JP5149707B2 - X-ray generator - Google Patents

Description

  The present invention relates to an X-ray generator used as an X-ray source in X-ray nondestructive inspection or the like.

As a conventional X-ray generator, Patent Document 1 describes an apparatus that focuses an electron beam emitted from an electron gun onto a target using an electromagnetic coil and emits X-rays from the target.
Japanese Patent No. 3999399

  However, in the X-ray generator described in Patent Document 1, even when an electron beam is focused on a target using an electromagnetic coil, some scattered electrons that cannot be focused reach the target and The focused spot of the electron beam may be blurred, and as a result, the resolution of the X-ray image may be reduced.

  Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide an X-ray generation apparatus capable of improving the resolution of an X-ray image.

  In order to achieve the above object, an X-ray generator according to the present invention is an X-ray generator that causes an electron beam emitted from an electron gun to enter a target and emit X-rays from the target. An electron path through which the electron beam emitted from the electron beam passes, and an electromagnetic coil for focusing the electron beam that passes through the electron path on the target. In the electron path, the inner wall surface of the first portion is in the first portion. On the other hand, the uneven surface is rougher than the inner wall surface of the second portion located on the electron gun side.

  In this X-ray generator, the inner wall surface of the first portion of the electron path closer to the target is closer to the target than the second portion of the electron path is a rough uneven surface. Reflection is suppressed. Therefore, according to this X-ray generator, it is possible to prevent the focused spot of the electron beam on the target from being blurred, and it is possible to improve the resolution of the X-ray image. The “rougher uneven surface” means an uneven surface having a larger difference in height between the top of the convex portion and the bottom of the concave portion.

  In the X-ray generator according to the present invention, it is preferable that the first portion includes an aperture portion provided with an electron passage hole for narrowing an electron beam, and the inner wall surface of the electron passage hole is an uneven surface. . In this case, not only the electron beam can be focused, but also the electrons incident on the inner wall surface of the electron passage hole can be prevented from being reflected to the target side, and the resolution of the X-ray image can be further improved. It becomes.

  In the X-ray generator according to the present invention, it is preferable that the inner wall surface of the first portion is an uneven surface by forming a screw thread and a screw groove. In this case, a highly accurate uneven surface can be easily obtained.

  In the X-ray generator according to the present invention, it is preferable that the first portion is provided with a through hole that communicates the electron gun side region and the target side region in the electron passage. In this case, for example, even if the diameter of the electron passage hole is reduced, the gas generated from the target by the incidence of the electron beam can be exhausted sufficiently and efficiently through the through hole.

  In the X-ray generator according to the present invention, it is preferable that the aperture portion is detachable from the first portion. In this case, by replacing the aperture portion, an electron passage hole having a desired shape or the like can be provided in the electron passage.

  In the X-ray generator according to the present invention, the inner wall surface of the first portion is preferably formed in a tapered shape that tapers toward the target side. In this case, it can suppress more reliably that the electron which injected into the inner wall face of the 1st part reflects in the target side.

  In the X-ray generator according to the present invention, the first portion is preferably made of a lighter element material than the second portion. In this case, since the first part of the electron path closer to the target than the second part of the electron path is made of a lighter element material, generation of X-rays due to the incidence of electrons is suppressed. Therefore, X-rays can be prevented from being emitted from a portion other than the focused spot of the electron beam on the target, and the resolution of the X-ray image can be further improved. The “lighter element material” means an element material having a lighter atomic weight.

  According to the present invention, the resolution of an X-ray image can be improved.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.
[First Embodiment]

  FIG. 1 is a cross-sectional view of the X-ray generator of the first embodiment. As shown in FIG. 1, the X-ray generator 1 makes an electron beam E emitted from a filament F of an electron gun 2 incident on a target 5 of a target unit T and moves forward from the target 5 (advancing of the electron beam E). The front side of the direction is “front” and the rear side is “rear”). The X-ray generator 1 is a device called an open type in which the filament F and the target unit T can be exchanged, and has a cylindrical main body 3 that houses the electron gun 2 and a hinge at the front end of the main body 3. And a cylindrical opening 6 that is tiltably connected via the portion 4. In the X-ray generator 1, the front end portion of the main body portion 3 can be opened and the filament F can be exchanged by laying down the opening portion 6 via the hinge portion 4.

  The open portion 6 includes a double cylindrical portion 8 including an inner cylindrical portion 8a and an outer cylindrical portion 8b that are integrally connected at a rear end portion, and a truncated cone fixed to a front end portion of the outer cylindrical portion 8b by a fixing screw 14. And an emission end portion 13 having a shape. A stainless steel pipe member 9 extending in the traveling direction of the electron beam E is inserted in the inner cylinder portion 8a, and an aluminum bobbin is provided between the inner cylinder portion 8a and the outer cylinder portion 8b. An electromagnetic coil 12 formed by winding an enamel wire around 11 is arranged. The double cylindrical portion 8 and the emission end portion 13 are made of a magnetic material such as soft iron and constitute a part of a magnetic circuit through which a magnetic flux generated by the electromagnetic coil 12 passes.

  The electron beam E emitted from the electron gun 2 travels in the pipe member 9 through the rear end portion of the pipe member 9 opened in the main body portion 3. That is, the pipe member 9 constitutes a part of the electron passage 7 through which the electron beam E emitted from the electron gun 2 passes, and the center line L1 of the electron passage 7 is the center line. The electromagnetic coil 12 focuses the electron beam E passing through the electron path 7 on the target 5.

  FIG. 2 is a cross-sectional view of a main part of the X-ray generator shown in FIG. As shown in FIG. 2, a stainless steel aperture member 17 is arranged inside the emission end portion 13. The aperture member 17 includes a bottomed cylindrical main body portion 15 that opens to the front side, and a disc-shaped flange portion 16 that is integrally formed with the front end portion of the main body portion 15. The main body portion 15 is inserted into the front end portion of the pipe member 9, and the flange portion 16 is fixed to the emission end portion 13 with a fixing screw 22.

  The bottom portion of the main body portion 15 includes an aperture portion 19 provided with an electron passage hole 18 for narrowing the electron beam E. The electron passage hole 18 has the center line L1 of the electron passage 7 as a center line, and the inner wall surface 18a of the electron passage hole 18 is an uneven surface by forming threads and screw grooves. Here, since the inner wall surface 9 a of the pipe member 9 is smooth, the inner wall surface 18 a of the electron passage hole 18 of the main body portion (first portion) 15 is positioned on the electron gun 2 side with respect to the main body portion 15. The uneven surface is rougher than the inner wall surface of the pipe member (second portion) 9.

  A bottomed cylindrical aperture member 21 that opens to the rear side is inserted into the main body portion 15. The bottom portion of the aperture member 21 includes an aperture portion 24 provided with an electron passage hole 23 for narrowing the electron beam E. The aperture portion 24 is inserted into the emission hole 13 a of the emission end portion 13. The electron passage hole 23 and the emission hole 13a have the center line L1 of the electron passage 7 as the center line.

  As described above, in the X-ray generator 1, the electron passage 7 is configured by the pipe member 9, the main body portion 15, the aperture member 21, and the emission end portion 13. The electromagnetic coil 12 focuses the electron beam E passing through the electron path 7 onto the target 5, but the lens center of the electromagnetic coil 12 is located on the center line L <b> 1 between the aperture portion 19 and the aperture portion 24. . Therefore, the aperture part 19 cuts the peripheral part of the diverging electron beam E to narrow the electron beam E, and the aperture part 24 cuts the peripheral part of the focused electron beam E to narrow the electron beam E. .

  A resin sheet 25 provided with an opening 25a facing the electron path 7 at the emission end 13 (that is, facing the emission hole 13a) is disposed on the front surface 13b of the emission end 13. The target unit T is arranged. The resin sheet 25 is made of an electrically insulating resin material (for example, polyimide). The target unit T includes a circular thin plate-shaped support member 26 that supports the target 5, and the rear surface of the support member 26 is in contact with the front surface of the resin sheet 25. The support member 26 is made of stainless steel, and a holding frame 27 having a circular outer shape is integrally formed on the support member 26. A beryllium X-ray emitting plate 28 is fixed to the holding frame 27, and a tungsten target 5 is formed on the rear surface of the X-ray emitting plate 28. The holding frame 27 holds the target 5 on the inner side so as to face the emission hole 13 a through the opening 25 a of the resin sheet 25.

  The support member 26 is pressed against the emission end 13 by a cap-shaped pressing member 29 made of an electrically insulating resin. Between the emission end portion 13 and the support member 26, it is located inside the opening 25 a of the resin sheet 25 and surrounds the electron passage 7 at the emission end portion 13 (that is, surrounds the emission hole 13 a). In addition, an O-ring 31 is disposed as an airtight sealing member for maintaining a vacuum. In the pressing member 29, the holding frame 27 of the supporting member 26 is fitted into the fitting hole 29a, and the O-ring 31 is pressed and the rear surface of the supporting member 26 is in contact with the front surface of the resin sheet 25. At the same time, it is fixed to the emission end 13 by a fixing screw. In the X-ray generator 1, the target unit T can be exchanged by removing the pressing member 29. Since the fixing screw 33 does not protrude forward from the front surface of the pressing member 29, the X-ray irradiated object can be brought closer to the X-ray emitting plate 28. Further, the positioning groove of the O-ring 31 is not limited to the rear surface of the support member 26, and may be provided on the front surface of the emission end portion 13.

  A target current detection terminal 32 is attached to the emission end 13 and the flange portion 16 of the aperture member 17, and the target current detection terminal is in contact with the rear surface of the support member 26 of the target unit T on the resin sheet 25. An insertion hole 25 b through which 32 is inserted is provided. When the X-ray generator 1 is in operation, it is necessary to evacuate the space through which the electron beam E passes, such as the electron passage 7, so that as shown in FIGS. An O-ring 41 as an airtight sealing member is disposed between the open portion 6, between the aperture member 17 and the pipe member 9, between the aperture member 17 and the emission end portion 13, and the like.

  In the X-ray generator 1 configured as described above, the electron beam E is emitted from the filament F of the electron gun 2 while evacuating the space where the electron beam E passes, such as the electron passage 7. The The emitted electron beam E is focused on the target 5 of the target unit T by the electromagnetic coil 12 while passing through the electron path 7. As a result, X-rays are emitted forward from the focused spot of the electron beam E on the target 5. At this time, in the electron passage 7, the inner wall surface 18 a of the electron passage hole 18 is a rough uneven surface in the main body portion 15 closer to the target 5 than the pipe member 9. Therefore, not only can the electron beam E be focused, but also the electrons incident on the inner wall surface 18a of the electron passage hole 18 can be prevented from being reflected to the target 5 side, and the resolution of the X-ray image can be improved. It becomes possible.

Moreover, in the X-ray generator 1, a highly accurate uneven surface can be easily provided on the inner wall surface 18a of the electron passage hole 18 by forming a screw thread and a screw groove.
[Second Embodiment]

  FIG. 3 is a cross-sectional view of a main part of the X-ray generator of the second embodiment. As shown in FIG. 3, the X-ray generator 1 according to the second embodiment differs from the X-ray generator 1 according to the first embodiment described above in the configuration of the main body 15 of the aperture member 17. That is, the main body portion 15 of the aperture member 17 includes a region on the electron gun 2 side (a region on the rear side with respect to the electron passage hole 18) and a region on the target 5 side (the front side with respect to the electron passage hole 18) A plurality of through-holes 15 a communicating with the electron passage hole 18 are provided.

  According to the X-ray generator 1 configured as described above, the diameter of the electron passage hole 18 of the aperture portion 19 is reduced, and the electron beam E is incident even when the inner wall surface 18a of the electron passage hole 18 is a rougher uneven surface. This prevents the gas generated from the target 5 from being trapped and exhausts such a gas sufficiently and efficiently through the through hole 15a.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described embodiment, the uneven surface is formed of a screw thread and a screw groove, but a plurality of concentric grooves arranged in parallel with the traveling direction of the electron beam E, a mesh-like surface, or a satin-like shape It may be formed from the surface. In addition, the height difference between the top part of the convex part and the bottom part of the concave part on the concave / convex surface is preferably 0.1 mm to 8 mm from the viewpoint of suppressing reflection of electrons incident on the concave / convex surface to the target 5 side.

  In the aperture member 17, the aperture portion 19 may be detachable from the main body portion 15. As shown in FIGS. 4A and 4B, if the flange portion 19 a is provided at the front end portion of the separate aperture portion 19, it is possible to prevent the aperture portion 19 from falling into the pipe member 9. . 4 (b) and FIGS. 5 (a) and 5 (b), if a female screw is formed on the inner wall surface of the main body portion 15 and a male screw is formed on the outer wall surface of the aperture portion 19, Even when the aperture portion 19 is removed, the main body portion 15 can be used as the electron passage hole 18 having a larger diameter. Note that the inner wall surface of the main body 15 and the outer wall surface of the aperture 19 shown in FIG. 5B are formed in a tapered shape that tapers toward the target 5 side. Therefore, when the aperture portion 19 is tightened with respect to the main body portion 15, the aperture portion 19 can be stopped at a predetermined position with respect to the main body portion 15. As described above, by making the aperture portion 19 detachable from the main body portion 15, the electron passage hole 18 having a desired shape or the like can be provided in the electron passage 7.

  Moreover, if the inner wall surface which becomes an uneven surface in the electron path 7 is formed in the taper shape which tapers toward the target 5 side (refer FIG.5 (b)), the electron which injected into the inner wall surface will be the target 5 side. Can be more reliably suppressed.

  In addition, if the portion of the electron path 7 that is the uneven surface is made of a lighter element material than the portion on the electron gun 2 side, the generation of X-rays due to the incidence of electrons is suppressed, and therefore the electron beam E on the target 5 X-rays can be prevented from being emitted from portions other than the focused spot, and the resolution of the X-ray image can be further improved. As an example of the material of the uneven surface, when the material of the electron gun 2 side is stainless steel, carbon, titanium, aluminum, and the like can be given. In the aperture member 17 shown in FIG. 5A, the aperture 19 is made of a lighter element material. The peripheral portion of the electron beam E to be cut is irradiated to the flange 19a of the aperture 19. Therefore, it is preferable from the viewpoint of suppressing the generation of X-rays in the aperture unit 19.

  Furthermore, the X-ray generator 1 is not limited to a single-coil structure, but may have a two-stage coil structure.

It is sectional drawing of the X-ray generator of 1st Embodiment. It is principal part sectional drawing of the X-ray generator shown by FIG. It is principal part sectional drawing of the X-ray generator of 2nd Embodiment. It is sectional drawing of the aperture member of the X-ray generator of other embodiment. It is sectional drawing of the aperture member of the X-ray generator of other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... X-ray generator, 2 ... Electron gun, 5 ... Target, 7 ... Electron passage, 9 ... Pipe member (2nd part), 9a ... Inner wall surface, 12 ... Electromagnetic coil, 15 ... Main-body part (1st Part), 15a ... through hole, 18 ... electron passage hole, 18a ... inner wall surface, 19 ... aperture part, E ... electron beam.

Claims (7)

An X-ray generator for causing an electron beam emitted from an electron gun to enter a target and emitting X-rays from the target,
An electron path through which the electron beam emitted from the electron gun passes;
An electromagnetic coil that focuses the electron beam passing through the electron path onto the target,
In the electron passage, the inner wall surface of the first portion is a rough surface rougher than the inner wall surface of the second portion located on the electron gun side with respect to the first portion. X-ray generator. The first portion includes an aperture portion provided with an electron passage hole for narrowing the electron beam,
The X-ray generator according to claim 1, wherein an inner wall surface of the electron passage hole is the uneven surface.   The X-ray generator according to claim 2, wherein the inner wall surface of the first portion is the uneven surface by forming a screw thread and a screw groove.   4. The X-ray generation according to claim 2, wherein the first portion is provided with a through hole that communicates the electron gun side region and the target side region in the electron passage. 5. apparatus.   The X-ray generator according to any one of claims 2 to 4, wherein the aperture portion is detachable from the first portion.   The X-ray generator according to any one of claims 1 to 5, wherein an inner wall surface of the first portion is formed in a tapered shape that tapers toward the target side.   The X-ray generator according to claim 1, wherein the first portion is made of a lighter element material than the second portion.

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