JP2913388B2 - Superconducting magnet device using a refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet device using a refrigerator.

[0002]

2. Description of the Related Art In a superconducting magnet device, a superconducting coil is arranged in a vacuum vessel, cooled to a predetermined temperature (10 K to 4 K) using liquid helium, brought into a superconducting state, generates a high magnetic field, and uses various materials. Used for testing. By the way, the above liquid helium is very expensive and has a high volatility, so that great care must be paid to measures for preventing evaporation and leakage, and since maintenance is difficult, the GM (Gifford McMahon) type is used. A superconducting magnet device using a refrigerator as a cooling means instead of liquid helium is known.

FIG. 5 shows an example of a superconducting magnet device using a GM refrigerator. 1 is a vacuum container. The vacuum container 1 includes a concave container 2 and a top plate 3 that covers an opening of the container 2.

[0004] Inside the vacuum vessel 1, an inner chamber body 4 for heat shielding is suspended by a cylinder portion C-1 described later. The inner chamber 4 includes an outer cylindrical wall 5, a top plate 6, and a bottom plate 7. Further, a cylinder portion C described later is provided in the inner chamber body 4.
-2 fixed plate 8 suspended by
And a superconducting magnet 10 attached to the lower surface of the device. There is an empty space 9 in the center of the superconducting magnet 10.
Is formed, and the inside of the space 9 is used as a high magnetic field space.

In the illustrated example, the loading and unloading of the test piece material is carried out by disassembling and assembling the inner chamber 4 and the vacuum vessel 1 each time. There is an open type in which the high magnetic field space is opened by being depressed along the empty space 9 so that the material can be charged and unloaded without disassembling and assembling the inner chamber body 4 and the vacuum vessel 1. .

Reference numeral 11 denotes a GM refrigerator, and a refrigerator mounting flange 12 is fixed to the top plate 3 of the vacuum vessel 1. Refrigerator 1
1, one-stage cylinder portion C-1, one-stage cold head portion F-
1st and 2nd stage C-2, 2nd stage cold head F-
2 is inserted into the vacuum vessel 1, the top plate 6 of the inner chamber body 4 is fixed to the mounting flange 13 of the one-stage cold head F-1, and the mounting flange 1 of the two-stage cold head F-2 is mounted.
The fixing plate 8 is fixed to 3A.

As described above, in the superconducting magnet device having the refrigerator 11, the refrigerator 11 is connected to the top plate 3 of the vacuum vessel 1.
, And a single-stage cold head F-
1, the top plate 6 of the inner chamber 4 and the two-stage cold head F
The fixing plates 8 are respectively fixed to −2. The amount of cold generated in each cold head portion is transferred by solid surface contact, and the inside of the inner chamber body 4 in which the heat entering from the room temperature side is shielded by the one-stage cold head portion F-1 is reduced to about 70K to 40K. The superconducting magnet 10 is cooled by the two-stage cold head unit F-2 to about 10K to 4K.

In this superconducting magnet apparatus, since the superconducting magnet 10 is heavy and has a large heat capacity, it is necessary to cool the superconducting magnet 10 to a predetermined cryogenic temperature (10K to 4K) at which a superconducting state occurs. In fact, it requires a very long time (the time required for cooling varies depending on the weight of the coil, but the time required for cooling is 48 hours or more), and reduction of the cooling time has been eagerly desired.

Therefore, as shown in FIG. 5, a cooling pipe 14 is provided near the superconducting coil, and liquid nitrogen is circulated through the cooling pipe 14 so that the superconducting liquid One that performs pre-cooling of the magnet 10 has been considered. This conventional apparatus has a number of drawbacks, such as the necessity of special liquid nitrogen, and the requirement of operators for handling liquefied gas.

[0010]

As a result of intensive studies on the GM refrigerator, as shown in the graph of FIG. 2, the present inventors have found that the GM refrigerator has an initial cooling stage from normal temperature to around 50K. The present invention has been completed by paying attention to the fact that the two-stage cold head has a cooling capacity four times higher than that of the two-stage cold head. The present invention can be used at room temperature to 5
Provided is a superconducting magnet device using a refrigerator capable of shortening the time required for cooling a superconducting magnet by assisting the transfer of cold heat from a first-stage cold head portion to a two-stage cold head portion in an initial stage of cooling to around 0K. With the goal.

[0011]

A superconducting magnet apparatus using a refrigerator according to the present invention comprises a top plate of an inner chamber fixed to a single-stage cold head and a fixing plate fixed to a two-stage cold head. during the one end fixed to one of the top board or fixed plate and the other end is arranged a contact and separation freely and has been heat transfer member by contact plate to the other, the heat transfer body is a two-stage cylinder A temperature measuring sensor for detecting the temperature of the superconducting magnet; and an actuator for detecting a temperature of the superconducting magnet, and an actuator based on a signal from the sensor. And a control device for instructing a switching output to the working fluid supply switching unit.

Further, the superconducting magnet apparatus using the refrigerator of the present invention is characterized in that a top plate of the inner chamber fixed to the first-stage cold head portion and a fixing plate fixed to the second-stage cold head portion. One end is fixed to one of the top plate and the fixed plate, and the other end is provided with a heat transfer member that is freely movable toward and away from the other end by a contact plate. A rod connected to the contact plate of the heat transfer body and having the other end extended outside the vacuum vessel, a temperature measuring sensor for detecting the temperature of the superconducting magnet, and a sensor And a monitor for displaying the detected temperature.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 and 3 are explanatory diagrams of a superconducting magnet device using a refrigerator according to the present invention. FIG.
The same parts as in the conventional example are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 1, reference numeral 20 denotes a top plate 6 of the inner chamber 4.
And a fixing plate 8 fixed to the two-stage cold head portion F-2. The heat transfer member is arranged so as to surround the two-stage cylinder portion C-2 and the two-stage cold head portion F-2. . The upper end of the heat transfer body 20 is fixed to the top plate 6 of the inner chamber body 4. A two-stage cylinder part C-
2 has a structure 20A that can expand and contract in the longitudinal direction, and a contact plate 21 is provided at the lowermost end. An actuator 23 is connected to the contact plate 21 via a heat insulating material rod 22.
Is connected. Then, the contact plate 21 is pressed against the fixed plate 8 by the actuator 23 to be joined by solid surface contact and to be separated.
Although FIG. 4 shows an example in which the contact plate 21 is pressed against the fixed plate 8 by two actuators 23, 23, the number and the arrangement of the
It may be determined appropriately in accordance with the size of 1.

Numeral 24 denotes a temperature measuring sensor installed near the superconducting coil constituting the superconducting magnet 10, 25
Is a control device provided with a temperature setting device (not shown). The control device receives a temperature signal detected by the temperature measurement sensor 24 and compares it with the set temperature of the setting device. When both values match, an output signal is issued from the control device. As a result, the air valve 26 is shut off, and the rod 22 extending from the actuator 23 is contracted into the actuator 23 by a built-in spring to separate the contact plate 21 from the fixed plate 8.

When the superconducting magnet 10 is cooled, the refrigerator 11 is operated, and at the same time, the pressure is supplied to the actuator 23 so that the rod 22 is extended from the actuator 23 against the elasticity of the built-in spring to transfer the power. The contact plate 21 at the lower end of the heating element 20 is pressed against the fixed plate 8 as shown by a broken line in FIG. As a result, a solid heat transfer path is formed between the top plate 6 and the fixed plate 8 by the heat transfer body 20.
A part of the cold generated in the step cold head F-1 is transmitted to the fixed plate 8 through the heat transfer body 20.
The fixed plate 8 is supplied with a combination of the cold heat from the two-stage cold head portion F-2 and the cold heat transmitted from the one-stage cold head portion F-1 via the heat transfer member 20, and the cooling speed is increased.

When the temperature detected by the temperature measuring sensor 24 reaches a predetermined temperature (50 K) set in a setting device in the control device 25, an output signal is output from the control device 25 and the air valve 26 is closed. With Actuator 2
The pressurized air in 3 is released to the outside of the device, and the rod 22 contracts into the actuator 23 by the restoring force of the built-in spring to separate the contact plate 21 from the fixed plate 8. Thereafter, the superconducting magnet 10 is moved to the two-stage cold head portion F-
2 to a very low temperature (10K to 4K). After measuring the time required to cool the coil,
It was found that the time can be reduced to about 30 hours or less.

In the above embodiment, the control device 25 and the actuator 23 are provided for automatic disconnection control. In the case of this manual disconnection, as shown in FIG. 3, a monitor 30 for displaying the temperature is provided, and a rotary joint 32 is provided in the middle of the insulating material rod 22 for operating the contact plate 21,
Further, a spring 31 is provided so as to always push down the rod 22. Then, when the detected temperature received from the temperature detection sensor 24 is displayed as 50 K on the monitor 30, the operator raises the rod 22 against the pressing force of the spring 31 to manually separate the contact plate 21 from the fixed plate 8. Like that.

In the example shown in FIG. 3, the outer end of the rod 22 that has been pulled up is rotated by about 90 ° and locked to the stopper 33. To bring the contact plate 21 into contact with the fixed plate 8, the outer end of the rod 22 is rotated to remove it from the stopper 33, and the rod 22 is pushed down by the restoring force of the spring 31. Further, the heat transfer body 20 is opposite to the illustrated example,
A contact plate 21 is provided at the upper end, and the contact plate 21 is
May be joined to and separated from the top plate 6 by the actuator 23.

Further, as shown in FIG.
Is equipped with a manual valve 26A, or a heating mode (not shown) is provided in the control device 25, and the valves 26, 26A
When the contact plate 21 is pressed against the fixed plate 8 by supplying pressure air to extend the rod 22 extending from the actuator 23, the heat transfer member 2 is used for maintenance of the superconducting magnet 10 and the like.
The time required for restoring the superconducting magnet from the extremely low temperature state to the normal temperature state can be shortened by utilizing the heat transfer effect of zero.

[0021]

According to the present invention, in the initial stage of cooling from room temperature to around 50K, the cooling time of the superconducting magnet can be easily reduced by supporting the transfer of cold from the first cold head to the second cold head. 5 can be reduced (about 30 hours or less) and the conventional apparatus shown in FIG. 5 can only cool the liquid nitrogen to a temperature of 77K.
It has the effect of being able to cool down to about K and exhibiting a large pre-cooling effect.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a superconducting magnet device using a refrigerator according to the present invention.

FIG. 2 is a graph showing the cooling performance of a first-stage cold head unit and a two-stage cold head unit of a GM refrigerator.

FIG. 3 is an explanatory diagram of another embodiment of the present invention.

FIG. 4 is an explanatory diagram of still another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a superconducting magnet device using a conventional refrigerator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 4 Inner body 23 Actuator 6 Top plate 24 Temperature measurement sensor 8 Fixed plate 25 Control device 10 Superconducting magnet 30 Monitor 20 Heat transfer body C-2 Two-stage cylinder part 20A Stretchable structure F-1 One-stage cold head part 21 Contact Plate F-2 Two-stage cold head part 22 Rod

Claims (3)

(57) [Claims] An end is fixed to one of a top plate and a fixed plate between a top plate of an inner chamber fixed to a one-stage cold head portion and a fixing plate fixed to a two-stage cold head portion. the other end is arranged is separable freely and has been heat transfer member by contact plate to the other, said heat transfer body has a mechanism that can stretch in the longitudinal direction of the two-stage cylinder, the heat transfer A temperature measurement sensor that detects the temperature of the superconducting magnet, including an actuator that operates the contact plate of the heating element,
A superconducting magnet device using a refrigerator, comprising: a control device for commanding a switching output to a working fluid supply switching portion of the actuator based on a signal from the sensor. 2. One end is fixed to one of the top plate and the fixed plate between a top plate of the inner chamber fixed to the one-stage cold head portion and a fixing plate fixed to the two-stage cold head portion. The other end is provided with a heat transfer body which is freely movable toward and away from the other side by a contact plate. The heat transfer body has a mechanism capable of expanding and contracting in the longitudinal direction of the two-stage cylinder portion. A rod connected to the contact plate of the heat body and having the other end extended out of the vacuum vessel, a temperature measuring sensor for detecting the temperature of the superconducting magnet, and a monitor for displaying the detected temperature of the sensor are provided. A superconducting magnet device using a refrigerator. 3. A superconducting magnet apparatus using a refrigerator according to claim 2, wherein an urging spring and a rotary joint are provided on the rod.