the operating temperature. To come down easily.

  The superconducting coil according to claim 3 is the superconducting coil according to claim 1 or 2, wherein the superconducting coil is arranged between the outer body part and the inner body part, and contacts the mutually opposite parts of both body parts. The outer body portion is positioned with respect to the inner body portion so as to have the gap between the inner body portion and the outer body portion. And a spacer that allows the outer body portion to contract in the radial direction.

  With such a spacer, it is possible to easily secure a gap between the outer body part and the inner body part, and to shrink the outer body part in the radial direction within the gap during cooling. .

  The superconducting coil according to claim 4 is the superconducting coil according to claim 3, wherein the spacer is made of a material having a linear expansion coefficient equal to or higher than the linear expansion coefficient of the outer body portion.

  If the spacer is made of the above material, the amount of thermal shrinkage in the radial direction of the spacer due to cooling is equal to or greater than the amount of thermal contraction in the radial direction of the outer body, so Heat shrinkage can be reliably allowed.

  The superconducting coil of the present invention can be easily assembled and can suppress quenching.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a front sectional view of a superconducting coil according to an embodiment of the present invention. FIG. 2 is a front sectional view of the superconducting coil in a state cooled to the operating temperature. First, the configuration of the superconducting coil 1 according to an embodiment of the present invention will be described.

  The superconducting coil 1 of the present embodiment is configured to generate a high magnetic field by being excited while being cooled to a predetermined operating temperature (about 4K).

  As shown in FIG. 1, the superconducting coil 1 includes a winding frame 10 and a coil portion 20. In addition, the code | symbol R in a figure has shown the axial center of the said superconducting coil 1. FIG.

  The superconducting coil 1 is impregnated with an impregnating material such as epoxy in a wound state before cooling. Thereby, it is suppressed that the superconducting wire 60 constituting the coil unit 20 is slightly displaced during the excitation operation, and the occurrence of quenching due to the minute displacement is prevented.

  The winding frame 10 includes a body portion 30 and a pair of flange portions 41 and 42 that extend radially outward from both axial ends of the body portion 30 and face each other.

  Here, the body part 30 of the reel 10 of the present embodiment includes a cylindrical outer body part 31 and a cylindrical inner part provided with a radial gap D on the radially inner side of the outer body part 31. The body portion 32 and a pair of upper and lower ring-shaped spacers 33 disposed between the body portions 31 and 32 are configured.

  The outer periphery of the outer body portion 31 is adjacent to the inner periphery of the coil portion 20. That is, the coil part 20 is laminated in a solenoid shape and a plurality of layers in the radial direction around the outer body part 31 in a region where the superconducting wire 60 is sandwiched between the pair of flange parts 41 and 42. It is formed by winding.

  Further, the outer body part 31 contracts in the radial direction within the gap D by being cooled to the operating temperature, and contracts in the axial direction independently of the inner body part 32.

  And the outer side trunk | drum 31 is formed from the material of the linear expansion coefficient larger than the linear expansion coefficient of the coil part 20. As shown in FIG. As a result, the amount of heat shrinkage in the radially inward direction of the outer body portion 31 due to cooling becomes larger than the amount of heat shrinkage in the radially inward direction of the coil portion 20, and in the state where the superconducting coil 1 is cooled to the operating temperature, The surface pressure in the radial direction between the trunk portion 31 and the coil portion 20 decreases.

  The inner trunk portion 32 is provided so as to be concentric with the outer trunk portion 31 and extends in the axial direction and is connected to the pair of flange portions 41 and 42.

  The inner body portion 32 has an interval between the pair of flange portions 41 and 42 larger than the axial dimension of the coil portion 20 regardless of the axial contraction of the outer body portion 31 due to cooling to the operating temperature. It keeps in.

  The inner body portion 32 is formed of a material having a linear expansion coefficient smaller than that of the coil unit 20. Thereby, the amount of thermal contraction in the axial direction of the coil portion 20 becomes larger than the amount of thermal contraction in the axial direction of the inner body portion 32 due to cooling, and in a state where the superconducting coil 1 is cooled to the operating temperature, each flange portion 41, The surface pressure in the axial direction between 42 and the coil part 20 decreases.

  Each spacer 33 is in contact with the outer periphery of the outer body part 31 and the inner periphery of the inner body part 32 facing each other, and the gap D is provided between the outer body part 31 and the inner body part 32. It has a function of positioning with respect to the inner body portion 32 in a state. Thereby, in the state before cooling, rattling of the outer trunk 31 is suppressed by the spacer 33, so that the superconducting wire 60 can be stably wound around the outer circumference of the outer trunk 31.

  Each spacer 33 is made of a material having a linear expansion coefficient equal to or higher than the linear expansion coefficient of the outer body portion 31 and is displaced in the radially inward direction while being cooled to the operating temperature, whereby the diameter of the outer body portion 31 is increased. Heat shrinkage in the inward direction is allowed.

  In addition, the inner body portion 32 and the upper flange portion 41 are fixed to each other with a plurality of screws 50. When the coil 1 is assembled, the flange portion 41 is detached from the inner body portion 32, and the outer body portion 31 and the pair of spacers 33 are attached in this state. The inner body portion 32 and the lower flange portion 42 are fixed to each other by connection means (not shown).

As a preferable combination of each component of such a superconducting coil 1, for example, the superconducting wire 60 of the coil part 20 is made of NbTi, the outer body part 31 is made of aluminum, and the inner body part 32 and the flange parts 41 and 42 are made of stainless steel. It is made of steel and the spacer 33 is made of Teflon (registered trademark). In addition to the above example, for example, the superconducting wire 60 is made of Nb ₃ Sn, the outer body 31 is made of brass, acrylic resin, nylon, Teflon (registered trademark), or the like, and the spacer 33 is made of acrylic resin. Further, it can be made of nylon or the like, and can be appropriately changed within a range satisfying the relationship between the linear expansion coefficients of the respective members.

  In addition, since the impregnating material also enters the inside of the outer body portion 31, the linear expansion coefficient of the impregnating material is the linear expansion coefficient of the outer body portion 31 in order not to inhibit the shrinkage of the outer body portion 31 in the radially inward direction. Is preferably larger. The linear expansion coefficient of the resin such as epoxy used for the impregnating material is generally higher than that of the material for the outer body portion 31.

  Next, the process from the formation process of the superconducting coil 1 having the above configuration to the operation process will be described.

  First, the outer body part 31 is moved from the outer side in the axial direction (upper side) with respect to the inner body part 32 connected to the lower flange part 42, and the inner body part is concentric with the inner body part 32. 32 is arranged outside in the radial direction. Then, the pair of spacers 33 are pushed and set between the inner trunk portion 32 and the outer trunk portion 31. As a result, the outer body 31 is positioned with a gap D with respect to the inner body 32. Thereafter, the upper flange portion 41 is fixed to the inner body portion 32 using a plurality of screws 50, thereby forming the winding frame 10.

  Then, the coil part 20 is formed by winding the superconducting wire 60 on the outer periphery of the outer body 31 of the winding frame 10 formed in this manner so as to be laminated in a solenoid shape and in a plurality of layers in the radial direction. To do. Thereby, the superconducting coil 1 is formed.

  The superconducting coil 1 is impregnated with an impregnating material, then cooled to a predetermined operating temperature, and excited at an extremely low temperature.

  In the superconducting coil 1 of the present embodiment, during the cooling, that is, until the operating temperature is reached, both the radial surface pressure and the axial surface pressure acting between the winding frame 10 and the coil portion 20 decrease. Thereby, both 10 and 20 peel.

  That is, as shown in FIG. 2, the impregnating material between the outer body part 31 and the coil part 20 is cracked, and the outer body part 31 and the coil part 20 are separated (see d1 in FIG. 2). Moreover, a crack generate | occur | produces in the impregnation material between the upper flange part 41 and the coil part 20, and the flange part 41 and the coil part 20 peel (refer d2 of FIG. 2).

  Even if the winding frame 10 and the coil part 20 do not peel off during cooling, the surface pressure between them is sufficiently reduced, so that both the parts 10 and 20 are peeled off by a relatively weak electromagnetic force at the initial stage of excitation. To do. Therefore, the peeling of both 10 and 20 does not occur during operation in a high magnetic field state where the superconducting coil 1 is completely excited.

  According to the superconducting coil 1 of the present embodiment, as described above, the winding frame 10 and the coil portion 20 are easily separated at the initial stage of excitation of a relatively low magnetic field during cooling to the operating temperature or after completion of cooling. And since the impregnated material once cracked does not re-adhere, it is possible to prevent the reel 10 and the coil part 20 from peeling off during operation in a high magnetic field state where the coil 1 is completely excited. The occurrence of quenching due to the peeling can be suppressed.

  Moreover, in the superconducting coil 1 of this embodiment, the quench suppression effect is acquired by being cooled and excited while supporting the coil part 20 with the winding frame 10 of the said structure. Accordingly, the coil 1 can be easily assembled as compared with the conventional case where the work such as the removal of the winding frame is involved.

  In the superconducting coil 1 of the present embodiment, as described above, the superconducting wire 60 made of NbTi, the outer body 31 made of aluminum, and the inner body 32 made of stainless steel are used. Both the radial surface pressure and the axial surface pressure acting between the coil 20 and the coil 20 are easily lowered while the coil 1 is cooled to the operating temperature.

  Further, according to the superconducting coil 1 of the present embodiment, the spacer 33 can easily ensure the gap D between the outer trunk portion 31 and the inner trunk portion 32, and the outer trunk portion 32 can be cooled during cooling. In the range of the gap D, it can be contracted in the radial direction.

  Further, in the superconducting coil 1 of the present embodiment, as described above, the spacer 33 made of a material having a linear expansion coefficient equal to or higher than the linear expansion coefficient of the outer body portion 31 is used, so that the spacer 33 is radially inwardly cooled. Since the amount of heat shrinkage is equal to or greater than the amount of heat shrinkage in the radially inward direction of the outer body 31, the heat shrinkage in the radially inward direction of the outer body 31 due to cooling can be reliably allowed.

  Next, it is verified whether the superconducting coil according to the embodiment in which dimensions such as specific materials and thicknesses are set can obtain the above-described effect, that is, whether peeling occurs during cooling to the operating temperature. The superconducting coil of this example will also be described using the same reference numerals as in the above embodiment.

  Below, the surface pressure between the winding frame 10 and the coil part 20 of the superconducting coil 1 when the superconducting coil 1 is cooled to a predetermined operating temperature (about 4 K) is obtained, and the tensile stress acting between the two is obtained. . And the said verification is performed by comparing the magnitude | size of the tensile stress and the adhesive force (adhesion strength) of an impregnation material.

  In the superconducting coil 1 of this embodiment, the outer body portion 31 is formed of aluminum, the inner body portion 32 and the pair of flange portions 41 and 42 are formed of stainless steel, and the superconducting wire 60 of the coil portion 20 is formed of NbTi. . The impregnation material was epoxy. In the superconducting coil 1 of this embodiment, the spacer 33 is omitted.

  The inner radius of the inner trunk portion 32 was 58 mm and the thickness was 7 mm, and the inner radius of the outer trunk portion 31 was 70 mm and the thickness was 5 mm.

  And the coil part 20 was formed by winding the said superconducting wire 60 which consists of said NbTi to the said outer side trunk | drum 31, until the thickness became 20 mm.

  Moreover, the physical property value of each material is shown below.

The average linear expansion coefficient from room temperature (293K) to the operating temperature (4K) is 1.44 × 10 ⁻⁵ for aluminum, 1.06 × 10 ⁻⁵ for stainless steel, and 1.18 for coil portion 20. × 10 ⁻⁵ (Note that the linear expansion coefficient of the coil part 20 was calculated assuming that Nb-45Ti was 92% and the insulating material was 8%, and that the linear expansion coefficient of the insulating material was the same as that of Teflon (registered trademark). ) And the epoxy is 3.98 × 10 ⁻⁵ .

  The Young's modulus is 80 GPa for aluminum, 200 GPa for stainless steel, and 76 GPa for the coil portion 20 (note that the Young's modulus for the coil portion 20 is 92% for NbTi and 8% for the insulating material. Was calculated to be the same as Teflon (registered trademark)), and the epoxy was 28 GPa. The Poisson's ratio of all the materials was 0.34.

  The surface pressure acting between the outer body portion 31 and the coil portion 20 when the superconducting coil 1 having such a configuration is cooled from the normal temperature (293K) to the operating temperature (4K) is about −10 MPa. This indicates that a tensile stress of 10 MPa in a direction away from each other acts on the outer body portion 31 and the coil portion 20.

  And since the general adhesive force of the epoxy impregnation material was about 9 MPa, it turned out that the tensile stress which acts between both 31 and 20 exceeds the adhesive force of an impregnation material.

  Therefore, when the superconducting coil 1 of the present embodiment is cooled to the operating temperature, the impregnating material between the outer body portion 31 and the coil portion 20 breaks without being able to withstand the tensile stress acting between the two, thereby 20 was found to peel.

  Moreover, the surface pressure which acts between the flange part 41 and the coil part 20 when the superconducting coil 1 of this embodiment is cooled from room temperature to the operating temperature is about −10 MPa. This shows that a tensile stress of 10 MPa in a direction away from each other acts on the flange portion 41 and the coil portion 20.

  From this, it was found that the tensile stress acting between both 41 and 20 exceeds the adhesive strength of the impregnating material.

  Therefore, when the superconducting coil 1 of the present embodiment is cooled to the operating temperature, the impregnating material between the flange portion 41 and the coil portion 20 breaks without being able to withstand the tensile stress acting between them, thereby both 41 and 20. Was found to peel.

  From the above, in the superconducting coil 1 of the present embodiment, the winding frame 10 and the coil portion 20 are peeled simultaneously in both the radial direction and the axial direction, and the peeling of the both 10 and 20 during excitation is sufficiently prevented. I understood it.

  In the above embodiment, the outer body 31 is positioned by arranging the pair of spacers 33 between the inner body 32 and the outer body 31. However, the present invention is not limited to this, and the outer body 31 is pinned. The outer body 31 is positioned by fixing it to the flange portions 41, 42 with the like, and the pin is removed before cooling, thereby allowing the outer body 31 to be thermally contracted in the radial direction. Also good.

  Moreover, in the said embodiment, although the structure which connects a pair of flange parts 41 and 42 with the cylindrical inner trunk | drum 32 was shown, it is not restricted to this, The several circular-arc-shaped member (inner trunk | drum which extends in the circumferential direction) ) May be arranged with a gap therebetween in the circumferential direction, and both ends of each arcuate member in the axial direction may be connected to the pair of flange portions 41 and 42, respectively.

  Further, a spacer may be provided between the coil portion 20 and at least one flange portion 41 (42) so as to be thermally contracted in the axial direction larger than the coil portion 20 by cooling. Thereby, the surface pressure between the flange part 41 (42) and the coil part 20 falls more largely by cooling, and both come to peel reliably.

It is front sectional drawing which showed the structure of the superconducting coil by one Embodiment of this invention. It is front sectional drawing of the superconducting coil in the state cooled to the operating temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Superconducting coil 10 Winding frame 20 Coil part 30 Trunk part 31 Outer trunk part 32 Inner trunk part 33 Spacer 41, 42 Flange part 60 Superconducting wire D Clearance

Claims (4)

A winding frame including a body portion and a pair of flange portions extending radially outward from both axial ends of the body portion and facing each other, and a solenoid around the body portion in a region sandwiched between the pair of flange portions A superconducting coil that is impregnated with an impregnating material in a winding state.
The body portion is formed in a cylindrical shape and is provided with an outer body portion adjacent to the inner periphery of the coil portion, and a radial gap on the radially inner side of the outer body portion, and extends in the axial direction. And an inner trunk portion connected to the pair of flange portions,
The outer body portion is made of a material having a linear expansion coefficient larger than the linear expansion coefficient of the coil section, and is cooled to a predetermined operating temperature, thereby contracting in a radial direction within the gap and the inner body Arranged to contract in the axial direction independently of the part,
The inner body part is made of a material having a linear expansion coefficient smaller than that of the coil part, and the pair of flange parts regardless of the axial contraction of the outer body part due to cooling to the operating temperature. A superconducting coil characterized in that the distance between them is kept larger than the axial dimension of the coil portion. The superconducting wire of the coil portion is made of NbTi,
The outer body is made of aluminum;
The superconducting coil according to claim 1, wherein the inner body portion is made of stainless steel.   The inner body is arranged between the outer body part and the inner body part so that the outer body part is in contact with the mutually facing portions of the two body parts and the outer body part has the gap between the inner body part and the inner body part. A spacer is provided, which is positioned with respect to the body portion, and is displaced to a radially inward direction by being cooled to the operating temperature to allow a contraction in a radial direction of the outer body portion. The superconducting coil according to 1 or 2.   The superconducting coil according to claim 3, wherein the spacer is made of a material having a linear expansion coefficient equal to or higher than that of the outer body part.

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