JP2001266781A - Radiation transmissive window structure and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation transmissive window structure having few brokages of output window, and to provide its manufacturing method. SOLUTION: The radiation transmissive window structure comprises the radiotronsparer output window 17 which is jointed to an opening portion of a vacuum envelope 12, the vacuum envelope 12 and the output window 17 jointed to each other via an intermediate material 18, formed of at least one metal of copper, silver and these alloy attached to the junction of the vacuum envelope 12 to the output window 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation transmitting window structure used for an X-ray tube or the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art An electron tube such as an X-ray tube, a proportional counter tube and an X-ray intensifier tube has a configuration in which radiation such as X-rays generated in the tube is output to the outside or radiation is input into the tube. I have. Therefore, in these electron tubes, a part of the vacuum envelope constituting the electron tube is provided with a radiation transmission window for transmitting radiation.

Here, a conventional radiation transmitting window structure will be described with reference to FIG. Reference numeral 51 denotes a vacuum envelope. The vacuum envelope 51 includes a cylindrical portion 52 made of, for example, metal or glass, and a stainless steel joint ring 53 joined to an end of the cylindrical portion 52. Have been. The joining ring 53 is formed in a cylindrical shape as a whole, and a projecting portion 54 projecting inward is formed in the middle thereof. The upper surface 55 of the protrusion 54 is formed by a flat portion 55a and an arc-shaped portion 55b, and the lower surface 56 is formed flat. An output window 57 that transmits radiation such as X-rays is joined to the upper surface 55 of the protrusion 54.

The upper surface 55 of the projection 54 and the output window 57 are joined by an intermediate member 58, for example, a brazing sheet having a thickness of about 0.1 mm by a method such as brazing or diffusion bonding. Output window 5 when brazing or diffusion bonding
A diffusion layer 59 is formed between 7 and the intermediate member 58.

[0005] In the radiation transmitting window structure having the above-described structure, the outside of the vacuum envelope 51 is atmospheric and the inside is vacuum.
Therefore, due to the pressure difference between the inside and outside, as shown in FIG.
Deforms in a concave shape on the vacuum side. At this time, the output window 57
A portion of the contact portion comes into contact with the surface of the arc-shaped portion 55b provided on the upper surface of the projecting portion 54 to reduce the inward bending of the output window 57, and stress is generated in the vicinity of the joining portion between the joining ring 53 and the output window 57. I try not to concentrate.

Next, another conventional radiation transmitting window structure will be described with reference to FIG. 5 taking an X-ray tube for analysis as an example.
Reference numeral 61 denotes a vacuum envelope constituting the X-ray tube. The outer diameter of the vacuum envelope 61 is gradually reduced at the tip, and the front surface 62 is formed flat. An opening 63 is provided at the center of the front surface 62,
An output window 64 that transmits X-rays is provided in the opening 63. The output window 64 is made of a material having a small X-ray attenuation, for example, beryllium (hereinafter referred to as Be), and has a thickness of several tens μm to several hundreds μ in order to reduce the X-ray attenuation.
m. The vacuum envelope 61 and the output window 64 are brazed using a brazing material 65 such as silver brazing.

A support 6 is provided at the center in the vacuum envelope 61.
The anode target 67 is arranged at a position facing the output window 64 on the support 66. A focusing electrode 68 is arranged outside the anode target 67, and the focusing electrode 6
A cathode filament 69 is arranged outside of the reference numeral 8. The cathode filament 69 is supported by an annular support member 70 fixed to the outer periphery of the focusing electrode 68. The internal space 71 of the support 66 that supports the anode target 67 is a cooling water passage that cools the anode portion. Further, a cooling water channel 72 for cooling the vacuum envelope 61 is provided in a part of the vacuum envelope 61.

[0008]

In the case of the radiation transmitting window structure shown in FIG. 4, it is possible to efficiently transmit radiation such as X-rays to the output window 57 and to maintain the inside of the vacuum envelope 51 at a vacuum. As described above, it is required to have a mechanical strength that is not damaged by a pressure difference between the inside and outside of the vacuum envelope 51.
For this reason, the thickness of the output window 57 is usually several tens μm to 1 μm.
It is set in the range of 00 μm.

However, when the output window 57 and the joining ring 53 are joined by brazing, a diffusion layer 59 is formed between the output window 57 and the intermediate member 58 to a thickness of about several tens of μm.
The diffusion layer 59 has low mechanical strength, and a thickness having sufficient mechanical strength to maintain vacuum tightness may not be secured at the joint of the output window 57.

When the output window 57 and the joining ring 53 are joined by diffusion joining, the intermediate member 58 remains at a joining portion with a certain thickness, and the output window 57 cannot have a sufficient thickness. Further, when the intermediate member 58 remains, when the output window 57 is deformed inward due to a pressure difference between the inside and outside of the vacuum envelope 51, the arc-shaped portion 55b on the upper surface of the protruding portion 54 and the output window 57 hardly come into contact with each other. As a result, the inward bending of the output window 57 increases, and stress concentrates near the joint with the intermediate member 58,
In some cases, the output window 57 is damaged, and the inside of the vacuum envelope 51 cannot be kept airtight.

The analysis X-ray tube described in the example of FIG. 5 is required to improve the analysis accuracy. In order to improve the analysis accuracy, it is necessary to increase the X-ray intensity, and generally, the output window is formed thin. For example, Kα rays or Lα rays are used as X-rays for analysis. Since the Lα ray used for light element analysis has a large absorption in the output window, the output window is made as thin as possible. On the other hand, mechanical strength is required to maintain vacuum tightness. When the output window is made thinner, the stress per unit area applied to the outer peripheral portion of the output window increases, and the output window may be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to provide a radiation transmitting window structure with less damage to an output window and a method for manufacturing the same.

[0013]

According to the present invention, there is provided a radiation transmitting window structure in which an output window for transmitting radiation is joined to an opening of a vacuum envelope, and a joint surface of the vacuum envelope with the output window. The vacuum envelope and the output window are joined via a film of at least one of copper and silver, and an alloy of each of these metals, which are attached to the vacuum envelope.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. Reference numeral 11 denotes a vacuum envelope, and the vacuum envelope 11 is composed of a cylindrical portion 12 made of metal or glass, a stainless steel joining ring 13 joined to an end of the cylindrical portion 12, and the like. ing. The joining ring 13 is formed in a cylindrical shape as a whole, and a protruding portion 14 protruding inward is formed in a ring shape in the middle thereof. Projection 1
The upper surface 15 of 4 has an outer portion formed on a flat portion 15a, and a portion near the inner opening side is formed on an arc-shaped portion 15b. The lower surface 16 is formed flat. The arc-shaped portion 15b is formed such that a cross section thereof draws an arc from the flat portion 15a of the upper surface 15 toward the lower surface 16. An output window 17 made of Be that transmits radiation such as X-rays is joined to an opening of the vacuum envelope 11, for example, a flat portion 15 a of the projection upper surface 15 so as to cover the opening of the vacuum envelope 11. I have.

When the output window 17 is joined to the upper surface 15 of the protrusion, for example, the upper surface 15 of the protrusion
An intermediate material 18, for example, a metal film such as a silver solder is formed on the flat portion 15a to a thickness of about several μm by plating or the like in advance. Thereafter, the output window 17 is joined to the region of the upper surface 15 of the protruding portion 15 where the intermediate member 18 is attached by diffusion bonding, for example, by applying pressure to the joint region and heating the intermediate member 18 to a temperature at which the intermediate member 18 does not melt. The intermediate material 18 is not limited to the above-mentioned silver solder, but may be copper or silver, or at least one of alloys of these metals.

When the joining ring 13 and the output window 17 are joined by diffusion joining, a few μm is provided between the output window 17 and the intermediate member 18.
A diffusion layer 19 of Be and Cu is formed with a thickness of about m.
However, as described above, a method in which the metal film of the intermediate material 18 is formed in advance by plating or the like, and then the output window 17 is diffusion-bonded is that the thickness of the diffusion layer 19 is small, and Is ensured, and accidents such as breakage are prevented. Further, since the intermediate member 18 is as thin as about several μm, when the output window 17 is deformed inward due to a pressure difference between the inside and outside of the vacuum envelope 11, the output window 17 surely contacts the arc-shaped portion 15 b of the upper surface 15 of the protruding portion 15. I do. Therefore, the inward bending of the output window 17 is reduced, and stress concentration on the outer peripheral portion of the output window 17 is avoided, and breakage is prevented.

In FIG. 1, the bonding ring 13 and the output window 17 are diffusion bonded. However, the same effect can be obtained in the case where the joining ring 13 and the output window 17 are brazed, that is, the heating temperature for the intermediate member 18 is increased, and the intermediate member 18 is melted and joined.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, as the material of the joining ring 13, for example, copper suitable for vacuum hermetic joining with Be is used. In this case, the copper of the joint ring 13 and the output window 17
Be has the property of easily diffusing. Therefore, FIG.
The joining ring 13 and the output window 17 are directly joined by diffusion joining without using an intermediate material as in the embodiment. A diffusion layer 19 of Cu and Be is formed at the joint between the joint ring 13 and the output window 17, as in the embodiment of FIG.

Also in FIG. 2, the thickness of the diffusion layer 19 is small.
The output window 17 at the junction has a sufficient thickness,
The mechanical strength is increased, and accidents such as breakage are prevented. Further, when the output window 17 is deformed inward due to a pressure difference between the inside and outside of the vacuum envelope 11, the output window 17 comes into contact with the arc-shaped portion 15b of the projecting portion upper surface 15, and the inward bending of the output window 17 is reduced. . Therefore, stress concentration on the outer peripheral portion of the output window 17 is avoided, and breakage is prevented.

Next, another embodiment of the present invention will be described with reference to FIG. 3 taking an X-ray tube for analysis as an example. Code 3
Reference numeral 1 denotes a vacuum envelope made of, for example, stainless steel, which constitutes an X-ray tube.
The front surface 32 is formed flat. An opening 33 is provided at the center of the front surface 32, and an output window 34 that transmits X-rays is provided so as to close the opening 33. At this time, a thin portion 35 having a small thickness is provided at an edge portion of the front surface 32 adjacent to the opening 33, and an outer peripheral portion of the output window 34 is joined to a surface of the thin portion 35.

The vacuum envelope 31 and the output window 34 are joined by brazing using a brazing material 36 such as silver brazing. At this time, between the output window 34 and the thin portion 35, for example, an annular stress buffering member 37 made of Be of the same material as the output window 34 is arranged. The stress buffering member 37 has an outer peripheral portion sandwiched between the output window 34 and the thin portion 35 and an inner peripheral portion having the opening 3.
It extends into three parts. In FIG. 3, the output window 34 is deformed inward due to a pressure difference between the inside and outside of the vacuum envelope 31, and accordingly, the stress buffering member 37 is also deformed inward.

In the output window 34, Be with little attenuation of X-rays
The thickness is 100 μm or less, for example, several tens μm in order to reduce attenuation of transmitted X-rays.
It is formed as thin as １００100 μm.

A support 3 is provided at the center of the vacuum envelope 31.
An anode target 39 is supported at an end of the support 38 at a position facing the output window 34. A focusing electrode 40 is arranged outside the anode target 39, and a cathode filament 41 is arranged outside the focusing electrode 40. The cathode filament 41 is supported by an annular support member 42 fixed to the outer periphery of the focusing electrode 40. The internal space 43 of the support 38 supporting the anode target 39 is a cooling water channel for cooling the anode portion. Further, a cooling water passage 44 for cooling the portion of the vacuum envelope 31 is provided in a part of the vacuum envelope 31.

In the above-described configuration, when the output window 34 is joined to the thin portion 35 formed on the front surface 32 of the vacuum envelope 31, for example, a brazing material 36 such as silver brazing is attached to the thin portion 34.
And a flat plate-like stress buffer 37, a brazing material 36 such as silver brazing, and an output window 34 are sequentially stacked, and these parts are brazed by applying heat.

According to the above configuration, the stress buffer 37 is disposed on the vacuum side of the output window 34. Therefore, when the output window 34 is deformed inward due to a pressure difference between the inside and outside of the vacuum envelope 31, a part of the output window 34 comes into contact with the stress buffer 37. As a result, a large inward bending of the output window 34 is suppressed, stress applied to the outer peripheral portion of the output window 34 per unit area is reduced, and damage to the output window 34 is prevented.

Further, according to the above configuration, the output window 34
Can be made as thin as several tens of μm, and high output can be achieved. When Be of the same material as that of the output window 34 is used as the stress buffer 37, the coefficient of thermal expansion of the stress buffer 37 and the output window 34 becomes the same, and the local stress on the vicinity of the joint decreases. A certain effect can be obtained.

In the above embodiment, the stress buffer 3
7, Be of the same material as that of the output window 34 is used.
However, the same material as the anode target 39, for example, rhodium (Rh) can be used instead of Be.
As described above, when the same material as that of Be or the anode target 39 is used for the stress buffer material 37, it is possible to prevent the purity of the generated X-rays from lowering.

[0029]

According to the present invention, it is possible to realize a radiation transmitting window structure with less damage to the output window and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining another embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining another embodiment in which the present invention is applied to an X-ray tube for analysis.

FIG. 4 is a cross-sectional view for explaining a conventional example.

FIG. 5 is a cross-sectional view for explaining another conventional example used for an X-ray tube for analysis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Vacuum envelope 12 ... Cylindrical part 13 ... Joining ring 14 ... Projecting part of joining ring 15 ... Upper surface of projecting part 15a ... Flat part of upper surface of projecting part 15b ... Arc-shaped part of upper surface of projecting part 16 ... Projecting part Lower surface 17 ... output window 18 ... intermediate material 19 ... diffusion layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsunori Shimizu 7-1-1 Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in Toshiba Electronics Engineering Co., Ltd. 5J011 FA01

Claims (10)

[Claims] 1. A radiation transmitting window structure having a radiation transmitting output window joined to an opening of a vacuum envelope, wherein copper and silver are adhered to a joining surface of the vacuum envelope with the output window. A radiation transmitting window structure, wherein the vacuum envelope and the output window are joined via at least one metal film of an alloy of each of these metals. 2. The radiation transmitting window structure according to claim 1, wherein the material of the output window is beryllium. 3. A first step of adhering a metal film made of at least one of copper and silver and an alloy of these metals to a bonding surface of a vacuum envelope to be bonded to an output window that transmits radiation. A second step of joining the output window to a joining surface of the vacuum envelope to which a metal film is attached, the method comprising the steps of: 4. The method for manufacturing a radiation transmitting window assembly according to claim 3, wherein the metal film is adhered to the bonding surface of the vacuum envelope with the output window by plating. 5. A radiation transmitting window structure in which an output window that transmits radiation is joined to an opening of a vacuum envelope, wherein a member forming a joining surface of the vacuum envelope with the output window is made of copper and copper. A radiation transmitting window assembly comprising silver and at least one of alloys of these metals, wherein the vacuum envelope and the output window are directly joined by diffusion joining. 6. A first step of forming a member forming a bonding surface of a vacuum envelope to be bonded to an output window that transmits radiation by using at least one of copper and silver and an alloy of these metals; A second step of directly bonding a beryllium output window to the bonding surface of the vacuum envelope by diffusion bonding. 7. A radiation transmitting window assembly in which an output window that transmits radiation is joined to an opening of a vacuum envelope, wherein a radiation window is provided between a joining surface of the vacuum envelope and the output window and the output window. A radiation transmitting window structure, wherein a stress buffer is disposed. 8. The radiation transmitting window structure according to claim 7, wherein an inner end of the stress buffering material is located at an opening of the vacuum envelope. 9. The radiation transmitting window structure according to claim 7, wherein the stress buffer is made of the same material as the output window or the X-ray generating target. 10. A first surface of a vacuum envelope connected to an output window.
A first step of disposing a brazing material, a second step of disposing a stress buffer on the first brazing material, and a second step of disposing a stress buffer on the first brazing material
A third step of disposing a brazing material, a fourth step of disposing an output window on the second brazing material, and heating a joint between the vacuum envelope and the output window to sandwich the stress buffer material And a fifth step of joining the vacuum envelope and the output window.