JP3599259B2 - X-ray analyzer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray analyzer for sealing an X-ray detector together with a cooling device in a vacuum vessel, cooling the same, and detecting and analyzing characteristic X-rays emitted from a sample through an X-ray entrance window.
[0002]
[Prior art]
FIG. 2 is a diagram showing a configuration example of a conventional X-ray analyzer.
In an electron microscope, an energy dispersive X-ray analyzer is used as an apparatus for performing elemental analysis on a small region of a sample. In this energy dispersive X-ray analyzer, a primary ray 5 generated from an excitation ray generator 1 is irradiated on a sample 4 as shown in FIG. 2, and an X-ray 6 generated thereby is detected by an X-ray detector 8. Qualitative and quantitative analysis by converting to electrical signals. The excitation ray generator 1 includes an ion source, an electron beam generator, an X-ray generator, a radiation source, and the like. The X-ray detector 8 is made of a silicon semiconductor element or the like, and is sealed together with the cooling device 10 in a vacuum vessel 3 having an X-ray entrance window 7 with a beryllium (Be) thin film or an organic thin film in front thereof, and contains liquid nitrogen. It is cooled via a heat conducting rod 9 by a cooling device 10 such as a container or a refrigerator.
[0003]
As described above, when high-performance analysis is expected in the X-ray analyzer, the X-ray detector 8 is cooled to improve the signal-to-noise ratio. In the case of the X-ray detector 8 used after cooling, it is a general method to use the X-ray detector 8 in the vacuum vessel 3 in order to increase the cooling efficiency. In order to introduce X-rays into the vessel 8, a very thin X-ray entrance window 7 such as beryllium or an organic film is used.
[0004]
[Problems to be solved by the invention]
In the X-ray analyzer that uses the X-ray detector 8 cooled in the vacuum vessel 3 as described above, if the sample 4 is a liquid, a biological sample with a high water content, or a highly volatile substance, the sample chamber 2 is It cannot be analyzed as a high vacuum. Therefore, in such a case, the measurement of the sample 4 is performed by setting the sample chamber 2 to a low vacuum or a gas atmosphere. However, when the analysis is performed in a gas atmosphere, if the distance between the sample 4 and the X-ray incident window 7 is long, Since sensitivity is reduced by absorption of X-rays by the gas, a light gas such as helium or hydrogen is used.
[0005]
However, since a light gas has small molecules, there is a problem that the light gas penetrates through the X-ray entrance window 7 and enters the vacuum vessel 3 in which the X-ray detector 8 is sealed. This is the same phenomenon that a balloon inflated with helium or hydrogen gas will wither in a few days. When gas enters the vacuum vessel 3, the degree of vacuum in the vacuum vessel 3 decreases. As a result, since a high voltage is applied to the X-ray detector 8, discharge occurs, cooling efficiency deteriorates, and performance of the X-ray detector 8 deteriorates. Further, the cooling efficiency is deteriorated, so that the consumption of the liquid nitrogen of the cooling device 10 is increased.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems, and it is an object of the present invention to prevent a gas from entering a vacuum vessel used for cooling an X-ray detector, and to prevent deterioration in cooling efficiency due to a decrease in the degree of vacuum.
[0007]
For this purpose, the present invention provides an X-ray analyzer for sealing and cooling an X-ray detector together with a cooling device in a vacuum vessel and detecting and analyzing characteristic X-rays emitted from a sample through an X-ray entrance window. A vacuum isolation chamber having a second X-ray entrance window is provided between the X-ray entrance side of the X-ray entrance window of the vacuum vessel enclosing the X-ray detector and a sample chamber having the sample in a gas atmosphere. Wherein the differential chamber reduces the differential pressure on both sides of the X-ray entrance window of the vacuum vessel, thereby isolating the gas atmosphere from the sample chamber and the X-ray entrance window of the vacuum vessel, The vacuum isolation chamber is a vacuum chamber having a pump for evacuating or a vacuum sealed chamber.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing an embodiment of an X-ray analyzer according to the present invention, wherein 1 is an excitation line generator, 2 is a sample chamber, 3 is a vacuum vessel, 4 is a sample, 5 is a primary line, and 6 is X-ray. Reference numerals 7 and 13 denote X-ray entrance windows, 8 denotes an X-ray detector, 9 denotes a heat conducting rod, 10 denotes a cooling device, 11 denotes an isolation room, and 12 denotes a rotary pump.
[0009]
In FIG. 1, an excitation beam generator 1 includes an ion source, an electron beam generator, an X-ray generator, a radiation source, and the like, and generates a primary beam 5. The primary radiation 5 is, for example, an X-ray or γ-ray source. The sample chamber 2 holds a sample 4 to be irradiated with a primary beam 5 from the excitation beam generator 1 in the atmosphere or a gas atmosphere such as helium or hydrogen. The X-ray detector 8 detects the X-rays 6 generated from the sample 4 by the irradiation of the primary rays 5 and incident through the X-ray incidence windows 13 and 7. The X-rays are converted into electric signals to perform qualitative quantitative analysis. Do. The X-ray detector 8 is cooled via a heat conducting rod 9 by a cooling device 10 using liquid nitrogen as a refrigerant, for example, and the vacuum vessel 3 has an X-ray entrance window 7. 8, the heat conducting rod 9, and the cooling device 10 are vacuum-sealed.
[0010]
The isolation chamber 11 is for isolating the sample chamber 2 from the vacuum vessel 3, has an X-ray incident window 13, and the rotary pump 12 is for exhausting the isolation chamber 11 and keeping it in a vacuum. . That is, the isolation chamber 11 is a vacuum chamber to reduce the differential pressure on both sides of the X-ray entrance window 7. Therefore, the X-ray 6 generated from the sample 4 is detected by the X-ray detector 8 through the X-ray entrance window 13 of the isolation chamber 11 and the X-ray entrance window 7 of the vacuum vessel 3. However, since the isolation chamber 11 is evacuated by the rotary pump 12, the differential pressure on both sides of the X-ray entrance window 7 of the vacuum vessel 3 can be reduced, and gas enters through the X-ray entrance window 7 of the vacuum vessel 3. Can be prevented. That is, the space between the sample chamber 2 and the vacuum vessel 3 is isolated by the vacuum isolation chamber 11 between the two X-ray incidence windows 13 and 7.
[0011]
With the above configuration, when the measurement of the sample 4 is performed by setting the sample chamber 2 to the atmosphere or a gas atmosphere of helium, hydrogen, or the like, the X-ray incident window 7 disposed in front of the X-ray detector 8 directly Since the gas does not come into contact with the gas on the sample chamber 2 side, it is possible to prevent the gas from entering and to prevent the cooling efficiency from being deteriorated due to a decrease in the degree of vacuum.
[0012]
Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, a configuration in which the isolation chamber is evacuated by a rotary pump and vacuum is drawn is shown, but a vacuum-sealed isolation chamber may be used without using such a rotary pump. Further, the example of the isolation chamber 11 in which the vacuum chamber is completely isolated from the sample chamber has been described. Is also good.
[0013]
【The invention's effect】
As is clear from the above description, according to the present invention, since the thin film of the X-ray entrance window arranged in front of the X-ray detector does not directly contact helium or hydrogen gas, it passes through the X-ray entrance window, If there is gas leakage through the field, the amount can be reduced by at least three orders of magnitude due to the pressure differential across the diaphragm. As a result, it is possible to prevent the cooling efficiency from being deteriorated due to the decrease in the degree of vacuum. Therefore, the life of the X-ray detector can be significantly extended, and the consumption of a refrigerant such as liquid nitrogen can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an X-ray analyzer according to the present invention.
FIG. 2 is a diagram showing a configuration example of a conventional X-ray analyzer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Excitation line generator, 2 ... Sample chamber, 3 ... Vacuum container, 4 ... Sample, 5 ... Primary line, 6 ... X-ray, 7, 13 ... X-ray entrance window, 8 ... X-ray detector, 9 ... Heat Conducting rod, 10: cooling device, 11: isolation chamber, 12: rotary pump

Claims (3)

The X-ray detector is sealed in a vacuum vessel together with a cooling device and cooled, and an X-ray analyzer for detecting and analyzing characteristic X-rays emitted from a sample through an X-ray entrance window, wherein the X-ray detector is A vacuum isolation chamber having a second X-ray entrance window is provided between the X-ray entrance side of the sealed X-ray entrance window of the vacuum vessel and a sample chamber containing the sample in a gas atmosphere. An X-ray analyzer, wherein a differential pressure on both sides of an X-ray entrance window of the vacuum vessel is reduced to isolate the sample chamber in the gas atmosphere from the X-ray entrance window of the vacuum vessel. 2. The X-ray analyzer according to claim 1, wherein the vacuum isolation chamber is a vacuum chamber having a pump for evacuating. The X-ray analyzer according to claim 1, wherein the vacuum isolation chamber is a vacuum sealed chamber.

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