JPH06109339A - Element cooling device for EDS detector - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an element cooling device that can cool elements of an EDS detector by simple operation without managing liquid nitrogen [Configuration] EDS detector for elemental analysis of electron microscope (1) This EDS detector element and pulse tube refrigerator
The cold heat generating part (5) of (6) is thermally connected via a cold heat transfer rod. A spare gas chamber (23) is arranged between the high pressure gas passage (24) from the compressor (18) of the pulse tube refrigerator (6) and the gas return passage (25) to the compressor (18). Spare gas chamber (23) and high pressure gas passage (2
4) The flow path opening / closing valves (26) (27) are arranged between the gas return path (25) and 4). By controlling the opening / closing of the flow path on-off valves (26) (27), the initial cooling is increased to accelerate cooling.
The gas pressure wave oscillation is reduced by reducing the amount of gas sent to the cold heat generating section (5) of the pulse tube refrigerator (6) during steady operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
It relates to a cooling device for cooling the elements of a DS detector.

[0002]

2. Description of the Related Art Conventionally, an element cooling device for an EDS detector mounted on an electron microscope has a liquid nitrogen container supported in a retractable state with respect to a lens barrel of the electron microscope. The element is thermally connected via a cold heat transfer rod, and the cold heat of liquid nitrogen is used to cool the element of the EDS detector.

[0003]

In the conventional element cooling device for the EDS detector, liquid nitrogen is used because the element of the detector must be cooled while vibration is suppressed during the detection work. However, in this case, there is a problem in that the consumption of liquid nitrogen must be compensated and the management of liquid nitrogen is troublesome. Further, since the lens barrel portion of the electron microscope has to support the weight of the liquid nitrogen contained in the liquid nitrogen container and the inside of the liquid nitrogen container, the supporting structure must be firmly formed and the center of gravity becomes high.
There is also a problem that the vibration resistance of the electron microscope becomes insufficient. The present invention has been made focusing on such points,
An object of the present invention is to provide an element cooling device capable of cooling the element of an EDS detector by a simple operation without management of liquid nitrogen and improving the vibration resistance of an electron microscope equipped with the element.

[0004]

In order to achieve the above object, the present invention provides a pulse by connecting the element of the EDS detector and the cold heat generating portion of the pulse tube refrigerator thermally through a cold heat transfer rod. A spare gas chamber is placed between the high-pressure gas passage from the compressor of the tube refrigerator and the gas return passage to the compressor, and the flow passage is opened and closed between the spare gas chamber and the high-pressure gas passage and the gas return passage. By controlling the opening and closing of the valve, the amount of gas is increased during initial cooling for accelerated cooling, and the amount of gas sent to the cold heat generation part of the pulse tube refrigerator during steady operation is reduced to reduce gas pressure wave oscillation. It is characterized by having done.

[0005]

According to the present invention, the element of the EDS detector and the cold heat generating portion of the pulse tube refrigerator are thermally connected via the cold heat transfer rod,
Flow path arranged between the high pressure gas passage from the compressor of the pulse tube refrigerator and the gas return passage to the compressor and between the high pressure gas passage and the gas return passage. By controlling the on-off valve to open and close, the amount of gas is increased during initial cooling for accelerated cooling, and the amount of gas sent to the cold heat generation part of the pulse tube refrigerator during steady operation is reduced to reduce gas pressure wave oscillation. Since the detection element of the EDS detector is directly cooled by the cold heat generated by the pulse tube refrigerator, the EDS detector is rapidly cooled in the initial stage of cooling and is not affected by pressure wave vibration during steady operation. The element can be cooled. This makes it unnecessary to manage liquid nitrogen.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a pulse tube refrigerator, FIG. 2 is a schematic configuration diagram of an element cooling device of an EDS detector, and FIG. It is a principal part expanded sectional view of a generation part. In the figure, reference numeral (1) is an electron microscope in which the main body portion (2) is supported on the floor surface (3) via a vibration absorber (4) such as a spring, and (5) is a pulse tube refrigerator (6).
This is the cold heat generating part of the electron microscope.
The cold heat generating part (5) is fixed to the retract rail (7) fixed to the main body part (2) of (1) through the traveling platform (8), so that the cold heat generating part (5) is main part (2) of the electron microscope (1). On the other hand, the retract is movable.

The pulse tube refrigerator (6) has a cold heat generating section (5),
It is composed of a compressor unit (9) and a gas switching motor section (10) arranged between the compressor unit (9) and the cold heat generating section (5), and the compressor unit (9) and the gas switching motor are included. Division (10)
And are separated from the cold heat generating section (5). The gas switching motor section (10) is composed of an inverter motor (11) and a flow path switching valve (12) composed of a rotary valve. The flow path switching valve (12) and the cold heat generating section (5) are Flexible gas meter conduit (1
Connected in 3).

The flexible gas meter conduit (13) has a structure in which the outer circumference of a tetrafluoroethylene resin pipe is covered with a metal spiral tube, and the metal spiral tube is covered with a metal braided tube.
The gas meter conduit (13) is supported by a vibration isolation block (15) mounted on the floor. As a result, minute vibrations generated by the compressor unit (9) and the gas switching motor section (10) are damped and absorbed by the vibration isolation block (15). Therefore, the microvibration that hinders the microscopic examination in the electron microscope is prevented from being transmitted to the lens barrel of the electron microscope through the flexible gas meter conduit (13).

Compressor unit (9) of pulse tube refrigerator (6)
Is a compressor (18), cooler (19), oil separator (20), oil adsorber (2
1), a pressure maintaining valve (22) and a spare gas chamber (23). The backup gas chamber (23) is a high pressure gas passage (24) from the oil adsorber (21) to the flow passage switching valve (12) and a gas return passage (24) from the flow passage switching valve (12) to the compressor (18). 25) and the solenoid valves (26) and (27) respectively.

High pressure side solenoid valve (26) arranged in the connecting path (28) between the auxiliary gas chamber (23) and the high pressure gas path (24), and the auxiliary gas chamber (23)
The low-pressure side solenoid valve (27) arranged in the connection path (29) between the gas return path (25) and the gas return path (25) is controlled to be opened and closed based on the temperature information detected by the temperature sensor provided in the EDS detector. .

The cold heat generating section (5) of the pulse tube refrigerator (6) is
As shown in FIGS. 1 and 3, the pulse tube (30) and the regenerator (31)
And the lower end portions thereof are connected to each other by a heat absorption connecting path (32). Further, the pulse tube (30) has rectifying plates (33) arranged at both upper and lower ends thereof, and the regenerator (31) has a stainless steel or copper mesh body laminated inside thereof and has both upper and lower ends thereof. A rectifying plate (34) is arranged in the section.

The upper end of the regenerator (31) is connected to the flow path switching valve (12) through the gas introduction path (35) by the flexible gas meter conduit (13). The upper end of the pulse tube (30) is the buffer tank (37).
It is connected to and connected via an orihuis (38).

Next, the operation of the element cooling device for the EDS detector will be described. At the initial stage of cooling, the high pressure side solenoid valve (26) placed in the connection path (28) between the auxiliary gas chamber (23) and the high pressure gas path (24)
Is closed and the low pressure side solenoid valve (27) arranged in the connection path (29) between the auxiliary gas chamber (23) and the gas return path (25) is opened. Then, the low pressure gas flowing into the compressor (18) is stored in the auxiliary gas chamber (23).
Since the gas is supplied from the compressor (18), the gas displacement of the compressor (18) is increased and the cooling capacity is increased.

When the temperature sensor provided in the EDS detector reaches a predetermined temperature (for example, 123K), the low pressure side solenoid valve (27) is closed and the high pressure side solenoid valve (26) is opened, and the compressor (18) is opened. A part of the discharge gas from the gas flows into the auxiliary gas chamber (23) and the auxiliary gas chamber (23) is maintained in a high pressure state. Therefore, a part of the circulating gas in the compressor unit system is
(23) is filled as a high pressure gas. As a result, a part of the circulating gas is released to the outside of the system, the low pressure is lowered and the high pressure is lowered, so that the cooling capacity is lowered and the pressure wave oscillation is lowered.

[0015]

According to the present invention, since the element of the EDS detector and the cold heat generating portion of the pulse tube refrigerator are thermally connected via the cold heat transfer rod, the detecting element of the EDS detector is pulse tube frozen. Since it can be directly cooled by the cold heat generated by the machine, it becomes unnecessary to manage liquid nitrogen.

Further, in the present invention, a spare gas chamber is arranged between the high pressure gas passage from the compressor of the pulse tube refrigerator and the gas return passage to the compressor, and the spare gas chamber, the high pressure gas passage and the gas return passage are arranged. By controlling the opening and closing of the flow path on-off valve placed between the passage and the passage, the apparent amount of gas in the compressed gas circulation system in the refrigerator is changed, and it is increased during the initial cooling to accelerate cooling. The gas pressure wave vibration is reduced by reducing the amount of gas sent to the cold heat generation part of the pulse tube refrigerator during steady operation, so it is affected rapidly by pressure wave vibration at the initial stage of cooling and during steady operation. It is possible to cool the elements of the EDS detector without.

Further, in the present invention, since only the cold heat generating portion of the pulse tube refrigerator is supported by the lens barrel portion of the electron microscope, the weight of the liquid nitrogen storage container, which is a heavy load, is supported by the lens barrel. The support structure can be simplified compared to the conventional one, and the position of the center of gravity of the electron microscope equipped with it can be lowered, improving the vibration resistance of the electron microscope and improving the image quality of the speculum image. Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a pulse tube refrigerator.

FIG. 2 is a schematic configuration diagram of an element cooling device of an EDS detector.

FIG. 3 is an enlarged cross-sectional view of a main part of a cold heat generating portion of the pulse tube refrigerator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron microscope, 5 ... Cold heat generation part of pulse tube refrigerator, 6 ... Pulse tube refrigerator, 9 ... Compressor unit, 10 ... Gas switching motor part, 13 ... Flexible gas meter conduit, 14 ... Electron microscope Frame, 15 ... Vibration isolation block, 16 ... Electron microscope lens barrel, 18 ... Pulse tube refrigerator compressor, 23 ... Spare gas chamber, 24 ... High pressure gas passage, 25 ... Gas return passage, 26/27 ... Flow Road open / close valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuji Kawaguchi 1095 Katsube-cho, Moriyama City, Shiga Prefecture Iwataniprantec Co., Ltd. Shiga Plant (72) Tomio Nishitani 1095 Katsubecho, Moriyama-shi, Shiga Prefecture Iwataniplantec Co., Ltd. Shiga Plant (72) Inventor Masayuki Hira 3-12, Musashino, Akishima-shi, Tokyo Nihon Denshi Co., Ltd. (72) Inventor Eiichi Watanabe 3-1-2 Musashino, Akishima-shi, Tokyo Nihon Denshi Co., Ltd. (72) Inventor Satoshi Hosokawa 3-1-2, Musashino, Akishima-shi, Tokyo Inside JEOL Ltd.

Claims (4)

[Claims] 1. An EDS for elemental analysis of an electron microscope (1).
A detector is arranged, and the element of this EDS detector and the cold heat generating part (5) of the pulse tube refrigerator (6) are thermally connected via a cold heat transfer rod to compress the pulse tube refrigerator (6). High pressure gas path (24) from the machine (18)
And the gas return (25) to the compressor (18) between the spare gas chamber (2
By arranging 3) and controlling opening / closing of the flow passage opening / closing valves (26) (27) arranged between the auxiliary gas chamber (23) and the high pressure gas passage (24) and the gas return passage (25), In addition to increasing the amount of gas during cooling to accelerate cooling, a pulse tube refrigerator is used during steady operation.
An element cooling device for an EDS detector, characterized in that the amount of gas sent to the cold heat generating section (5) of (6) is reduced to reduce gas pressure wave oscillation. 2. A compressor unit of a pulse tube refrigerator (6)
The EDS according to claim 1, wherein the gas switching speed is increased during the initial cooling and cooling by making the switching speed variable in the gas switching motor section (10) disposed between the (9) and the cold heat generating section (5).
Device cooling device for detector. 3. A temperature sensor is arranged in the EDS detector,
The element cooling device for an EDS detector according to claim 1 or 2, wherein a feedback function of pulse tube accelerated cooling and steady cooling is provided by setting a specified temperature, and the device is automatically operated. 4. EDS for elemental analysis of an electron microscope (1)
A detector is arranged, and the element of this EDS detector and the cold heat generating part (5) of the pulse tube refrigerator (6) are thermally connected via a cold heat transfer rod to compress the pulse tube refrigerator (6). The compressor unit (9) and the gas switching motor section (10) are arranged separately from the cold heat generating section (5), and the compressor unit (9) and the gas switching motor section (10) are respectively supported for vibration isolation. An element cooling device for an EDS detector in which the gas switching motor unit (10) and the cold heat generating unit (5) are connected by a flexible gas meter conduit (13).