JP2013143478A - Superconducting magnet device and current lead used in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting magnet device which includes a refrigeration unit for cooling a current lead and makes vibrations generated in the refrigeration unit unlikely to be transmitted to a superconducting coil, and to provide a current lead used in the superconducting magnet device.SOLUTION: A superconducting magnet device includes: a superconducting coil 12; a cooling container 14 housing the coil 12; a thermal insulation container 20 housing the cooling container 14; a refrigeration unit 40 disposed at a position separated from the cooling container 14; and a current lead 30 connecting the superconducting coil 12 with an external power source. The current lead 30 has a metal flexible conductor part 34. The flexible conductor part 34 extends from the cooling container 14 to the refrigeration unit 40, has a low temperature end 34a to which the superconducting coil 12 is connected and a high temperature end 34b to which the refrigeration unit 40 and the external power source are connected, and has a length dimension that deflects so as to absorb the vibrations of the refrigeration unit 40.

Description

  The present invention relates to a superconducting magnet device and a current lead used in the device.

  A conventional superconducting magnet device includes a superconducting coil, a cooling container for accommodating and cooling the superconducting coil, and a current lead for connecting a power supply provided outside the cooling container and the superconducting coil. . For example, the cooling container accommodates a superconducting coil and a refrigerant such as liquid helium for cooling the inside thereof to cool the superconducting coil and maintain the superconducting state.

  As for the current lead, heat penetration into the cooling container through the current lead becomes a big problem. Copper with high conductivity is often used for the current lead, but this copper has high thermal conductivity and easily allows heat intrusion from the outside, and also due to the electrical resistance of the copper itself. Heat generation is a major factor in the heat penetration. This heat intrusion causes an increase in consumption of the refrigerant (liquid helium or the like). In particular, the superconducting coil is operated in the driving mode in which the superconducting coil and the external power source are connected to each other by the current lead instead of the permanent current mode in which the superconducting coil is disconnected from the current lead. In a magnet device, for example, a device in which a superconducting coil is made of an oxide-based superconducting wire and it is difficult to use a permanent current switch, it is desired to suppress heat penetration through the current lead.

  Conventionally, as a superconducting magnet device that suppresses heat intrusion through the current lead as described above, for example, a device described in Patent Document 1 is known. The superconducting magnet device includes a refrigeration device connected to a current lead, and the current lead is cooled by the refrigeration device, thereby suppressing heat penetration through the current lead.

JP 2010-60245 A

  When the refrigeration apparatus is driven in the superconducting magnet apparatus, vibration is generated in the refrigeration apparatus. When this vibration is transmitted to the superconducting coil through the current lead to which the refrigeration apparatus is connected, the vibration affects the magnetic field formed by the superconducting magnet device provided with the coil. For this reason, when the superconducting magnet device is used as a means for forming a magnetic field in another device (for example, an analysis device using a magnetic field), the vibration is an analysis result or a measurement result in the other device. In some cases, this may cause problems such as a decrease in accuracy.

  Accordingly, in view of the above problems, a superconducting magnet apparatus having a refrigeration apparatus for cooling the current leads, in which vibration generated in the refrigeration apparatus is difficult to be transmitted to the superconducting coil, and a current lead used in the apparatus is provided. The purpose is to provide.

  In order to solve the above-mentioned problems, the present invention is a superconducting magnet device, comprising a superconducting coil, a cooling container for accommodating and cooling the superconducting coil, and a vacuum heat insulating layer between the cooling container. A heat insulating container for accommodating the cooling container therein, a refrigeration apparatus disposed at a position away from the cooling container, and the superconducting coil and a power supply external to the heat insulating container. A current lead. The current lead has a flexible conductor portion made of a conductive metal disposed in the heat insulation container, and the flexible conductor portion extends from the cooling container toward the refrigeration apparatus, and A low temperature end to which the superconducting coil is connected, and a high temperature end to which the refrigerating apparatus is connected and cooled while being connected with the power supply And has a length that can be bent and deformed so as to absorb vibration generated in the refrigeration apparatus.

  According to the present invention, the flexible conductor portion extending in a specific direction absorbs the vibration generated in the refrigeration apparatus while suppressing the heat intrusion from the outside through the current lead by cooling the current lead by the refrigeration apparatus. Therefore, it is possible to effectively suppress the vibration generated by the refrigeration apparatus from being transmitted to the superconducting coil through the current lead.

  Specifically, in this superconducting magnet device, the high temperature end of the flexible conductor portion is cooled by the refrigeration device, so that the high temperature end near the space outside the heat insulation container at room temperature and the position near the cryogenic cooling container are located. It is possible to suppress the thermal gradient in the flexible conductor portion between the low temperature end and effectively prevent heat from entering the current lead from the high temperature end. That is, the electric wire or the like connecting the external power source and the current lead is arranged in a normal temperature atmosphere and has a higher temperature than in the heat insulation container, but the temperature gradient of the current lead (flexible conductor) is reduced by a refrigeration apparatus. Thus, it is possible to effectively prevent the heat of the electric wire or the like from entering the current lead through the high temperature end to which the electric wire or the like is connected. In addition, since the current lead is cooled, heat generated by the electric resistance of the current lead itself can be suitably suppressed. Furthermore, since the flexible conductor portion made of metal has a predetermined length, vibrations from the refrigeration apparatus connected to the high temperature end can be absorbed by the bending of the flexible conductor portion itself, The vibration is difficult to reach the low temperature end. As a result, the transmission of the vibration via the current lead to the superconducting coil connected to the low temperature end is suppressed.

  For example, when the superconducting magnet apparatus is used in an NMR apparatus, specifically, the flexible conductor portion includes a main peak signal corresponding to an analysis target substance detected when an analysis is performed in the NMR apparatus, and this It has a length dimension such that the height ratio of the peak signal of the sideband appearing on one side or both sides of the main peak signal is less than 0.10.

  In the superconducting magnet apparatus according to the present invention, the heat retaining container includes a container main body that accommodates the cooling container, and a tubular portion that extends in a direction from the container main body toward the refrigeration apparatus and communicates with the inside of the container main body. The flexible conductor portion is preferably disposed in the tubular portion in a posture in which the longitudinal direction is along the direction in which the tubular portion extends.

  As described above, the heat insulating container is constituted by the container main body and the tubular portion, so that the heat insulating container is accommodated therein, and the flexible conductor portion extending from the cooling container side toward the refrigeration apparatus. It is possible to make the shape conforming to the shape of the heat insulating container, and the flexible conductor portion is accommodated in the heat insulating container in a vacuum heat insulating state to achieve heat insulation of the flexible conductor portion and avoidance of frost adhesion. An increase in size can be prevented.

  The tubular portion extends from the container body, communicates with the interior of the container body, and accommodates the flexible conductor portion therein so that the high temperature end protrudes from the distal end surface. A cover portion that surrounds the periphery of the high-temperature end protruding from the tubular portion main body and the refrigeration apparatus connected to the high-temperature end together with the tip end surface in an airtight state, and the cover portion is attached to and detached from the tubular portion main body It is preferable to be able to attach.

  According to such a configuration, since the cover portion can be removed, maintenance work of the refrigeration apparatus is facilitated.

  In this superconducting magnet device, the inside of the heat insulation container is in a vacuum state (vacuum heat insulation state) in order to avoid heat insulation and adhesion of frost, but by the internal space of the container body and the tubular part body, the tip surface and the cover part. Since the enclosed space is an independent space, the refrigeration apparatus can be exposed to the outside while maintaining the vacuum insulation state in the container body by removing the cover. For this reason, it is possible to perform maintenance of the refrigeration apparatus while keeping the cooling container warm.

  In addition, it is possible to shorten the work time for placing the surroundings of the refrigeration apparatus in a vacuum insulation state after maintenance of the refrigeration apparatus. That is, compared to the case where the entire space in the heat insulation container is in a vacuum heat insulation state, only in the space surrounded by the cover portion and the distal end surface of the tubular portion main body is in a vacuum heat insulation state as in the superconducting magnet device. This can shorten the time for exhaust work and the like.

  The current lead portion has a superconducting conductor portion made of an oxide-based superconducting material that becomes a superconducting state when it becomes a predetermined temperature or less, and the flexible conductor portion and the superconducting conductor portion are arranged in parallel with each other, It extends from the cooling container toward the refrigeration apparatus, and is superposed on each other in a direction perpendicular to the longitudinal direction, and joined so as to be electrically connected to each other at an arbitrary position within the superposed region. preferable.

  According to such a configuration, the superconducting conductor is cooled by the refrigeration apparatus and the temperature in the heat insulation container to be in a superconducting state, thereby generating heat due to the internal resistance when supplying current from the external power source to the superconducting coil through the current lead. As a result, heat penetration through the current lead can be more effectively suppressed. In addition, even when the temperature of a part of the superconducting conductor portion rises and becomes a normal conducting state, the flexible conductor portion that is superposed on the region and can be conducted allows the current to flow with low resistance. Therefore, this current lead can provide a current path with the lowest resistance in the cooling state regardless of the cooling state of the superconducting conductor portion.

  Further, in order to solve the above problems, the present invention provides a vacuum heat insulating layer formed between the superconducting coil, a cooling container for accommodating and cooling the superconducting coil, and the cooling container. A current lead used in a superconducting magnet device comprising a heat retaining container that houses the cooling container therein and a refrigeration device disposed at a position away from the cooling container, the current lead being disposed in the heat retaining container and A flexible conductor made of conductive metal, the flexible conductor extending from the cooling container toward the refrigeration apparatus, and being connected to the superconducting coil at the end of the cooling container; It has a low temperature end and an end on the refrigeration apparatus side, and has a high temperature end to which the refrigeration apparatus is connected and cooled, and to which the power supply is connected, and so as to absorb vibration generated in the refrigeration apparatus Deflection change It has a length dimension as possible.

  When such a current lead is used in the superconducting magnet device, the current lead is cooled by the refrigeration apparatus, thereby preventing heat from entering from the outside through the current lead and extending in a specific direction. When the part absorbs the vibration generated in the refrigeration device, the vibration generated by the refrigeration device is effectively suppressed from being transmitted to the superconducting coil.

  For example, when a superconducting magnet device in which the current lead is used is used in an NMR apparatus, specifically, the flexible conductor portion is a main corresponding to an analysis target substance detected when analysis is performed in the NMR apparatus. It has a length dimension such that the height ratio of the peak signal and the peak signal of the sideband appearing on one side or both sides of the main peak signal is less than 0.10.

  As described above, according to the present invention, a superconducting magnet apparatus having a refrigeration apparatus for cooling a current lead, in which vibration generated in the refrigeration apparatus is difficult to be transmitted to the superconducting coil, and a current lead used in the apparatus. Can be provided.

It is a cross-sectional front view which is the superconducting magnet apparatus for NMR which concerns on this embodiment, and shows the whole structure in the state to which the current cable from an external power supply was connected. It is a figure which shows the structure of the current lead of the said superconducting magnet apparatus. It is a figure for demonstrating the main peak signal and sideband peak signal which were detected by the said NMR apparatus. It is a longitudinal cross-sectional view which shows the principal part of the current lead which concerns on other embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  In the present embodiment, an NMR apparatus (nuclear magnetic resonance apparatus) 10 is shown as a specific example of the superconducting magnet apparatus according to the present invention, but the use of the superconducting magnet apparatus according to the present invention is not limited.

  As shown in FIG. 1, the NMR apparatus 10 includes a superconducting coil 12, a cooling tank (cooling container) 14 for accommodating and cooling the superconducting coil 12, and a plurality of (main book) surrounding the cooling tank 14. Two heat shields 16 and 18 in the embodiment, a vacuum chamber (heat-retaining container) 20 that houses each of these components 12, 14, 16, and 28, a current lead 30, and the current lead 30 And a refrigeration apparatus 40 for cooling the apparatus.

  The superconducting coil 12 is a so-called solenoid coil in which a superconducting wire is wound in a hollow cylindrical shape, and the cooling tank 14, the heat shields 16 and 18, and the vacuum tank 20 are also vertically moved according to this shape. It is formed in a cylindrical shape surrounding the central sample space 11 that extends.

  The cooling tank 14 accommodates the superconducting coil 12 and a refrigerant (for example, liquid helium) 13 that cools the superconducting coil 12, and cools the superconducting coil 12 to a superconducting state. Specifically, the superconducting coil 12 is disposed inside the cooling tank 14, and a sufficient amount of refrigerant (for example, liquid helium) 13 is accommodated in which the superconducting coil 12 is immersed.

  The plurality of heat shields 16 and 18 include a first heat shield (for example, 40K shield) 16 disposed on the outside of the cooling bath 14 and a second heat shield (for example, disposed on the outside of the first heat shield 16). For example, 77K shield tank) 18. Each of the heat shields 16 and 18 is cooled by a refrigeration apparatus (not shown) (for example, the first heat shield 16 is cooled to 40K, the second heat shield 18 is cooled to 77K), and the inside (cooling tank). 14 side).

  The vacuum tank 20 accommodates the cooling tank 14 therein so that the vacuum heat insulating layer 19 is formed between the vacuum tank 20. The vacuum heat insulating layer 19 of the present embodiment is formed between the second heat shield 18 and the vacuum chamber 20 by evacuating the interior of the vacuum chamber 20 by a vacuum pump (not shown) connected to the vacuum chamber 20. It is formed. The vacuum heat insulating layer 19 is also formed between the first heat shield 16 and the second heat shield 18 and between the cooling bath 14 and the first heat shield 16. The vacuum chamber 20 includes a tank body (container body) 21 that houses the cooling tank 14 and the heat shields 16 and 18, and a tubular portion 22 that extends from the tank body 21 toward the refrigeration apparatus 40. The tank body 21 has a shape corresponding to the second heat shield 18 or the like, that is, a cylindrical shape surrounding the sample space 11. And the tank main body 21 has the liquid nitrogen tank 24 in which the liquid nitrogen 23 is accommodated while surrounding the shield 18 in the circumferential direction at a position spaced from the second heat shield 18 in the radial direction. That is, the tank body 21 has the liquid nitrogen tank 24 on the side wall (circumferential wall) 25 surrounding the second heat shield 18 from the outside.

  The tubular portion 22 extends upward from the top wall 26 of the tank body 21, and the inside thereof communicates with the tank body 21. For this reason, the inside of the tubular portion 22 is also in a vacuum heat insulating state. Specifically, the tubular part 22 includes a tubular part main body 27 and a cover part 28.

  The tubular portion body 27 extends from the tank body 21 and communicates with the inside of the tank body 21. The tubular portion main body 27 accommodates the current lead 30 therein so that the end portion of the current lead 30 (the high temperature end 34b of the bus bar (flexible conductor portion) 34) protrudes from the tip end surface 27a. Thereby, the current lead 30 is located in the vacuum heat insulating layer 19, and it is possible to prevent heat from entering from outside and adhesion of frost.

  The cover portion 28 surrounds the periphery of the high temperature end 34b protruding from the tubular portion main body 27 and the refrigeration apparatus 40 connected thereto in an airtight state together with the distal end surface 27a. The cover portion 28 is detachably attached to the tubular portion main body 27. A vacuum pump (not shown) is connected to the cover portion 28, and the space surrounded by the cover portion 28 and the distal end surface 27a can be evacuated independently of the inside of the tank body 21. By connecting the vacuum pump in this manner, the surroundings of the high temperature end 34b and the refrigeration apparatus 40 can be in a vacuum insulation state, and heat penetration and frost adhesion to the high temperature end 34b and the refrigeration apparatus 40 can be prevented. Can do.

  As shown in FIG. 2, the current lead 30 connects the superconducting coil 12 and an unillustrated power source (external power source) outside the vacuum chamber 20. In this embodiment, a pair of current leads 30 are arranged, and a direct current is supplied to the superconducting coil by the external power source. Each current lead 30 has a lead body 32 extending from the first heat shield 16 toward the refrigeration apparatus 40, and a lead wire 33 connecting the lead body 32 and the superconducting coil 12.

  The lead main body 32 includes a bus bar (flexible conductor portion) 34 and a heat insulating portion 35 disposed between the bus bar 34 and the first heat shield 16.

The bus bar 34 absorbs the vibration generated by the driving of the refrigeration apparatus 40, thereby suppressing the vibration from being transmitted to the superconducting coil 12 through the current lead 30. The bus bar 34 is disposed in the vacuum chamber 20 and is made of a conductive metal. The bus bar 34 of this embodiment is formed of copper or a copper-based alloy. Specifically, the bus bar 34 extends from the vicinity of the first heat shield 16 toward the refrigeration apparatus 40, and the low-temperature end 34 a and the refrigeration apparatus 40 that are ends on the first heat shield 16 side (cooling tank 14 side). It has a high temperature end 34b which is an end on the side. That is, the bus bar 34 of the present embodiment extends in the vertical direction, and the lower end forms a low temperature end 34a and the upper end forms a high temperature end 34b. The superconducting coil 12 is connected to the low temperature end 34 a via a heat insulating part 35 and a lead wire 33. On the other hand, the refrigeration apparatus 40 is connected to the high temperature end 34 b and the external power source is connected via a current cable (electric wire) 50. The bus bar 34 has a length dimension that can be bent and deformed so as to absorb vibration generated in the refrigeration apparatus 40. Specifically, the bus bar 34 has a main peak signal S ₁ corresponding to the substance to be analyzed as shown in FIG. 3 detected when the NMR apparatus 10 performs analysis, and one or both sides of the main peak signal S _1. The length ratio S ₂ / S ₁ with the sideband peak signal S ₂ appearing in FIG. For example, the bus bar 34 of the present embodiment has a rectangular cross-sectional shape in which the thickness dimension (dimension in the direction perpendicular to the paper surface in FIG. 2) is 1/5 with respect to the width dimension (dimension in the left-right direction in FIG. 2). , And a length dimension (dimension in the vertical direction in FIG. 2) that is 50 times the width dimension. Here, the main peak signal S ₁ is a peak (absorption line) of a spectrum obtained at a frequency position corresponding to the analysis target substance when the NMR signal of the analysis target substance is measured by the NMR apparatus 10. The sideband peak signal S ₂ is a spectrum peak that appears at a frequency position close to the main peak signal S ₁ when the NMR signal of the substance to be analyzed is measured by the NMR apparatus 10. This is a noise component caused by vibration transmitted from the refrigeration apparatus 40 for cooling 30 to the superconducting coil 12. When the sideband peak signal S ₂ is larger than the main peak signal S ₁ , specifically, the height ratio S ₂ / S ₁ between the main peak signal S ₁ and the sideband peak signal S ₂ is If it is 0.10 or more, it becomes difficult to identify the molecular structure of the substance to be analyzed.

The bus bar 34 is not limited to this shape (tape shape with a rectangular cross section), and may be a solid cylindrical shape or the like. In other words, bus bar 34 is a length dimension (preferably that can be flexibly deformed so as to absorb the vibrations caused refrigerating apparatus 40, the height ratio of the peak signal S ₂ of the main peak signals S ₁ and the side band 0 It is sufficient that the length dimension is less than 10).

  Such a bus bar 34 is attached by connecting the heat insulating portion 35 to the low temperature end 34 a and fixing the heat insulating portion 35 to the first heat shield 16. Thereby, the bus bar 34 is in a posture in which the longitudinal direction is along the direction in which the tubular portion 22 extends. At this time, the high temperature end 34 b protrudes from the distal end surface 27 a of the tubular portion main body 27. The bus bar 34 penetrates the top wall 18 a of the second heat shield 18.

  The heat insulating part 35 has a superconducting bulk 36 made of an oxide-based superconducting material and an electrode 37 made of a conductive material, and heat from the bus bar 34 is on the cooling tank 14 side (in this embodiment, the first heat shield). 16) is prevented from being transmitted. The superconducting bulk 36 of the present embodiment is made of a Y-based oxide superconducting material and has dimensions of a width of 30 mm, a thickness of 8 mm, and a length of 70 mm. The superconducting bulk 36 is coated with solder containing silver. The electrode 37 is made of copper and has dimensions of 30 mm in width, 2 mm in thickness, and 30 mm in length. The electrode 37 is also coated with solder containing silver. In the thermal insulation part 35, electrodes 37 are connected to the upper end part and the lower end part of the superconducting bulk 36, respectively. Further, the lower end (low temperature end) 34 a of the bus bar 34 is connected to the electrode 37 on the upper end side.

  The lower end of the lead main body 32 configured as described above is fixed to the top wall 16a of the first heat shield 16 by the fixing member 38 made of aluminum nitride. The fixing member 38 is not limited to aluminum nitride, and may be any member that has electrical insulation and high thermal conductivity.

  The heat insulating portion 35 is located between the first heat shield 16 and the second heat shield 18 in a state where the heat insulating portion 35 is fixed to the first heat shield 16 by the fixing member 38. In the present embodiment, since the first heat shield 16 is a 40K shield and the second heat shield 18 is a 77K shield, the superconducting bulk 36 of the heat insulating portion 35 located therebetween is cooled to a very low temperature. In a superconducting state. In this state, the heat insulating portion 35 prevents the heat from entering from the bus bar 34 to the cooling tank 14 side, but allows the passage of current.

  The refrigeration apparatus 40 is disposed at a position away from the cooling tank 14 and cools the current lead 30. The refrigeration apparatus 40 of this embodiment is a pulse tube refrigerator, and is disposed above the cooling tank 14. The refrigeration apparatus 40 is connected to the upper end of the lead body 32 (the high temperature end 34 b of the bus bar 34) via the thermal anchor 42 and the insulating portion 44. The thermal anchor 42 of the present embodiment is a copper flat knitted wire, and one end is connected to the first stage cooling stage of the refrigeration apparatus 40 and the other end is connected to the high temperature end 34 b via the insulating portion 44. The insulating portion 44 has electrical insulation and high thermal conductivity. Insulating part 44 of this embodiment consists of aluminum nitride.

  In the present embodiment, when the refrigeration apparatus 40 cools the high temperature end 34b to, for example, 82K, the high temperature end of the heat insulating portion 35 of the lead main body 32 (connection portion with the low temperature end 34a of the bus bar 34) becomes 63K. At this time, the temperature of the low-temperature end (end portion on the cooling tank 14 side) of the heat insulating portion 35 is 41K.

  According to the NMR apparatus 10 described above, the bus bar 34 extending in a specific direction is generated in the refrigeration apparatus 40 while suppressing heat intrusion from the outside through the current lead 30 by cooling the current lead 30 by the refrigeration apparatus 40. By absorbing this, it is possible to effectively suppress the vibration generated by the refrigeration apparatus 40 from being transmitted to the superconducting coil 12 through the current lead 30.

  Specifically, in the NMR apparatus 10, the high-temperature end 34 b of the bus bar 34 is cooled by the refrigeration apparatus 40, so that the high-temperature end 34 b near the space outside the vacuum chamber 20 that is normal temperature and the cryogenic cooling tank 14. The thermal gradient in the bus bar 34 between the low temperature end 34a at a close position is suppressed. This effectively suppresses heat from entering the current lead 30 from the high temperature end 34b. That is, the current cable 50 or the like for connecting the external power source and the current lead 30 is disposed in a normal temperature atmosphere and has a higher temperature than that in the vacuum chamber 20, but the temperature gradient of the current lead 30 (bus bar 34) by the refrigeration apparatus 40. By reducing the current, it is possible to effectively prevent the heat of the current cable 50 or the like from entering the current lead 30 through the high temperature end 34b to which the current cable 50 or the like is connected. In addition, since the current lead 30 is cooled, heat generated by the electric resistance of the current lead 30 itself can be suitably suppressed. Furthermore, since the bus bar 34 made of metal has a predetermined length, vibrations from the refrigeration apparatus 40 connected to the high temperature end 34b can be absorbed by the bending of the bus bar 34 itself, thereby the vibrations. Becomes difficult to reach the low temperature end 34a. As a result, transmission of the vibration via the current lead 30 to the superconducting coil 12 connected to the low temperature end 34a is suppressed.

  Further, as in the NMR apparatus 10 of the present embodiment, the vacuum tank 20 is constituted by the tank body 21 and the tubular portion 22, so that the vacuum tank 20 can be refrigerated from the cooling tank 14 and the vicinity of the cooling tank 14. It is possible to make the shape in accordance with the shape of the current lead 30 (bus bar 34) extending toward 40. For this reason, in the NMR apparatus 10, the bus bar 34 is accommodated in the vacuum chamber 20 in a vacuum insulation state, and the vacuum chamber 20 can be prevented from being enlarged while achieving insulation of the bus bar 34 and avoidance of frost adhesion. It becomes possible.

  In addition, since the tubular portion 22 includes the tubular portion main body 27 and the cover portion 28 that is detachably attached to the tubular portion main body 27, maintenance work of the refrigeration apparatus 40 is facilitated.

  Specifically, in this NMR apparatus 10, the inside of the vacuum chamber 20 is in a vacuum heat insulation state in order to avoid heat insulation and adhesion of frost, but the internal space of the tank body 21 and the tubular part body 27, and the tubular part body 27 The space surrounded by the tip surface 27a and the cover portion 28 is an independent space. For this reason, the refrigeration apparatus 40 can be exposed to the outside while the vacuum state in the tank body 21 is maintained by removing the cover portion 28. As a result, it is possible to perform maintenance of the refrigeration apparatus 40 while keeping the cooling tank 14 warm.

  In addition, it is possible to shorten the work time for bringing the surroundings of the refrigeration apparatus 40 into a vacuum insulation state after the maintenance of the refrigeration apparatus 40. That is, as compared with the case where the entire space in the vacuum chamber 20 is in a vacuum insulation state, only the inside of the space surrounded by the cover portion 28 and the distal end surface 27a of the tubular portion main body 27 as in the NMR apparatus 10 is in a vacuum insulation state. In the case of making it, it is possible to shorten the time for exhaust work and the like.

  The superconducting magnet device of the present invention and the current lead used in the device are not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the scope of the present invention.

  For example, the heat insulating part 35 is not essential in the lead body 32, and the low temperature end 34 a of the bus bar 34 may be fixed to the heat shields 16, 18 and the cooling bath 14.

  Moreover, in the lead main body 32 of the said embodiment, although the site | part which absorbs the vibration which generate | occur | produced in the freezing apparatus 40 is comprised only by the bus bar 34, it is not limited to this. For example, as shown in FIG. 4, the portion that absorbs the vibration may include a bus bar 34 and a superconducting conductor (superconducting conductor portion) 52. The superconducting conductor 52 is made of an oxide-based superconducting material. This oxide-based superconducting material can be brought into a superconducting state by being cooled to a predetermined temperature (transition temperature) or lower by the temperature in the vacuum chamber 20 and cooling by the refrigeration apparatus 40. For example, a Bi-based high temperature superconducting material or a Y-based high temperature superconducting material having a transition temperature of 90 K or higher is suitable. In the example shown in FIG. 4, the superconducting conductor 52 has a sheet shape thinner than the bus bar 34 and is superimposed on the bus bar 34 in the thickness direction. Specifically, the superconducting conductor 52 is overlapped with the bus bar 34 over the entire length of the bus bar 34 and fixed by soldering. That is, the bus bar 34 and the superconducting conductor 52 are arranged in parallel to each other, extend along the tubular portion 22, and overlap each other in a direction orthogonal to the longitudinal direction, and at an arbitrary position in the overlapping region. They are joined so that they can conduct each other.

  According to this configuration, the superconducting conductor 52 is cooled by the refrigeration apparatus 40 and the temperature in the vacuum chamber 20 and becomes a superconducting state below the transition temperature, whereby a current is supplied from the external power source to the superconducting coil 12 through the current lead 30. Heat generation due to the internal resistance of the current lead 30 when supplying the current can be suppressed. As a result, even though the bus bar 34 is long and made of a material having a relatively high internal resistance for absorbing the vibration, heat penetration through the current lead 30 can be more effectively suppressed. In addition, even if the temperature of a part of the superconducting conductor 52 rises to become a normal conducting state, the bus bar 34 that is superposed on the normal conducting state and can be conducted is allowed to flow with a low resistance. To do. Therefore, the current lead 30 can provide a current path having the lowest resistance in the cooling state regardless of the cooling state of the superconducting conductor 52.

  In the superconducting magnet device 10 of the above embodiment, each component (superconducting coil 12, cooling tank 14, heat shields 16, 18, and vacuum tank 20 etc.) is configured such that the sample space 11 extends vertically. The constituent elements may be configured such that the sample space extends from side to side.

  The superconducting magnet device 10 of the above embodiment is configured so that the superconducting coil 12 is cooled by a refrigerant (liquid helium in this embodiment) 13 but is cooled by a refrigeration apparatus or the like without using the refrigerant 13. Also good.

  Here, in order to evaluate whether the vibration generated in the refrigeration apparatus 40 in the NMR apparatus (superconducting magnet apparatus) 10 of the above embodiment is transmitted to the superconducting coil 12 through the current lead 30, the NMR apparatus of the above embodiment. 10 and the lead main body is not provided with a bus bar (that is, a configuration in which the current cable 50 and the refrigeration apparatus 40 are connected to the thermal insulation unit 35), and has the same configuration as the NMR apparatus 10 of the above embodiment. The NMR signal of the hydrogen nuclei of the pure sample was measured with an NMR apparatus (first comparative NMR apparatus). In Example 1, the bus bar 34 having a width of 10 mm, a thickness of 2 mm, and a length of 500 mm was used in the NMR apparatus of the above embodiment.

  A 220 A direct current is supplied from an external power source to each NMR apparatus (the NMR apparatus 10 of the above embodiment and the first comparative NMR apparatus), whereby a 18.8 T magnetic field (this magnetic field) is supplied to each NMR apparatus. The resonance frequency of the hydrogen nucleus in is 800 MHz.). The magnetic field homogeneity was adjusted in each NMR apparatus, and the NMR signal of the hydrogen nuclei of the pure sample was measured.

In the NMR signal detected by the NMR apparatus 10 of the above embodiment, the ratio S ₁ / S ₂ of the height of the sideband peak signal S _{2 to} the main peak signal S ₁ of 800 MHz was 0.082. Thus, in the NMR apparatus 10 of the above-described embodiment, the height ratio S ₁ / S ₂ could be suppressed to less than 0.10, which becomes an obstacle to the molecular structure identification of the sample.

On the other hand, the detected NMR signal in NMR apparatus for the first comparison, the main peak signals _{S 1} and the side ratio of the height of the peak signal _{S 2} of the band _S 1 / _{S 2} is 0.34, sideband peak signal S ₂ of which is an obstacle of the molecular structure identification.

As described above, vibrations generated by the refrigeration system 40 is the peak signal S ₂ of the side bands caused by being transmitted to the superconducting coil 12 is suitably suppressed in the NMR apparatus 10 of the above embodiment. From this, it is possible to effectively suppress the vibration of the refrigeration apparatus 40 from being transmitted to the superconducting coil 12 by providing the current lead 30 with the bus bar (flexible conductor portion having a predetermined length) 34 of the above-described embodiment. I was able to confirm.

  Moreover, the NMR signal of the hydrogen nucleus of a pure sample was measured with the NMR apparatus (2nd comparative NMR apparatus) of the same structure as the NMR apparatus 10 of the said embodiment except the length of a bus bar being 400 mm.

  As in Example 1 above, a 220 A direct current was supplied from an external power source to the second comparative NMR apparatus, and in the second comparative NMR apparatus, a 18.8 T magnetic field (resonance frequency of hydrogen nuclei in this magnetic field). Is 800 MHz). Then, the magnetic field uniformity was adjusted, and the NMR signal of the hydrogen nucleus of the pure sample was measured.

In the NMR signal detected by the second comparative NMR apparatus, the ratio S ₁ / S ₂ of the height of the sideband peak signal S _{2 to} the main peak signal S ₁ of 800 MHz is 0.15, peak signal S ₂ is an obstacle to molecular structure identification.

As described above, if the shape of the bus bar (cross-section) is the same, by increasing the length of the bus bar, it was confirmed that it is possible to further suppress the peak signal S ₂ of the side bands.

10 NMR device (superconducting magnet device)
12 Superconducting coil 14 Cooling tank (cooling vessel)
19 Vacuum insulation layer 20 Vacuum chamber (heat insulation container)
21 Tank body (container body)
22 Tubular portion 27 Tubular portion body 27a Tip surface 28 Cover portion 30 Current lead 34 Bus bar (flexible conductor portion)
34a Low temperature end 34b High temperature end 40 Refrigeration apparatus S ₁ Main peak signal S ₂ Sideband peak signal

Claims (7)

A superconducting magnet device,
A superconducting coil;
A cooling vessel for accommodating the superconducting coil and cooling it;
A heat retaining container for accommodating the cooling container therein so that a vacuum heat insulating layer is formed between the cooling container, and
A refrigeration apparatus disposed at a position away from the cooling container;
A current lead for connecting the superconducting coil and a power supply outside the heat insulation container;
The current lead has a flexible conductor portion made of a conductive metal and disposed in the heat insulation container, and the flexible conductor portion extends from the cooling container toward the refrigeration apparatus, and the cooling container A low temperature end to which the superconducting coil is connected, and a high temperature end to which the refrigerating apparatus is connected and cooled while being connected to the power source. And the superconducting magnet apparatus which has a length dimension which can bend and deform | transform so that the vibration which arose in the said freezing apparatus may be absorbed. The superconducting magnet device according to claim 1,
The superconducting magnet device is used for an NMR device,
The flexible conductor portion includes a main peak signal corresponding to a substance to be detected that is detected when analysis is performed in the NMR apparatus, and a sideband peak signal that appears on one side or both sides of the main peak signal. A superconducting magnet device having a length dimension such that the thickness ratio is less than 0.10. The superconducting magnet device according to claim 1 or 2,
The heat retaining container includes a container main body that houses the cooling container, and a tubular portion that extends in a direction from the container main body toward the refrigeration apparatus and communicates with the inside of the container main body.
The flexible conductor portion is a superconducting magnet device that is disposed in the tubular portion in a posture in which a longitudinal direction thereof extends along a direction in which the tubular portion extends. The superconducting magnet device according to claim 3,
The tubular portion extends from the container body, communicates with the interior of the container body, and accommodates the flexible conductor portion therein so that the high temperature end protrudes from the distal end surface. A cover portion that surrounds the periphery of the high temperature end protruding from the tubular portion main body and the refrigeration apparatus connected thereto in an airtight state together with the tip end surface,
The cover part is a superconducting magnet device that is detachably attached to the tubular part body. The superconducting magnet device according to any one of claims 1 to 4,
The current lead portion has a superconducting conductor portion made of an oxide-based superconducting material that becomes a superconducting state when it becomes a predetermined temperature or lower,
The flexible conductor portion and the superconducting conductor portion are arranged in parallel to each other, extend from the cooling container toward the refrigeration apparatus, and are overlapped with each other in a direction perpendicular to the longitudinal direction thereof. Superconducting magnet device joined so as to be able to conduct each other at any position. A superconducting coil, a cooling container for accommodating and cooling the superconducting coil, and a heat retaining container for accommodating the cooling container therein so that a vacuum heat insulating layer is formed between the cooling container, A current lead used in a superconducting magnet device comprising a refrigeration device disposed at a position away from the cooling container,
There is a flexible conductor portion made of a conductive metal disposed in the heat insulation container, and the flexible conductor portion extends from the cooling container toward the refrigeration apparatus and is an end portion on the cooling container side. A refrigeration apparatus having a low temperature end to which the superconducting coil is connected and an end on the refrigeration apparatus side that is connected to the refrigeration apparatus to be cooled and connected to the power supply. A current lead having a length that can be bent and deformed so as to absorb the vibration generated in step 1. The current lead according to claim 6,
The superconducting magnet device in which the current lead is used is used in an NMR device,
The flexible conductor portion includes a main peak signal corresponding to a substance to be detected that is detected when analysis is performed in the NMR apparatus, and a sideband peak signal that appears on one side or both sides of the main peak signal. A current lead having a length dimension such that the thickness ratio is less than 0.10.

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