JPH01112133A - Low-temperature device for sample - Google Patents

Abstract

PURPOSE:To simplify the mechanism of a moving section by controlling a stop valve provided at the mid-point of a conduit for introducing a liquefied gas to a sample part by a shape memory alloy and an electric heater near said alloy. CONSTITUTION:A liquefied gas vessel 3 contg. the liquefied gas 4 such as liquid nitrogen is provided in a vacuum vessel 1 and the liquefied gas conduit 6 is connected to the bottom thereof. A sample mounting part 6 having a bottomed cylindrical shape is formed to the lower part of the conduit 5 and a powder sample 8 is packed into the recess of a sample base 7 provided into said part. X-rays are projected to the sample 8 through X-ray windows 9, 10 and, for example, an X-ray diffraction angle is measured. A valve seat 14 having a hole 13 is formed in the conduit 5 and the valve 15 is disposed to the lower part thereof. The valve 15 is pressed by an open/shut pressing body 16 formed of the shape memory alloy which is expanded or contracted by the electric heater 20 in which current flows according to the sample temp. The inflow or shut off of the liquefied gas is thus executed.

Description

Detailed Description of the Invention The present invention provides an apparatus for cooling a sample to a desired temperature with liquefied gas when observing the physical properties of the sample at low temperatures, such as light reflection characteristics, X-ray diffraction characteristics, etc. Concerning.

In such an apparatus, conventionally, a sample attachment part is formed at the tip of a conduit connected to a container of liquefied nitrogen or other suitable liquefied gas, and the sample is cooled by the liquefied gas flowing into the conduit, and the temperature is controlled by: For example, by inserting a heat insulating rod made of Teflon or the like into the conduit to prevent the inflow of liquefied gas, and in this state heating the sample part with an electric heater to maintain it at a desired temperature, loss of the liquefied gas can be prevented. Measures were taken to prevent this. However, such devices are complicated to operate, and automatic temperature control is extremely difficult. Therefore, the present invention provides an apparatus that can easily control the sample temperature automatically, has a simple structure, and causes extremely little loss of liquefied gas.

The sample cryogenic apparatus of the present invention is provided with an on-off valve in the middle of a conduit that guides liquefied gas to a sample part, whose on-off control body is made of a shape memory alloy, and an electric heater is provided near this control body, and an electric heater is provided in the vicinity of this control body. The valve is opened and closed by temperature control. Therefore, when the temperature of the sample falls below a predetermined value, if a heating current is applied to the electric heater described above,
Since the on-off valve closes due to the deformation of the shape memory alloy,
The supply of liquefied gas to the sample portion is cut off, and the temperature of the sample gradually increases. In addition, if the electric heater is configured to be shut off when the temperature exceeds the upper limit of the allowable range, the shape of the alloy will change one day later, the valve will open, and liquefied gas will be replenished into the sample area. Temperature decreases. Therefore, it is possible to automatically maintain a predetermined temperature, and the temperature can be easily controlled by program.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is an enlarged longitudinal sectional view of the main part in FIG. 1, and FIG. 3 is an enlarged view of the AA cross section in FIG. 2. That is, a liquefied gas container 3 is provided inside a container 2 kept in a vacuum by an exhaust pipe 1, and contains a suitable liquefied gas 4 such as liquid nitrogen. A liquefied gas conduit 5 is connected to the bottom of this container 3, a bottomed cylindrical sample attachment part 6 is formed at the bottom, and a powder sample 8 is attached to four parts of a sample stage 7 provided inside as shown in FIG. It is filled with. Note that this sample attachment part 6 and the container 2 are provided with an X-ray window 9.
．． By forming an IO, X-rays are made incident on the sample, and the diffracted X-rays are taken out to measure, for example, the X-ray diffraction angle. In addition, a hole 11 is provided in the sample mounting portion 6, and an electric heater 12 is provided behind the sample for finely adjusting the temperature thereof.

Furthermore, a valve seat I4 having a hole 13 is formed inside the conduit 5, and a valve 15 is arranged below the valve seat I4, and this valve 15 is connected to an opening/closing control body 16 made of a coil spring made of a shape memory alloy.
The valve seat 14 is brought into pressure contact with the valve seat 14 by pressing. Both ends of this control body I6 are fixed to a valve 15 and a sample attachment part 6, and the valve 15 has liquefied gas passages 17, 17, etc. formed on its periphery and a small hole 18 in its center. A check valve I9 is disposed at the lower end to allow gas to flow from the bottom to the top in the figure through this hole.

Further, an electric heater 20 is provided outside the conduit 5 so as to face the control body 16 . Also, Fig. 4 shows the opening/closing control body I6.
In another example, a coil spring 22 made of an arbitrary spring material is attached to one end of a memory portion 21 formed of a band-shaped shape memory alloy in a meandering shape.
It is a concatenation of.

In the above apparatus, the temperature of the sample is monitored by a thermocouple contact (not shown) attached to the sample 8 or its vicinity, and when the temperature falls below a predetermined value, a heating current is applied to the electric heater 20, and - the above-mentioned temperature When the current is reached, this current is cut off. Therefore, when the sample temperature becomes higher than a predetermined value, the axial length of the shape memory alloy control body 16 shown in FIG. Because of the inflow, the temperature of the sample mounting portion 6 decreases, and the sample 8 is cooled to a predetermined temperature. Further, when this temperature falls below a predetermined value, the control body I6 is heated by the electric heater 20 and expands, so that the valve 15 is closed and the supply of the liquefied gas 4 is cut off. In addition, since the liquefied gas in the conduit 5 below the valve 15 gradually vaporizes and escapes through the check valve 19, the temperature of the sample 8 gradually increases. As mentioned above, when this temperature exceeds a predetermined value, the electric current of the electric heater 20 is cut off, but the temperature of the sample 8 gradually rises due to the lack of liquefied gas in the lower part of the conduit 5, until the temperature reaches the predetermined value. If the value exceeds 1, the control body 16 contracts as described above, causing the valve 1 to close.
5 opens.

The above embodiment uses a helical spring made of a shape memory alloy, but as shown in FIG. It can also be formed by the memory portion 21 made of an alloy bent in a serpentine shape and the coil spring 22 made of a normal spring material. Furthermore, although the two-legged explanation has been given for the case where the temperature of the sample is held constant, it is of course possible to perform program control by changing the reference voltage to which the output of the thermocouple is compared.

As described above, since the apparatus of the present invention adjusts the sample temperature by controlling the flow of liquefied gas, the amount of liquefied gas consumed can be extremely reduced, and the mechanism of the movable part is extremely simple.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a part of FIG. 1, FIG. 3 is a Δ-A sectional view of FIG.
The figure shows another example of the control body. In the figure, 3 is a liquefied gas container, 5 is a liquefied gas conduit, 6 is a sample attachment part, and 15 is a liquefied gas conduit.
1 is an on-off valve, 16 is an on-off control body, and 20 is an electric heater.

Claims (1)

[Claims] forming a sample attachment part at the lower end of a liquefied gas conduit connected to the bottom of the liquefied gas container, providing an on-off valve in the middle of the conduit, and forming an opening/closing control body for this valve from a shape memory alloy;
and a sample cryogenic device, characterized in that an electric heater is provided near the opening/closing control body for controlling the opening/closing of the valve by changing its shape.