JP2007005440A - Superconducting magnet device and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting magnet device capable of supplying to a sample a current exceeding an output current capacity of power supply equipment while reducing heat intrusion from room temperature. <P>SOLUTION: The superconducting magnet device comprises a primary side superconducting coil 1b, a first low temperature container 1a for accommodating the primary side superconducting coil 1b, a secondary side superconducting coil 2a magnetically coupled to the primary side superconducting coil 1b, and a second low temperature container 5 for accommodating the secondary side superconducting coil 2a. The primary side superconducting coil 1b and the secondary side superconducting coil 2a can be controlled to another temperature. The secondary side superconducting coil 2a is constructed by permitting a plurality of secondary coils to be connected in parallel. To the secondary side superconducting coil 2a there is electrically connected a superconducting conductor sample 4 controllable to another temperature from the primary side superconducting coil 1b and the secondary side superconducting coil 2a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a superconducting magnet device including a secondary superconducting coil that is magnetically coupled to a primary superconducting magnet and a method for operating the superconducting magnet device, and particularly to high efficiency of a large current capacity conductor used in a superconducting energy storage system or the like. The present invention relates to a technique suitable for evaluating a large current.

  For example, an apparatus disclosed in Patent Document 1 is known as a current-carrying characteristic measuring apparatus for a superconducting material.

  FIG. 10 is an example showing a basic configuration example of a conventional apparatus for energizing a superconducting conductor to observe voltage generation and measure a critical current value. In this configuration example, the superconducting conductor sample 4 is immersed in the refrigerant 6 in the cryogenic vessel 16 and cooled to a cryogenic temperature. A superconducting coil 12 for applying an external magnetic field is also immersed in the refrigerant 6. The superconducting coil 12 for applying an external magnetic field is connected to a magnet excitation power source 13 outside the cryogenic vessel 16 through a magnet current lead 15b. A current lead 15a for supplying current is connected to both ends of the superconducting conductor sample 4, and the current lead 15a is connected to a power source 14 for the superconducting sample through a current introduction terminal at room temperature. As the current lead 15a, a copper alloy such as copper or phosphorus deoxidized copper is usually used.

  As another conventional example, a superconducting conductor sample may be subjected to a test after being conductively cooled by a cryogenic small refrigerator.

  Normally, the current lead is designed so that its length and cross-sectional area are optimized so as not to increase the heat load on the cryogenic part, but depending on the conditions of heat exchange with the refrigerant evaporative gas, a heat intrusion close to 50 mW per 1A may occur. If a large current needs to be applied to the sample, the cross-sectional area of the current lead is designed to be large in proportion to the current value. Further, in order to measure the magnetic field dependence of the superconducting characteristics of the conductor sample, it is necessary to apply an external magnetic field to the sample by the superconducting coil 12, and the same low-temperature vessel 16 for applying an external magnetic field as shown in the configuration example of FIG. The current lead 15b for exciting the superconducting coil is provided.

On the other hand, FIG. 11 shows a conventional apparatus in which a test superconducting conductor sample 4 and a secondary superconducting coil 17 are installed inside a primary superconducting coil 1b of an external magnetic field applying superconducting magnet and current is supplied by electromagnetic induction. This is an example showing the basic configuration of. In this configuration, the superconducting coil 1 b for applying an external magnetic field, the secondary superconducting coil 17, and the test superconducting conductor sample 4 are installed in the same low temperature container 16.
JP 2003-149278 A

  When current is supplied to the superconducting conductor sample from the outside via a current lead as in the conventional configuration example, the refrigerant evaporates due to heat penetration. Further, a heat load is generated on the cryogenic temperature portion from the current lead that supplies current to the superconducting coil for applying the external magnetic field. As a result, the time during which the energization test can be performed is limited because the liquid level of the refrigerant decreases. On the other hand, the current value that can be supplied to the sample is limited by the current capacity of the external power supply, and the conventional method cannot evaluate a conductor sample having a critical current value that exceeds the output current value of the power supply equipment that it possesses.

  In the case of supplying current by electromagnetic induction using a superconducting magnet for applying an external magnetic field, the test sample and the superconducting magnet for applying a magnetic field are stored in the same low temperature container in the conventional example. In addition, it takes time to cool and raise the temperature of the superconducting magnet for applying a magnetic field.

  The present invention has been made in view of the above problems, and provides a superconducting magnet device capable of energizing a sample with a current value equal to or greater than the output current capacity of a power supply facility while reducing heat intrusion from room temperature, and an operating method thereof. The purpose is to do.

  In order to achieve the above object, a superconducting magnet device according to the present invention includes a primary superconducting coil, a first low-temperature container that accommodates the primary superconducting coil, and a magnetic coupling to the primary superconducting coil. A secondary superconducting coil and a second low-temperature container that accommodates the secondary superconducting coil so that the primary superconducting coil and the secondary superconducting coil can be controlled to different temperatures. It is comprised by these.

  The superconducting magnet apparatus operating method according to the present invention is an operating method of a superconducting magnet apparatus having a primary superconducting coil and a secondary superconducting coil magnetically coupled to the primary superconducting coil. The temperature of the primary side superconducting coil and the temperature of the secondary side superconducting coil are separately controlled.

  ADVANTAGE OF THE INVENTION According to this invention, the structure which enables the electric current value more than the output current capacity | capacitance of a power supply installation to be able to energize a sample can be implement | achieved, reducing the heat penetration | invasion from room temperature.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to the following embodiment, It can deform | transform suitably and implement in the range which does not change the summary. In the following description, parts common to those of the prior art, or parts that are the same or similar to each other, are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a longitudinal sectional view showing a first embodiment of a superconducting magnet apparatus according to the present invention, in which a secondary superconducting coil and a superconducting conductor sample are immersed and cooled in a same secondary side cryocontainer with a refrigerant and tested. Show the case.

  A secondary side superconducting coil 2a having a vertical axis is accommodated in a cylindrical secondary cryogenic vessel 5 having a vertical axis. The secondary superconducting coil 2a has a plurality of (for example, four) coils arranged along the vertical axis. The current introduction terminal 2b of the secondary superconducting coil 2a is arranged inside the coil, and these are connected in parallel to the lead wire 20 at the connection portion 18a. This lead wire 20 is connected to a superconducting conductor sample (superconducting load) 4 disposed above the secondary superconducting coil 2a at a connecting portion 18b. A liquid refrigerant 6 is stored in the secondary-side cryocontainer 5, and the secondary-side superconducting coil 2 a, current introduction terminal 2 b, superconducting conductor sample 4, and lead wire 20 are immersed in the refrigerant 6.

  An annular primary superconducting magnet 1 is disposed so as to surround the periphery of the secondary cryogenic vessel 5, and the secondary superconducting coil 2 a is disposed in a bore 1 d that is an inner space of the annular primary magnet 1. Become a relationship. The primary superconducting magnet 1 has a primary superconducting coil 1b accommodated in an annular primary cryogenic container 1a. The primary superconducting coil 1b is disposed opposite to the secondary superconducting coil 2a so as to be magnetically coupled to the secondary superconducting coil 2a, and is electrically connected to the power supply 3 for the primary superconducting magnet. ing. The primary superconducting coil 1b is thermally connected to the primary magnet cryogenic refrigerator 1c by a solid heat conductor.

  In this embodiment, the secondary circuit has a plurality of parallel superconducting coils and supplies current to the superconducting conductor sample 4. Since the secondary side circuit has a plurality of coils, it is possible to supply the superconducting conductor sample with several times the number of superconducting conductors around which the secondary side coil is wound.

  Further, when the magnetic field of the primary superconducting magnet 1 is applied to the secondary side which is a parallel circuit, current drift may occur due to the geometric positional relationship between the circuits. Is independent, the relative position of the coils can be moved, and adjustment can be made such that current drift is suppressed. The secondary side superconducting coil 2a may be arranged in such a way that four coils of the same size may be arranged as shown in FIG. 2, but the distance from the equator plane 30 of the primary side superconducting coil as shown in FIG. 3 or FIG. Accordingly, the number of turns of the secondary coil 2a can be changed to make a design in which drift does not easily occur. Generally, it is preferable to arrange the secondary superconducting coil 2a symmetrically with respect to the equator plane 30 of the primary superconducting magnet. Here, the “equatorial plane” is a plane perpendicular to the axial direction at a height that is half the axial height of the annular primary superconducting coil.

  Further, since the position of the superconducting conductor sample 4 inside the secondary-side cryocontainer 5 can be arbitrarily selected within a range not exceeding the liquid level of the refrigerant 6, leakage generated by the primary-side superconducting magnet 1 is possible. It is also possible to observe the magnetic field dependence of the superconducting characteristics of the superconducting conductor sample 4 by applying a magnetic field to the superconducting conductor sample 4.

  That is, the primary superconducting coil 1b not only functions as an induction circuit, but also can provide the superconducting conductor sample 4 with its leakage magnetic field. There are two primary current sweep conditions that determine the peak value of the secondary current value: the sweep speed (di / dt) of the primary current and the flat top value (F / T) of the primary current. is there. Therefore, if di / dt is changed, the same secondary current peak value can be obtained by arbitrarily selecting the F / T value. Since the F / T value corresponds to the magnetic field generated by the primary superconducting coil 1b, the magnetic field dependence of the superconducting conductor sample 4 can be evaluated by repeating the test using the F / T value as a parameter in this apparatus.

  Next, an example of the specifications and test results of the test apparatus that was prototyped for the embodiment shown in FIG.

  The specifications of the test apparatus are as follows. The two secondary superconducting coils A are installed at a position of Z = ± 40 mm with respect to the equator plane (Z = 0) of the primary superconducting magnet. Similarly, the two secondary superconducting coils B are , Z = ± 120 mm.

  (1) For the primary superconducting magnet, the inner diameter was 450 mm, the outer diameter was 517 mm, the shaft length was 266 mm, the winding number was 14997 turns, the rated energization current value was 117 A, the central magnetic field was 4 T, and the inductance was 101 H.

  (2) For the secondary superconducting coil A, the inner diameter was 160 mm, the outer diameter was 260 mm, the shaft length was 25 mm, the number of turns was 54 turns, and the inductance was 0.76 mH.

  (3) For the secondary superconducting coil B, the inner diameter was 122 mm, the outer diameter was 260 mm, the shaft length was 25 mm, the number of turns was 74 turns, and the inductance was 1.1 mH.

  In this configuration, a phosphorus-deoxidized copper piece whose residual resistivity was measured in advance on the secondary side circuit was connected in series, and the voltage value generated at both ends thereof was measured to calibrate the current value induced on the secondary side. Since the resistance value of the circuit is rate-limiting at the peak of the current value induced on the secondary side, the primary side refrigerator conduction cooling superconducting magnet was excited at 0.078 A / sec during the calibration test. The resistance value of the phosphorous deoxidized copper piece for current measurement was designed so that the peak value sometimes became 200 A or less.

  FIG. 5 shows the result of calibrating the secondary current value by immersing and cooling the secondary superconducting coil with liquid helium, exciting the primary-side refrigerator conduction cooling superconducting magnet at 0.078 A / sec. In this figure, the dotted line 19 indicates the primary side current, and the solid line 20 indicates the secondary side current. The current value induced on the secondary side was 172A, which was almost the same as the value obtained by numerical analysis.

  Next, FIG. 6 shows the current peak value of the secondary circuit when the excitation speed of the primary superconducting magnet is changed. The peak value of the secondary current proportional to the sweep speed of the primary magnet was obtained.

  As described above, according to this embodiment, it is possible to realize a structure that allows a sample to be energized with a current value equal to or greater than the output current capacity of the power supply facility while reducing heat intrusion from room temperature. In addition, the use of a conduction-cooled superconducting magnet on the primary side and a separate low-temperature container for the secondary side coil make it possible to vary the sample temperature without any time constraints on the energization test. The superconducting conductor evaluation test can be performed while avoiding the problem that the test is restricted by the evaporation of power and the limit of the power output.

[Second Embodiment]
FIG. 7 is a longitudinal sectional view showing a second embodiment of the superconducting magnet device according to the present invention. In this embodiment, the vacuum heat insulating container 10a is arranged above the liquid level of the refrigerant 6 in the secondary low-temperature container 5, and the superconducting conductor sample 4 is arranged in the vacuum heat insulating container 10a. A heat conducting member 9 is disposed through the vacuum heat insulating container 10 a, and this member 9 is in direct contact with the superconducting conductor sample 4. The cooling stage 8 of the secondary side small refrigerator 7 is disposed above the vacuum heat insulating container 10 a, and the cooling stage 8 is in contact with the heat conducting member 9.

  The secondary superconducting coil 2 a is immersed and cooled by the refrigerant 6. Further, the superconducting conductor sample 4 is installed inside the vacuum heat insulating container 10 a and is cooled by conduction from the cooling stage 8 of the secondary side small refrigerator 7 through the heat conducting member 9. Thereby, the temperature of the superconducting conductor sample 4 can be made higher or lower than the temperature of the refrigerant 6 to measure the superconducting characteristics in various temperature ranges. As a result, the temperature dependence of the superconducting characteristics of the superconducting conductor sample 4 can be measured.

[Third Embodiment]
FIG. 8 is a longitudinal sectional view showing a third embodiment of the superconducting magnet device according to the present invention. In this embodiment, the gas helium container 10b is disposed above the liquid level of the refrigerant 6 in the secondary-side cryogenic container 5, and the superconducting conductor sample 4 is disposed in the gas helium container 10b. The vicinity of the bottom of the secondary-side cryogenic vessel 5 and the gas helium vessel 10b are connected by a communication pipe 32 via a needle valve (throttle valve) 11a. The gas helium container 10b is connected to a vacuum pump (not shown) through a vacuuming pipe 34 via a vacuuming valve (throttle valve) 11b.

  The secondary superconducting coil 2 a is immersed and cooled by the refrigerant 6. On the other hand, the superconducting conductor sample 4 is cooled by helium vapor introduced into the gas helium vessel 10b through the needle valve 11a. The helium gas flow rate is adjusted by adjusting the opening degree of the needle valve 11a and the vacuuming valve 11b, and the superconducting conductor sample 4 can be kept at a predetermined temperature.

  This makes it possible to adjust the temperature of the superconducting conductor sample 4 separately from the temperature of the secondary superconducting coil 1b as in the second embodiment (FIG. 7), and the temperature dependence of the superconducting characteristics. Can be measured.

[Fourth Embodiment]
FIG. 9 is a longitudinal sectional view showing a fourth embodiment of the superconducting magnet device according to the present invention. In this embodiment, a secondary side superconducting coil 2a having a vertical axis is accommodated in a cylindrical vacuum heat insulating container 10a having a vertical axis, and superconducting is performed above the secondary side superconducting coil 2a in the vacuum heat insulating container 10a. A conductor sample 4 is arranged. A secondary side small refrigerator 7 is disposed in the vacuum heat insulating container 10a, and the refrigerator cooling stage 8 is disposed in the vacuum heat insulating container 10a. The refrigerator cooling stage 8 is thermally connected to the secondary side superconducting coil 2 a and the superconducting conductor sample 4 via the heat conducting member 9.

  Here, the secondary superconducting coil 2a is in contact with the heat conducting member 9, but an eddy current may be generated in the heat conducting member 9 due to a magnetic field fluctuation, which may cause heat generation. Therefore, it is preferable to design such that the eddy current loop is cut or a material whose conductivity is selected to a level at which heat generated by the eddy current does not adversely affect the secondary coil is preferable.

It is a typical longitudinal section showing a 1st embodiment of a superconducting magnet device concerning the present invention. It is a typical longitudinal section showing an example of composition of a secondary side coil in a superconducting magnet device concerning the present invention. It is a typical longitudinal cross-sectional view which shows the other structural example of the secondary side coil in the superconducting magnet apparatus which concerns on this invention. It is a typical longitudinal cross-sectional view which shows the further another structural example of the secondary side coil in the superconducting magnet apparatus which concerns on this invention. It is a graph which shows the result of having performed the excitation and the electricity supply test using the apparatus prototyped along 1st Embodiment of the superconducting magnet apparatus which concerns on this invention. It is a graph which shows the electric current value measurement result of the secondary side circuit when the sweep speed of the primary side circuit is changed using the apparatus manufactured as a prototype along the first embodiment of the superconducting magnet apparatus according to the present invention. It is a typical longitudinal section showing a 2nd embodiment of a superconducting magnet device concerning the present invention. It is a typical longitudinal section showing a 3rd embodiment of a superconducting magnet device concerning the present invention. It is a typical longitudinal section showing a 4th embodiment of a superconducting magnet device concerning the present invention. It is a typical longitudinal section showing the basic composition of the conventional superconducting magnet device. It is a typical longitudinal section showing the basic composition of the conventional superconducting magnet device which supplies with electricity by electromagnetic induction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Primary side superconducting magnet, 1a ... Primary side cryocontainer, 1b ... Primary side superconducting coil, 1c ... Cryogenic refrigerator for primary magnet, 1d ... Bore of primary magnet, 2a ... Secondary side superconducting coil 2b ... current introduction terminal of secondary superconducting coil, 3 ... excitation power source for primary superconducting magnet, 4 ... superconducting conductor sample, 5 ... secondary cryogenic container, 6 ... refrigerant, 7 ... small refrigeration for secondary side 8 ... Refrigerator cooling stage, 9 ... Heat conducting member, 10a ... Vacuum heat insulation container (cold container), 10b ... Gas helium container (cold container), 11a ... Needle valve, 11b ... Vacuum evacuation valve, 12 ... External Superconducting coil for magnetic field application, 13 ... Magnet excitation power source, 14 ... Power source for superconducting conductor sample, 15a ... Current lead for sample energization, 15b ... Current lead for magnet, 16 ... Low temperature vessel, 17 ... 2 Side superconducting coil ... 18a ... connecting portion, 18b ... connecting portion, the equatorial plane of 30 ... primary superconducting coil, 32 ... connection pipe, 34 ... vacuum pipe

Claims (14)

A primary superconducting coil;
A first cryocontainer that houses the primary superconducting coil;
A secondary superconducting coil magnetically coupled to the primary superconducting coil;
A second cryogenic container that accommodates the secondary superconducting coil;
Have
A superconducting magnet device characterized in that the primary superconducting coil and the secondary superconducting coil can be controlled to different temperatures.   The superconducting magnet device according to claim 1, wherein the secondary superconducting coil has a configuration in which a plurality of secondary coils are connected in parallel.   3. A plurality of secondary coils of the secondary superconducting coil are configured such that the relative arrangement of coils and the number of turns are configured so that the currents induced for each coil are substantially equal to each other. The superconducting magnet device described in 1.   The superconducting magnet device according to claim 2 or 3, wherein a plurality of secondary coils of the secondary superconducting coil are arranged symmetrically with respect to the equator plane of the primary superconducting coil.   5. A superconducting conductor sample is connected to the secondary side superconducting coil, and the temperature of the superconducting conductor sample is configured to be controlled separately from the temperature of the secondary side superconducting coil. The superconducting magnet device according to any one of the above. The secondary superconducting coil is immersed in a liquid refrigerant in a second cryogenic container;
The superconducting conductor sample is housed in a third cryocontainer;
The second low-temperature container and the third low-temperature container are connected by piping through a throttle valve, and the third low-temperature container is a liquid refrigerant that flows from the second low-temperature container through the pipe. Being configured to be cooled by steam,
The superconducting magnet device according to claim 5.   6. The superconducting magnet apparatus according to claim 5, wherein the temperature of the secondary superconducting coil and the superconducting conductor sample is controlled by a temperature control mechanism including a cryogenic refrigerator and a conductive cooling member. .   It has a mechanism for controlling the temperature of the connecting portion of the superconducting conductor sample, and by controlling the temperature, the resistance value of the circuit including the superconducting conductor sample and the secondary superconducting coil is adjusted to obtain the secondary current value. 6. The superconducting magnet device according to claim 5, further comprising a mechanism for controlling.   The secondary superconducting coil is disposed in the bore of the primary superconducting coil, and a terminal for introducing a current of the secondary superconducting coil is disposed inside the secondary superconducting coil. A superconducting magnet device according to any one of claims 1 to 8.   The superconducting magnet device according to any one of claims 1 to 9, wherein the primary superconducting coil is of a refrigerator conduction cooling type.   An operating method of a superconducting magnet device having a primary side superconducting coil and a secondary side superconducting coil magnetically coupled to the primary side superconducting coil, the temperature of the primary side superconducting coil and the secondary side A method of operating a superconducting magnet device, wherein the temperature of the superconducting coil is separately controlled. The superconducting magnet device has a conductive conductor sample electrically connected to the secondary superconducting coil;
The superconducting magnet apparatus operating method according to claim 11, wherein the temperature of the conductive conductor sample is controlled separately from the temperature of the primary superconducting coil and the temperature of the secondary superconducting coil.   A superconducting conductor sample is connected to the secondary superconducting coil, a magnetic field is generated by passing a current through the primary superconducting coil, and the magnetic field is applied to the superconducting conductor sample, thereby superconducting the superconducting sample. The superconducting magnet apparatus operating method according to claim 11, wherein the empirical magnetic field dependence of characteristics is evaluated. Excitation is performed by passing a current through the primary superconducting coil, and by controlling the excitation speed of the primary superconducting coil, heat generation due to AC loss of the superconducting conductor sample connected to the secondary superconducting coil is controlled. 14. The method of operating a superconducting magnet device according to claim 11, wherein the temperature dependence of the superconducting characteristics of the superconducting conductor sample is evaluated thereby.

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