JP5204548B2 - Superconducting magnet device - Google Patents

Description

  The present invention relates to a magnet device provided with a superconducting coil.

  The superconducting magnet device cools the superconducting coil to a cryogenic temperature and uses the superconducting coil in a superconducting state with zero electric resistance. Since the superconducting coil is used in a superconducting state, there is no Joule heat generation, and a high magnetic field can be generated with less power than a normal conducting magnet device. An example of a superconducting magnet device is disclosed in Patent Document 1. The superconducting magnet device disclosed in Patent Document 1 is a magnet device having a configuration in which a superconducting magnet is disposed in a vacuum vessel and the superconducting magnet is cooled to a cryogenic temperature by a refrigerator mounted on the vacuum vessel.

  The vacuum container of such a superconducting magnet device is attached to the outer surface thereof with electrode pins to which an excitation power source for exciting the superconducting coil is connected. Here, the electrode pin is exposed to room temperature (about 300K), but the lead wire (conductive wire) connecting the electrode pin and the superconducting coil is cooled to a very low temperature. For this reason, the electrode pin itself connected to the lead wire is also cooled, and the electrode pin may have water droplets or frost. The adhesion of water drops causes rusting of the electrode pins, and if frost adheres to the electrode pins, problems such as a short circuit occur.

  In the technology related to the superconducting magnet device, as a technology related to measures against adhesion of water droplets and frost, there is one disclosed in Patent Document 2, for example. In the technique disclosed in Patent Document 2, a micro space is provided between an inner container that contains a superconducting coil and a refrigerant such as liquid nitrogen, and an outer container, and dry air or nitrogen gas at a room temperature or higher is provided in the micro space. It is what flows. According to this configuration, Patent Document 2 states that the surface of the outer container is maintained at a temperature near room temperature, and water droplets and frost do not adhere to the surface of the outer container.

JP 2004-169991 A Japanese Patent Laid-Open No. 9-149893

  However, with the technique disclosed in Patent Document 2 in which a minute space is provided between the inner container and the outer container, and a gas having a temperature of about room temperature or higher is allowed to flow through the minute space, there is a concern that cooling of the superconducting coil may be hindered. The Further, since the lead wire cooled to a low temperature is directly connected to the electrode pin in the superconducting magnet device, it is difficult to sufficiently suppress the electrode pin from being excessively cooled.

  The present invention has been made in view of the above circumstances, and its purpose is to suppress overcooling of the electrode attached to the vacuum vessel without hindering cooling of the superconducting coil, and as a result, water droplets / frost on the electrode. It is an object to provide a superconducting magnet device that can prevent the adhesion of a magnetic field.

Means and effects for solving the problems

  In order to achieve the above object, the present invention provides a superconducting coil, a vacuum container that accommodates the superconducting coil, an electrode attached to the vacuum container, wiring in the vacuum container, the electrode and the superconducting coil, A superconducting magnet device, wherein a part of the conducting wire is thermally connected to the inner surface of the vacuum vessel.

  According to this configuration, a part of the conductive wire connecting the electrode and the superconducting coil is thermally connected to the inner surface of the vacuum vessel, so that intrusion heat from the outside can be suppressed to a low level. The cooling of the superconducting coil is not hindered as in the prior art disclosed in FIG. Further, the cold heat of the conducting wire is conducted from the thermal connection portion between the inner surface of the vacuum vessel and the conducting wire to the vacuum vessel and radiated to the atmosphere. Accordingly, it is possible to prevent the electrode from being overcooled without impeding the cooling of the superconducting coil, and to prevent water droplets / frost from adhering to the electrode.

  Further, in the present invention, a cooling container that contains the superconducting coil and is placed in the vacuum container is provided, and the conductive wire is thermally connected to the cooling container, and is connected to the electrode and the inner surface of the vacuum container. The length of the conducting wire between the conducting wire and the first thermal connection portion is greater than the length of the conducting wire between the first thermal connecting portion and the second thermal connecting portion of the conducting wire with respect to the cooling vessel. Is also preferably short.

  According to this configuration, the thermal connection position of the conductor with respect to the inner surface of the vacuum vessel is a position far from the superconducting coil and closer to the electrode on the path of the conductor. Thereby, it is possible to further suppress the intrusion heat from the thermal connection position to the superconducting coil through the conducting wire, and to prevent the cooling of the superconducting coil from being hindered.

  Furthermore, in the present invention, in the first thermal connection portion, the conductive wire directly wound with the electrical insulating tape is thermally connected to the inner surface of the vacuum vessel via the electrical insulating tape. Is preferred. According to this configuration, the efficiency of heat conduction to the cold vacuum vessel of the conducting wire is improved. That is, it is possible to further suppress the cooling of the electrode connected to the conductive wire.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

(Configuration of superconducting magnet device)
FIG. 1 is a partial cross-sectional schematic view showing a superconducting magnet apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, the superconducting magnet device 1 of the present embodiment accommodates a superconducting coil 19, a radiation shield 4 (cooling container) that accommodates the superconducting coil 19, and a radiation shield 4 that accommodates the superconducting coil 19. The vacuum vessel 5 and the refrigerator 3 attached to the upper part of the vacuum vessel 5 are provided.

(Superconducting coil)
The superconducting coil 19 has a winding frame 9 and a superconducting wire 2 wound around the winding frame 9 in a spiral shape. The reel 9 is made of a nonmagnetic material such as aluminum or stainless steel. The superconducting wire 2 is obtained by embedding, for example, a niobium-titanium (NbTi) alloy ultrafine multi-core wire in a copper base material.

(Vacuum container)
The vacuum vessel 5 is a vessel whose inside is kept at a high vacuum and suppresses intrusion heat into the superconducting coil 19 and the radiation shield 4. The vacuum vessel 5 has an end plate 5a that seals the upper part thereof. Examples of the material of the vacuum vessel 5 (end plate 5a) include an aluminum material and a stainless material. The end plate 5a is a thick plate. The outer surface of the vacuum vessel 5 (end plate 5a) is exposed to room temperature (about 300K).

(electrode)
Electrode pins 8 (electrodes) made of a copper material are attached to the end plate 5a of the vacuum vessel 5. The electrode pin 8 includes an anode pin and a cathode pin, and an excitation power source (not shown) for exciting the superconducting wire 2 is connected to the electrode pin 8. Moreover, a part of electrode pin 8 protrudes outside, and is exposed to the atmosphere (outside air).

(Radiation shield)
The radiation shield 4 has a shield body 4a and a plate 4b attached to the upper opening of the shield body 4a. Examples of the material of the radiation shield 4 (plate 4b) include an aluminum material and a copper material.

(refrigerator)
The refrigerator 3 is a two-stage regenerative refrigerator, and includes a drive unit 12 and a cylinder 11 disposed below the drive unit 12. The cylinder 11 has an upper first cylinder 11a and a lower second cylinder 11b. A first cooling end 12a is provided at the lower end of the first cylinder 11a, and a second cooling end 12b is provided at the lower end of the second cylinder 11b. Each of the first cooling end portion 12a and the second cooling end portion 12b has a flange shape. The first cooling end 12a is attached to the plate 4b of the radiation shield 4 by fixing means such as bolts, and the second cooling end 12b is attached to the heat transfer member 14 by fixing means such as bolts. Yes. The heat transfer member 14 is thermally connected to the outer periphery of the superconducting coil 19. Helium gas is supplied to the drive unit 12, and the supplied helium gas is ejected to the lower part of the first cylinder 11a and the lower part of the second cylinder 11b. The refrigerator 3 cools the radiation shield 4 and the superconducting coil 19 to about 40K and about 4K through the first cooling end 12a and the second cooling end 12b, respectively.

(Conductor)
The electrode pin 8 and the superconducting wire 2 are connected by a copper wire 6 (conductive wire) through a cylindrical oxide current lead 7. The copper wire 6 is a lead wire having high thermal conductivity, while the oxide current lead 7 has a function of hardly transferring heat. The copper wire 6 and the oxide current lead 7 are wired in the vacuum vessel 5. Here, FIG. 2 is a detailed view around the electrode pin 8 of the superconducting magnet apparatus 1 shown in FIG. 2A is an enlarged view of a portion A in FIG. 1, and FIG. 2B is a detailed view taken along the line BB ′ in FIG. 2A. FIG. 3 is an enlarged view of a portion C in FIG. The arrows in FIG. 3 indicate the movement of cold heat.

  As shown in FIGS. 1 to 3, a part of the copper wire 6 is thermally connected to the inner surface (vacuum side surface) of the end plate 5 a of the vacuum vessel 5. This thermal connection part is shown in FIGS. 1 to 3 as a first thermal connection part 15. Here, a glass tube 17 is put on the copper wire 6, and a glass tape 18 (thickness is thinner than that of the glass tube 17), which is an electrical insulating tape, is wound around the outer side of the copper wire 6 for insulation. However, the copper wire 6 of the first thermal connection portion 15 is not covered with the glass tube 17, and only the glass tape 18 thinner than the glass tube 17 is directly wound. Further, both ends of the copper wire 6 are pressed against the end plate 5a by the saddle 10 so that the copper wire 6 does not float. The saddle 10 includes an arc-shaped plate portion and flat plate portions extending on both sides thereof, and is attached to the inner surface of the end plate 5a by a fixing means such as a bolt. The saddle 10 is made of stainless steel. Further, in order to bring the copper wire 6 into close contact (contact) with the end plate 5a, the copper wire 6 is covered with the clay 11 and brought into close contact with the end plate 5a. Examples of the electrical insulating tape wound around the copper wire 6 include a Mylar sheet and a Teflon (registered trademark) tape in addition to the glass tape 18. The electrical insulating tape is preferably a thin tape.

  Further, a part of the copper wire 6 closer to the superconducting wire 2 (or the oxide current lead 7) than the first thermal connection portion 15 is thermally connected to the plate 4b of the radiation shield 4. . This thermal connection is shown in FIGS. 1 and 2 as a second thermal connection 16. In the second thermal connection portion 16, as shown in FIG. 2, the connection member 13 having an L-shaped cross section is attached to the plate 4b with a bolt. And the copper wire 6 by the side of the electrode pin 8 and the copper wire 6 by the side of the superconducting wire 2 are attached to the connecting member 13 by bolts via the crimp terminal 20a and the crimp terminal 20b, respectively. Note that the crimp terminals 20a and 20b are not necessarily used. And the 2nd thermal connection part 16 is cooled to about 40K level with the refrigerator 3 through the plate 4b. By cooling the second thermal connection portion 16, intrusion heat transmitted from the electrode pin 8 side to the superconducting wire 2 through conduction is suppressed.

  The first thermal connection 15 is located between the electrode pin 8 and the second thermal connection 16, and the length of the copper wire 6 between the electrode pin 8 and the first thermal connection 15. L1 is provided so as to be shorter than the length L2 of the copper wire 6 between the first thermal connection 15 and the second thermal connection 16. That is, the first thermal connection 15 is provided near the electrode pin 8 attached to the end plate 5 a of the vacuum vessel 5.

(Regarding heat conduction through copper wire)
The copper wire 6 is cooled by the second thermal connection portion 16, and the cold heat travels through the copper wire 6 and reaches the first thermal connection portion 15. According to this embodiment, as indicated by arrows in FIG. 3, the cold heat of the copper wire 6 is the first thermal connection that is the thermal contact portion of the copper wire 6 with respect to the inner surface of the end plate 5 a. The portion 15 conducts heat in the end plate 5a and radiates heat to the atmosphere. In addition, since only a part of the copper wire 6 connecting the electrode pin 8 and the second thermal connection portion 16 is thermally connected to the inner surface of the end plate 5a, the invasion heat from the outside is reduced. The cooling of the superconducting wire 2 is not greatly hindered. Therefore, it is possible to suppress the cooling of the electrode pin 8 without hindering the cooling of the superconducting wire 2 and to prevent water droplets and frost from adhering to the electrode pin 8. Further, according to the present embodiment, new parts such as a temperature adjusting heater are not necessary, which is advantageous in terms of cost.

  Moreover, since the 1st thermal connection part 15 is made into the position far from the superconducting wire 2 and the electrode pin 8 on the path | route of the copper wire 6, the 1st thermal connection part from the end plate 5a to the superconducting wire 2 is carried out. The intrusion heat through 15 can be further suppressed, and the cooling of the superconducting wire 2 can be prevented from being hindered. Furthermore, in the 1st thermal connection part 15, since the copper wire 6 is thermally connected only through the glass tape 18 thinner than the glass tube 17 with respect to the end plate 5a, the cold heat which the copper wire 6 has The heat conduction efficiency to the end plate 5a is improved. Thereby, it can suppress more that the electrode pin 8 connected to the copper wire 6 is too cold.

(Variation of end plate of vacuum vessel)
Next, a modification of the end plate 5a of the vacuum vessel 5 will be described. FIG. 4 is a schematic view for showing a modification of the end plate 5a. FIG. 4A is a diagram according to the present modification corresponding to FIG. 3 showing an enlargement of the portion C in FIG. 2, and FIG. 4B is a view as seen from the direction of arrow D in FIG. In FIG. 4, the same members as those shown in FIG. 3 are denoted by the same reference numerals.

  The inner surface (vacuum side surface) of the end plate 5a of the first thermal connection portion 15 part to which a part of the copper wire 6 is thermally connected is formed flat, but as shown in FIG. On the inner surface (vacuum side surface) of the end plate 51a according to this modification, two concave portions 20 (groove portions) having an arcuate cross section along the wiring direction of the copper wire 6 are provided. Wiring (fixing) of the copper wire 6 is facilitated by thermally connecting the copper wire 6 to the inner surface of the end plate 5a along the recess 20 having an arcuate cross section. Further, since the surface area of the end plate 51a of the first thermal connection portion 15 is also increased, the cold heat from the copper wire 6 is likely to spread to the end plate 51a. Furthermore, the recess 20 improves the adhesion of the copper wire 6 to the end plate 51a.

  In addition, what is formed in the inner surface of the end plate 51a of the first thermal connection portion 15 does not necessarily need to be the concave portion 20 having an arcuate cross section. For example, fine irregularities may be used. By forming fine irregularities on the inner surface of the end plate 51a, the surface area of the end plate 5a can be increased, and heat can easily spread.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

  For example, in the above-described embodiment, the refrigerant-free superconducting magnet device 1 in which the superconducting wire 2 is cooled and operated by the refrigerator 3 is shown. However, the present invention is also applied to a superconducting magnet device in a form containing liquid helium. can do.

It is a partial cross section schematic diagram which shows the superconducting magnet apparatus which concerns on one Embodiment of this invention. FIG. 2 is a detailed view around an electrode pin of the superconducting magnet device shown in FIG. 1. It is the C section enlarged view of FIG. It is a schematic diagram for showing the modification of the end plate of a vacuum vessel.

Explanation of symbols

1: Superconducting magnet device 2: Superconducting wire 3: Refrigerator 4: Radiation shield (cooling container)
5: Vacuum container 6: Copper wire (conductor)
8: Electrode pin (electrode)
15: 1st thermal connection part 16: 2nd thermal connection part 19: Superconducting coil

Claims (3)

A superconducting coil;
A vacuum vessel containing the superconducting coil;
An electrode attached to the vacuum vessel;
A wire that is wired in the vacuum vessel and connects between the electrode and the superconducting coil; and
A part of the conducting wire is thermally connected to the inner surface of the vacuum vessel. In the superconducting magnet device according to claim 1,
A part of the conducting wire is thermally connected to the inner surface of the vacuum vessel in the vicinity of the electrode . In the superconducting magnet device according to claim 2,
An electrical insulating tape is directly wound around a part of the conducting wire ,
Some of the conductors, characterized in that it is thermally connected via the electrically insulating tape to the inner surface of the vacuum container, a superconducting magnet apparatus.

Images