JP4282628B2 - Non-inductive winding frame, permanent current switch, and superconducting magnet - Google Patents

Description

  The present invention relates to a densely wound non-inductive winding, a winding frame for the non-inductive winding, a permanent current switch including these, and a superconducting magnet including the permanent current switch.

  Superconducting coils such as superconducting magnetic energy storage systems, nuclear fusion systems, nuclear magnetic resonance devices, magnetic levitation trains, and superconducting magnets for physics and chemistry experiments are disconnected from the DC power supply during operation and short-circuited with a permanent current switch, and current is passed through the closed loop. Is generally used in a so-called permanent current mode that continues to flow for a long time. A superconducting permanent current switch is an indispensable element for realizing a permanent current circuit in combination with a superconducting magnet. In an apparatus for operating a superconducting magnet in a permanent current state, a superconducting coil and a permanent current switch are connected in parallel as shown in the schematic circuit diagram of the superconducting magnet shown in FIG. 1, and this parallel circuit is supplied to a desired power source. A configuration in which connection is made via a lead has become common. In FIG. 1, 1 is a permanent current switch, and 2 is a superconducting coil for generating a magnetic field. The superconducting wire constituting the superconducting coil is in a superconducting state at an extremely low temperature and has an electric resistance value of zero, and theoretically a current continues to flow forever (see, for example, Patent Documents 1 and 2 below). .

  The permanent current switch is a non-inductively wound superconducting coil. This non-inductive winding is a structure in which a superconducting wire is folded back into two, and the bent portion at the tip is inserted and fixed in a groove provided on the winding frame, and then wound in units of two (for example, the following patents) Reference 3), the current flowing in the superconducting wire can always flow in the opposite direction of these two superconducting wires and cancel each other out of the magnetic field. The first reason for adopting such a non-inductive winding in the permanent current switch is to excite the superconducting coil and close the permanent current switch (in a state where no current flows from the external heater power source to the heater portion of the permanent current switch). This is to prevent the coil current from changing due to the voltage generated in the permanent current switch when the power supply current is lowered to complete the permanent current loop. The second reason is that, as is well known, the superconducting wire has a characteristic that the critical current decreases as the magnetic field is stronger, so that the strength of the magnetic field generated by the superconducting winding is reduced. The third reason is to prevent disturbance of the magnetic field generated by the superconducting coil.

  In addition, when the permanent current switch is in a normally conducting state (open) (current is flowing from the external heater power source to the heater portion of the permanent current switch), the current is shunted to the permanent current switch by the excitation voltage of the coil. It is desirable that the diversion is as small as possible. Therefore, since it is desirable that the resistance value in the normal conduction (open) state of the permanent current switch is large, it is desirable that the permanent current switch is manufactured by winding a superconducting wire as long as possible.

  However, as described in Patent Document 3, in order to realize non-inductive winding, in the method of winding in a state in which two long wires are folded in advance, the long wires are folded in two. Due to the difficulty of work, it was not possible to use a very long wire.

  In order to improve this, in Patent Documents 4 and 5 below, non-inductive winding using a long wire is realized by sandwiching a spacer having a groove between layers and forming a winding in which the winding direction is reversed every turn.

JP 2001-52920 A JP 2001-185414 A Japanese Utility Model Publication No. 62-34408 JP 2004-55913 A JP 2004-63705 A

  However, the non-inductive windings disclosed in Patent Documents 4 and 5 cannot be said to be easily formed with the winding direction of the superconducting wire reversed every turn, and cannot be densely wound. Therefore, when this non-inductive winding is used for a permanent current switch, the overall dimension with respect to the wire length becomes large and the heat capacity becomes large, so that high-speed switching from the normal conducting state to the superconducting state cannot be performed.

  Accordingly, an object of the present invention is to provide a non-inductive winding formed by densely winding a long superconducting wire, a winding frame for the non-inductive winding, a permanent current switch including these, and this permanent current switch. Provided is a superconducting magnet.

Means and effects for solving the problems

  The non-inductive winding according to the present invention is provided on the one end side of the first superconducting coil layer formed by spirally and densely winding a single superconducting wire around the winding drum. The folded portion is folded with the remaining superconducting wire after winding the first superconducting coil layer, and the folded superconducting wire is connected between the superconducting wires of the first superconducting coil layer. And a second superconducting coil layer formed by wrapping in the opposite direction along the recess.

  Further, the non-inductive winding of the present invention has a superconductivity of the nth layer (n is any number up to an even number, the same shall apply hereinafter) at the folded portion provided on the other end side of the winding drum. The remaining superconducting wire after winding the coil layer is folded and folded, and the folded superconducting wire is wound in the opposite direction along the concave portion between the superconducting wires of the nth superconducting coil layer. The n + 1th superconducting coil layer and the folded portion provided on one end side of the winding drum are folded over the remaining superconducting wire after winding the n + 1th superconducting coil layer, An n + 2 superconducting coil layer formed by wrapping the folded superconducting wire in a reverse direction along the recess between the superconducting wires of the (n + 1) th superconducting coil layer. It is preferable. Note that “n is a number up to any one of even numbers” includes the following. For example, the numbers up to 6 out of the even numbers are 2, 4, 6, and the numbers up to 10 out of the even numbers are 2, 4, 6, 8, 10.

  With the above configuration, since the superconducting wire is densely wound and formed, the overall dimension of the superconducting wire with respect to the length of the wire is minimized, so that a non-inductive winding with the smallest heat capacity can be provided. Accordingly, since heat can be efficiently conducted, a non-inductive winding capable of high-speed switching between the normal conducting state and the superconducting state can be provided. Further, since the winding of the long superconducting wire can be made very easily and densely, a non-inductive winding having a large resistance value in the normal conducting state and almost zero inductance can be provided.

The winding frame of the present invention is for the non-inductive winding described above, and includes a winding drum and disk-shaped flanges provided at both ends of the winding drum, and the flange is provided in a radial direction thereof. It is preferable to have a protruding member. The winding frame of the present invention is for the non-inductive winding, and includes a winding drum and flanges provided at both ends of the winding drum, and the flange bottoms the end of the winding drum. It may be composed of two plate-like members arranged side by side so as to form a groove portion.
With the above configuration, a winding frame capable of densely winding the non-inductive winding can be provided.

The permanent current switch of the present invention is preferably provided with the non-inductive winding. Furthermore, it is preferable that any one of the above-described reels is provided.
When the non-inductive winding is in a normal conducting state, the resistance value of the non-inductive winding is large and the inductance is almost zero, so that it is possible to provide a permanent current switch in which almost no current flows.

The superconducting magnet of the present invention preferably includes the permanent current switch.
When exciting the magnetic field generation superconducting coil by passing the current from the superconducting magnet power source, if the permanent current switch is off (the superconducting coil is in the normal conducting state), the current from the superconducting magnet power source flows into the permanent current switch. Since it becomes difficult, it leads to suppression of generation of Joule heat and suppresses a rise in temperature of the superconducting magnet, so that the superconducting magnet can be stably operated.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view of the permanent current switch according to the first embodiment of the present invention. 3A is a front view of a reel used in the permanent current switch of FIG. 2, and FIG. 3B is a side view of FIG. 3A. FIG. 4 is a partially enlarged view around the flange portion when the superconducting wire is wound around the winding frame of FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 4.

  A permanent current switch 10 according to an embodiment of the present invention includes a winding frame 3, a heater 4, a superconducting coil 5, and a heat insulating material 6.

As shown in FIG. 3A, the winding frame 3 includes a winding drum 3a for winding a wire and flanges 3b and 3c provided at both ends of the winding drum 3a. As shown in FIG. 3B, the flanges 3b and 3c are formed by extending projecting members 3b ₁ and 3c ₁ from the bottom of the recesses cut out in the radial direction in the radial direction and in the external direction, respectively. ing.

  As shown in FIGS. 2 and 6, the heater 4 is formed by winding a wire made of manganin or the like around the winding drum 3 a of the winding frame 3 to form one layer. As shown in FIG. 6, an adhesive tape 7 is wound around the outer peripheral portion of the heater 4 in order to smooth the surface. In addition, the heater 4 may not be one in which a wire rod is wound around the winding frame 3 but a sheet-like one.

The superconducting coil 5 is composed of a superconducting wire 5a wound non-inductively around the winding frame 3. Specifically, as shown in FIGS. 4 to 6 and FIGS. 7A to 7C, the superconducting coil 5 is formed by spirally and densely winding a single superconducting wire around the surface of the adhesive tape 7. The first superconducting coil layer thus formed and the remaining superconducting wire after the first superconducting coil layer is wound around the protruding member 3b ₁ are folded and folded, and the folded superconducting wire is connected to the first superconducting coil. A second superconducting coil layer formed by wrapping in the opposite direction along the concave portion between the superconducting wires of the first superconducting coil layer is formed. Similarly, although not shown, the protruding member 3c ₁ provided on the other end side of the winding drum 3a is folded over the remaining superconducting wire after winding the second superconducting coil layer, A third superconducting coil layer is formed by winding the folded superconducting wire in the opposite direction along the concave portion between the superconducting wires of the second superconducting coil layer. The fourth and subsequent superconducting coil layers can be formed in the same manner as the second and third superconducting coil layers. Thus, the non-inductive winding superconducting coil 5 having the desired number of superconducting coil layers can be formed. Note that the superconducting wire 5a between the left of the projecting member 3b ₁ in FIG. 6, but are wound with a spacing, may also be wound packed. Although not shown, it is preferable that the winding start portion of the superconducting coil 5 is wound around the winding drum 3a after passing through a groove between the protruding member and the flange body.

  The superconducting wire 5a is a superconducting wire made of NbTi or the like. Since the superconducting wire is densely wound and formed, the overall dimension of the superconducting wire with respect to the length of the wire is minimized, so that it is possible to provide a non-inductive winding whose heat capacity is minimized. Accordingly, since heat can be efficiently conducted, a non-inductive winding capable of high-speed switching between the normal conducting state and the superconducting state can be provided. Further, since the winding of the long superconducting wire can be made very easily and densely, a non-inductive winding having a large resistance value in the normal conducting state and almost zero inductance can be provided.

  The heat insulating material 6 is made of a resin such as a resin. The heat insulating material 6 also has a role of protecting the superconducting coil 5.

  Next, the operation of the permanent current switch 10 will be described. Since heat is generated in the heater 4 while a current flows through the heater 4, the superconducting coil 5 is heated. Therefore, even if it is cooled from the outside, if the heat exceeds it, the superconducting coil 5 will not be in the superconducting state and will have electric resistance. The electrical resistance of the permanent current switch 10 is densely wound even in the same volume as that of the conventional non-inductive wire-wound permanent current switch. While no current flows through the heater 4, the superconducting coil 5 is not heated, so when it is cooled from the outside and reaches the superconducting transition temperature, it becomes a superconducting state, and the electric resistance becomes zero.

  According to the above embodiment, since the superconducting wire 5a is densely wound around the winding frame 3, the overall dimension with respect to the wire length of the superconducting wire is minimized, so that the heat capacity is minimized. Winding can be formed. Furthermore, since it can conduct heat efficiently, it is possible to provide the permanent current switch 10 having a non-inductive winding capable of high-speed switching between the normal conducting state and the superconducting state. In addition, since the winding of the long superconducting wire can be made very easily and densely, a non-inductive winding having a large normal conduction state resistance and almost zero inductance can be formed. A permanent current switch 10 can be provided.

  Therefore, when the permanent current switch 10 of this embodiment is used instead of the permanent current switch 1 of the superconducting magnet shown in FIG. 1, when the current of the superconducting magnet power source is passed through the magnetic field generating superconducting coil 2 and excited, If the current switch 10 is in the off state (the superconducting coil 5 is in the normal conducting state), the current of the superconducting magnet power source is less likely to flow into the permanent current switch 10, which leads to the suppression of Joule heat generation and the temperature of the superconducting magnet. Since the rise can be suppressed, the superconducting magnet can be stably operated.

Next, a permanent current switch according to a second embodiment of the invention will be described.
FIG. 7A is a front view of a reel used for the permanent current switch, and FIG. 7B is a side view of FIG. 7A. Since the permanent current switch according to the second embodiment of the present invention is substantially the same as the permanent current switch according to the first embodiment except for the periphery of the flange, the same parts (the heater 13 and the adhesive tape are described below). 14) may be omitted.

As shown in FIG. 7A, the winding frame 11 includes a winding drum 11a for winding a wire and flanges 11b and 11c provided at both ends of the winding drum 11a. As shown in FIG. 7B, the flange 11b is composed of _two plate-like members 11b ₁ and 11b ₂ arranged side by side so as to form a groove having the bottom of the end of the winding drum 11a. The flange 11c includes two plate-like members 11c ₁ and 11c ₂ similar to the flange 11b. The width of the groove portion may be equal to or greater than the width of the wire to be wound, and the width is not particularly limited. Therefore, the wire may be in a state of being stacked one by one as in the present embodiment, or when a wide width is provided, the wire may be wound to fill the width.

The superconducting coil 12 is composed of a superconducting wire 12 a that is non-inductively wound around the winding frame 11. Specifically, as shown in FIGS. 8 to 11, the superconducting coil 12 is a first superconducting coil formed by spirally and densely winding a single superconducting wire around the surface of the adhesive tape 14. Layer and the groove formed by the _two plate-like members 11b ₁ and 11b _{2 of} the flange 11b, the remaining superconducting wire that has finished winding the first superconducting coil layer is hung on the opposite side, A second superconducting coil layer is formed by winding the folded superconducting wire in the opposite direction along the recess between the superconducting wires of the first superconducting coil layer. The winding method of the superconducting coil 12 around the winding drum 11a is the same as that in the first embodiment. Similarly, although not shown, the second superconducting coil layer is formed in a groove formed by _two plate-like members 11c ₁ and 11c _{2 of} the flange 11c provided on the other end side of the winding drum 11a. The remaining superconducting wire is wound and folded on the opposite side, and the folded superconducting wire is wound in the opposite direction along the concave portion between the superconducting wires of the second superconducting coil layer. A third superconducting coil layer is formed. The fourth and subsequent superconducting coil layers can be formed in the same manner as the second and third superconducting coil layers. Thus, the non-inductive winding superconducting coil 12 having the desired number of superconducting coil layers can be formed. In addition, although the superconducting wire 12a of the groove part of the flange 11b in FIG. 11 is wound in the same direction, it may be wound in a different direction. Although the periphery of the flange 11c is not shown, it is the same. Although not shown, it is preferable that the winding start portion of the superconducting coil 12 is wound around the winding drum 11a after passing through the groove.

  With the above configuration, according to the present embodiment, the same effect as that of the first embodiment can be obtained. Therefore, when the permanent current switch of this embodiment is used in place of the permanent current switch 1 of the superconducting magnet shown in FIG. 1, the current of the superconducting magnet power is supplied to the magnetic field generating superconducting coil 2 as in the first embodiment. If the permanent current switch is in an off state (the superconducting coil 12 is in a normal conducting state), the current of the superconducting magnet power source is less likely to flow into the permanent current switch. Since the increase in the temperature of the magnet can be suppressed, the superconducting magnet can be stably operated.

Example 1
In this example, a permanent current switch having the same configuration as the permanent current switch according to the first embodiment of the present invention was produced.

(Comparative Example 1)
In this comparative example, a conventional method, that is, a superconducting wire is folded back into two, and a bent portion at the tip is inserted and fixed in a groove provided inside the flange of the winding frame, and then wound in units of two to produce a permanent current switch. did. The size and shape of the winding drum of the reel are the same as those in the first embodiment.

  The specifications and thermal balance of the permanent current switch of Example 1 and Comparative Example 1 were measured, and each of the permanent current switches of Example 1 and Comparative Example 1 was incorporated in the same conduction cooling superconducting magnet (similar to FIG. 1). Circuit configuration) and various measurements (see Table 1 below).

  When Example 1 and Comparative Example 1 are compared, Comparative Example 1 has a resistance of 100Ω in normal conduction (open) due to restrictions on the length of wire that can be wound. In addition, it can be seen that a wire having a length four times as long as the same external dimensions as Comparative Example 1 could be wound non-inductively because it can be densely wound. Therefore, the resistance at the time of normal conduction (open) of the permanent current switch of Example 1 at this time is 400Ω. As a result, since the heat generation due to Joule heat of the permanent current switch during excitation can be reduced to ¼, the magnet temperature is kept low by about 0.9K and stable operation can be performed. In other words, if the same operating temperature is allowed, a high magnetic field can be generated with the same magnet, or if the generated magnetic field is the same, it can be realized with a smaller magnet. Although the amount of wire was quadrupled, that is, the heat capacity was quadrupled, the permanent current switch of Example 1 was improved in thermal conductivity by densely winding, so the time required to open and close the switch Is suppressed to 1.5 times that of Comparative Example 1, and there is no practical problem.

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples. For example, the projecting member and the groove need not be ordered as in the above-described embodiment, and need only be wound only for folding.

It is a circuit schematic diagram of a general superconducting magnet. It is a schematic sectional drawing of the permanent current switch which concerns on 1st Embodiment of this invention. (A) is a front view of the reel used for the permanent current switch of FIG. 2, (b) is a side view of (a). It is a partially expanded view which shows the winding state of the superconducting wire in the flange peripheral part of Fig.3 (a). It is a VV arrow sectional view of Drawing 4. It is VI-VI arrow sectional drawing of FIG. It is a perspective view used in order to explain the winding method of the permanent current switch concerning a 1st embodiment of the present invention. (A) is a front view of the reel used for the permanent current switch which concerns on 2nd Embodiment of this invention, (b) is a side view of (a). It is a partially expanded view which shows the winding state of the superconducting wire in the flange peripheral part of Fig.8 (a). It is XX arrow sectional drawing of FIG. It is XI-XI arrow sectional drawing of FIG.

Explanation of symbols

1, 10 Permanent current switch 2 Magnetic field generating superconducting coil 3, 11 Winding frame 3a, 11a Winding drum 3b, 3c, 11b, 11c Flange 3b ₁ 3c ₁ Protruding member 4, 13 Heater 5, 12 Conductive wire 6 Heat insulating material 7, 14 Adhesive tape 11b ₁ , 11c ₁ Plate member

Claims (4)

A winding drum,
Two disc-shaped flanges provided at both ends of the winding drum ;
A non-inductive winding , and
Each of the flanges has a protruding member provided in the radial direction as a folded portion ,
The non-inductive winding includes: (1) a first superconducting coil layer formed by spirally and densely winding a single superconducting wire around the winding drum; and (2) one end of the winding drum. folded over the remainder of the superconducting wire has finished winding the superconductive coil layer of the first layer to the folded portion provided on the side, the superconducting coil layers of the folded superconducting said first layer a second layer of superconducting coils layers formed by winding in opposite directions along the recesses between the superconducting wire, (3) the n the folded portion provided at the other end of the winding drum The superconducting coil layer of the layer (n is a number up to any one of even numbers) is wound around the remaining superconducting wire, and the folded superconducting wire is folded back to the nth superconducting coil layer. and the (n + 1) th layer of the superconducting coil layers formed by winding in opposite directions along the recesses between the superconducting wire, (4 The remaining folded back over the superconducting wire, the first (n + 1) th layer of the folded superconducting wire finished wound superconducting coil layers of the first (n + 1) th layer to the folded portion provided on one end of the winding drum between the (n + 2) th layer of the superconducting coil layers formed by winding in opposite directions along the recesses between the superconducting wire of the superconductive coil layer, and e Bei a winding frame for unguided winding. A winding drum,
Two flanges provided at both ends of the winding drum ;
A non-inductive winding , and
Each of said flanges, the groove to the base end portion of the winding drum, which is arranged so as to form a folded portion, Ri Do from two plate-like members,
The non-inductive winding includes: (1) a first superconducting coil layer formed by spirally and densely winding a single superconducting wire around the winding drum; and (2) one end of the winding drum. folded over the remainder of the superconducting wire has finished winding the superconductive coil layer of the first layer to the folded portion provided on the side, the superconducting coil layers of the folded superconducting said first layer a second layer of superconducting coils layers formed by winding in opposite directions along the recesses between the superconducting wire, (3) the n the folded portion provided at the other end of the winding drum The superconducting coil layer of the layer (n is a number up to any one of even numbers) is wound around the remaining superconducting wire, and the folded superconducting wire is folded back to the nth superconducting coil layer. and the (n + 1) th layer of the superconducting coil layers formed by winding in opposite directions along the recesses between the superconducting wire, (4 The remaining folded back over the superconducting wire, the first (n + 1) th layer of the folded superconducting wire finished wound superconducting coil layers of the first (n + 1) th layer to the folded portion provided on one end of the winding drum between the (n + 2) th layer of the superconducting coil layers formed by winding in opposite directions along the recesses between the superconducting wire of the superconductive coil layer, and e Bei a winding frame for unguided winding. Persistent current switch example Bei the winding frame according to claim 1 or 2. A superconducting magnet comprising the permanent current switch according to claim 3 .

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