JPH10106829A - Superconducting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting device capable of preventing heat unbalance in a current lead and drift current caused by dispersion of resistance of normal conducting wire and so on. SOLUTION: A current lead has normal conducting wires (61, 62, 65, and 66) electrically insulated from each other. Normal conducting wires forming the current lead are connected to a single wire (2a and 2b) forming superconductor or a bundle of single wires respectively, and normal conductors are electrically connected at the normal temperature portion of the current lead.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a superconducting device,
In particular, the present invention relates to a superconducting device in which the current sharing between the wires of a superconducting coil formed by winding a conductor composed of a plurality of wires is made uniform.

[0002]

2. Description of the Related Art The structure of a conventional superconducting device is shown in FIG. For details of the superconducting device shown in FIG. 16, reference is made to, for example, Japanese Patent Application Laid-Open No. Hei 4-320305.

In FIG. 16, reference numeral 1 denotes a superconducting coil;
Reference numerals a and 3b denote current leads, reference numeral 4 denotes a cryostat, reference numeral 5 denotes liquid helium, reference numerals 10a and 10b denote refrigerant gas outlets, respectively.

Here, in order to simplify subsequent calculations,
The superconducting coil 1 is formed, for example, by winding a superconducting conductor in which two superconducting wires subjected to electrical insulation are twisted. Usually, a large current superconducting conductor is manufactured by bundling superconducting wires having a low current value. Further, in order to reduce the AC loss, the superconducting wires are electrically insulated.

FIG. 17 schematically shows a configuration of a superconducting coil 1 in which two superconducting wires are twisted. In FIG. 17, 2a is one superconducting element wire, and 2b is the other superconducting element wire. 1a is a unit superconducting coil in which one superconducting element wire 2a is wound, and 1b is the other superconducting element wire 2a.
b is a unit superconducting coil wound with b.

Next, the operation when exciting the conventional superconducting device shown in FIG. 16 will be described. Superconducting coil 1
Are the current leads 3a and 3b connecting the cryogenic part and the normal temperature part.
, And the current leads 3a and 3b are connected to an excitation power supply (not shown) via lead wires.

FIG. 18 shows this connection state in an equivalent circuit. In FIG. 18, La denotes the superconducting element wire 2
a, the self-inductance, Lb is the other superconducting wire 2b
Is the self-inductance of the superconducting wires 2a and 2b
, Rb is の of the connection resistance between superconducting wires 2b and 2a, Rc1 is the internal resistance of current lead 3a,
Rc2 is the internal resistance of the current lead 3b. The currents flowing through the strands 2a and 2b are defined as Ia and Ib.

The equation of the circuit shown in FIG. 18 is expressed by the following equation (1).

[0009]

(Equation 1)

Here, M is a mutual inductance between the strands Ia and Ib.

Now, assuming that the superconducting coil 1 is excited at a constant excitation speed, the above equation (1) is rearranged, and (Ia-Ib)
When the relationship of / (Ia + Ib) is obtained, it can be expressed as the following equation (2).

[0012]

(Equation 2)

Here, by substituting representative values, (Ia−
Ib) / (Ia + Ib) will be obtained.

In the case of a two-stranded wire, the wires are usually uniformly twisted as shown in FIG. 19, but if there is a twist as shown in FIG. 20, the strands 2a and 2b have slightly longer lengths. There is a difference. Assuming that the wires 2a and 2b have a slight difference in length, the self-inductances La and Lb of the wires 2a and 2b are considered.
Are set to La = 1.000H and Lb = 1.001H, and the mutual inductance M between the strands 2a and 2b is M = 1.0004H since the magnetic coupling is sufficiently large in the case of a stranded wire.
(Coupling coefficient 0.9999). The values shown here are possible values for an actual coil.

The connection resistance when the wires 2a and 2b were connected to the current lead 3 was 0.1 μΩ.
The excitation speed (dIa / dt + dIb / dt) is 5
A / s. FIG. 21 shows the calculation results. Referring to FIG. 21, Ia + Ib shows a state where it is held at a constant value when it reaches 100A.

As is apparent from FIG. 21, when the time is 20 seconds, the current Ia is about 300 A on the plus side and the current Ia is
b is flowing about 200A to the minus side, and the wires 1a and I
There is a large difference in the current flowing through b.

Such imbalance of current is not preferable in operation. Since the superconducting wire cannot pass a current higher than the critical current, the current imbalance increases, and when the critical current is exceeded, the superconducting wire 2a or 2b is quenched, and the current cannot be supplied. I will.

[0018]

As described above,
In the conventional superconducting device, a large imbalance occurs in the current flowing through the bundled superconducting wires, and when the current exceeds the critical current, the superconducting wires are quenched and the current cannot be supplied. There was a problem.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a superconducting device which suppresses and reduces the occurrence of current drift in each of the bundled superconducting wires. It is in.

[0020]

In order to achieve the above object, a superconducting device according to the present invention comprises a superconducting coil formed by winding a superconducting conductor formed by twisting strands, and an external power supply connected to the superconducting coil. And a cryostat that keeps the superconducting coil in a superconducting state, wherein the current lead comprises a plurality of normal conducting conductors electrically insulated from each other. Provided, bundling at least the first twist of the element wire constituting the superconducting conductor, connected to the normal conductor constituting the current lead, and the plurality of normal conductors at a substantially room temperature portion of the current lead. Electrically coupled,
It is characterized by the following.

Further, the superconducting device according to the present invention comprises a superconducting coil formed by winding a superconducting conductor constituted by twisting strands, and a current lead for supplying a current to the superconducting coil from an external power supply. A cryostat for keeping the superconducting coil in a superconducting state, wherein the current lead comprises a plurality of normal conducting conductors electrically insulated from each other, and a wire constituting the superconducting conductor is provided. For a book or for a plurality of bundled wires, a plurality of normal conducting wires constituting the current lead are connected to each other, and the plurality of The present invention is characterized in that the normal conductors are electrically connected.

A preferred embodiment of the present invention is the following claim 3.
11 to 11 and will be described in the following preferred embodiments.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

[Embodiment 1] The present invention is directed to the first embodiment of the present invention, in which a superconducting coil formed by winding a superconducting conductor formed by multiply twisting element wires, and applying a current to the superconducting coil from the outside, It is composed of a plurality of normal conductors that are supplied and electrically insulated or formed with a high resistance film, and are connected to the normal conductor by bundling at least the first twist of the superconducting element wire of the superconducting conductor, and being connected to the normal conductor at almost room temperature. It comprises a current lead to which a normal conductor is electrically coupled, and a cryostat for keeping a superconducting coil in a superconducting state.

In the embodiment of the present invention, the normal conducting wires (61, 62 and 65, 66) of the current leads are respectively connected to the superconducting wires (2a, 2b in FIG. 1). That is, the superconducting wires (2a, 2a in FIG. 1)
b) (self-inductance L in FIG. 2)
a, Lb) respectively represent the resistance of the normal conducting wire of the current lead (Rc11, Rc12, Rc22, Rc2 in FIG. 2).
1) is configured to be connected in series.

For this reason, in the embodiment of the present invention, the time constant of the circulating current flowing between the superconducting wires becomes short, and when the superconducting coils are excited, a uniform current flows between the respective superconducting wires. And the current drift is reduced.

Further, in the embodiment of the present invention, a structure may be adopted in which a plurality of superconducting wires are bundled and a normal conducting wire constituting a current lead is connected to each of them (FIG. 7).
reference). That is, the resistance of the normal conducting wire of the current lead is connected in series with the plurality of superconducting wires having the bundled inductance.

Here, since the geometric arrangement is less likely to be disturbed on the low-order stranded wire side, current drift hardly occurs in each of the bundled superconducting wires.

[Second Embodiment] The present invention is directed to the second embodiment, wherein a superconducting coil formed by winding a superconducting conductor formed by multiply twisting element wires, and applying a current from outside to the superconducting coil is provided. And a plurality of normal conductors on which an electrically insulated or high-resistance film is formed, and for one superconducting element wire of the superconducting conductor, or
A cryostat that keeps a superconducting current lead and a superconducting coil in which a plurality of normal conducting wires are connected to a plurality of bundled superconducting wires, respectively, and the normal conducting conductor is electrically coupled at almost normal temperature. And with.

In the embodiment of the present invention, a plurality of normal conducting wires of the current lead are connected to one superconducting wire (for example, one superconducting wire 2a with reference to FIG. 9).
On the other hand, one end is connected to the normal conducting wires 61 and 62, and the other end is connected to the normal conducting wires 67 and 68).

In the embodiment of the present invention, even if a thermal imbalance occurs in the current lead and the resistance value of each normal conducting wire varies, a plurality of parallelly connected normal conducting wires may cause a current drift. The effect can be reduced.

[Third Embodiment] In the third embodiment of the present invention, there is provided a superconducting coil formed by winding a superconducting conductor formed by multiply twisting element wires, and applying a current to the superconducting coil from outside. And the normal conducting wires (61, 62, 65, 6 in FIG. 9) to the room temperature portion side from the outlet (10a, 10b in FIG. 9) of the refrigerant gas discharged from the current lead.
6), and a normal conductor (61 in FIG. 9)
Current leads (17a, 17b in FIG. 9) in which the superconducting coils are electrically connected to each other and cryostats (4 in FIG. 1) for keeping the superconducting coil in a superconducting state.
And with.

In the embodiment of the present invention, since the normal conducting wire is arranged from the outlet of the refrigerant gas discharged from the current lead to the room temperature portion side, it is not directly cooled by the refrigerant gas of the normal conducting wire. High temperature part increases. Therefore, the resistance value of the current lead is increased, the time constant of the circulating current is shortened, and current drift is less likely to occur.

[Fourth Embodiment] In the fourth embodiment of the present invention, an electric insulation of a normal conducting wire forming a current lead is provided by an oxide film in the fourth embodiment. Since the oxide film is very thin and has good heat transfer with the refrigerant gas, the cross-sectional area of the ordinary conducting wire can be reduced, which contributes to the miniaturization (compactness) of the current lead.

[Fifth Embodiment] The present invention is directed to a fifth embodiment of the present invention, wherein a superconducting coil formed by winding a superconducting conductor composed of multiple twisted strands is provided, and a current is supplied to the superconducting coil from the outside. , A cryostat that keeps the superconducting coil in a superconducting state, and a device that controls the refrigerant gas flow rate of the current lead (12a to 12 in FIG. 10).
d, and 13) and a device for detecting a refrigerant gas flow rate (FIG. 1)
0 11a to 11d). The inside of the current lead is divided into a plurality of members (19a and 19b in FIG. 10).
Is divided into a plurality.

In the embodiment of the present invention, by detecting the flow rate of the refrigerant gas discharged from the current lead and controlling the flow rate, the normal conducting wire (6 in FIG. 11) of the current lead is detected.
1, 62, 65, and 66) are reduced, and current drift is less likely to occur.

[Embodiment 6] The present invention is directed to a sixth embodiment of the present invention, in which a superconducting coil formed by winding a superconducting conductor constituted by multiple twists of strands is provided, and a current is supplied to the superconducting coil from the outside. , A cryostat that keeps the superconducting coil in a superconducting state, and a device that controls the flow rate of the refrigerant gas in the current lead (12a to 1 in FIG. 11).
2d and 13), a device for detecting a refrigerant gas temperature (FIG. 1)
1 14a to 14d).

In the embodiment of the present invention, by detecting the temperature of the refrigerant gas discharged from the current lead and controlling the flow rate of the refrigerant gas, the normal conducting wires (61, 62 in FIG. 11) of the current lead are detected. , 65, and 66) are reduced, and current drift is less likely to occur.

[Seventh Embodiment] The present invention is directed to the seventh embodiment of the present invention, in which a superconducting coil formed by winding a superconducting conductor formed by multiple strands of wires is provided, and a current is supplied to the superconducting coil from the outside. , A cryostat that keeps the superconducting coil in a superconducting state, and a device that controls the refrigerant gas flow rate of the current lead (12a to 12a in FIG. 12).
12d and 13) and a device for detecting the temperature of the normal conducting wire of the current lead (15a to 15d in FIG. 12).

In the embodiment of the present invention, the normal conducting wires (61, 62, 65, 6 in FIG. 12) of the current leads are used.
By detecting the temperature of 6) and controlling the flow rate of the refrigerant gas, variation in the resistance value of the current lead can be reduced, and current drift is less likely to occur.

[Eighth Embodiment] The present invention is directed to a seventh embodiment of the present invention, wherein a superconducting coil formed by winding a superconducting conductor constituted by multiple twists of strands is provided, and a current is supplied to the superconducting coil from the outside. , A cryostat that keeps the superconducting coil in a superconducting state, and a device that controls the refrigerant gas flow rate of the current lead (12a to 12 in FIG. 13).
d and 13) and a device for detecting the voltage of the current lead (20a to 20d in FIG. 13).

In the embodiment of the present invention, by detecting the voltage of the current lead and controlling the flow rate of the refrigerant gas, the variation of the resistance value of the current lead can be reduced, and current drift is less likely to occur.

[Ninth Embodiment] The present invention is directed to a ninth embodiment according to the present invention, wherein a superconducting coil is formed by winding a superconducting conductor formed by single or multiple twisting of a superconducting element wire, and 14 includes a current lead (6a in FIG. 14) configured to prevent the current from drifting, and a cryostat for keeping the superconducting coil in a superconducting state.

In the embodiment of the present invention, the current lead is used at least at one end of the superconducting coil, so that the device can be simplified and current drift can be prevented.

[Embodiment 10] The present invention relates to a tenth embodiment.
In the embodiment, the superconducting bus bar (16 in FIG. 15) is used.
a, 16b), a current lead (6a, 6b in FIG. 15) for supplying a current to the superconducting bus bar from the outside, at least one of which prevents current drift, and a cryostat (FIG. 15) for keeping the superconducting bus bar in a superconducting state. 15-4)
And with.

In the embodiment of the present invention, the device can be simplified and the current can be prevented from being deflected by providing the current lead having the configuration for preventing the deflection at least on one side of the superconducting bus line.

[0047]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

Embodiment 1 FIG. 1 is a diagram showing a configuration of a superconducting device according to a first embodiment of the present invention. Referring to FIG. 1, superconducting wires 2a and 2b, superconducting coils 1a and 1b formed by winding the wires, and cryostat 4 have the same configuration as that of the above-described conventional technology.

In FIG. 1, reference numerals 6a and 6b denote current leads, and reference numerals 61, 62 and 65 and 66 denote current leads 6a,
And 6b show electrically insulated normal conducting wires,
It is connected at the part close to the normal temperature and normal temperature part. In this embodiment, one ends of a plurality of superconducting wires 1a and 1b are connected to normal conducting wires 61 and 62, respectively, and the other ends are connected to normal conducting wires 65 and 66, respectively. And 6
2. The normal conducting wires 65 and 66 are both electrically connected at a portion close to the room temperature portion.

FIG. 2 shows an equivalent circuit of the circuit configuration shown in FIG. In FIG. 2, La is the self-inductance of the superconducting wire 2a, and Lb is the other superconducting wire 2a.
b, the self-inductance of the superconducting wires 2a and 2a
b is 1/2 of the connection resistance of superconducting wires 2b and 2a, and Rc11 and Rc12 are current leads 6
a, the internal resistance of the normal conducting wires 61 and 62, Rc2
1, Rc22 is a normal conducting wire 6 constituting the current lead 6b.
5 and 66 represent the internal resistance.

Next, the basic operation of this embodiment will be described. The basic equations are the same as in the prior art. Substitute specific numerical values. As with the prior art described above,
Assuming that the superconducting wires 2a and 2b have a slight difference in length, La = 1.000H and Lb = 1.001H, and the inductance between the wires 2a and 2b is 1.0004H assuming that the magnetic coupling is sufficiently large. (Coupling coefficient 0.9999)
And The connection resistance when the superconducting wires 2a and 2b were connected to the current lead 6 was set to 0.1 μΩ. The voltage drop at the current lead is usually about 10 mV.

Since the current value per normal conducting wire is 50 A, if the voltage drop is 10 mV, Rc1
1, Rc12, Rc21 and Rc22 each have a resistance of 2
It becomes 00 μ ohm. This value is sufficiently larger than the connection resistances Ra and Rb, and it can be inferred that current imbalance hardly occurs. Excitation speed (dIa / dt +
dIb / dt) is 5 A / s, as in the above-described conventional technique.
FIG. 3 shows the calculation result.

As is apparent from FIG. 3, there is almost no difference between Ia and Ib, and it can be seen that the current imbalance as in the above-mentioned prior art can be eliminated.

In this calculation, the case of using two superconducting wires is shown for simplicity. However, as shown in FIG. 5, three superconducting wires 2a, 2b, and 2c are used as shown in FIG. Even in the configuration, it is needless to say that the current imbalance can be eliminated. In FIG. 4, 2a, 2b and 2c are superconducting wires. In FIG. 5, 1a, 1b, 1
c is a superconducting coil, 7a and 7b are current leads, 61 and 6
Reference numerals 2, 63, 65, 66, and 67 are normal conducting wires constituting current leads.

Further, even in the case of a 3 × 3 multi-stranded wire as shown in FIG. 6, it is a matter of course that the imbalance of current can be eliminated by applying this embodiment. In FIG. 6, 2a, 2b, 2c, 2d, 2e, 2f, 2
g, 2h and 2i are superconducting wires.

Further, a multiply stranded wire, or 3
It goes without saying that the same applies to other than the stranded wire.

FIG. 7 is a partially enlarged view showing, as a modification of the embodiment of the present invention, a state of a connection portion with a current lead when a multi-stranded conductor is used.

In the first embodiment shown in FIG. 1, a single superconducting element wire in the current lead is connected to each of a plurality of superconducting element wires. As shown in the figure, by connecting a plurality of superconducting wires and then connecting them to the normal conducting wires in the current lead, the number of normal conducting wires can be reduced. The balance can be eliminated. On the low-order stranded wire side of the multi-stranded wire, twisting and the like are small, and the arrangement is geometrically almost symmetrical, so that the imbalance of inductance is relatively hard to occur. Therefore, the superconducting element wires may be bundled and connected to the lower order twisted wire side.

Although FIG. 7 shows a double twisted wire, the same can be said for a triple twisted wire or a multiple twisted wire. The number of twists to be bundled may be determined in consideration of the current imbalance.

Referring to FIG. 5, superconducting wires 1a,
1b and 1c are electrically insulated, but the superconducting wires 1
Even when a, 1b, and 1c are in contact with high resistance, the same phenomenon occurs, and the same operation and effect can be obtained.

[Embodiment 2] FIG. 8 is a diagram showing a configuration of a superconducting device according to a second embodiment of the present invention. In FIG. 8, superconducting wires 2a and 2b, superconducting coils 1a and 1b around which they are wound, and a cryostat 4 are the same as those in the above-described conventional technology.

In FIG. 8, 8a and 8b are current leads, and 61, 62, 63, 64 and 65, 66, 6
Reference numerals 7 and 68 denote electrically insulated normal conducting wires constituting the current leads 8a and 8b, respectively.
63 and 64 are connected at a portion near the room temperature portion, and the normal conducting wires 65, 66, 67 and 68 are also connected at a portion near the room temperature portion.

In the low temperature part, two normal conducting wires in the current lead are connected in parallel to one of the superconducting wires 2a and 2b.

Next, the operation of this embodiment will be described. The basic operation is the same as in the first embodiment.

Since the current leads are generally cooled by a cryogenic gas, when the normal conducting wires are cooled with different thermal efficiencies, each normal conducting wire exhibits a different temperature distribution. For this reason, the resistance value of the normal conducting wire connected in series to the superconducting wire becomes different, which may cause a current imbalance.

In order to avoid this state, it is sufficient to make each of the ordinary conducting wires have a uniform temperature distribution, but this is very difficult.

Therefore, as shown in FIG. 8, a plurality of normal conducting wires are connected in parallel to one superconducting wire, and the temperature distribution of the plurality of normal conducting wires is different and the resistance value is different. Even if they are different, the current is unbalanced because they are averaged.

In FIG. 8, two superconducting wires are shown, but the present invention is not limited to this. Further, although an example is shown in which two normal conducting wires are connected in parallel to one superconducting strand, the number of normal conducting wires connected in parallel is not limited to two. The greater the number of parallel connections, the more effective the averaging.

FIG. 8 shows an example in which two superconducting wires are connected in parallel to one superconducting wire, but as shown in FIG. The same effect can be obtained even when a part is bundled or when a plurality of normal conducting wires are connected to the bundled superconducting wires.

[Embodiment 3] FIG. 9 is a diagram showing a configuration of a superconducting device according to a third embodiment of the present invention. Referring to FIG. 9, in this embodiment, one end is connected to a refrigerant gas outlet 1.
The normal conducting wires 61, 62, and 6 which extend beyond 0a and 10b to the room temperature side and are electrically connected to each other.
5 and 66 are provided.

Next, the operation of this embodiment will be described. The normal conducting wires 61, 62, 65 and 66 are generally copper wires. Copper wires change resistance with temperature. As the temperature decreases, the resistance value also decreases. Therefore, the resistance Rc11 of the current lead shown in FIG.
Rc12, Rc21, and Rc22 exhibit higher resistance as the temperature increases (the longer the portion of the normal conducting wire located in the normal temperature section increases), the time constant of inductance and resistance decreases, and the current drifts. Can be further reduced.

In FIG. 9, outlets 10a, 10b of the refrigerant gas
The normal conducting wires 61 and 62 and 65 and 6
6, the resistance Rc of the current lead shown in FIG.
11, Rc12, Rc21, and Rc22 can be increased in value (resistance value), and the effect of reducing the drift is great.

[Embodiment 4] A fourth embodiment of the present invention will be described.

Since the current lead has a structure in which the normal conducting wire inside is cooled by a cryogenic gas, it is desirable that the heat exchange rate between the cryogenic gas and the normal conducting wire be higher. In addition, since the normal conducting wires that are electrically insulated from each other have substantially the same potential at the same position, the electrical insulation can be simple.

Normally, enamel or the like is used for electrical insulation of the ordinary conducting wire. However, since the thermal conductivity of the enamel is low, the heat exchange rate becomes poor as the film thickness increases.

When an oxide film is applied to the ordinary conducting wire, electrical insulation can be secured without significantly lowering the heat exchange rate.

[Embodiment 5] FIG. 10 is a diagram showing a configuration of a superconducting device according to a fifth embodiment of the present invention. In FIG. 10, 11a, 11b, 11c and 11d are refrigerant gas flow rate detecting devices, 12a, 12b, 2c and 12d are refrigerant gas flow rate adjusting devices, 13 is a refrigerant gas flow rate controlling device,
Reference numerals 8a and 18b denote current leads provided with dividing members 19a and 19b for dividing a portion of the current lead through which the refrigerant gas flows into two parts.

Next, the operation of this embodiment will be described.
The refrigerant gas flowing through the current lead is divided into two parts by the dividing members 19a and 19b, and flows independently.

The normal conducting wires 61, 62, 65, 66
Generally, a copper wire is used. Copper wires change resistance with temperature. As the temperature decreases, the resistance value also decreases.
Therefore, the larger the flow rate of the refrigerant gas, the greater the
The resistance Rc of the current lead in FIG.
The values (resistance values) of 11, Rc12, Rc21, and Rc22 decrease. The lower the flow rate of the refrigerant gas, the higher the resistance value.

Therefore, each of the normal conducting wires 61, 62, 6
If there is a difference in the refrigerant gas flowing around 5, 66, a difference occurs in the resistance values Rc11, Rc12, Rc21, Rc22,
Current drift occurs. In order to solve this problem, it is sufficient to make substantially the same refrigerant gas flow through each normal conducting wire.

As the number of ordinary conducting wires increases, the flow of the refrigerant gas is likely to be disturbed.

For this reason, it is necessary to reduce the number of ordinary conducting wires as much as possible and to make the flow of the refrigerant gas less likely to be disturbed.

Therefore, in this embodiment, the current lead 18
a, 18b, the dividing members 19a, 19b are inserted to make the flow independent, and the flow rate of the refrigerant gas is detected by the flow rate detecting devices 11a, 11
b, 11c, and 11d, and the flow rate of the refrigerant gas is controlled by using the flow rate control device 13 and the flow rate adjustment devices 12a, 12b, 12c, and 12d.
11, Rc12, RC21, and Rc22 are unlikely to have a difference, and current drift is suppressed and reduced.

[Embodiment 6] FIG. 11 is a diagram showing a configuration of a superconducting device according to a sixth embodiment of the present invention. FIG.
, 14a, 14b, 14c and 14d are temperature detectors for measuring the temperature of the refrigerant gas.

Next, the operation of this embodiment will be described.
In the fifth embodiment, the flow rate is controlled by detecting the flow rate of the refrigerant gas. However, if the flow rate of the refrigerant gas is controlled by detecting the temperature of the refrigerant gas, the flow rate detection devices 11a, 11b, 11
c, 11d, the temperature detecting devices 14a, 14b, 14
Since c and 14d are generally inexpensive, they can be configured inexpensively as a system.

[Embodiment 7] FIG. 12 is a diagram showing a configuration of a superconducting device according to a seventh embodiment of the present invention. In FIG. 12, reference numerals 15a, 15b, 15c and 15d denote temperature detecting devices housed in the current leads 18a and 18b.

Next, the operation of this embodiment will be described.
In the sixth embodiment, the flow rate is controlled by detecting the outlet temperature of the refrigerant gas. However, in this embodiment, the temperatures of the normal conducting wires 61, 62, 65, and 66 are directly detected to By controlling the flow rate, the temperature of the ordinary conducting wire can be directly controlled. This makes it difficult for the resistance values of Rc11, Rc12, Rc21, and Rc22 shown in FIG. 2 to differ from each other, so that the current drift can be more effectively suppressed and reduced.

[Eighth Embodiment] FIG. 13 is a diagram showing a configuration of a superconducting device according to an eighth embodiment of the present invention. In FIG. 13, reference numerals 20a, 20b, 20c, and 20d denote voltage taps for measuring the voltages of the current leads 18a and 18b.

Next, the operation of this embodiment will be described.
In this embodiment, the voltages of the current leads 18a and 18b are measured, and the flow rate of the refrigerant gas is controlled so that the measured voltage becomes substantially constant, whereby the Rc11 and Rc11 shown in FIG.
The resistance values of Rc12, Rc21, and Rc22 are unlikely to differ from each other, so that current drift can be further reduced.

Ninth Embodiment FIG. 14 is a diagram showing a configuration of a superconducting device according to a ninth embodiment of the present invention. As shown in FIG. 14, in this embodiment, the superconducting coil 1
A current lead formed by connecting a plurality of normal conducting wires in parallel is connected to one end of each of a and b. In this embodiment, Rc11 and Rc in FIG.
12, the resistance values of Rc21 and Rc22 are halved, and the effect of reducing the current drift is halved. However, if the drift is originally small, the configuration like this embodiment can reduce the drift. Can be expected to have a sufficient effect. Also, since a plurality of normal conducting wires are connected only to one side of the superconducting coil composed of a plurality of wires (the other end of the superconducting coil is connected to one current lead), the device is simple. become.

[Embodiment 10] FIG. 15 shows a tenth embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of a superconducting device according to an example of FIG. FIG.
In 5, 16 a and 16 b are superconducting bus bars.
Superconducting busbars are not usually coiled, they are almost straight,
Alternatively, they are arranged along a predetermined route. In order to increase the current capacity, superconducting bus bars 16a, 16b are usually connected in parallel. If there is a difference in the connection resistance at the ends, a drift occurs as in the case of the coil. As shown in FIG. 15, a plurality of superconducting bus bars 16a and 16b are connected in parallel,
Even in the case where the current value that can be passed is increased, the current drift is reduced by using the current leads including the plurality of normal conducting wires 61, 62, and 65 and 66, as in the case where the current leads are connected to the superconducting coils 1a and 1b. it can.

[0092]

As described above, according to the present invention,
In any case, the effect of suppressing and reducing the current drift is exhibited. This will be described in detail below.

According to the first aspect of the invention, the time constant of the circulating current flowing between the superconducting wires becomes short, and when the superconducting coils are excited, a uniform current flows between the respective superconducting wires. Thus, current drift is reduced.

According to the second aspect of the present invention, even if a thermal imbalance occurs in the current lead and the resistance value of each of the normal conducting wires varies, the current drift can be achieved by connecting a plurality of the normal conducting wires in parallel. Influence can be reduced.

According to the fourth or fifth aspect of the present invention, the normal conducting wire constituting the current lead is provided with an oxide film. Since the oxide film is very thin and has good heat transfer with the refrigerant gas, the cross-sectional area of the ordinary conducting wire can be reduced, which contributes to the miniaturization (compactness) of the current lead.

According to the present invention, by detecting the flow rate of the refrigerant gas discharged from the current lead and controlling the flow rate, the resistance of the normal conducting wire of the current lead is reduced. Variations in values are reduced, and current drift is less likely to occur.

According to the tenth or eleventh aspect of the present invention,
Since the current lead is used at least at one end of the superconducting coil, the device can be simplified and current drift can be prevented.

According to the twelfth aspect of the present invention, since the normal conducting wire is arranged from the outlet of the refrigerant gas discharged from the current lead to the room temperature portion side, it is not directly cooled by the refrigerant gas of the normal conducting wire. That is, a portion having a high temperature increases. Therefore, the resistance value of the current lead is increased, the time constant of the circulating current is shortened, and current drift is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a superconducting device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an equivalent circuit of the superconducting device according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram illustrating a current imbalance according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of another superconducting device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of a superconducting device according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of another superconducting device according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of another superconducting device according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration of a superconducting device according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating a configuration of a superconducting device according to a fourth embodiment of the present invention.

FIG. 10 is a diagram illustrating a configuration of a superconducting device according to a fifth embodiment of the present invention.

FIG. 11 is a diagram illustrating a configuration of a superconducting device according to a sixth embodiment of the present invention.

FIG. 12 is a diagram illustrating a configuration of a superconducting device according to a seventh embodiment of the present invention.

FIG. 13 is a diagram illustrating a configuration of a superconducting device according to an eighth embodiment of the present invention.

FIG. 14 is a diagram illustrating a configuration of a superconducting device according to Embodiment 9 of the present invention.

FIG. 15 is a diagram illustrating a configuration of a superconducting device according to a tenth embodiment of the present invention.

FIG. 16 is a diagram showing a configuration of a conventional superconducting device.

FIG. 17 is a diagram showing a configuration of a conventional superconducting device.

FIG. 18 is a diagram showing an equivalent circuit of a conventional superconducting device.

FIG. 19 is a view for explaining a conventional superconducting device.

FIG. 20 is a view for explaining a conventional superconducting device.

FIG. 21 is a characteristic diagram illustrating the operation of a conventional superconducting device.

[Explanation of symbols]

 Reference Signs List 1 superconducting coil 1a superconducting coil 1b superconducting coil 1c superconducting coil 2a superconducting element wire 2b superconducting element wire 2c superconducting element wire 3a current lead 3b current lead 4 cryostat 5 refrigerant 6a current lead 6b current lead 7a current lead 8b current lead 8a Current lead 10a Refrigerant gas outlet 10b Refrigerant gas outlet 11a Flow rate detector 11b Flow rate detector 11c Flow rate detector 11d Flow rate detector 12a Flow rate regulator 12b Flow rate regulator 12c Flow rate regulator 12d Flow rate regulator 13 Flow rate controller 14a Temperature detector 14b Temperature detection device 14c Temperature detection device 14d Temperature detection device 15a Temperature detection device 15b Temperature detection device 15c Temperature detection device 15d Temperature detection device 16a Superconducting bus bar 16b Superconducting bus -17a Current lead 17b Current lead 18a Current lead 18b Current lead 19a Dividing material 19b Dividing material 20a Voltage tap 20b Voltage tap 20c Voltage tap 20d Voltage tap 61 Normal conducting wire 62 Normal conducting wire 63 Normal conducting wire 64 Normal conducting element Wire 65 normal conducting wire 66 normal conducting wire 67 normal conducting wire 68 normal conducting wire 69 normal conducting wire La self-inductance of superconducting coil 1a Lb self-inductance of superconducting coil 1b Ra connection resistance of superconducting coil 1a and 1b 1/2 Rb 1/2 of connection resistance of superconducting coils 1a and 1b Rc1 Internal resistance of current lead Rc2 Internal resistance of current lead Rc11 Internal resistance of current lead Rc12 Internal resistance of current lead Rc21 Internal resistance of current lead Rc22 Current lead Internal resistance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Morita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Kazutake Senoo 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (12)

[Claims] 1. A superconducting coil formed by winding a superconducting conductor formed by multiply twisting element wires, a current lead for supplying a current to the superconducting coil from an external power supply, and bringing the superconducting coil into a superconducting state. A cryostat to be kept, and wherein the current lead comprises a plurality of normal conductors electrically insulated from each other, and bundles at least the first twist of the strands constituting the superconductor. A superconducting device, wherein the superconducting device is connected to the normal conductor constituting the current lead, and the plurality of normal conductors are electrically connected at a substantially normal temperature portion of the current lead. 2. A superconducting coil formed by winding a superconducting conductor formed by multiply twisting element wires, a current lead for supplying a current to the superconducting coil from an external power supply, and bringing the superconducting coil into a superconducting state. A superconducting device comprising: a cryostat for maintaining; and wherein the current lead includes a plurality of normal conductors electrically insulated from each other, and a single wire constituting the superconducting conductor, or bundled. The plurality of normal wires constituting the current lead are connected to the plurality of wires, respectively, and the plurality of normal conductors are electrically connected at a substantially normal temperature portion of the current lead. A superconducting device, which is connected. 3. The superconducting device according to claim 1, wherein said current lead comprises a plurality of normal conducting conductors having a high resistance film formed on a surface thereof. 4. The superconducting device according to claim 1, wherein the electric insulation of the normal conducting wire constituting the current lead is constituted by an oxide film. 5. The superconducting device according to claim 3, wherein said high resistance film is formed of an oxide film. 6. A means for dividing the inside of the current lead into a plurality of regions, detecting and controlling the flow rate of the refrigerant gas discharged from the current lead, wherein the refrigerant gas is provided in a plurality of divided regions of the current lead. The superconducting device according to any one of claims 1 to 4, wherein the superconducting device is controlled so that a flow rate of the superconducting gas is substantially constant. 7. A means for dividing the inside of the current lead into a plurality of regions, detecting means for detecting a temperature of the refrigerant gas discharged from the current lead, and means for controlling a flow rate of the refrigerant gas, The superconducting device according to any one of claims 1 to 4, wherein the temperature of the refrigerant gas is controlled to be substantially constant in a plurality of divided regions. 8. A means for dividing the inside of the current lead into a plurality of parts, a means for detecting a temperature of a normal conducting wire constituting the current lead, and a means for controlling a flow rate of the refrigerant gas, The superconducting device according to any one of claims 1 to 4, wherein the superconducting device is controlled so that the temperature of a normal conducting wire constituting a current lead disposed in the divided region is substantially constant. 9. A means for dividing the inside of the current lead into a plurality of parts, detecting a voltage of a plurality of normal conducting wires disposed in the plurality of divided areas, and controlling a flow rate of the refrigerant gas. Means, wherein the flow rate of the refrigerant gas is controlled so that the voltage of the current lead in the plurality of divided areas is substantially constant. Superconducting device. 10. The superconducting device according to claim 1, wherein said current lead is used at least at one end of said superconducting coil. 11. The superconducting device according to claim 1, wherein said current lead is used at least at one end of a superconducting bus line. 12. The apparatus according to claim 1, wherein the plurality of normal conducting wires constituting the current lead extend through a discharge port of the refrigerant gas and are further electrically connected to each other at a normal temperature portion side. 8. The superconducting device according to any one of 7 above.