JPH02272400A - Soft x-ray taking-out window - Google Patents

Abstract

PURPOSE:To prevent the degradation of airtightness and radiation by providing two fitting faces on both window frames on the vacuum side and the atmospheric pressure side and evacuating air in the space between them and holding an X-ray transmission material on the fitting face on the inner peripheral side interposing a metallic foil between them. CONSTITUTION:Flat and smooth annular projections 2a and 2b are formed on inside peripheral parts of an extrahigh vacuum-side window frame 5 and an atmospheric pressure-side window frame 6, and conflat edges 10c and 10d are formed on outer peripheral sides of projections 2a and 2b, and a through hole 14 connected to the space formed between projections 2a and 2b and edges 10c and 10d is provided. A oxygen free copper gasket 11 is clipped between edges 10c and 10d, and a metallic beryllium foil 1 is clipped between projections 2a and 2b interposing an annular aluminium foil 4 between them, and it is clamped by a bolt 7, a spring washer 8, and a flat washer 9, and air between window frames 5 and 6 is evacuated by connecting an oil rotary pump to a through hole 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a soft X-ray extraction window provided in an ultra-high vacuum container, and particularly to its structure.

[Conventional technology] Conventionally, X-ray transparency has been used as an X-ray transparent material.

Metallic beryllium foil is widely used because of its mechanical strength, good heat dissipation, and airtightness of the transparent material itself. In addition, in the soft X-ray region, it is necessary to create an ultra-high vacuum in the X-ray path to eliminate X-ray attenuation due to the atmosphere.
Not only the radiolucent material itself but also the joint between it and the ultra-high vacuum container must be airtight. Brazing and electron beam welding are methods for joining metal beryllium foil and ultra-high vacuum containers that satisfy both airtightness and mechanical fixation.

Adhesion using epoxy resin is used.

[Problem to be solved by the invention] However, among the conventional methods of joining metal helium foil and the wall of an ultra-high vacuum container, such as brazing and electron beam welding, it is difficult to connect all or part of the transparent material. The method of raising the temperature causes an increase in the crystal grain size of metallic helillium and grain boundary segregation, which causes the mechanical strength of metallic beryllium to deteriorate and the airtightness of the foil to be bonded to be lost. There are drawbacks.

In addition, when bonding with epoxy resin, there is no temperature rise during bonding, so the aforementioned deterioration of mechanical strength and airtightness does not occur, but when used as an X-ray extraction window, the epoxy resin covered with organic matter The drawback is that long-term reliability cannot be expected due to radiation deterioration caused by radiation.

The purpose of the present invention is to solve the above-mentioned problems, and to enable highly reliable and long-life airtight maintenance without causing deterioration of the mechanical strength or airtightness of soft X-ray transparent materials or deterioration of windows due to radiation.
To provide a soft X-ray extraction window having a structure that allows easy repair and regeneration of the window.

[Means for Solving the Problems] The present invention provides a soft material made of an X-ray transparent material formed at a predetermined location of an ultra-high vacuum container and sandwiched between an ultra-high vacuum side window frame and an atmospheric pressure side window frame. In the X-ray extraction window, each inner circumferential portion of the ultra-high vacuum side window frame and the atmospheric pressure side window frame is a flat and smooth first frame that is fastened to the X-ray transparent material while sandwiching the X-ray transparent material through a soft metal foil.
and has a second frosted mating surface that is airtightly joined to the peripheral portion of each window frame outside the first rubbing surface, and has a second frosted mating surface that is airtightly joined to the first rubbing surface. This soft X-ray extraction window is characterized in that a vacuum evacuation means is connected to the space within the window frames formed by the two rubbing surfaces.

[Operation: The ultra-high vacuum flange tightening method has been in practical use for some time, in which flat, smooth, small-area rubbing surfaces are placed opposite each other, aluminum foil is sandwiched between them, and the flange is firmly tightened from both sides.

On the other hand, since the thin metal beryllium foil used as the material for the soft X-ray extraction window does not have a high surface smoothness, applying this method as is is insufficient in terms of maintaining airtightness.

The present invention places emphasis on maintaining this airtightness.

FIG. 2 is an explanatory diagram for explaining the present invention in detail, and shows a partial cross section of the lower half of an axisymmetric circular window. A flat and smooth rubbing surface 22 of thin metal beryllium foil 21
Ultra-high vacuum window frame 23a, 2 having a, 22b
3b, it is not necessary that both sides of the foil 21 are airtightly joined. That is, if the left side of the foil 21 is the ultra-high vacuum side and the right side is the high pressure side in the figure, then A
It is sufficient that the passage of gas is blocked only in the part B, and the part B does not need to be in an airtight connection. At this time, the pressure in the space C sandwiched between the window frames on both sides becomes the same pressure as the right side of the foil 21 due to leakage from the path B.

However, ultra-high vacuum of about 1O-7Pa and atmospheric pressure (105
In the soft X-ray extraction window which is separated from pa) by a sheet of metal helium foil 21, it is necessary to prevent vacuum leakage only with a sealing material of soft metal foil such as aluminum against a pressure ratio of 1012 on both sides of the window. It is not easy to maintain the above pressure ratio only by vacuum sealing at part A. This is because, as mentioned above, the surface of the thin metal beryllium foil is not very smooth, but although it is soft, the deformability of the metal foil is not so large, and it is difficult to expect perfect adhesion.

Therefore, in the present invention, not only the leakage route A but also the leakage route B is provided.
The path is vacuum-sealed in the same manner, and the space C is made into a closed space separated from both the right and left sides of the beryllium foil 21, and is evacuated by evacuation means. If the pressure in space C is in the molecular flow region, even if there is microscopic imperfection in the vacuum sealing of path A, there will be no pressure between the left side of the foil 21 and the ultra-high vacuum in the molecular flow region. Leakage rarely occurs.

On the other hand, since the pressure on the right side of the foil 21 is in the viscous flow region, if there is microscopic incomplete adhesion in the path B, there is a pressure difference between the pressure in the space on the right side of the foil 21 (atmospheric pressure) and the pressure in the space C. By,
Gas flows into space C through path B, but this gas is removed from the system by a low vacuum exhaust pump connected to space C.

This is a type of differential pumping, but in the structure of the present invention, the pressure in the space C, which can be called an intermediate chamber, does not affect the deformation of the metal beryllium foil 21 due to the pressure difference, and this deformation occurs on both sides of the foil 21. Another feature is that it is determined only by the pressure difference. For example, if we consider a case where the right and left sides of the foil 21 are filled with different types of gas at the same pressure, and the space C is evacuated to a lower pressure, the differential pumping by the space C will function effectively. Since the gases on both sides of @21 do not mix, and the foil 21 is kept completely undeformed,
This is desirable from the viewpoint of the mechanical resistance of the foil.

Note that the heat generated by the absorption of X-rays by the metal beryllium foil 21 is not only conducted through the smooth rubbing surfaces 22a and 22b to the window frames 23a and 23b, but also caused by one side of the beryllium foil 21 being filled with high pressure. It is also dissipated by gases.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view schematically showing the structure of an embodiment of the present invention. This embodiment is an axially symmetrical circular window, and the figure shows only the half below the axis of symmetry. A metal beryllium foil 1 with a thickness of 30 strands and a diameter of 50 strands with guaranteed airtightness is passed through an annular aluminum foil 4 with a thickness of 80 strands to the window frame 5 on the ultra-high vacuum side and the window frame 6 on the atmospheric pressure side. Flat and smooth annular ridge with a width of 2.5 mm (first rubbing point) 2a,
2b, 12 M8 hexagon socket head bolts 7 and spring washers 8. Tighten using flat washer 9. two window frames 5
．． 6 are all made of stainless steel SUS 304 with a diameter of 152mm, and have conflated edges 10a on both sides.
~10d. Also, an annular protuberance 2a.

Since the inner diameter of 2b is 35 mm, the effective diameter of the soft X-ray extraction window in this embodiment is 35 mm.

Before tightening the bolts 7, the inner conflat edges (second rubbing surfaces) 10c, 1 of each window frame 5, 6 are
An oxygen-free copper gasket 11 is sandwiched between 0b and 0b.

This caskerat 11 is tightened by the inner bulge 2a.

This is done simultaneously with the sandwiching of the beryllium foil 1 by tightening the port 7 into the M8 tap hole 12 provided near the hole 2b. The M8 tapped holes 13 (16 locations on the circumference) penetrating the frame frames 5 and 6 are installed on the conflat edge 10d for installation on the ultra-high vacuum side and on the conflat edges 1 to 10a for attachment on the atmospheric pressure side, respectively. This is for attaching the main extraction window to the ultra-high vacuum container with the oxygen-copper gasket in between, so it will not affect the tightening of the intermediate gasket 11. The torque for tightening the Poldor is 2001U] f-cm.

The through hole 14 (only one location) that passes through the ultra-high vacuum side window frame 5 and communicates with the internal space is the space between the window frame 5°6 sealed with the aluminum foil 4 and the oxygen-free copper caskerat 11. A stainless steel pipe 15 welded to the window frame 5 and a stainless steel pipe 15 for vibration isolation are used to exhaust the air.
It is connected through an l'l bellows to an oil rotary pump with foreline trap (not shown).

In this embodiment, aluminum foil, which can be easily shaped into an annular shape, was used as the gas keratin 1 between the metal beryllium foil 1 and the window frames 5 and 6, but gold foil was used.

Foils of soft metals such as silver, oxygen-free copper, and indium with low vapor pressure can also be used. The shape of the window is not limited to circular,
Any shape is fine.

According to the structure of the present invention, a highly airtight bond can be easily realized, and since no heat is applied to the X-ray transparent material during sensitization, there is no deterioration in the strength of the window material, which improves reliability. A high soft X-ray extraction window can be obtained. Furthermore, since no organic material is used, there is no problem with either vacuum deterioration due to organic material scattering or short life caused by radiation deterioration. Furthermore, unlike brazing, welding, or epoxy bonding, it is easy to replace even when X-ray transmission rate changes over time or fatigue occurs, and the window can be reused.

All of these effects effectively contribute to improving the reliability and reducing the cost of the soft X-ray extraction window.

[Effects of the Invention] As described above, according to the present invention, airtightness can be maintained with high reliability and long life without causing deterioration of the mechanical strength and airtightness of the X-ray transparent material and without causing radiation deterioration of the window body. It is possible to provide a soft X-ray extraction window with a structure that allows for easy repair and reproduction of the window.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a soft X-ray extraction window according to the present invention, and FIG. 2 is an explanatory view for explaining the present invention in detail. 1.21... Metal beryllium foil 2a, 2b... Annular protuberance 4... Annular aluminum foil 5... Ultra-high vacuum side window frame 6... Atmospheric pressure side window frame 7... Bolt 8... Spring washer 9...
Flat washers 10a to 10d...Conflat edge 11...
Oxygen-free copper gasket 12...Tapped hole 13...Through tapped hole 14...Through hole 15...Pipe 22a
, 22b... rubbing surfaces 23a, 23b
···Window frame

Claims (1)

[Claims] (1) A soft X-ray extraction window formed at a predetermined location of the ultra-high vacuum container and made of an X-ray transparent material sandwiched between the ultra-high vacuum side window frame and the atmospheric pressure side window frame, which The inner peripheries of the high vacuum side window frame and the atmospheric pressure side window frame are
A second rub that has a flat and smooth first rubbing surface that is fastened while sandwiching the radiation transmitting material, and that is airtightly joined to the periphery of each window frame outside the first rubbing surface. A soft X-ray having a mating surface, and a space within the window frame formed by the first rubbing surface and the second rubbing surface is connected to an evacuation means. Take-out window.