JPH02145936A - Sample cooling using cryogenic refrigerating machine - Google Patents

Abstract

PURPOSE:To enable cooling at an even temperature regardless of a shape and size of a sample by cooling the sample immersed in a smaller container using a feed through and a metal seal ring through a heat exchange with helium. CONSTITUTION:A chamber flange 10 with a feed through 9 is mounted at the tip of a refrigerating machine 1 as a small vacuum closed container with a seamless indium plated metal ring 11 interposed between the flange and a small container 6. A sample holder 2 is mounted in the container 6 and a measuring lead 3 attached to a sample is made to communicate with a measuring device outside the refrigerating machine 1 and a helium gas is sealed into the container 6 with a metallic capillary tube 8 from outside the refrigerating machine 1 after being replaced with air. Then, after a vacuum exhaustion 4 is computed inside the refrigerating machine 1, a cryogenic refrigerator is started to perform a physical characteristic measurement of the sample under a very low temperature. Thus, the sample is cooled at an even temperature without limit of a shape and size, thereby creating a technique handily and easily to eliminate external withdrawal of the lead 3 and a leakage of the helium gas.

Description

[Detailed Description of the Invention] Technical Field of the Invention When measuring the physical properties of a sample for research and development at extremely low temperatures using a cryogenic refrigerator, a method for uniformly cooling and measuring the sample is needed. There is.

Background of the technology A method for easily cooling samples in the shape of molded solids, bulk porous bodies, thin films, powders, fluids, etc. to a uniform temperature distribution using a cryogenic refrigerator, and then measuring these substances. was desired.

Prior Art and Problems In order to clarify the solutions to the above-mentioned problems, a conventional method for cooling a sample will be explained with reference to FIGS. 1 and 2. Cooling methods include heat conduction cooling and helium gas heat exchange cooling.

First, thermal conduction cooling will be explained. (See Figure 1) 1. Attach the sample holder (2) with the sample directly attached to the tip of the cryogenic refrigerator (1). A measurement lead (3) for measuring physical properties is attached to the sample, taken out of the cryogenic refrigerator (1), and connected to a measuring instrument.

2. Vacuum exhaust device (4) inside the cryogenic refrigerator (1)
Evacuate the tank by using After that, the cryogenic refrigerator (1)
and a compressor unit (5). At this time, the sample is cooled by thermal conduction, and physical properties are measured at extremely low temperatures.

This heat conduction cooling method is limited to the shape of the sample being a molded solid. Moreover, its size is also limited from the viewpoint of achieving uniform temperature distribution.

Next, heat exchange cooling using helium gas will be explained. (See Figure 2) 3. Place the sample in a small container (6) at the tip of the cryogenic refrigerator (1).
) in the sample holder (2). Small container (6)
In order to vacuum-tightly seal the flange surface, the indium wire (7) is usually used to seal the flange surface.The indium wire is cut to match the circumference of the flange surface, made into a ring shape, and sealed. Use it as a ring.The joints of the indium wire seal rings should be aligned diagonally to each other.Creating this small vacuum sealed container requires a high degree of skill.The measurement lead (3) attached to the sample should be Low temperature refrigerator (1
) and contact the measuring instrument.

4. Introduce helium gas into the small container (6) from the outside of the cryogenic refrigerator (1) using a metal capillary tube (8) to replace the air in the small container (6).

5. Vacuum exhaust device (4) inside the cryogenic refrigerator (1)
Evacuate the tank by using Then, start up the cryogenic freezing equipment. At this time, the small vacuum sealed container is cooled by heat conduction. The helium gas inside it is also cooled. As a result, the sample is cooled by heat exchange with helium gas, making it possible to measure physical properties at extremely low temperatures.

This helium gas heat exchange cooling method is a method that compensates for the insufficiency of the above-mentioned heat conduction cooling method, but it is difficult to develop a technology to prevent leakage of helium gas from a small vacuum sealed container. Furthermore, when replacing the sample, the indium wire, which is a malleable metal, adheres to the flange surface of the small container (6), making it troublesome to remove it from the flange surface. Unless the processing technology for taking out the measurement lead (3) to the outside of the small container is sophisticated, there may be problems such as leakage of helium gas.Purpose of the InventionThe cooling method of the present invention can be used in a cryogenic refrigerator. Using (1), samples in the shape of molded solids, bulk porous bodies, thin films, powders, fluids, etc. are cooled to a uniform temperature by heat exchange with helium gas;

2゜It is a means to facilitate the measurement of physical properties and to conduct cryogenic experiments efficiently.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Practical Methods of the Invention Examples featuring the present invention will be described below with reference to the drawings.

FIG. 3 illustrates an embodiment of the present invention.

Chamber 7 with a feedthrough (9) for introducing the measurement lead (3) at the tip of the cryogenic refrigerator (1)
Lunge αQ is installed as a small vacuum-tight container by sandwiching a seamless indium-plated metal seal ring OD between the flanges of the small container (6). The sample holder (2) with the sample attached is placed inside the small container (6). The measurement lead (3) attached to the sample is taken out of the cryogenic refrigerator (1) and connected to the measuring instrument. After replacing helium gas with air from the outside of the cryogenic refrigerator (1) into a small container (6) using a metal capillary tube (8), it is sealed.

The inside of the cryogenic refrigerator (1) is evacuated by a vacuum evacuation device (4). After that, the cryogenic freezing equipment is activated and the physical properties of the sample are measured at cryogenic temperatures. In other words, the snow surrounding the sample becomes cooled helium gas, making it possible to cool the sample to a uniform temperature without being restricted by the shape or size of the sample. Further, by using the feedthrough (9), the processing technique for taking out the measurement lead (3) to the outside of the small container (6) becomes easy.

By using the metal seal ring Ql), it is possible to make the small container [6] completely small and vacuum-tight, thereby simplifying the technique for eliminating helium gas leakage. Incidentally, the metal seal ring αD can be reused more than 50 times, so it is also economical.

(Effect of the invention) As described above, helium gas is sealed in the small container (6) using the feedthrough (9) and the metal seal ring α0, and the sample attached to the small container (6) is Shaped solid by cooling by heat exchange with helium gas,
It becomes possible to cool samples such as bulk porous bodies, thin films, powders, and fluids to a uniform temperature regardless of their shape or size.

Feedthrough (9) and metal seal ring 00, which make small vacuum-tight containers, are commercially available, but their reliability at the extremely low temperatures (-269°C) generated by cryogenic refrigeration equipment has not been guaranteed until now. However, it can be used satisfactorily even at extremely low temperatures. Therefore, it is a sufficiently effective means for experimenters who measure physical properties at extremely low temperatures to conduct measurements easily and efficiently.

[Brief explanation of the drawing]

1 and 2 are conventional configuration diagrams, and FIG. 3 is a diagram showing an embodiment of the present invention. 1. Cryogenic refrigerator, 2. Sample holder 13. Measurement lead, 4. Vacuum exhaust device, 5. compressor unit.

Claims (1)

[Claims] How to cool a sample when measuring its physical properties using a cryogenic refrigerator