JPH0719693B2 - Superconducting coil - Google Patents

Description

The present invention relates to an annular forced cooling type superconducting coil, and more particularly to a superconducting toroidal magnetic field coil in a fusion reactor.

[Conventional technology]

In a fusion reactor, a plurality of superconducting toroidal magnetic field coils (hereinafter abbreviated as toroidal coils) formed in an annular shape surrounding a vacuum container are arranged in a donut shape in order to confine plasma in the donut-shaped vacuum container. A toroidal magnetic field having a high magnetic flux density that circulates in a vacuum container in a donut shape is generated.

FIG. 2 is a perspective sectional view showing a schematic structure of the toroidal coil. In the figure, 1A, 1B and 1C are metal plates of a plurality of layers made of a metal material having high rigidity, and are formed in a flat plate ring shape having a hole 2 through which a donut-shaped vacuum container penetrates in the central portion, and the inner peripheral side thereof. By applying a tightening load in the stacking direction of the metal plates through the insertion holes 3 of the plurality of tightening bolts formed on the outer peripheral side and the outer peripheral side, respectively, the coil support 1 having a high rigidity, which is a stack of the metal plates, is formed. It is formed. In addition, a coil housing groove 4 extending over the metal plates on both sides of the metal plate is formed in a spiral shape around the hole 2 along the stack surface, and the superconducting coil conductor is housed in the spiral shape in the spiral shape. As a result, a plurality of layers of coils (layer coils) 5A, 5B are formed.

In addition, the coils 5 adjacent to each other via the metal plate 1B
A and 5B are connected in series by an inner peripheral side connecting portion 6 passing through a hole penetrating the metal plate 18 on the inner peripheral side thereof to form a two-layer coil 5 commonly called double pancake winding. Further, the outer peripheral side end of each layer coil is pulled out to the outside through a hole penetrating the metal plate in the radial direction.
Is formed. Multiple sets of double pancake winding coils 5
Are connected in series by an outer peripheral side connecting portion 17 connecting the lead-out portions 7 to each other to form a superconducting coil 10 in which a plurality of sets of double pancake winding coils 5 are connected in series. The toroidal coil thus configured is housed in a vacuum atmosphere of a strong coil container (not shown), and a plurality of annular vacuum containers (not shown) are attached to the toroidal magnetic field 100 shown by an arrow in the vacuum container. Occur.

FIG. 3 is a cross-sectional view showing a superconducting coil conductor, and the superconducting coil conductor 11 is a conduit pipe having an insulating coating 12.
A large number of superconducting wires 14 are stored in 13
It is electrically insulated from the metal plate by 12 and the superconductivity of the superconducting wire 14 is maintained by flowing helium 9 as a refrigerant through the conduit pipe 13.

Since a pulsed poloidal magnetic field 110 shown by an arrow in the figure is applied to each metal plate of the toroidal coil from a poloidal magnetic field coil (not shown), in order to prevent eddy currents between the metal plates due to this magnetic field change, , A thin insulating layer is interposed to insulate the metal plates from each other. In order to generate a toroidal magnetic field with the device configured as described above, an exciting current is supplied to the superconducting coil 10,
When this exciting current is cut off, an abnormal voltage exceeding 20KV is usually generated. In the conventional apparatus shown in FIG. 2, since the metal plate laminate 1 is held at the ground potential, the superconducting coil conductor 11 has its insulating coating 12 over its entire length.
It is necessary to maintain the withstand voltage performance between the superconducting coil 10 and the laminated body 1 of the metal plates as the coil support as a thickness that can withstand an abnormal voltage of KV or more. In the toroidal coil configured as described above, the cross-sectional area of the insulating coating 12 occupying the coil housing groove 4 becomes large, which causes the space factor of the superconducting wire 14 in the superconducting coil conductor 11 to decrease, which causes The magnetic flux density of the toroidal magnetic field 100 is reduced.

Therefore, as shown in the cross-sectional view of the improved conventional toroidal coil in FIG. 4, reference numeral 21 denotes a power feeding portion for making the lead-out portion 7 or the transition portion 17 on the outer peripheral side and the metal plate have the same potential,
Reference numeral 22 is a power feeding portion for making the inner peripheral crossover portion 6 and the metal plate have the same potential. By electrically connecting adjacent metal plates to the superconducting coil 10 alternately on the outer peripheral side and the inner peripheral side, A metal that equalizes the maximum potential difference between each layer coil and the metal plates on both sides of it (the burden voltage of the insulation coating 12) to the shared voltage of each layer coil, and withstands the potential difference corresponding to the shared voltage of each layer coil between the metal plates. The applicant of the present application has already proposed a structure in which the inter-plate insulating layer 40 is provided and the abnormal voltage is shared by the insulating coating layer 12 of the superconducting coil conductor and the plurality of metal inter-plate insulating layers 40.

In the toroidal coil thus configured, the voltage shared by the insulating coating of the superconducting coil conductor is reduced to a fraction of the number of coil layers, so that the space factor of the superconducting wire 14 can be increased accordingly.

[Problems to be Solved by the Invention]

In the prior art, as the metal plate insulating layer 40, a laminated film having a plastic film such as a polyimide film as a central layer and thermosetting prepreg sheets of a glass fiber base material as both layers is interposed on the laminated surface of the metal plates. , Which forms the inter-metal-plate insulating layer 40 made of a hardened layer of a laminated material by heating the entire toroidal coil, or an annular plastic molding having a square cross section that covers the laminated surface of the metal plates across the coil storage groove. There has been proposed a material for forming an insulating layer between metal plates using a material or a plastic molding material having prepreg sheet layers on both sides. The inter-metal plate insulating layer 40 formed in this manner has, for example, a semi-cured resin impregnated in a prepreg sheet that once has increased fluidity in a heating and curing process, and thus has a gap between the metal plates and a gap between each layer coil insulating coating layer. The gap between the two is filled up, and at the time of curing, an insulating layer between metal plates which does not contain voids and has excellent withstand voltage performance is formed. However, the inner peripheral edge and the outer peripheral edge of the metal plate, or the peripheral edge portion of the insertion hole 3 of the insulating bolt 31 forms a gap with the edge portions of the pair of metal plates sandwiching the thin metal plate insulating layer. Since the spark voltage between the gaps is lower than the dielectric breakdown voltage of the insulating layer between metal plates made of a solid insulator, there arises a problem that the withstand voltage performance between the metal plates is affected by the spark voltage at this portion.

An object of the present invention is to improve the withstand voltage performance between metal plates by increasing the flashover voltage at the edges of the metal plates.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, according to the present invention, a laminated body of metal plates formed in a flat plate ring shape, a coil storage groove formed in a spiral shape along the laminated surface, and a coil storage groove A plurality of layers of coils having an insulating coating housed therein, an inter-metal-plate insulating layer that insulates the metal plates from each other, and an insulation bolt that connects the metal plates to each other are provided, and each adjacent phase coil has an inner peripheral side. The connecting parts are alternately connected in series by the connecting part and the outer connecting part, and one of a pair of metal plates sandwiching each coil is held at the same potential as the outer connecting part and the other is held at the same potential as the inner connecting part. A groove formed by cutting out the outer peripheral edge, the inner peripheral edge of the metal plate and the peripheral edge of the through hole of the insulating bolt which are adjacent to each other substantially symmetrically with respect to the laminated surface of the both, and the groove. Said metal plate insulating layer and made by a formed by extending the insulating partition wall portion.

[Action]

In the above means, the inner and outer peripheries of the flat plate ring-shaped metal plates adjacent to each other and the edge portions of the through holes of the insulating bolts are notched at a desired radius or angle to form a groove, and the metal plate insulating layer is formed into a groove. By forming the insulating barrier ribs extending inward, the spark voltage between the gaps in the concave groove can be improved by the electric field relaxation effect of the metal plate edge portion, and the streamer of the spark discharge progresses due to the barrier effect of the insulating barrier ribs. Is prevented, the flashover voltage between the metal plates can be improved. In addition, since the insulating partition wall portion is housed in the groove and does not project to the outside of the laminated body of the metal plates, it is possible to prevent the insulating partition wall from becoming large and damaging the insulating partition wall.

〔Example〕

 The present invention will be described below based on examples.

FIG. 1 is a cross-sectional view of a toroidal coil showing an embodiment of the present invention, in which the same parts as those of the conventional device are designated by the same reference numerals, and detailed description thereof will be omitted. To simplify the explanation, the double pancake winding coil 5 consisting of layer coils 5A and 5B is sandwiched between three metal plates 1A, 1B and 1C and tightened with insulating bolts 31 inserted into the through holes 3 for the sake of simplicity. The metal plates are alternately conductively connected to the inner peripheral side and the outer peripheral side connecting portions of the layer coils 5A and 5B, and the metal plates 1A and 1B adjacent to each other and It is assumed that an abnormal voltage corresponding to the shared voltage of the layer coil 5A or 5B is generated between 1B and 1C, and between the metal plates, an insulating layer 40A, 40B between the metal plates having a thickness t made of, for example, a plastic molding material. Is provided.

The inner peripheral corners of the diameter Φ of each metal plate, the outer peripheral corners, and the corners of the insertion holes 3 of the insulating bolts 31 have a notch at the peripheral edge Θ with respect to the laminated surface of the metal plates. A concave groove formed at an angle of 2Θ is formed along the groove. Further, the inter-metal plate insulating layers 40A and 40B are extended toward the concave groove 41 to form the insulating partition wall portion 42. In the figure, the corner of the metal plate is notched at an angle Θ to form a groove, but the groove is formed by forming a rounded quadrant with a radius r in the notch. Needless to say, it is a good thing.

In the example toroidal coil thus formed, the electric field in the gap in the concave groove 41 defined by the insulating partition 42 into two is gradually weakened by the increase in the gap length spreading at the angle Θ, and the corners are Since the electric field concentration in the gap is significantly reduced compared to the case of the right angle, the spark voltage in the gap can be significantly increased. Further, even if spark discharge with a small gap is generated in the inner part of the groove where the electric field is highest (the portion with the smallest gap length), the insulating partition wall 42 has a barrier effect of preventing the spark discharge from proceeding, so the insulating partition wall The flashover voltage at which the discharge streamer bridges the portion 42 and the withstand voltage performance deteriorates can be further increased. Therefore, by determining the angle Θ of the notch, the depth of the groove, the radius of curvature of the notch, etc. according to the abnormal voltage generated between the metal plates, the withstand voltage performance of the metal-plate insulating layer and the metal It is possible to obtain an insulation system that is well balanced with the flashover voltage of the gap at the plate peripheral portion and the bolt insertion hole portion.

〔The invention's effect〕

As described above, the present invention is configured such that the corner portions of the metal plate are cut out at the laminated surface to form the concave groove, and the insulating layer between the metal plates is extended into the concave groove to form the insulating partition wall portion. . As a result, an abnormal voltage value that causes a flashover voltage at the peripheral edge of the inter-metal plate insulating layer between the metal plates due to the electric field relaxation effect at the metal plate corners due to the formation of the groove and the barrier effect due to the insulating partition walls. Accordingly, it is possible to provide a superconducting coil provided with an insulating layer between metal plates having excellent withstand voltage performance, and in particular, a superconducting toroidal magnetic field coil. Further, there are advantages that the insulating partition wall portion is located in the concave groove and mechanical damage can be avoided, and the device can be prevented from becoming large and difficult to handle due to the insulating layer protruding outside the metal plate.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, FIG. 2 is a perspective sectional view showing a conventional structure, FIG. 3 is a sectional view of a superconducting coil conductor, and FIG. 4 is an improved conventional structure. It is sectional drawing shown. 1 ... Coil support (metal plate stack), 1A, 1B,
1C: Metal plate, 2 ... Hole, 3 ... Tightening bolt insertion hole, 4 ... Coil storage groove, 5A, 5B ... Layer coil, 5 ...
… Double pancake winding coil, 6,17 …… Crossover, 10…
… Superconducting coil, 21, 22 …… Power supply part, 30 …… Tightening bolt, 31 …… Insulation bolt, 40 …… Insulation layer between metal plates,
41 ... Concave groove, 42 ... Insulating partition, Θ ... Notch angle,
t: thickness of insulating layer between metal plates, Φ: diameter of through hole 2 (inner diameter of metal plate).

Claims (1)

[Claims] 1. A plurality of layers having a laminated body of metal plates formed in a flat ring shape, a coil accommodating groove formed in a spiral shape along the lamination surface, and an insulating coating accommodated in the coil accommodating groove. Of the coil and an insulating layer between the metal plates for insulating the metal plates from each other and an insulating bolt for connecting the metal plates to each other, and the coils of each phase adjacent to each other are alternated by the inner peripheral side transition part and the outer peripheral side transition part. Which are connected in series with each other, one of a pair of metal plates sandwiching each layer coil is held at the same electric potential as the outer peripheral side connecting part, and the other is held at the same electric potential as the inner peripheral side connecting part. A concave groove formed by cutting out the outer peripheral edge and the inner peripheral edge of the plate and the peripheral edge of the through hole of the insulating bolt in a substantially symmetrical manner with respect to the laminated surface of the both, and the inter-metal plate insulating layer in the concave groove. Superconducting coil, characterized by comprising a formed by long insulating partition wall.