JP3841340B2 - Electromagnetic coil and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic coil using an inorganic insulated metal-coated cable (Mineral Insulated Cable: hereinafter referred to as MIC) used in places exposed to radiation, and more particularly, a water channel for passing cooling water, and an MIC. The present invention relates to a structure for fixing a coil wound around a wire.
[0002]
[Prior art]
Various accelerators are used to accelerate charged elementary particles and ions to a high energy state and collide with the target to study the structure of the nucleus. In this apparatus, Lorentz force is used for acceleration of elementary particles or ions and direction control, so it is necessary to install a large number of electromagnets for generating a high magnetic field. And in an accelerator, generation | occurrence | production of the various radiation accompanying particle acceleration is unavoidable, and the countermeasure with respect to a radiation is needed also about the electromagnet to be used.
[0003]
Conventionally, an electromagnetic coil of an electromagnet used for an accelerator is used in an environment where the radiation dose is 10 ⁶ Gy (gray) to 10 ⁸ Gy, and the radiation dose level is 10 ⁸ Gy or less as a countermeasure against insulation deterioration of the electromagnetic coil due to radiation. Then, an organic insulator having high radiation resistance is used, and an inorganic insulator is used at a radiation dose level of 10 ⁸ Gy or more. In the case where the radiation dose is 10 ⁸ Gy or higher and the level is particularly high, it is necessary to configure the insulator only with an inorganic substance.
[0004]
Moreover, in general, in such an electromagnetic coil, in order to prevent a failure due to heat generation due to energization, a hollow conductor is used for the winding, or a water pipe is separately provided along the conductor, It is necessary to operate while passing cooling water through the hollow portion.
[0005]
In this case, if a hollow conductor is used for the MIC, it is necessary to insulate the inner periphery of the hollow conductor, and the structure is complicated in order to prevent accidents due to leakage of cooling water and deterioration of insulation of the coil. It becomes expensive. Further, in the structure in which the water pipe is provided along the MIC, since the conductor is covered with an inorganic insulator, there arises a problem that a reduction in cooling efficiency cannot be avoided.
[0006]
For this measure, magnesium oxide, which has a relatively high thermal conductivity, is used as the inorganic insulator covering the conductor, and a non-magnetic low melting point metal is interposed between the MIC and the water pipe. A technique for fixing the material is disclosed. Since the electromagnetic coil having this configuration is filled with a metal having high thermal conductivity between the water flow pipe and the MIC, heat generated by energization of the conductor can be removed very quickly.
[0007]
FIG. 4 is a diagram showing a cross section of an example of an MIC, where 401 is a conductor made of oxygen-free copper, 402 is an insulator made of magnesium oxide, and 403 is a sheath made of copper. FIG. 5 is a cross-sectional view showing an example of an electromagnetic coil in which the MIC and the water flow pipe are fixed with a non-magnetic low melting point metal. 501 is the MIC, 502 is the water flow pipe made of stainless steel, and 503 is the water flow pipe. A nonmagnetic low-melting-point metal mainly composed of tin, 504 indicates a case made of stainless steel.
[0008]
[Problems to be solved by the invention]
In the electromagnetic coil using the MIC, the cooling efficiency can be increased as described above by adopting the structure as shown in FIG. 5, but the problem here is that the nonmagnetic property in the manufacturing process of the electromagnetic coil This is a reduction in wall thickness due to elution into a non-magnetic low-melting point metal such as a sheath of MIC or a water passage pipe when filling the low-melting point metal. This phenomenon is unavoidable to some extent due to the relationship of phase equilibrium, especially when the MIC is bent, it has a large effect on the wrinkles that occur in the inner sheath, leading to a decrease in the reliability of the electromagnetic coil. It is.
[0009]
Therefore, the technical problem of the present invention is that the cooling efficiency is improved by adopting a structure in which a nonmagnetic low-melting-point metal is filled between the winding of the MIC and the water pipe, and a level of 10 ⁸ Gy or more. It is an object of the present invention to provide an electromagnetic coil that can withstand the radiation of the above, and an electromagnetic coil that prevents elution of the material constituting the sheath of the MIC and the pipe for passing water into the nonmagnetic low-melting-point metal and a method for manufacturing the same.
[0010]
[Means for Solving the Problems]
The present invention has been made as a result of examining the composition of a nonmagnetic low-melting-point metal interposed between the MIC and the water flow pipe in order to solve the above problems.
[0012]
That is, the present invention relates to a stainless steel containing a conductor, an inorganic insulator covering the conductor, an inorganic insulating metal-coated cable comprising a copper sheath covering the insulator, and nickel of cooling water adjacent to the inorganic insulating metal-coated cable. In the electromagnetic coil formed by winding a water passage pipe made of the above, the inorganic insulating metal-coated cable and the cooling water passage pipe are 0.3 to 1.95 parts by weight of copper, 0 parts per 100 parts by weight of tin. An electromagnetic coil characterized by being fixed by a nonmagnetic low melting point metal made of an alloy to which 0.05 to 0.15 parts by weight of nickel is added in total to 2.0 parts by weight or less.
Moreover, the present invention is the electromagnetic coil according to the above-mentioned electromagnetic coil, wherein the nonmagnetic low melting point metal has a melting point of 300 ° C. or less .
[0014]
The present invention is the electromagnetic coil according to the above-described electromagnetic coil, wherein the inorganic insulator includes magnesium oxide.
[0015]
In the electromagnetic coil according to the present invention, the inorganic insulator includes aluminum nitride.
[0016]
In addition, the present invention forms a coil by winding a conductor, an inorganic insulator covering the conductor, and an inorganic insulated metal-coated cable comprising a sheath covering the conductor, and passing cooling water in accordance with the shape of the coil. The method for producing an electromagnetic coil according to claim 1, wherein a water pipe is formed, and the coil and the formed water flow pipe are fixed with a nonmagnetic low melting point metal.
[0017]
[Action]
As described above, the nonmagnetic low melting point metal used by filling the gap between the MIC and the water pipe is indium (melting point: 157 ° C.), tin (melting point: 231 ° C.), lead (327 ° C.), zinc. (Melting point: 420 ° C.), solder which is an alloy of tin and lead. Among these, tin is preferable in consideration of toxicity, price, and the like.
[0018]
However, when these molten metals are brought into contact with other metals, it is inevitable that the metals in contact with the molten metal are eluted up to the saturation concentration at the temperature of the molten metal. FIG. 1 shows a part of a two-component phase diagram composed of tin and copper. According to this figure, it can be seen that about 3% by weight of copper dissolves at around 300 ° C., which is a temperature necessary to dissolve tin and fill the gap between the MIC and the water flow pipe.
[0019]
From this, it can be expected that by adding copper to tin within the above range, elution of the copper sheath of the MIC can be prevented when filling the molten metal. Further, stainless steel may be used for the water passage pipe, and in this case, it can be expected that nickel elution can be prevented by the same method. FIG. 2 shows a part of a phase diagram of a two-component system composed of tin and nickel, and adding nickel to tin within a range of 0.2% by weight or less can contribute to solving the above problem. Suggests that.
[0020]
From this point of view, the result of examining the concentration of the metal added to the tin, the concentration of copper added to prevent the elution of copper, relative to the tin 100 parts by weight, and optimally it is under 2 parts by weight or less there were. A more desirable appropriate range is that the concentration of copper added to prevent elution of copper is 0.3 to 1.2 parts by weight . The concentration of nickel added to prevent the elution of nickel, relative to the tin 100 parts by weight, 0. It was optimal at most 1 part by weight. A more desirable appropriate range is that the concentration of nickel added to prevent elution of copper is 0.05 to 0.15 parts by weight.
[0021]
The MIC used in the present invention uses magnesium oxide or aluminum nitride as an inorganic insulator covering the conductor. The reason for limiting the inorganic material to magnesium oxide is that magnesium oxide and aluminum nitride have the same thermal conductivity as beryllium oxide, or the highest thermal conductivity after beryllium oxide, among the oxides that can be used as insulators. This is because the heat generated therewith can be quickly moved.
[0022]
By the way, the numerical values (unit: Wm-1K-1) of the thermal conductivity at 200 ° K and 300 ° K are 1.14 and 1.38 for quartz glass and 55 and 36 for polycrystalline alumina. Magnesium oxide is 94,60. The thermal conductivity of beryllium oxide is 424 at 200 ° K and 272 at 300 ° K, which is very large compared to the inorganic material. However, the use is limited in consideration of handling properties such as toxicity. Is better. Aluminum nitride also has a high thermal conductivity of 70 to 270, but magnesium oxide is superior in terms of price and availability.
[0023]
Further, when magnesium oxide is left in the air, it undergoes a chemical reaction with water vapor or carbon dioxide gas, and its characteristics change. In addition, compared with a general polymer compound as an insulator, mechanical strength is insufficient, and there is a possibility that troubles may occur in operations such as winding. However, in the present invention, since the insulator is protected by the metal sheath, such a phenomenon does not occur. Therefore, the MIC used in the present invention has both high insulation and thermal conductivity.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings with specific examples.
[0025]
Here, an example in which the dissolution rate of copper in a tin melt with varying concentrations of copper and nickel is first examined. FIG. 3 shows the examination result of the dissolution rate of copper in the molten metal. The examination method is to immerse a copper plate having a side of 25 mm and a thickness of 1.5 mm at a required temperature and then measure the thickness of the copper plate after being immersed for a required time.
[0026]
In FIG. 3, 301 is a state in which a nonmagnetic low melting point metal having a composition of 99.3% by weight of tin, 0.6% by weight of copper, and 0.1% by weight of nickel is maintained at 240 ± 5 ° C. The result of immersing the copper plate is shown. 302 is a nonmagnetic low melting point metal having a composition of 100% tin, held at 235 ± 5 ° C. and dipped in the copper plate. As a result, 302 is a nonmagnetic low melting point having a composition of 100% tin. The result of immersing the copper plate while maintaining the molten metal at 240 ± 5 ° C. is shown.
[0027]
As is clear from this result, by using a non-magnetic low-melting-point metal containing copper and nickel, the elution of copper constituting the MIC sheath and stainless steel constituting the water flow pipe into the molten metal is suppressed. Can be estimated. Therefore, the decrease in the thickness of the sheath of the MIC and the thickness of the water flow pipe can be extremely reduced, and the reliability of the electromagnetic coil wound with the MIC can be improved. And the nonmagnetic low melting-point metal of such a composition is applicable also to the electromagnetic coil shown in FIG.
[0028]
FIG. 6 is a cross-sectional view of a portion where the MIC and the water flow pipe are wound in the first example of the electromagnetic coil according to the present invention. In the example of FIG. 6, a water passage pipe 602 made of stainless steel is arranged along the upper and lower portions of the MIC 601 in the drawing. The MIC wound by bending is brazed between each adjacent MIC to form a coil. Similarly, the water flow pipe 602 is also bent and brazed to form a coil shape.
[0029]
The gap between the MIC 601 and the water pipe 602 is filled with a nonmagnetic low melting point metal having a composition of 99.3% by weight of tin, 0.6% by weight of copper, and 0.1% by weight of nickel. Yes, the MIC 601 and the water flow pipe 602 are fixed. As described above, since the metal having high thermal conductivity is interposed between the MIC 601 and the water flow pipe 602, the Joule heat generated in the MIC 601 can be quickly transferred to the outside. Reference numeral 604 denotes a case made of stainless steel that protects the entire electromagnetic coil.
[0030]
FIG. 7 is a cross-sectional view of a portion around which a water flow pipe made of MIC and copper is wound in a second example of the electromagnetic coil according to the present invention. Also in the example of FIG. 7, the MIC 701 is bent and wound, and brazed between each of the adjacent MICs 701 to form a coil. Here, the coil is 99.3% by weight of tin and 0.3% of copper. A stainless steel case 704 is provided after covering with a nonmagnetic low melting point metal 703 having a composition of 6% by weight and nickel of 0.1% by weight. The water passage pipe 702 is fixed to the outside of the case 704 by brazing.
[0031]
In this case, the manufacturing process can be further simplified as compared with the first example shown in FIG. 6, and a sufficient amount of nonmagnetic low resistance is provided between the brazed case 704 and the water flow pipe 702. By interposing a melting point metal, the cooling efficiency is not lowered. However, since the water pipe 302 is exposed to the outside of the case, it is necessary to handle it more carefully than in the first example shown in FIG.
[0032]
FIG. 8 is a diagram of a portion in which a water flow pipe made of MIC and copper is wound in a third example of the electromagnetic coil according to the present invention. Also in the example of FIG. 8, the MIC 801 is bent and wound. The adjacent MIC 801 is brazed to form a coil. A copper plate 805 is interposed between the upper and lower MICs in FIG. 8, and water pipes 802 are attached to both ends of the copper plate 805.
[0033]
Note that solder 806 is used to join the MIC 801 and the water flow pipe 802 to the copper plate 805. Solder has good wettability to copper, and MIC801, copper plate 805, and water flow pipe 802 are integrated as a heat flow path, so it is not always filled with non-magnetic low melting point metal as in the examples described so far There is no need to do.
[0034]
In the example of FIG. 8, the entire fixing is performed using a low melting point metal 803 having a composition of 99.3% by weight of tin, 0.6% by weight of copper, and 0.1% by weight of nickel. Alumina cement can be used in addition to the nonmagnetic low melting point metal shown in the examples described above.
[0035]
FIG. 9 is a perspective view showing the appearance of the electromagnetic coil described so far. In FIG. 9, 901 is a MIC, 902 is a water flow pipe, 903 is a non-magnetic low melting point metal, 904 is a stainless steel case, and 905 is a bus bar. Reference numeral 906 denotes an insulating terminal having a function of preventing current leakage to the sheath of the MIC, the solder 903, and the case 904.
[0036]
Next, in order to evaluate the cooling performance of the electromagnetic coil according to the present invention, with the structure shown in FIG. 6, the electromagnetic coil in which the pipes for water flow are arranged on both the upper and lower sides of the MIC, The temperature rise was measured when the electromagnetic coil in which the pipe was arranged was energized and the cooling water was passed. At that time, for comparison, an electromagnetic coil composed of a hollow conductor, and an electromagnetic coil having the structure shown in FIG. 6 and using an alumina cement instead of solder to which the MIC and the water flow pipe are fixed, have the same conditions. The temperature rise was measured at In addition, also when alumina cement was used, the arrangement | positioning of the water flow pipe was made into two types of the both sides of a MIC, and one side.
[0037]
FIG. 10 collectively shows the evaluation results of the cooling performance of these electromagnetic coils. In FIG. 10, 1001 is an electromagnetic coil in which alumina cement is used and a water passage pipe is disposed only on one side of the MIC, 1002 is an electromagnetic coil in which alumina cement is used and water passage pipes are disposed above and below the MIC, and 1003 is a main coil. 1004 is an electromagnetic coil using hollow conductors when 1004 is an electromagnetic coil according to the present invention, and 1005 is an electromagnetic coil using a hollow conductor. In this case, water is passed through the hollow portion of the conductor.
[0038]
From these results, the temperature rise of the electromagnetic coil by direct cooling using the hollow conductor is the smallest, but the electromagnetic coil of the present invention has high cooling efficiency even with indirect cooling with the water pipe along the MIC conductor. It can be seen that it is possible to operate in a state where no trouble is caused by the temperature rise.
[0039]
【The invention's effect】
As described above, according to the present invention, in order to give the electromagnetic coil using the MIC a structure capable of expressing sufficient cooling efficiency, a non-magnetic low gap is provided in the gap between the MIC and the water flow pipe. In the step of filling the melting point metal, it is possible to prevent obstruction due to elution into the nonmagnetic low melting point metal. Thereby, the reliability of the electromagnetic coil used in the environment exposed to radiation can be significantly improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a part of a phase diagram of a two-component system composed of tin and copper.
FIG. 2 is a diagram showing a part of a two-component phase diagram composed of tin and nickel.
FIG. 3 is a diagram showing a result of examining a dissolution rate in molten metal.
FIG. 4 is a diagram showing a cross section of an example of an MIC.
FIG. 5 is a view showing a cross section of an example of an electromagnetic coil in which a MIC and a water flow pipe are fixed with a nonmagnetic low melting point metal.
FIG. 6 is a cross-sectional view of a portion where an MIC and a water flow pipe are wound in a first example of an electromagnetic coil according to the present invention.
FIG. 7 is a view showing a cross section of a portion where an MIC and a water flow pipe are wound in a second example of an electromagnetic coil according to the present invention.
FIG. 8 shows a cross section of a portion where an MIC and a water flow pipe are wound in a third example of an electromagnetic coil according to the present invention.
FIG. 9 is a perspective view showing the appearance of the electromagnetic coil of the present invention.
FIG. 10 is a view showing an evaluation result of cooling performance of an electromagnetic coil.
[Explanation of symbols]
301 Result of composition with 99.3% by weight of tin, 0.6% by weight of copper and 0.1% by weight of nickel MIC302 Result of composition with 100% of tin, temperature of 235 ± 5 ° C. Result of 303 with 100 of tin % Composition, results at a temperature of 240 ± 5 ° C. 400, 501, 601, 701, 801, 901 MIC
401 Conductor 402 Insulator 403 Sheath 502, 602, 702, 802, 902 Water pipe 503, 603, 703, 803, 903 Non-magnetic low melting point metal 504, 604, 704, 804, 904 Case 805 Copper plate 806, 903 Solder 905 Busbar 906 Insulation terminal 1001 Electromagnetic coil 1002 with water flow pipe disposed only on one side of MIC Electromagnetic coil 1003 with water flow pipe disposed above and below MIC Electromagnetic coil with water flow pipe disposed on only one side of MIC 1004 Electromagnetic coil in which pipes for water flow are arranged above and below the MIC 1005 Electromagnetic coil using a hollow conductor

Claims (5)

An electromagnetic formed by winding a conductor, an inorganic insulator covering the conductor, an inorganic insulating metal-coated cable made of a copper sheath covering the insulator, and a cooling water passage pipe adjacent to the inorganic insulating metal-coated cable in the coil, wherein the water passage pipe is made of stainless steel containing nickel, it said inorganic insulating metal sheathed cable and the cooling water passage for water pipes, with respect to tin 100 parts by weight, 0.3 to 1.95 parts by weight of copper , 0.05 to 0.2 to 15 parts by weight of nickel, in total. 0 electromagnetic coil, characterized by comprising fixed in a non-magnetic low melting point metal consisting of parts by weight was added alloy. The electromagnetic coil according to claim 1 , wherein the nonmagnetic low melting point metal has a melting point of 300 ° C. or less. 3. The electromagnetic coil according to claim 1 , wherein the inorganic insulator includes magnesium oxide. 4. 3. The electromagnetic coil according to claim 1 , wherein the inorganic insulator includes aluminum nitride. A coil is formed by winding a conductor, an inorganic insulator covering the conductor, and an inorganic insulating metal-coated cable comprising a sheath covering the conductor, and forming a cooling water flow pipe in accordance with the shape of the coil. the method of the electromagnetic coil according to any one of claims 1 to 4, characterized in that the coil and the molded passing water pipe, fixed in a non-magnetic low melting point metal.

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