JP3632090B2 - Sample cooling method for sample driving device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sample cooling method for a sample driving device for efficiently cooling a sample to an extremely low temperature in a sample driving device such as a sample manipulator and a sample goniometer.
[0002]
[Prior art]
FIGS. 1A and 1B are conceptual diagrams of a conventional sample cooling method in a sample driving apparatus (hereinafter, simply referred to as a driving apparatus) that controls the position and orientation of this type of sample. . Reference numeral 1 denotes a sample to be cooled, 2 a sample holder for fixing the sample 1, and 3 a universal cooling joint 4 between the sample holder 2 and a low-temperature maintenance device described later. Reference numeral 4 denotes a low-temperature maintaining device for cooling the sample, 6 denotes a structure at the tip of the driving device, 7 denotes a heat radiation shield, and 8 denotes a support for holding the structure at the tip of the driving device. In FIG. 1 and other figures, the hatched portions indicate the same temperature.
[0003]
In the conventional technique as shown in FIG. 1A, the sample 1 and the sample holder 2 are cooled by the low temperature maintaining device 4 via the universal cooling joint 3. In this case, the structure 6 at the tip of the driving apparatus adjacent to the sample holder 2 is not cooled, and the structure 6 at room temperature is transferred to the sample 1 and the sample holder 2 to the extremely low temperature by heat conduction and heat radiation. It is difficult to cool efficiently. Furthermore, the amount of cryogen consumed by the low temperature maintenance device 4 is large due to the influence of heat radiation and heat conduction to the sample 1 from the outside, and it takes a long time to reach the lowest temperature, and efficient cooling cannot be performed.
[0004]
In order to reduce the influence of radiation in some conventional devices, there is a device in which a radiation shield 7 is attached to the outside of the sample holder 2 and the structure 6 as shown in FIG. Although it seems that the cooling efficiency is somewhat improved by the heat radiation shield 7, the structure 6 at room temperature is also incorporated together in the heat radiation shield 7, and is more effective due to the influence of heat radiation from the structure 6. Achieving cryogenic temperatures is still difficult. Furthermore, a disadvantage of this method is that since the heat radiation shield 7 is attached to the outside of the structure 6, there is a problem of an increase in the size of the apparatus, so that there are many restrictions on practical use.
[0005]
As an example of FIG. 1 (a), a substrate holder device for vacuum deposition disclosed in Japanese Patent Laid-Open No. 2-107767, Rev. Sci. Instrum. Vol.57 No.3 pp. 487-489 (March 1986), a 6-axis manipulator, Meas. Sci. Technol. Vol.8 No.3 pp. 25-261 (March 1997), a 3-axis goniometer, the main sample manipulator of Thermo Vacuum Generators (UK), and the GB-16 sample goniometer of Thermonics (USA).
[0006]
An example of FIG. 1 (b) is Cryoax II from Thermo Vacuum Generators (UK). This apparatus is a single-axis goniometer used only for in-plane rotation used in a manipulator, which cools a heat radiation shield attached to the outside of the goniometer with liquid nitrogen and cools a sample with liquid helium.
[Patent Document 1]
JP-A-2-107767 [Non-Patent Document 1]
Thomas Engel, Donald Braid, and Edward H .; Conrad; Three-axis sample manipulator with XYZ translation for use in UHV; Review of Scientific Instruments, Vol. 3, American Institute of Phar.
[Non-Patent Document 2]
A Raukema, A P de Jongh, H P Alberda, R Boddenberg, F G Giskes, Ede Haas, A W Kleyn, H Neerings, R Schaafsma and H Veerman; A three-axis goniometer in an UHV molecular beam experiment; Measurement Science and Technology; UK Institute of Physics; March 1997, Vol. 8, No. 3, P253-261
[0007]
[Problems to be solved by the invention]
In order to cool a sample subjected to this type of position and orientation control to an extremely low temperature, it is necessary to improve the influence of heat conduction and heat radiation on the sample holder holding the sample.
[0008]
The basic method for efficiently cooling the sample to extremely low temperature is efficient by reducing the influence of heat radiation on the sample holder by incorporating a heat radiation shield outside the sample holder and cooling the heat radiation shield. Cryogenic temperatures can be achieved. At this time, the influence of heat radiation on the universal cooling joint between the cryostat and the sample holder must also be reduced by the heat radiation shield. The method of driving the sample holder incorporating the heat radiation shield and the universal cooling joint is practically impossible because of problems such as an increase in the size of the apparatus and a restriction on the drive control range.
[0009]
Therefore, the object of the present invention is to reduce the influence of thermal radiation and efficiently cool the specimen holder and the structural material for free cooling to the cryogenic temperature without being restricted by the size of the specimen drive device or the control range. Another object of the present invention is to provide a sample cooling method for a sample driving device.
[0010]
[Means for Solving the Problems]
In order to achieve such an object, according to the present invention, the structure at the tip of the driving device that controls the position and orientation of the sample is cooled by the first-stage low temperature maintaining device, and the main body of the driving device is sampled And the sample is cooled to a very low temperature by cooling the sample with a second-stage low temperature maintaining device different from the first-stage low temperature maintaining device. It is characterized by.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1C shows a conceptual diagram of a sample cooling method in a driving apparatus that controls the position and orientation of a sample to which the present invention is applied. In order to solve the conventional problems, the structure 6 at the front end of the driving device is cooled by another low temperature maintaining device (first stage) 5, and the sample 1, sample holder 2, free from this structure 6 The influence of heat conduction on the cooling joint 3 is improved and the structure 6 itself is arranged as a heat radiation shield, thereby reducing the influence of heat radiation on the sample 1 and the sample holder 2. The sample 1 and the sample holder 2 cool the sample 1, the sample holder 2, and the universal cooling joint 3 to a very low temperature by using a low-temperature maintenance device (second stage) 4 for the sample. Since the structure 6 itself serves as a radiation shield, the size of the driving device including the cooling mechanism is comparable to that of the conventional device, and is not restricted by the control range of the position and orientation of the sample.
[0013]
In such an embodiment, in order to cool the structure 6 at the tip of the driving device, the material of the structure 6 is made of a material having good heat conduction. This structure 6 is held by a support column 8 having a normal temperature external environment and poor heat conduction. The structure 6 is cooled by the first-stage low-temperature maintenance device 5 and used as a heat radiation shield for the sample 1, the sample holder 2, and the universal cooling joint 3. The sample holder 2 and the universal cooling joint 3 incorporated in the structure 6 are cooled by another second stage low temperature maintaining device 4 to efficiently cool the sample 1 to a very low temperature.
[0014]
(Example 1)
Sample Cooling Goniometer A conventional sample cooling goniometer is shown in FIGS. 2 (a) and 2 (b). 11 is a sample to be cooled, 12 is a sample holder for fixing the sample 11, 13 is a universal cooling joint 14 between the sample holder 12 and the low temperature maintaining device, and 14 is a low temperature maintaining device. Due to the influence of heat conduction and heat radiation from the goniometer structure at room temperature to the sample holder 12 and the universal cooling joint 13, it is not possible to efficiently cool to a very low temperature.
[0015]
FIGS. 3A and 3B show a cooling method for the sample goniometer to which the present invention is applied. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. One of the novel features of the present invention is that a low temperature maintaining device 15 (first stage of the present invention) for cooling the goniometer body is incorporated. In order to cool the goniometer, it is manufactured using oxygen-free copper or the like having a good thermal conductivity as a structural material. The goniometer body is cooled by the first-stage low-temperature maintenance device 15, and the sample holder 12 and the universal cooling joint 13 are cooled by another second-stage cooling maintenance device 14, thereby efficiently It becomes possible to cool to a very low temperature.
[0016]
FIG. 4 shows the temperature change of the sample attached to the prior art and the goniometer according to the present invention. Liquid helium was used as a cryogen in a conventional cryogenic maintenance device for sample cooling. Liquid nitrogen was used as the cryogen for the cryogenic cooling device for the goniometer structure (first stage) according to the present invention, and liquid helium was used as the cryogen for the sample cooling (second stage) cryostat. Thirty minutes before starting the cooling of the sample using the second stage cryostat, the goniometer structure was precooled using the first stage cryostat. At that time, the sample was cooled to about −20 ° C. by heat radiation and heat conduction from the structure to the sample. The minimum temperature achieved by the prior art was about −233 ° C., and the minimum temperature achieved by the present technology was about −253 ° C. Compared with the conventional technique, the liquid helium consumption of the technique according to the present invention was about half.
[0017]
This sample cooling goniometer can be used for various sample preparation / evaluation apparatuses that require control of the position and orientation of the sample and efficient temperature control up to extremely low temperatures.
[0018]
(Example 2)
In order to cool the detector attached to the rotating arm, etc., the detector is built in the tip of the arm, the arm body is cooled by the first stage cooling device, and further, the second stage low temperature maintenance device is used. Cools the free cooling structure and detectors inside the arm. This cooling arm can be used in an analyzer incorporating a detector or the like that requires azimuth control and temperature control to extremely low temperatures.
[0019]
【The invention's effect】
As described above, by cooling the structure itself using the first-stage low-temperature maintenance device, the influence of heat radiation and heat conduction from the structure to the sample is reduced.
[0020]
In addition, this makes it possible to reduce the consumption of the cryogen used in the second stage low-temperature maintenance device for sample cooling.
[Brief description of the drawings]
FIGS. 1A and 1B are conceptual diagrams for explaining a sample cooling method in a conventional vacuum driving apparatus. (C) is a conceptual diagram for demonstrating the sample cooling method by this invention.
FIG. 2A is a front view for explaining a sample cooling method attached to a goniometer according to the prior art. (B) is a vertical side view of (a).
FIG. 3A is a front view for explaining a sample cooling method attached to a goniometer according to the present invention. (B) is a vertical side view of (a).
FIG. 4 is a characteristic diagram showing a change in temperature of a sample attached to a conventional technique and a goniometer according to the present invention.
[Explanation of symbols]
1, 11 Sample 2, 12 Sample holder 3, 13 Free cooling joint 4, 5, 14, 15 Low temperature maintenance device 6 Structure 7 Radiation shield 8 Strut

Claims (1)

The structure at the tip of the driving device that controls the position and orientation of the sample is cooled by the first stage low temperature maintenance device,
Arrange the body of the drive device to be a heat radiation shield for the sample,
The sample cooling method for a sample driving apparatus, wherein the sample is cooled to a very low temperature by cooling with a second stage low temperature maintaining apparatus different from the first stage low temperature maintaining apparatus. .

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