JP2000257967A - Cooling system of high-temperature superconducting filter system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact cooling system that makes a high-temperature superconducting filter to function. SOLUTION: A chamber 20 is placed on the upper part of a compressor 30, a vacuum container 10, a temperature adjuster (a temperature controller) 40, and a power supply 42 are arranged inside the chamber 20, and the vacuum container 10 can cool an outer wall by cooling water and can cover the outer wall with a heat insulator 12. A high-temperature superconducting filter, that is not illustrated and is used as a center of a system, is accommodated into the vacuum container 10, a pulse pipe-refrigerating machine is arranged in the vacuum container, and the operation fluid in the pulse pipe is flow-tightly interlocked to the compressor 30. By the compression and expansion of the operation fluid due to the compressor, cooling is made down to a prescribed cooling temperature (approximately 70K), and the temperature is maintained, thus allowing the high-temperature superconducting filter arranged near cold storage equipment to show superconductivnity performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for applying a high-temperature superconducting filter system to a base station for mobile communication, and more particularly, to a high-temperature superconducting filter, a low-noise amplifier, and a small refrigerator for cooling them. And a high-temperature superconducting reception filter system comprising a thin-film coaxial cable and a technique for making the system function irrespective of changes in the environment of the base station.

[0002]

2. Description of the Related Art Among components, members and elemental technologies constituting a high-temperature superconducting reception filter system, first, technologies relating to production of a high-temperature superconducting film and design, production and processing of a filter substrate have been almost completed. For small refrigerators, the challenge is to improve the cooling efficiency. Although some experimental results have been obtained, there is still room for improvement.

[0003] A high-temperature superconducting filter does not exhibit the superconducting function unless it is cooled below the critical temperature inherent in the superconducting film material and is maintained below that critical temperature. In the case of a YBCO superconducting film, the critical temperature is 93K, and the superconducting filter and the low-noise amplifier operate in a vacuum container cooled to about 70K. The vacuum vessel is used for the purpose of preventing heat from being introduced into the inside from the outer wall, and is maintained at a vacuum degree of about 1/100 Pa so that convection does not occur in the gas in the vacuum vessel. Furthermore, with the transmission of the communication signal to the vacuum vessel, the communication signal is adiabatically transmitted through a special communication cable so that heat from the outside does not enter through the conducting wire.
After being brought into an adiabatic vacuum vessel and the communication signal is narrowed down to a predetermined communication band by a superconducting filter, the passed signal is amplified by an amplifier. A low-noise amplifier placed in a vacuum vessel and having less noise at lower temperatures also has the effect of providing high-quality communications.

A high-temperature superconducting receiving filter system composed of a vacuum vessel and a small refrigerator for cooling the vacuum vessel requires a highly-completed technology from the viewpoint of thermal management.

[0005]

The high-temperature superconducting reception filter system is used in various environments (from below freezing to about 60, 70 ° C.).

When the temperature of the chamber containing the vacuum container rises due to the influence of the environmental temperature, it is inevitable that heat flows from the outer wall of the vacuum container to the inside of the container. This vacuum vessel has a high degree of vacuum, so it can block heat transfer due to convection of gas, but it cannot avoid the inflow of heat due to radiation.Therefore, the load on the refrigerator increases to maintain the cooling temperature of the vacuum vessel. I do. Therefore, it is necessary to provide a refrigerator having a large refrigerating capacity to guarantee a high temperature of 50 to 70 ° C. in the use environment. Then, the size of the refrigerator is increased, and the system itself cannot be made compact because the size of the refrigerator is increased.

Therefore, an object of the present invention is to create a cooling system which is high in thermal efficiency and rational as equipment, aiming at downsizing of a high-temperature superconducting receiving filter system.

[0008]

In order to achieve the above object, a compressor is arranged outside a chamber containing a vacuum vessel to improve heat radiation, and a radiation fin for promoting heat radiation is provided in a part of a rack. And increase the fin surface area to enhance the heat dissipation function. With this improvement, it is possible to reduce the equipment volume for newly installing fins and make the entire system compact.

Further, by cooling the vacuum vessel itself with water and / or covering the outside of the vacuum vessel with a heat insulating material, the heat load accompanying radiant heat can be reduced, and the refrigerator can be downsized.

Similarly, cooling the refrigerator itself by means of water cooling or the like or cooling the chamber itself with water can shut off the temperature change of the external environment, so that there is an advantage that the heat load is stabilized and the cooling of the system. It is effective for the method.

According to the first aspect of the present invention, a high-temperature superconducting filter made of a metal oxide thin film is placed in a vacuum vessel, and refrigeration means for making the filter function is compressed outside the chamber containing the vacuum vessel. A heat dissipating fin is provided around the compressor, and the outside of the vacuum vessel is covered with a heat insulating material. By adopting such a configuration, it is possible to make the high-temperature superconducting filter system compact.

As a heat insulating material, a thick sheet covering material of foamed polystyrene and a covering material such as glass wool, which have been widely used, are effective. Further, a material having an effect of reflecting or blocking radiant heat is used as an efficient heat insulating material without taking up a large volume. For example, the present invention can be used for coating a vacuum vessel with a vapor-deposited film shielding plate that reflects infrared or visible light in which a metal such as aluminum is vapor-deposited on the surface of a sheet made of an organic material. In addition, for example, a translucent film formed by sputtering indium oxide or titanium oxide on the surface of glass or an organic film, because the reflection, absorption, and transmission behavior changes depending on the wavelength of radiation corresponding to the optical thickness,
Appropriate conditions can be selected.

According to a second aspect of the present invention, in addition to the first aspect, the vacuum vessel is cooled by water cooling means to reduce the cooling load of the vacuum vessel itself due to an increase in environmental temperature.

As for the selection of the water cooling means, in addition to using low-temperature water such as groundwater, use of cooling water produced by ordinary refrigeration equipment may be selected. However, it is more preferable that the cooling water is produced not in the vicinity of the system of the present invention but in a remote place and can be easily used. For the water cooling of the vacuum vessel, a known means capable of directly or indirectly cooling the vessel can be employed.

[0015] The invention described in claim 3 is the invention according to claim 1 and / or
Alternatively, in addition to the invention of claim 2, the chamber itself and / or the refrigerator itself is cooled by water cooling means, and the cooling load of the refrigerator partially disposed in a vacuum vessel due to an increase in environmental temperature is reduced. It is to reduce. If the refrigerator is a pulse tube refrigerator, the tip of the pulse tube and the hot end of the regenerator become hot, so it is effective to water-cool these parts of the refrigerator (where the radiator is usually placed). Also, it is effective for heat load measures of the whole system.

As a supplement to the heat insulating material, the present invention utilizes a material having an action of reflecting or blocking radiant heat. For example, it can be used for covering a vacuum container with a vapor-deposited film shielding plate which reflects infrared or visible light in which aluminum is vapor-deposited on the surface of a polyester film or a polypropylene film. In addition, for example, a semi-transparent film (in a strict sense, formed by sputtering indium oxide, zirconium oxide, titanium oxide, or the like on a glass or organic film surface.
For example, titanium oxide can be expressed as partially reduced TiO _2-x instead of complete oxide.) Reflection and absorption depend on the wavelength of radiation corresponding to the optical thickness (refractive index and effective thickness). , The transmission behavior changes. The thickness of the oxide film can be adjusted so as to have an optical thickness at a temperature (below the freezing point to 70 ° C.) corresponding to the far-infrared wavelength.

When the vacuum vessel is covered with such a covering material, radiant heat to the vacuum vessel can be cut, and the load on the refrigerator can be reduced.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described with reference to the drawings.

FIG. 1 is a schematic view (front view) of an apparatus for cooling and maintaining a high-temperature superconducting filter system according to an embodiment of the present invention. In FIG. 1, the refrigeration system of the embodiment has a facility in which a chamber 20 (upper rack) is mounted on a lower rack occupied by a compressor 30, and a vacuum vessel 10 is provided inside the chamber 20. , A temperature controller (temperature controller) 40 and a power supply 42 are arranged, and the vacuum vessel 10 is covered with a heat insulating material 12. The high-temperature superconducting filter (not shown), which is the center of this cooling system,
It is housed inside the vacuum vessel 10, and a refrigerator represented by a pulse tube refrigerator is arranged in the vacuum vessel, and working fluid such as a pulse tube and a regenerator and a piston /
The cylinder part is fluidly connected. By compressing / expanding the working fluid by the compressor, the pulse tube, the regenerator and the like in the vacuum vessel 10 are cooled to a predetermined cooling temperature (about 70K) and maintained at that temperature. As a result, the high-temperature superconducting filter disposed near the regenerator can exhibit superconducting performance.

FIG. 2 shows the embodiment of FIG. 1 and shows a situation viewed from the side. The lower compressor 30 generates heat due to Joule heat from the conductive coil for driving the piston, and also generates heat of the fluid due to compression of the working fluid. Therefore, it is necessary to cool the compressor which generates a large amount of heat, and the fan 32 is provided on the side of the compressor for heat radiation of the compressor.

In order to make the cooling system of FIG. 1 more effective, it is also possible to directly or indirectly cool the vacuum vessel 10 with cooling water (not shown). It can be implemented by a procedure (not shown) wound around the outer wall of the vacuum vessel. Of course, other known means can be adopted.

In the present invention, first, by installing the compressor outside the chamber, the heat generated by the compressor is prevented from being transmitted to the vacuum vessel.

Further, as described above, the vacuum vessel is directly or indirectly water-cooled to avoid the influence from the external environment. The water cooling means may use low-temperature water such as groundwater, or may use cooling water generated by a refrigerator. However,
Preferably, the cooling water is produced not at the periphery of the cooling device of the present invention but at a location away from the device of the present invention and can be easily used.

As the heat insulating material for covering the vacuum vessel, a heat insulating material that reflects or blocks radiant heat is recommended. At least, it is necessary to be shielded from changes in the external environment temperature.

Further, the refrigerator and the chamber itself can be cooled in the same manner as the cooling of the vacuum vessel. Also in this case, the water cooling means is suitable, and low-temperature water such as groundwater can be used.

[0026]

According to the first aspect of the present invention, since the compressor is installed outside the chamber, the heat generated by the compressor is prevented from being transmitted to the vacuum vessel. When a material having a function is selected, there is an effect that the vacuum vessel is shielded from a change in the external environment temperature.

According to the second aspect of the invention, in addition to the effects of the first aspect, the vacuum vessel can be directly or indirectly water-cooled to avoid the influence from the external environment.

The invention of claim 3 also has an effect of suppressing the heat load of the cooler by cooling the refrigerator itself or the chamber itself, in addition to the effect of the invention of claim 1 or 2.

[Brief description of the drawings]

FIG. 1 is a front view (schematic diagram) showing an embodiment of the present invention.

FIG. 2 is a side view (schematic diagram) showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vacuum container 12 Insulation material 20 Chamber (rack) 30 Compressor 32 Fan 40 Temperature controller 42 Power supply

Claims (3)

[Claims] 1. A refrigeration means for placing a high-temperature superconducting filter made of a metal oxide thin film in a vacuum vessel and arranging a compressor outside a chamber containing the vacuum vessel in the refrigeration means for making the filter function. A cooling system for a high-temperature superconducting filter system, comprising: dissipating heat from a machine to a chamber; providing heat dissipation promoting fins around the compressor; and covering the outside of the vacuum vessel with a heat insulating material. 2. A cooling system for a high-temperature superconducting filter system according to claim 1, wherein the vacuum vessel itself is water-cooled. 3. A cooling system for a high-temperature superconducting filter system according to claim 1, wherein the refrigerator and / or the chamber itself is water-cooled.