JPH03235306A - Superconducting coil cooling device - Google Patents

Abstract

PURPOSE:To prevent air from entering from the outside by providing a pipe, or the like leading to a gas port, etc., with a gas introduction means for refrigerant gas supply. CONSTITUTION:A vacuum vessel 3 surrounds a helium vessel 2 which is a refrigerant vessel to contain a superconducting coil 1 and a refrigerant liquid helium 20. The discharge pipe 41, leading to a gas port 22a and a current port 22b, of this vessel 3 is provided with gas introduction means such as a gas introduction pipe 43 for supplying the refrigerant helium gas, the same as liquid helium, an open/close valve, and others. Accordingly, when refrigerant gas is supplied by a gas supply means even at the time of opening of each port for supply of the refrigerant, the insertion/extraction of a current lead, the air entrance from the outside can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to NMR (Nuclear Magnetic
Regarding superconducting coil cooling devices for Re5onance (Nuclear Magnetic Resonance) analysis, we have developed a superconducting coil cooling device that prevents air from entering the device when filling with cryogen such as liquid helium or inserting and removing current leads used to excite superconducting coils. This invention relates to a coil cooling device.

[Prior Art] For example, there is a conventional superconducting coil cooling device as shown in FIG. This helium tank 2 is housed inside a donut-shaped shield tank (not shown) containing liquid nitrogen or the like, and these are further connected to a donut-shaped vacuum tank 4 fixed in a predetermined place by a stand 5. It is housed inside in a vacuum state. The helium tank 2 is integrated with the vacuum tank 3, and includes a helium boat 22a into which a transfer tube used when filling with liquid helium 20 is inserted, and an insertion path for a current lead connected to the connector 11 when exciting the superconducting coil 1. It is integrally suspended from the upper fixed part of the vacuum chamber 3 via the current port 22b and the helium tubes 21a and 21b. helium port 22a
, and the upper part of the current port 22b are provided with seal portions 23a and 23b called Wilson seals, respectively, and sealing plugs 24a and 24b are normally inserted into these to seal them. There is. helium port 2
2a and the current port 22b are connected by a connecting pipe 4, and a current of 0.05 kgf/
A discharge pipe 41 is provided integrally with the connecting pipe 4 and has a leak valve 42 at its tip that opens at a pressure of about cm2G.

In the above configuration, when performing nuclear magnetic resonance analysis, a room temperature space (normal temperature bore) formed inside the inner cylinder of the vacuum chamber 3 is used.
A sample is put into the inner hole 3A of the outer chamber 11. which is connected to the connector 11. (not shown) to energize the coil l.

On the other hand, when filling the helium tank 2 with liquid helium due to a reduction in the amount of liquid helium 2o, remove the sealing plug 24a from the sealing part 23a, and insert a transfer tube for filling liquid helium from there with its tip end in the helium tank. 2
This is done by inserting it until it reaches.

[Problem to be solved by the invention]

However, according to conventional superconducting coil cooling devices, the insulation properties are extremely high, and the amount of evaporation of liquid helium is approximately 0.011.
Since the amount of helium gas is extremely small at 1/hour (rut in terms of waste amount, approximately o, 1i7 minutes), the flow rate of helium gas discharged to the outside when the sealing plugs 24a and 24b are opened is extremely small. For this reason, filling with liquid helium or connector 1
The sealing plug 24 is used for the purpose of insertion and removal of the current lead connected to 1.
If a and 24b are opened, even if you work quickly, the outside air (nitrogen gas, oxygen gas, water vapor, etc.), which has a higher specific gravity than helium gas, will become helium gas (22 a)
Otherwise, it may enter through the current port 22b, causing ice to form on the internal helium tubes 21a, 21b and the upper part of the helium tank 2. Normally, a superconducting coil cooling device for NMR analysis is operated continuously for 5 to 10 years or more unless there are any abnormalities, and during that time the helium tank 2 is always maintained at a temperature around 4.2 degrees, so The air that has turned into ice is never discharged to the outside, and each time the sealing plugs 24a and 24b are opened for the above-mentioned purpose, the small amount of air that enters causes the ice to become larger, and it becomes difficult to insert the transfer tube. In the worst case scenario, the helium tubes 21a and 21b may be completely blocked, or ice may form on the connector 11, making connection (fitting) with the current lead difficult or impossible. There is an inconvenience.

Therefore, an object of the present invention is to provide a superconducting coil cooling device that can prevent air from entering from the outside when a port is opened for the purpose of supplying a cryogen or inserting or removing a current lead for a superconducting coil. It is to be.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the present invention provides a gas port,
A superconducting coil cooling device is provided in which a gas introducing means for supplying the same cryogen gas as the evaporated gas of the cryogen is provided at an appropriate position of a tube leading to a current port.

That is, in the superconducting coil cooling device of the present invention, a cryogen tank containing a cryogen such as liquid helium is suspended, and an appropriate supply/discharge pipe for supplying the cryogen to the cryogen tank or discharging evaporated gas of the cryogen is provided. A gas introducing means for supplying the same cryogen gas as the evaporated gas is provided at the position. This gas introduction means is composed of, for example, a gas introduction pipe provided so as to branch from the supply/discharge pipe, and an on-off valve that opens and closes the introduction pipe. It has a configuration that allows cryogen gas to be supplied to the supply/discharge pipe by opening it. In addition, in a superconducting coil cooling device in which multiple ports are connected by connecting pipes,
A gas introduction means may be provided in the connecting pipe. In such a configuration, the internal pressure of the supply/discharge pipe and the cryogen tank can be increased by the cryogen gas supplied by the gas introduction means, and the current lead used for supplying the cryogen or excitation of the superconducting coil can be inserted or removed. Even if the supply/discharge pipe is opened for this purpose, the intrusion of air can be prevented by discharging the cryogen gas. Therefore, it is possible to prevent freezing inside the device due to air infiltration, and improve reliability and the like.

〔Example〕

Hereinafter, the superconducting coil cooling device of the present invention will be explained in detail.

FIG. 1 shows an embodiment of the present invention, and the same parts as in FIG. Gas introduction pipe 43 equipped with an on-off valve 44 on the side of the protruding discharge pipe 41
is provided.

In this configuration, when filling the helium tank 2 with liquid helium, first connect the gas supply pipe (not shown) to the gas introduction pipe 43, and before opening the sealing plug 24a,
4 to release helium gas into the device (connecting pipe 4, helium port 22a, current port 22b, helium pipe 21a
, 21b), and the pressure inside the device is increased to such an extent that the leak valve 42 does not open wide. In this state, the sealing plug 24a is opened and preparations are made for filling liquid helium. The helium gas supplied from the gas introduction pipe 43 passes through the upper end of the helium boat 22a and is released to the outside from the open seal portion 23a. At this time, the flow rate of helium gas is set to 10~15i! ,/minute or more, the flow of gas released from the seal portion 23a becomes sufficient and air can be prevented from entering from the outside. A predetermined operation is performed using the transfer tube, and after filling with liquid helium, the sealing plug 24a is fitted into the seal portion 23a to close the on-off valve 44.

This completes the liquid helium filling operation.

Further, if helium gas is supplied from the gas introduction pipe 43 during the connection work of the connector 11, the current lead can be inserted and removed without allowing air to enter the device.

In this way, by supplying helium gas from the gas introduction tube 43 when filling with liquid helium or when inserting/extracting the current lead, air does not enter into the open seal portions 23a, 23b, respectively, and the helium tubes 21a, 2
1b, the connector 11, the upper part of the helium tank 2, etc. can be prevented from freezing.

Further, in the above embodiment, the gas introduction pipe 43 is attached to the discharge pipe 41 of the connecting pipe 4, but the invention is not limited to this, and instead of using the connecting pipe, the helium boat 22a,
Two pieces may be individually attached to 22b. Further, the structure of the on-off valve 44 is not limited as long as it is always closed and opens when cryogen gas is supplied.

〔Effect of the invention〕

As explained above, according to the superconducting coil cooling device of the present invention, gas introduction means for supplying the same cryogen gas as the evaporated gas of the cryogen is provided at appropriate positions of the gas port and the pipe leading to the current boat. When each port is opened for the purpose of supplying current, inserting and removing current leads, etc., it is possible to prevent air from entering from the outside, and it is possible to prevent freezing inside the device.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a conventional superconducting coil cooling device. Explanation of symbols 1--------・--[tl coil 2-----...
......--Helium tank 3A...--1---
−−−−・Inner hole 3・−・・・・・・・・・・−・
−Vacuum chamber 4−−・−・−・Series of tubes 5・−
−−−−−−−−−・・・・Stand 11− ・・・−
・・・・・・Connector 20------------Liquid helium 21a, 21
b---111111 helium tube 22 a-1・-
-1------Helium port 22 b---m-・
------One current boat 23a, 23b----
-----------Seal parts 24a, 24b -
−−−−−−−−−−One sealing plug 41～−−−−・−・−
-----One discharge tube 4243・------
-Gas introduction pipe 44--Leak valve on/off valve

Claims (2)

[Claims] (1) A superconducting coil comprising a superconducting coil and a cryogen tank containing a cryogen, and a vacuum tank surrounding the cryogen tank in a vacuum state on its outer periphery, and a supply pipe for supplying the cryogen to the cryogen tank. A superconducting coil cooling device, characterized in that the supply pipe is provided with a gas introducing means for supplying the same cryogen gas as the evaporated gas of the cryogen. (2) The superconducting coil cooling device according to claim 1, wherein the gas introducing means is provided in a connecting pipe connecting a plurality of the supply pipes.