JPH041483B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to excitation of a superconducting magnet that is immersed and cooled in a cryogenic refrigerant housed in a cryogenic refrigerant container and placed in a room temperature environment. This invention relates to an improvement in a current supply lead for supplying current from a commercial power source.

(Prior art) Conventionally, a current is supplied from an excitation power supply placed in a normal temperature environment to a superconducting coil of a superconducting magnet that is immersed and cooled in a cryogenic coolant such as liquid helium stored in a cryogenic coolant container. As a means of
Current supply leads have been used. and,
Regarding the technology related to this type of current supply lead, heat exchange with the lead surface is performed by the evaporated cryogenic refrigerant due to the heat entering the cryogenic refrigerant at the low temperature end of the current supply lead, and the current supply lead is extended over its entire length. There are gas-cooled current supply leads configured to cool and reduce incoming heat.

However, in a superconducting magnet, such as a superconducting magnet for a gyrotron, which has two or more superconducting coils and adjusts the magnetic field configuration by independently exciting each of these superconducting coils, As a result, the number of current supply leads increases, and if the above-mentioned gas cooling current supply leads are independently applied to each current supply lead, the following problem will occur.

(a) The total cross-sectional area of the gas cooling current supply lead becomes very large, resulting in a large amount of heat intrusion into the cryogenic refrigerant container.

(b) If the length of the lead is increased in order to reduce the amount of heat intrusion mentioned above, the structure of the gas-cooled current supply lead not only becomes very complicated and large, but also
As each gas flow path becomes narrower and longer,
Even the slightest intrusion of air can cause the gas flow path to become clogged with moisture.

(c) Since the cooling gas flow rate for each current supply lead tends to be unbalanced, it is not possible to perform optimal limit design for each current supply lead, such as selection of lead cross section and design of gas cooling pipe.

(Problems to be Solved by the Invention) As described above, in the conventional gas cooling current supply lead, the amount of heat entering the cryogenic refrigerant container is large, the structure is complicated and large, and the current supply lead is There was a problem in that it was not possible to perform an optimal limit design for the supply lead.

Therefore, in the present invention, the amount of heat entering the cryogenic refrigerant container is reduced without increasing the length of the lead,
The object of the present invention is to provide a highly reliable gas-cooled current supply lead that is simple in structure and compact, and allows optimal limit design.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a superconducting magnet that is immersed and cooled in a cryogenic refrigerant housed in a cryogenic refrigerant container and is placed in a normal temperature environment. The current supply lead for supplying current from the excitation power source has an outer tube whose lower end is attached to the cryogenic refrigerant container and a hole for releasing evaporative gas of the cryogenic refrigerant on the upper end side. An inner tube is arranged with a certain gap inside the tube, and the inner tube is wound around the outer circumference of the inner tube to be longer than the length of the inner tube. and a plurality of current supply conductors for supplying current to the superconducting coils of the superconducting magnet, the evaporated cryogenic refrigerant is passed through the gap between the outer tube and the inner tube to evaporate the cryogenic refrigerant. The gas is discharged into the atmosphere through the inner tube through the gas discharge hole.

(Function) In the above-mentioned gas-cooled current supply lead, a plurality of current supply conductors for supplying current to the superconducting coil of the superconducting magnet are connected to a single conductor formed by the gap between the outer tube and the inner tube. Since they are commonly disposed in one gas flow path, each current supply conductor is cooled by the evaporated cryogenic refrigerant passing through this gas flow path without causing flow imbalance. Furthermore, since a plurality of current supply conductors are arranged within a single gas cooling pipe, the amount of heat entering the cryogenic refrigerant container is reduced. Furthermore, the above-mentioned reduction in the amount of heat intrusion eliminates the need to increase the length of the gas cooling pipe, resulting in a simple and compact configuration.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an example of the configuration of a gas-cooled current supply lead according to the present invention, and FIG. 2 is a plan view of FIG. 1.

In the figure, reference numeral 1 has a flange 1a connected to a vacuum container (not shown) at its upper end, and is an outer tube made of stainless steel, for example. It is attached to the container by welding, etc. On the other hand, 2
The inner tube has a flange 2a at its upper end and is made of, for example, GFRP with low thermal conductivity, and is disposed inside the outer tube 1 with a certain gap as shown in the figure. Moreover, this inner tube 2 is located at the illustrated position on the upper end side.
It has a plurality of holes 2b for releasing liquid helium evaporated gas along the circumferential direction, and on the outer peripheral side of the inner tube 2 below the holes 2b for releasing liquid helium evaporated gas, there is a hole 2b that is longer than the length of the inner tube 2. A plurality of current supply conductors 3 (two in this example) are wound in a spiral shape along the inner tube 2 so as to be long. Furthermore, a lead terminal 4 under a normal temperature environment is connected to these two current supply conductors 3, and a superconducting coil of a superconducting magnet (not shown) is connected to the excitation power supply under a normal temperature environment via the lead terminal 4. It is designed to supply current to. As described above, the evaporated liquid helium is passed through the gap between the outer tube 1 and the inner tube 2 and from the cryogenic refrigerant evaporated gas release hole 2b to the inner tube 2.
Each current supply conductor 3 is cooled by discharging it into the atmosphere through the inside of the current supply conductor 3. Note that as the material of the above-mentioned current supply conductor 3, for example, copper (phosphorus-deoxidized copper) having low thermal conductivity is used. Furthermore, from the lower end of the inner tube 2 to the hole 2b for releasing cryogenic refrigerant evaporated gas, a stuffing 5 of, for example, styrene foam is packed inside to prevent liquid helium gas from entering the tube.

In the gas cooling current supply lead having such a configuration, since the plurality of current supply conductors 3 are commonly arranged in a single gas cooling pipe consisting of the outer tube 1 and the inner tube 2, the gas cooling current supply lead is The total cross-sectional area of the leads becomes significantly smaller, and as a result, it becomes possible to significantly reduce the amount of heat entering the cryogenic refrigerant container. In addition, a plurality of current supply conductors 3 are connected to the outer tube 1.
Since they are commonly arranged in a single gas flow path formed by the gap between the inner tube 2 and the inner tube 2, evaporated liquid helium passing through this gas flow path causes
Each current supply conductor 3 is uniformly cooled without causing flow imbalance, and cooling efficiency can be improved. This allows selection of lead cross section,
It becomes possible to perform optimal limit design for each current supply conductor, such as the design of a gas cooling pipe. Furthermore, in order to reduce the amount of heat intrusion into the cryogenic refrigerant container, even if the length of the current supply conductor 3 is long, the length of the gas cooling tube consisting of the outer tube 1 and the inner tube 2 is short. This not only makes the configuration of the gas cooling current supply lead extremely simple and compact, but also makes the gas flow path wider and shorter, which prevents gas flow from being caused by moisture caused by a small amount of air intrusion. There will no longer be any road blockages. Furthermore, even if the number of current supply conductors 3 is multiple, only one gas cooling pipe is required, so the space on the top surface of the cryogenic container is small, and the number of pipes for recovering or discharging liquid helium is also one. Because it only requires a power grid, installation of gas cooling current supply leads is extremely easy.

It should be noted that the present invention is not limited to the embodiments described above, but can be similarly implemented in the following manner.

(a) In the above embodiment, the current supply conductor 3 is made of copper, which has low thermal conductivity; however, it is not limited to this, and may be formed using other materials with low thermal conductivity. be.

(b) In the above embodiment, the present invention was applied to a superconducting magnet for a gyrotron.
The present invention is not limited to this, and the present invention can be similarly applied to other superconducting magnets.

(c) In the above embodiment, the current supply conductor 3 is connected to the inner tube 2.
Although the case of winding in a linear shape has been described, the present invention is not limited to this, and it may be wound in other predetermined shapes so as to be longer than the length of the inner tube 2.

(d) In the above embodiment, a case was described in which eight current supply conductors 3 were wound around the inner tube 2, but the present invention is not limited to this, and two or more current supply conductors 3 were wound around the inner tube 2. It is also possible to wind it around.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, a current is supplied from an excitation power source placed in a normal temperature environment to a superconducting magnet immersed and cooled in a cryogenic refrigerant contained in a cryogenic refrigerant container. The lead has an outer tube whose lower end is attached to the cryogenic refrigerant container and a hole on the upper end side for releasing evaporated gas of the cryogenic refrigerant, and is arranged with a certain gap inside the outer tube. A plurality of coils are wound around the outer circumferential side of the inner tube so as to be longer than the length of the inner tube, and supply current to the superconducting coil of the superconducting magnet through lead terminals in a normal temperature environment. The evaporated cryogenic refrigerant is passed through the gap between the outer tube and the inner tube, and is passed inside the inner tube through the hole for releasing evaporated gas of the cryogenic refrigerant into the atmosphere. Since the structure is designed to release heat to the cryogenic refrigerant container, the amount of heat entering the cryogenic refrigerant container is reduced without increasing the length of the lead, simplifying the structure and downsizing, and making it possible to perform optimal limit design. This provides an extremely reliable gas-cooled current supply lead.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional configuration diagram showing an embodiment of the present invention, and FIG. 2 is a plan view of the same embodiment. 1... Outer tube, 1a... Flange, 2... Inner tube, 2a...
Flange, 2b...hole for releasing cryogenic refrigerant evaporative gas,
3... Current supply conductor, 4... Lead terminal, 5... Filling.

Claims (1)

[Scope of Claims] 1. In a current supply lead for supplying current from an excitation power source placed in a normal temperature environment to a superconducting magnet immersed and cooled in a cryogenic refrigerant contained in a cryogenic refrigerant container, the An outer tube having a lower end attached to a cryogenic refrigerant container, and an inner tube having a hole on the upper end side for releasing evaporated gas of the cryogenic refrigerant, and an inner tube arranged with a certain gap inside the outer tube. a tube, and a plurality of current supplies wound around the outer circumferential side of the inner tube so as to be longer than the length of the inner tube, and supplying current to the superconducting coil of the superconducting magnet through lead terminals in a normal temperature environment. and a conductor for discharging the evaporated cryogenic refrigerant into the atmosphere through the gap between the outer tube and the inner tube and through the cryogenic refrigerant evaporated gas release hole through the inside of the inner tube. A gas-cooled current supply lead characterized by: 2. The gas-cooled current supply lead according to claim 1, wherein copper, which has low thermal conductivity, is used as the material of the current supply conductor. 3. The gas-cooled current supply lead according to claim 1, wherein the current supply conductor is wound in a spiral shape along the inner tube.