CN109216139B

CN109216139B - Housing for a multi-focus X-ray tube and multi-focus X-ray tube

Info

Publication number: CN109216139B
Application number: CN201710523835.9A
Authority: CN
Inventors: 陈志强; 唐华平; 李元景; 王永刚; 秦占峰; 张丽
Original assignee: Nuray Technology Co ltd; Nuctech Co Ltd
Current assignee: Nuray Technology Co ltd; Nuctech Co Ltd
Priority date: 2017-06-30
Filing date: 2017-06-30
Publication date: 2024-06-21
Anticipated expiration: 2037-06-30
Also published as: CN109216139A

Abstract

A housing for a multi-focus X-ray tube and a multi-focus X-ray tube including the same are disclosed. A plurality of exit windows are provided on a housing for a multi-focal X-ray tube, the exit windows being aligned with respective target points on an anode, a window being provided on each exit window, the windows being arranged to seal the housing and allow a corresponding beam of X-rays within the housing to exit the housing through the windows. At least one of the outlet windows has a truncated cone shape that gradually expands from the inside to the outside in at least a part of a cross section in a thickness direction of the housing. Each extraction window corresponds to a target spot, has certain collimation and shaping effects on X-rays generated by the target spot, has enough strength and is connected with the shell of the ray tube into a whole in a tight connection mode, so that the high vacuum state inside the ray tube is realized.

Description

Housing for a multi-focus X-ray tube and multi-focus X-ray tube

Technical Field

Embodiments of the present invention relate to a housing for an X-ray tube, and in particular, to a housing for a multi-focus X-ray tube and a multi-focus X-ray tube comprising the same.

Background

X-rays have wide application in the fields of industrial nondestructive testing, safety inspection, medical diagnosis, treatment, and the like. The device for generating X-rays is called an X-ray source, and is generally composed of an X-ray tube, a power supply and control system, auxiliary devices such as cooling and shielding, and the like. The X-ray tube comprises three main parts, a cathode, an anode and a housing. The cathode generates a stream of electrons that is accelerated by a high voltage electric field between the cathode and the anode and impinges on a target on the anode, thereby generating X-rays.

The X-rays need to be extracted from a location on the housing, which is often referred to as an extraction window. The X-ray has strong penetrability, almost can penetrate various substances in nature, but the penetrability is related to the mass thickness of the penetrated substances, namely, the smaller the mass thickness is, the smaller the blocking of the X-ray by the object is. For better extraction of X-rays, the thickness of the extraction window is usually minimized, but the X-ray tube is a sealed high vacuum chamber where at least one atmospheric pressure is to be experienced, so the extraction window is usually designed to be very small round or square.

Disclosure of Invention

The technical problem to be solved by the embodiments of the present invention is to provide a housing and a multi-focal X-ray tube including such a housing, capable of guiding out a plurality of X-rays generated through a plurality of targets (focal points) on a plurality of cathodes, anodes, and the like.

According to an embodiment of one aspect of the present invention, there is provided a housing for a multi-focal X-ray tube, on which a plurality of extraction windows are provided, which are aligned with a plurality of X-rays within the housing, respectively. A window is provided on each of the exit windows, the window being arranged to seal the housing and allow a corresponding beam of X-rays to exit the housing through the window, at least a portion of a cross section of at least one of the exit windows in a thickness direction of the housing having a truncated cone shape that gradually expands from the inside to the outside.

According to an embodiment of the invention, the housing for a multi-focal X-ray tube has a truncated cone shape substantially conforming to the sector cross-section of the respective X-rays.

According to one embodiment of the invention, the ratio of the thickness of the window to the thickness of the housing is less than 1:5, preferably less than 1:10.

According to one embodiment of the invention, the housing for a multi-focus X-ray tube, the window has a thickness of less than 1mm, preferably between 0.02mm and 0.5mm.

According to a housing for a multi-focal X-ray tube according to one embodiment of the present invention, the window covers an area of the exit window portion of less than 1 square centimeter.

According to a housing for a multi-focus X-ray tube according to one embodiment of the invention, at least one of the exit windows has a square or circular cross-section, said window preferably having the same shape as the exit window.

According to a housing for a multi-focus X-ray tube according to one embodiment of the invention, the window is arranged inside, outside or between inside and outside of the exit window.

According to a housing for a multi-focal X-ray tube according to one embodiment of the invention, the window and the housing are made of different materials, the window being fixed to the housing by welding, sintering or crimping.

According to a housing for a multi-focal X-ray tube according to one embodiment of the invention, the window is fixed to the housing by a connection assembly comprising: an annular pressing plate configured to press the periphery of the window onto the housing; a fastener passing through the pressure plate at the periphery of the window to fix the pressure plate on the housing; and a seal ring disposed between the housing and the periphery of the window.

According to the housing for a multi-focus X-ray tube of one embodiment of the present invention, a stepped portion facing the outside of the housing is formed in the extraction window, and the periphery of the window is fixed on the stepped portion.

According to a housing for a multi-focus X-ray tube of one embodiment of the invention, the window has a skirt at its periphery extending towards the outside of the housing and conforming to the taper of the exit window, said skirt being fixed to the tapered side wall of the exit window.

A case for a multi-focal X-ray tube according to an embodiment of the present invention is made of metal, ceramic or glass, and the window is made of one metal foil selected from the group consisting of titanium foil, copper foil, aluminum foil, beryllium foil, stainless steel foil, or made of a ceramic sheet, a glass sheet or a quartz sheet.

According to one embodiment of the invention, the window and the housing are integrally made of the same material.

An embodiment of a multi-focus X-ray tube according to another aspect of the present invention comprises: the housing according to any one of the embodiments above; a cathode located within the housing and configured to respectively direct electron beam current from a plurality of locations; and an anode positioned within the housing and configured to align with the cathode to generate a plurality of X-rays from a plurality of targets.

According to the shell and the multi-focus X-ray tube of the working embodiment of the invention, the shell is provided with the plurality of extraction windows which are respectively aligned with the plurality of targets of the anode in the shell, so that the structure thickness of the extraction windows is obviously reduced compared with that of the shell, the extraction of X-rays is facilitated, each extraction window corresponds to one target, the X-rays generated by the target have certain collimation and shaping effects, and meanwhile, the X-rays have enough strength and are connected with the shell of the ray tube into a whole in a tight connection mode, and the high vacuum state inside the tube is realized.

Drawings

These and/or other aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic perspective view of a multi-focal X-ray tube according to an exemplary embodiment of the invention;

FIG. 2 is a schematic diagram of the operating principle of the multi-focal X-ray tube of FIG. 1 for emitting X-rays;

FIG. 3 is a schematic perspective view of the multi-focal X-ray tube of FIG. 1 emitting X-rays, wherein the housing shows only a sidewall provided with a plurality of exit windows;

FIG. 4 is a schematic cross-sectional view of one side wall of the housing of FIG. 3 in the thickness direction of the housing;

5A-5C are schematic cross-sectional views showing the window disposed in different positions of the housing, wherein FIG. 5A shows the window disposed inside the housing, FIG. 5B shows the window disposed between the inside and outside of the housing, and FIG. 5C shows the window disposed outside of the housing;

FIGS. 6A-6D are schematic plan views showing extraction windows having different shapes;

FIG. 7 is a schematic cross-sectional view illustrating a window being disposed inside a lead-out window using a welding process according to one embodiment of the present invention;

FIG. 8 is a schematic cross-sectional view illustrating a window being disposed between the inside and the outside of an exit window using a welding method according to another embodiment of the present invention;

FIG. 9 is a schematic cross-sectional view illustrating a window being disposed outside of a lead-out window using a welding method according to still another embodiment of the present invention;

FIG. 10A is a schematic plan view of a window to housing connection in accordance with yet another exemplary embodiment of the present invention;

FIG. 10B is a schematic cross-sectional view of FIG. 10A;

FIG. 11A is a schematic plan view of a window to housing connection in accordance with yet another exemplary embodiment of the present invention; and

Fig. 11B is a schematic cross-sectional view of fig. 11A.

Reference numerals:

1: a housing;

2: a cathode;

3: an anode;

4. 4', 41, 42, 43, 44, 45: a lead-out window;

5: a window;

6: a welding position;

6': welding solder;

7: a seal ring;

8: a pressing plate;

9: a fastener;

10: a step portion;

11: a skirt portion;

12: an external power interface;

21. 22, 23, 24, 25: cathode position;

31. 32, 33, 34, 35: a target spot;

E: electron beam current.

Detailed Description

Like reference numerals refer to like parts throughout the specification.

The technical scheme of the invention will be further specifically described by the following examples with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of embodiments of the present invention with reference to the accompanying drawings is intended to illustrate the general inventive concept and should not be taken as limiting the invention.

Furthermore, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in the drawings in order to simplify the drawings.

According to the present general inventive concept, there is provided a housing for a multi-focal X-ray tube, wherein a plurality of extraction windows are provided on the housing, the plurality of extraction windows being aligned with a plurality of X-rays within the housing, respectively. A window is provided on each exit window, the window being arranged to seal the housing and allow a corresponding beam of X-rays within the housing to exit the housing through the window.

Fig. 1 is a schematic perspective view of a multi-focal X-ray tube according to an exemplary embodiment of the invention; FIG. 2 is a schematic diagram of the operating principle of the multi-focal X-ray tube of FIG. 1 for emitting X-rays; FIG. 3 is a schematic perspective view of the multi-focal X-ray tube of FIG. 1 emitting X-rays, wherein the housing shows only one side wall provided with a plurality of exit windows; fig. 4 is a schematic cross-sectional view of one side wall of the case in fig. 3 in the case thickness direction.

As shown in fig. 1 to 4, a multi-focal X-ray tube according to an embodiment of the present invention includes: a housing 1, a cathode 2 and an anode 3. A high vacuum is formed in the housing 1. An anode 3 is positioned within the housing and is configured to align with the cathode to generate a plurality of X-rays from a plurality of targets on the anode. In particular, the extracted electron beam stream is accelerated by a high voltage electric field located between the cathode and the anode and gets energy to strike the anode target (or focus) to generate X-rays X. An external controller is electrically connected to the cathode 2 and the anode 3 through an external power interface 12 to control the cathode 2 and the anode 3.

A housing 1 for a multi-focus X-ray tube according to one embodiment of the invention is provided with a plurality of exit windows 4, which are aligned with a plurality of targets on the anode, respectively. The arrangement of the extraction windows 4 corresponds to the arrangement of the targets on the anode one by one. For example, at least 2 outlet windows are provided on the housing 1, and more preferably at least 5 outlet windows are provided. Correspondingly, at least 5 targets are provided on the anode 3. As shown in fig. 3, it is schematically shown that 5 outlet windows are provided on the housing 1, and correspondingly, 5 targets are provided on the anode. It will be appreciated by those skilled in the art that the number of extraction windows and frames shown in fig. 3 is merely exemplary and the present invention is not limited to the number of extraction windows and frames. The 5 exit windows of the multi-focal X-ray tube shown in fig. 3 are aligned with 5 targets, respectively. The cathode 2 can generate a plurality of electron beams E from a plurality of cathode locations 21, 22, 23, 24, 25, each of which electron beams E is accelerated by a high voltage electric field between the cathode 2 and the anode 3, gets energy and impinges on the anode 3, emitting X-rays at different locations on the anode 3, i.e. targets 31, 32, 33, 34, 35. A plurality of lead-out windows 41, 42, 43, 44, 45 are provided on the housing 1 corresponding to different targets of the anode 3. That is, each of the exit windows is provided on the corresponding X-ray transmission path. X-rays generated by the target spot 31 are led out of the leading-out window 41; x-rays generated by target spot 32 are extracted from extraction window 42; x-rays generated by the target spot 33 are led out from the leading-out window 43; x-rays generated by the target spot 34 are extracted from the extraction window 44; x-rays generated by the target spot 35 are extracted from the extraction window 45. The arrangement of the exit windows 41, 42, 43, 44, 45 is the same as the arrangement of the targets 31, 32, 33, 34, 35. In this way, X-rays generated from multiple targets can be extracted from the respective extraction windows.

A window 5 is provided on each exit window 4, said window being arranged to seal the housing 1 and to allow X-rays within the housing 1 to exit through the window 5. It will be appreciated that the exit window has a relatively much smaller thickness than other non-window positions of the housing 1, but is not completely open, as the X-ray tube needs to be vacuum sealed. In this way, the window 5 and the shell 1 form a vacuum sealing structure, so that the cathode 2 and the anode 3 are in a high vacuum environment, on one hand, the electron beam E generated by the cathode 2 can smoothly reach the anode 3 without being lost due to collision with air molecules; on the other hand, the insulating property of the vacuum allows the anode 3 to be in a high voltage state relative to the cathode 2 without easily creating a breakdown spark. X-rays generated at a plurality of target positions on the anode 3 are respectively led out of the shell of the X-ray tube through different leading-out windows 4 and through windows arranged on the leading-out windows for X-ray perspective imaging and other applications.

Fig. 5A-5C are schematic cross-sectional views of the window disposed at different locations of the housing, wherein fig. 5A shows the window disposed inside the housing, fig. 5B shows the window disposed between the inside and outside of the housing, and fig. 5C shows the window disposed outside of the housing.

In one embodiment, as shown in fig. 5A to 5C, 6D, at least a part of the cross section of at least one of the lead-out windows 4 in the thickness direction of the housing has a truncated cone shape that gradually expands from inside to outside. That is, each of the lead-out windows 4 shown in fig. 1 is smaller in size inside the housing than outside the housing. Further, the truncated cone shape substantially coincides with the sector-shaped cross section of the corresponding X-ray. Specifically, the X-rays are emitted outwards in a three-dimensional divergent manner from corresponding target points on the anode 3, and the sectional shape of the extraction window 4 is designed to be a cone angle vertex of a truncated cone shape and positioned on the anode 3, so that the X-rays are led out of the housing 1, and meanwhile, the housing 1 is kept to have stronger strength at the position of the extraction window.

In one embodiment, as shown in fig. 4, 6A, 6B, at least one of the lead-out windows 4 is rectangular in cross section in the thickness direction of the case. I.e. the exit window 4 has no taper. By the design, the window is simple in structure and convenient and quick to process.

In one embodiment, as shown in fig. 4, the thickness D of the window 5 is smaller than the thickness D of the housing 1, so that X-rays pass through the window 5 with a greater transmittance. For example, the ratio of the thickness of the window to the thickness of the housing is less than 1:5, preferably less than 1:10. in an exemplary embodiment, a window 5 is arranged at the exit window 4, the thickness of the window 5 being very thin, in the range of a few tenths of a millimeter to a millimeter. For example, the window has a thickness of less than 1mm, preferably 0.02mm to 0.5mm. In this way, the window 5 blocks the X-rays far less than the rest of the housing 1, so that the X-rays can be extracted to the maximum.

In one embodiment, the area of the portion of the window 5 corresponding to the exit window 4 is less than 1 square centimeter. In general, each extraction window 4 corresponds to only one target point, so that the extraction window 4 has a smaller area, the pressure born by the extraction window 4 is very small, the thickness d of the window body 5 can be designed to be very small, and the extraction window can be deformed slightly under the action of atmospheric pressure but cannot break.

Fig. 6A to 6D are schematic plan views showing the extraction windows 4 having different shapes. In one embodiment, at least one of the exit windows is square or circular in cross-section. Fig. 6A and 6C show an embodiment of a circular exit window, wherein the exit window in fig. 6A has no taper and the exit window in fig. 6C has a taper. Fig. 6B and 6D show an embodiment of a square extraction window, wherein the extraction window in fig. 6B has no taper and the extraction window in fig. 6D has a taper. The window has the same shape as the exit window 4. That is, the window and the extraction window both have a circular shape or a regular polygon shape, but the area of the window is larger than that of the extraction window so as to cover the extraction window. It will be appreciated by those skilled in the art that the window may also have a different shape than the exit window. The plurality of exit windows on one tube may be of the same shape or a combination of several different shapes.

FIG. 7 is a schematic cross-sectional view illustrating a window being disposed inside a lead-out window using a welding process according to one embodiment of the present invention; FIG. 8 is a schematic cross-sectional view illustrating a window being disposed between the inside and the outside of an exit window using a welding method according to another embodiment of the present invention; fig. 9 is a schematic cross-sectional view showing that a window is provided outside of a lead-out window by welding according to still another embodiment of the present invention.

In one embodiment, the window 5 is fixed to the inside of the exit window 4 by welding, as shown in fig. 7. At this time, the window may cover the lead-out window from the inside of the case. In another embodiment, the window 5 is fixed between the inside and the outside of the extraction window 4 by welding, as shown in fig. 8. At this time, the window periphery may be provided with a skirt 11, and then fixed to the side wall of the exit window by the skirt. With respect to the skirt in fig. 8, it will be described in detail below. In another embodiment, the window 5 is fixed to the outside of the exit window 4 by welding, as shown in fig. 9. In this case, the window may cover the lead-out window from the outside of the case. The fixed position of the window with respect to the lead-out window is not limited, and may be flexibly set as needed. The fixed position of the window with respect to the lead-out window may be the same or different in the same X-ray tube.

FIG. 10A is a schematic plan view of a window to housing connection in accordance with yet another exemplary embodiment of the present invention; fig. 10B is a schematic cross-sectional view of fig. 10A. FIG. 11A is a schematic plan view of a window to housing connection in accordance with yet another exemplary embodiment of the present invention; fig. 11B is a schematic cross-sectional view of fig. 11A.

As shown in fig. 5A to 5C, 10A to 10B, 11A to 11B, the window 5 is provided inside, outside, or between the inside and outside of the extraction window 4. The window 5 and the housing 1 are made of different materials. Further, the window 5 is fixed to the housing 1 by welding, sintering or crimping. For example, the case 1 is made of metal, ceramic or glass, the window 5 is made of one metal foil selected from the group consisting of titanium foil, copper foil, aluminum foil, beryllium foil, stainless steel foil, and the window 5 is fixed to the case 1 by welding or crimping and forms a vacuum sealing structure. Since the thickness of the metal foil is uniform, the window made of the metal foil has great convenience and cost advantages.

In an alternative embodiment, the housing 1 is made of metal, ceramic or glass, the window 5 is made of a non-metallic sheet material, such as ceramic, glass, quartz, etc., and the window 5 is fixed to the lead-out window 4 by welding or sintering and forms a vacuum-tight structure with the housing 1.

In an exemplary embodiment, as shown in fig. 7-9, the window 5 is fixed to the inside, the outside, and between the inside and the outside of the lead-out window 4, respectively, by welding. The window 5 made of metal foil can completely close the exit window 4 and form a seal with the housing. The weld location 6 surrounds the exit window 4 for a complete revolution so that the welded connection (fusion) between the window 5 and the housing 1 is a complete closed revolution, thereby bringing the window 5 into vacuum-tight connection with the housing 1. Welding means include, but are not limited to, argon arc welding, resistance welding, laser welding, brazing, electron beam welding, friction welding, diffusion welding, explosion welding, and the like.

In one exemplary embodiment, as shown in fig. 10A-10B, window 5 is secured to housing 1 by a connection assembly comprising: an annular pressing plate 8 configured to press the periphery of the window 5 against the housing 1; and a fastener 9 passing through the pressing plate 8 at the periphery of the window 5 to fix the pressing plate 8 to the housing 1. The window 5 has a large area with respect to the exit window 4, and can completely cover the exit window 4. Further, the connection assembly also comprises a sealing ring 7 arranged between the housing 1 and the periphery of the window 5. The sealing ring 7 has the sealing property of high vacuum and is a complete circle. A sealing ring 7 is placed between the perimeter of the housing 1 surrounding the outlet window 4 and the window 5. The pressing plate 8 is provided with a plurality of holes at positions corresponding to the leading-out windows 4, the pressing plate 8 is pressed on the window 5, and the sealing ring 7 can be uniformly extruded through the window 5. The fastener 9 connects the pressing plate 8 and the shell 1, the sealing ring 7 is extruded and deformed through the fastening action, and finally the window 5 and the shell 1 are connected in a vacuum sealing way. The fastener 9 comprises, for example, a screw or a rivet. In this way, the window 5 can be firmly fixed to the housing 1.

In an exemplary embodiment, as shown in fig. 11A to 11B, a stepped portion 10 facing the outside of the housing 1 is formed in the lead-out window 4', and the periphery of the window 5 is fixed to the stepped portion 10. The portion of the exit window 4' located inside the window 5 has a truncated cone shape that gradually increases outwards, and the portion of the exit window located outside the window 5 also has a truncated cone shape that gradually increases outwards. The taper of the exit window 4' inside the window 5 and the taper outside the window 5 are preferably different parts of the same taper. The step 10 in the exit window 4 'of the housing 1 is arranged to surround the step 10 of the exit window 4' a complete revolution. The step 10 has the solder 6 'placed thereon, the solder 6' also being arranged in a complete turn along the step 10. The outer circumference of the window 5 is smaller than the outer circumference of the step portion 10 of the lead-out window 4', and the window 5 is placed on the solder 6'. The shell 1, the welding solder 6' and the beam outlet window 5 are integrally placed into a high-temperature brazing furnace according to the position relation from inside to outside, the welding solder 6' is melted at high temperature, and the welding solder 6' fixes the window 5 on the shell 1 in a vacuum sealing manner when the temperature is reduced.

In one embodiment, as shown in fig. 8, the window 5 has, at its periphery, a skirt 11 extending towards the outside of the housing 1 and conforming to the taper of the extraction window, said skirt being fixed to the tapered side wall of the extraction window. In this way, the window 5 can be closely attached to the housing 1, and the lead window can be sealed to form a vacuum structure.

In another embodiment, the window 5 and the housing 1 are made in one piece from the same material. As shown in fig. 4, the window 5 is formed by removing a part of the material from the casing 1 having a thickness D, thereby forming the lead-out window 4. Thus, a small portion of the material having a thickness d remains to be used as the window 5 of the lead-out window 4, the window 5 being a part of the housing 1. That is, the window 5 is formed integrally with the housing 1, has excellent vacuum tightness, and is easily formed at the inside of the housing 1 or at a position between the inside and the outside (as shown in fig. 5A to 5B).

According to an embodiment of a further aspect of the present invention, as shown in fig. 1-3, there is provided a multi-focal X-ray tube comprising a housing as described in the working embodiment above; a cathode 2, the cathode 2 being located within the housing 1 and configured to respectively draw out electron beam streams E from a plurality of locations; and an anode 3, the anode 3 being located within the housing 1 and configured to be aligned with the cathode 2 to generate a plurality of X-rays X from a plurality of targets.

Although the shapes of the extraction windows and windows are illustrated as square, circular in the embodiment of the present invention, the present invention is not limited thereto, and the shapes of one, more or all of the extraction windows and windows in the multi-focal X-ray tube, for example, rectangular, may be changed according to specific needs.

According to the shell and the multi-focus X-ray tube of the working embodiment of the invention, the shell is provided with the plurality of extraction windows which are respectively aligned with the plurality of targets of the anode in the shell, so that the structure thickness of the extraction windows is obviously reduced compared with that of the shell, the X-ray tube is beneficial to extraction, and meanwhile, the X-ray tube has enough strength and is connected with the shell of the X-ray tube into a whole in a tight connection mode, and the high vacuum state in the X-ray tube is realized.

Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments. It will be appreciated by those skilled in the art that the above-described embodiments are exemplary and that modifications may be made thereto by those skilled in the art, and that the structures described in the various embodiments may be freely combined without structural or conceptual conflicts, to achieve a wide variety of housings and multi-focal X-ray tubes, while addressing the technical problems of the present invention.

Having described the preferred embodiments of the present invention in detail, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope and spirit of the following claims and that the invention is not limited to the implementations of the exemplary embodiments set forth in the specification.

Claims

1. A housing for a multi-focal X-ray tube, wherein,

A plurality of leading-out windows are arranged on the shell and are respectively aligned with a plurality of X-rays in the shell,

A window is provided on each exit window, the windows being arranged to seal the housing and allow a corresponding beam of X-rays within the housing to exit the housing through the windows,

At least one of the lead-out windows has a truncated cone shape in which at least a portion of a cross section in a thickness direction of the housing is gradually enlarged from inside to outside,

Wherein the truncated cone shape substantially coincides with the sector-shaped cross-section of the respective X-ray.

2. The housing for a multi-focal X-ray tube of claim 1 wherein,

The ratio of the thickness of the window to the thickness of the shell is less than 1:5.

3. The housing for a multi-focal X-ray tube of claim 2 wherein,

The ratio of the thickness of the window to the thickness of the shell is less than 1:10.

4. The housing for a multi-focal X-ray tube of claim 1 wherein,

The thickness of the window body is smaller than 1mm.

5. The housing for a multi-focal X-ray tube of claim 4 wherein,

The thickness of the window body is 0.02 mm-0.5 mm.

6. The housing for a multi-focal X-ray tube of claim 1 wherein,

The area of the window covering the exit window portion is less than 1 square centimeter.

7. The housing for a multi-focal X-ray tube of claim 1 wherein said window and said housing are made of different materials,

The window is secured to the housing by welding, sintering or crimping.

8. The housing for a multi-focal X-ray tube of claim 7 wherein,

The window is secured to the housing by a connection assembly comprising:

An annular pressing plate configured to press the periphery of the window onto the housing;

A fastener passing through the pressure plate at the periphery of the window to fix the pressure plate on the housing; and

And a seal ring disposed between the housing and the periphery of the window.

9. The housing for a multi-focal X-ray tube according to any of claims 1-7, wherein,

A stepped portion facing the outside of the housing is formed in the lead-out window, and the periphery of the window is fixed to the stepped portion.

10. The housing for a multi-focal X-ray tube according to any of claims 1-7, wherein,

The window has a skirt at its periphery extending towards the outside of the housing and conforming to the taper of the exit window, said skirt being secured to the tapered side wall of the exit window.

11. The housing for a multi-focal X-ray tube of claim 7 wherein,

The case is made of metal, ceramic or glass, and the window is made of one metal foil selected from the group consisting of titanium foil, copper foil, aluminum foil, beryllium foil, stainless steel foil, or made of a ceramic sheet, a glass sheet or a quartz sheet.

12. The housing for a multi-focal X-ray tube of claim 8 wherein,

13. The housing for a multi-focal X-ray tube of claim 9 wherein,

14. The housing for a multi-focal X-ray tube of claim 10 wherein,

15. The housing for a multi-focal X-ray tube according to any of claims 1-6, wherein,

The window and the housing are integrally made of the same material.

16. A multi-focal X-ray tube comprising:

The housing according to any one of claims 1-15;

A cathode located within the housing and configured to respectively direct electron beam current from a plurality of locations; and

An anode positioned within the housing and configured to be aligned with the cathode to generate a plurality of X-rays from a plurality of targets.