JPH0431167B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a superconducting magnet device and a method for connecting its external leads. This invention relates to a superconducting magnet device that is attached and detached in a low-temperature area remote from a room-temperature area, and a method for connecting its external leads.

[Conventional technology]

FIG. 8 shows a conventional superconducting magnet device disclosed in, for example, Japanese Patent Application Laid-open No. 55-127005, in which 1 is a low-temperature container filled with liquid helium 2, which is a refrigerant, and kept at an extremely low temperature. A superconducting coil 3 is placed inside and immersed in liquid helium 2. Lead ends 3a and 3b of the superconducting coil 3 are connected to cylindrical connecting members 4a and 4b placed above the surface of the liquid helium 2, respectively. The upper plate 1a that closes the upper opening of the container 1 is provided with through holes 5a and 5b at portions located above the connecting members 4a and 4b, respectively.
Cylindrical current leads 6a and 6b having tapered lower ends are inserted into the container 1 from the lower ends a and 5b, respectively. These current leads 6
a and 6b are removably fitted into the recesses of the connecting members 4a and 4b. In this state, current lead 6
The conduits of the connecting members 4a, 4b and the connecting members 4a, 4b are communicated with each other. Terminals 7a, 7b are attached to the upper end surfaces of the current leads 6a, 6b, and an excitation power source 8 for exciting the superconducting coil 3 is connected to these terminals.

On the other hand, lead ends 3a and 3b of the superconducting coil 3
is connected to a persistent current switch 9 placed below the surface of liquid helium 2 via a superconducting wire 10. A heater power source 11 is connected to the persistent current switch 9.

FIG. 9 shows an equivalent circuit of FIG. 8. 91,9
2 and 93 are a superconducting conductor, a heater, and a thermal insulator of the persistent current switch 9, respectively. The heater 92 is energized from the heater power supply 11 .

With the above configuration, the heater 92 is energized to raise the superconducting conductor 91 of the persistent current switch 9 to a critical temperature Tc.
By doing the above, resistance is generated in that part. In this state, the superconducting coil 3 is excited by the excitation power source 8. The superconducting coil 3 is energized to a predetermined current value.
After the current reaches a steady state, the heater 92 is de-energized. In this way, the persistent current switch 9 is cooled by the liquid helium 2, its temperature becomes below Tc, and its electrical resistance becomes zero. Thereafter, when the excitation current of the excitation power source 8 is made zero, the superconducting coil 3 is operated with a persistent current, and a current flows as shown by the arrow in the figure.
At this time, the leads 6a and 6b are electrically unnecessary, and since the leads 6a and 6b conduct heat from the normal temperature part to the low temperature part, they have the adverse effect of increasing the amount of evaporation of the liquid helium 2. Therefore, the leads 6a and 6b are usually removed from the low temperature container 1 for use. The electrical equivalent circuit at this time is shown in FIG.

In the above process, when the current leads 6a and 6b are attached and detached, the atmosphere outside the low temperature container 1 is removed from the through hole 5.
It penetrates into the container 1 through a and 5b. This atmosphere is usually air or air containing moisture, and since these gases are heavier than helium gas, they easily enter the container 1 if there is a gap in the container 1. For example, even if the through holes 5a and 5b are plugged immediately after the current leads 6a and 6b are removed, they will still enter the container 1 within a short period of time. Since the temperature inside the low-temperature container 1 is low, the moisture that has entered the container 1 solidifies.
Furthermore, the air itself solidifies into frost and accumulates on the connecting members 4a and 4b.

Further, when the superconducting magnet is operated with persistent current for a long period of time ranging from several weeks to several years, the current leads 6a and 6b remain removed during this period. During this time, it is necessary to replenish liquid helium 2 into the container 1 many times, but during this replenishment operation, the atmosphere outside the container 1 mixes into the container 1 and solidifies, and is gradually deposited onto the connecting members 4a and 4b. Time is accumulated.

[Problem that the invention seeks to solve]

In the conventional superconducting magnet device as described above, not only is it complicated to attach and detach the current leads, but also a significant amount of frost accumulates on the connecting members 4a, 4b.
There was a problem in that it was difficult to establish continuity.

On the other hand, if the temperature of the low-temperature container 1 is raised to room temperature, the frost naturally melts and falls into the cryogenic container through the gaps between the connecting members, so that it disappears from the surface of the connecting members. However, for example, in a superconducting magnet device for a human body magnetic resonance imaging device, it takes a long time of one month or more to raise the temperature to room temperature and then recool it, which is completely unrealistic from the standpoint of device utilization efficiency. do not have.

This invention was made to solve the above-mentioned problems, and it is possible to reliably and easily attach and detach the current lead while keeping it cooled at an extremely low temperature, and also to improve the electrical connection between the current lead and the connecting member. Continuity can be ensured. The object of the present invention is to obtain a superconducting magnet device equipped with a highly reliable lead attachment/detachment section.

Another invention of the present invention is to provide a method for connecting an external lead of a superconducting magnet device, which can eliminate frost accumulated on the fixed connection part when connecting the external lead to the fixed connection part in the low temperature container. The purpose is to obtain.

[Means for solving problems]

A superconducting magnet device according to the present invention includes a guide member vertically provided in the upper part of a low-temperature container containing a superconducting coil, a refrigerant, a persistent current switch, etc., a fixed connector for an internal lead fixed to the bottom of the guide member, and a guide member fixed to the bottom of the guide member. It is equipped with a removable lead having a movable connector that can be inserted and removed along.

In a method for connecting external leads of a superconducting magnet device according to another aspect of the present invention, the movable connector of the above-described superconducting magnet device is heated outside a cryogenic container and then connected to a fixed connector.

[Effect]

In this invention, by inserting and removing the movable connector along the guide member and attaching and detaching the movable connector to and from the fixed connector, the leads inside and outside the cryogenic container can be connected to and separated from each other.

In another aspect of the present invention, frost built up on the fixed connector is vaporized and removed by the heated movable connector.

〔Example〕

The present invention will be described below based on an embodiment shown in the drawings. In Fig. 1, 12 is a heater lead, 13 is a measurement lead, 14 is a helium gas exhaust pipe, 15 is a sensor for measuring temperature, pressure, strain, etc., and 16 is installed vertically at the top of the cryogenic container 1 and is detachable. A cylindrical guide member that serves as a guide when inserting the lead 100, 17 a measuring device for measuring the output of the sensor 15, and 18 a detachable lead 100.
It is a movable connector whose ends are connected and can move together with the detachable lead 100, and can be inserted into and removed from the guide member 16. 19 is a fixed connector on the superconducting coil 3 side,
Fixed to the bottom of the guide member 16, the lead end 3
a, 3b, heater lead 12, measurement lead 1
3. A liquid filling pipe 41 and the like are connected.

Both the movable connector 18 and the fixed connector 19 are disk-shaped, and are electrically connected by female pins and male pins respectively erected on opposing surfaces.

In addition, the same reference numerals in FIG. 8 indicate the same or corresponding parts.

FIG. 2 shows the fixed connector 19 and its surroundings covered with a large amount of frost 42 for the purpose of an experiment. It is formed by the solidification of the atmosphere outside the low-temperature container.
d indicates the thickness of the frost 42. 21 is a male pin and is within frost 42. The above situation in which frost 42 has accumulated is
This occurs during normal driving,
This is by no means a special phenomenon. For example, in a superconducting magnet device for magnetic resonance imaging, the persistent current operation period usually lasts several years, and once the superconducting coil 3 is excited by the excitation power source 8,
For several years after that, the removable lead 100 was removed, and as a matter of course, the excitation power source 8 was also removed. During this time, only the liquid helium 2 is replenished using the flange 200 dedicated to the liquid filling shown in FIG. The flange 200 is composed of a liquid filling pipe 50, a valve 51, and a disc 52 serving as a flange. A low-temperature pipe (not shown) connected to a liquid helium tank (not shown) is inserted into the pipe 50 by opening the valve 51 and filled with liquid. Although it is necessary to replenish liquid helium 2 about once a week or once a month, it is not possible to completely eliminate the atmosphere from outside the low temperature container 1 from entering inside during the filling operation. Therefore, the more times the liquid is added, the more frost 42 will accumulate.

Next, as shown in FIG. 4, the movable connector 18 of the removable lead 100 and its neighboring removable leads are blown with hot air 31 using a dryer 30 with a heater to heat the movable connector 18 to about 150°C. did.
Such a heating operation was performed outside the low temperature container 1 before the removable lead 100 was attached to the low temperature container 1. After this heating operation, the heating of the heated movable connector 18 and the detachable leads in its vicinity is stopped, and immediately the movable connector 18 is attached and detached into the cryogenic container 1 along the guide member 16 to prevent the temperature from decreasing. Lead 100 was inserted. This state is shown in FIG. In the figure, the arrow represents a state in which a portion of the frost 42 is vaporized and discharged to the outside of the cryogenic container 1 through the helium gas exhaust pipe 14.

As shown in FIG. 5, since the movable connector 18 was inserted into the fixed connector 19 in a heated state, the frost 42 that had accumulated on the fixed connector 19 was removed.
The helium gas was gradually heated and vaporized starting from the part closest to the movable connector 18, and was discharged to the outside of the low temperature container 1 through the helium gas exhaust pipe 14 disposed above the removable lead 100. In addition, some of the moisture passed through the gap between the fixed connectors 19 and fell into the low temperature container. Therefore, the amount of frost 42 on the fixed connector 19 has been drastically reduced, and the frost thickness d has become less than 10% of that before the heated detachable lead 100 is inserted. Note that even if moisture falls into the low-temperature container, there is no problem in terms of performance.

When the electrical continuity between the male pin 21 and the female pin 22 was measured in the above state, it was found that there was sufficient electrical continuity.

However, as is clear from the situation in FIG. 5 where the removable lead 100 is inserted after being heated, the frost 42 does not completely disappear with one insertion operation of the removable lead 100 and is fixed to the movable connector 18. Connector 19
In between, it was wedged between both connectors and remained in a compressed state. There is already continuity between the connectors, so there is almost no problem electrically, but there is a slight structural problem because the removable leads are not in the correct position. However, this situation was quickly resolved. That is, when the removable lead 100 in the situation shown in FIG. 6 was pulled out again, moved to the outside of the cryogenic container 1, and the above-described operation of heating and inserting the movable connector 18 was performed again, the frost 42 was completely removed. Disappeared. Naturally, there was electrical continuity between the connectors. FIG. 6 shows the state in which the removable lead 100 has been removed again. The surface of the male pin 21 at the top of the fixed connector 19 is completely free of frost 42. In this way, by inserting the removable lead 100 only twice,
The frost 42 that had piled up high has completely disappeared.
The removable lead 100 could be inserted in the correct position and very smoothly, and the electrical characteristics were completely satisfied.

In addition, the frost 42 completely disappears from around the attachment/detachment part of the liquid reservoir pipe 41 between the fixed connector 19 and the movable connector 18 and from inside the pipe, making it possible to supply liquid helium 2 to the cryogenic container 1 without any trouble. did it.

In addition, in the above embodiment, the movable connector 18 is
℃, but if it is clear that the main component of the frost 42 is solidified air,
Movable connector 18 may also be at a lower temperature.
That is, the movable connector 18 is heated to 40°C to 70°C by a dryer with a heater, and the fixed connector 19 is heated to 40°C to 70°C.
I tried to connect to it, but the air solidified and it turned out to be frost 4.
2, the frost 42 could be completely removed from the fixed connector 19 by inserting the removable lead and heating it only twice.

The heating temperature of the movable connector 18 can be appropriately selected from 0° C. or higher depending on the state of the frost 42. Moreover, the above heating temperature is the movable connector 18
It is desirable to set the temperature to the highest within the temperature range within which each part of the unit will not lose its original function.

In the above embodiment, the connector is connected to the persistent current switch 9 via a lead wire, or is a pipe for supplying refrigerant. The sensor 15 and the measuring device 17 may be connected to each other.

Further, in the above embodiment, the dryer 30 with a heater is used as the heating means, but it may also be an air conditioner in the room where the low temperature container 1 is installed, and the same effects as in the above embodiment can be obtained. Alternatively, a gas burner may be used, and in this case, it is possible to quickly heat up to a high temperature range, so that the work can be completed in a very short time.

FIG. 7 shows another embodiment, in which a helium gas recovery means is installed at the end of the helium gas exhaust pipe 14, and 70 is a recovery line for recovering the evaporated gas of the liquid helium 2. It is connected to the exhaust pipe 14. 71 is a gas bag that stores gas from the recovery line 70; 72 is a gas holder 7 that compresses the gas stored in the gas bag;
This is a compressor for packing into 3. Collection line 7
0 is set to a slightly positive pressure (0.01 atmosphere to 0.05 atmosphere) than the pressure outside the recovery line in order to avoid mixing of impure gas from outside the recovery line.

The recovery line 70 is usually piped under the floor or ceiling of the building, and collects gas from various cryogenic vessels 1. By the way, the helium gas in the recovery line 70 is usually quite contaminated due to dirt inside the pipe and air mixed in during gas recovery. However, in the structure shown in FIG. 7, the compressor 72 is turned on.
-off operation or when the amount of helium gas evaporated from the low temperature container 1 is very small, the pressure in the recovery line 70 often becomes considerably higher than the pressure in the low temperature container 1. Under such a situation, impure helium gas rapidly flows back into the cryocontainer 1 and is solidified by the liquid helium 2, forming a large amount of frost 42 and depositing on the fixed connector 19. Although such a situation does not occur when helium vapor gas is released to the atmosphere, helium, which is a very expensive gas, is typically recovered as much as possible. Therefore, if a system for recovering helium gas is attached to the low-temperature container 1, the present invention can exhibit an even more significant reliability improvement effect.

When frost adheres to the fixed connector portion of a superconducting magnet used in persistent current operation and electrical conductivity with the external lead cannot be established, the superconducting magnet becomes completely unusable. Therefore, the effectiveness of the present invention, which allows the connector section to be electrically and mechanically reliably attached and detached, can be fully understood.

〔Effect of the invention〕

As is clear from the above explanation, this invention
A fixed connector for the lead wire on the superconducting coil side is fixed to the bottom of a guide member provided inside the cryogenic vessel, and a removable lead with a movable connector that can be inserted and removed along the guide member is provided. You can connect the leads easily and reliably.
Improved reliability.

In addition, another invention of the present invention is that the movable connector is heated and connected to the fixed connector, so that frost accumulated on the fixed connector can be quickly removed, and the leads inside and outside the cryogenic container are It is possible to ensure continuity between the two.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention,
Fig. 1 is a front sectional view, Fig. 2 is a partially sectional perspective view for explaining the action, Fig. 3 is a partially front sectional view showing when refrigerant is injected, and Fig. 4 is a heating of the movable connector. FIG. 5 is a partial front sectional view showing the operation, FIG. 5 is a partial front sectional view showing the insertion mode of the movable connector, and FIG. 6 is a partial sectional perspective view showing the mode after frost removal. 7th
The figure is a schematic front view of another embodiment. Figures 8 to 10 show conventional superconducting magnet devices. Figure 8 is a front cross-sectional view, Figure 9 is an equivalent circuit diagram of the one in Figure 8, and Figure 10 is a diagram with the current lead removed. It is an equivalent circuit diagram. 1... Low temperature container, 2... Refrigerant, 3... Superconducting coil,
9... Persistent current switch, 16... Guide member, 18
...Movable connector, 19...Fixed connector, 100...
Detachable lead.

Claims (1)

[Claims] 1. A low-temperature container, a superconducting coil and a refrigerant housed in the low-temperature container, a persistent current switch connected in parallel to the superconducting coil, and a persistent current switch vertically disposed in the upper part of the low-temperature container. a fixed connector fixed to the bottom of the guide member and connected to the leads of the superconducting coil and the persistent current switch; and a movable connector that is inserted and removed along the guide member and attached to and removed from the fixed connector. A superconducting magnet device comprising a removable lead connected to a connector and leading to the outside of the cryogenic container. 2. The superconducting magnet device according to claim 1, comprising a movable connector to which the excitation power supply lead connected to the superconducting coil and the heater power supply lead connected to the persistent current switch are connected. 3. The superconducting magnet device according to claim 1, comprising a fixed connector and a movable connector for connecting and separating measurement leads that connect sensors and measuring instruments placed inside and outside the low-temperature container, respectively. 4. The superconducting magnet device according to claim 1, comprising a fixed connector and a movable connector that also connect and disconnect a liquid pipe for supplying refrigerant into a low-temperature container. 5. The superconducting magnet device according to claim 1, comprising a gas recovery means for recovering evaporated gas of the refrigerant. 6. The superconducting magnet device according to claim 5, comprising a gas recovery means consisting of a recovery line, a gas bag, a compressor, and a gas holder. 7. A low-temperature container, a superconducting coil and a refrigerant housed in the low-temperature container, a persistent current switch connected in parallel to the superconducting coil, and a cylindrical guide member vertically disposed in the upper part of the low-temperature container. A fixed connector is fixed to the bottom of the guide member to which the leads of the superconducting coil and the persistent current switch are connected, and a movable connector is connected to the fixed connector by being inserted into and removed from the fixed connector along the guide member. A method for connecting an external lead of a superconducting magnet device comprising a removable lead leading to the outside of a container, characterized in that the movable connector is heated outside the low-temperature container, and then the movable connector is coupled to the fixed connector. A method for connecting external leads to a superconducting magnet device. 8. A method for connecting external leads of a superconducting magnet device according to claim 7, wherein the operation of heating the movable connector and pressing it against the fixed connector is performed multiple times.