Electron beam emitting unit and electron beam irradiation device

Abstract

To provide an electron beam emitting unit that can prevent emission characteristics of an electron beam from changing.SOLUTION: An electron beam emitting unit 1 comprises: an electron discharge unit 2 that discharges electrons; and a first electrode 3 that adjusts the orbit of electrons emitted as an electron beam EB. The first electrode 3 includes: a mesh part 31 in which a plurality of through holes 31a is formed to pass the electrons discharged from the electron discharge unit 2 along a Z-axis direction; and a holding part 32 that includes a first projection 34 and a second projection 35 located, when seen from the Z-axis direction, outside an electron passage area 311a of the mesh part 31 where the plurality of through holes 31a is formed, and projecting to the opposite side of the electron discharge unit 2 with respect to the mesh part 31, and that holds the mesh part 31. The mesh part 31 and the holding part 32 are formed of different bodies from each other.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an electron beam emission unit and an electron beam irradiation device. [Background technology]

[0002] Patent Document 1 describes an electron beam device including a filament that emits electrons, a control grid that has a plurality of through-holes through which the electrons pass and controls the trajectory of the electrons, and an electron exit window that emits the electrons to the outside. In the electron beam device described in Patent Document 1, both edges of the control grid are bent so that they face each other, thereby forming a pair of bulges in the control grid. As a result, when a predetermined potential is applied to the control grid, an electric field is formed that causes electrons that have passed through the plurality of through-holes to travel toward the electron exit window. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6072023 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electron beam device described in Patent Document 1, the control grid is formed as a single unit. Therefore, when the control grid is heated by the radiant heat of the filament, the portion where the multiple through holes are formed and the pair of bulges are deformed due to the influence of each other's thermal expansion, and as a result, there is a risk that the emission characteristics of the electron beam may change over time.

[0005] An object of the present invention is to provide an electron beam emission unit capable of suppressing changes in the emission characteristics of an electron beam, and an electron beam irradiation apparatus including such an electron beam emission unit. [Means for solving the problem]

[0006] The electron beam emission unit of the present invention is [1] "an electron beam emission unit comprising: an electron emission section that emits electrons; and a first electrode that adjusts the trajectory of the electrons emitted as an electron beam, wherein the first electrode has: a mesh section in which a plurality of through holes are formed to allow the electrons emitted from the electron emission section to pass along a first direction; and a holding section that holds the mesh section, the holding section including at least one protrusion that is located outside an electron passing region of the mesh section in which the plurality of through holes are formed when viewed from the first direction and that protrudes on the opposite side of the electron emission section from the mesh section, wherein the mesh section and the holding section are formed as separate bodies."

[0007] In the electron beam emission unit described in [1] above, at least one protrusion is located outside the electron passing region of the mesh portion, in which multiple through-holes are formed, when viewed from a first direction, and protrudes from the mesh portion on the opposite side from the electron emitting portion. This allows an electric field to be formed in which electrons passing through the electron passing region travel along a predetermined trajectory when a predetermined potential is applied to the first electrode from the outside. Furthermore, the mesh portion, in which multiple through-holes are formed, and the holding portion, including the protrusion, are formed separately from each other. This prevents deformation of the mesh portion and the holding portion due to the influence of thermal expansion of each other, even if the first electrode is heated by radiant heat from the electron emitting portion, for example. Therefore, the electron beam emission unit described in [1] above can prevent changes in the electron beam emission characteristics.

[0008] The electron beam emission unit of the present invention may be [2] "the electron beam emission unit according to the above [1], wherein the thermal expansion coefficient of the mesh part is smaller than that of the holding part." The electron beam emission unit according to [2] can suppress deformation of the mesh part due to thermal expansion, and can stabilize the emission characteristics of the electron beam.

[0009] The electron beam emission unit of the present invention may be [3] "the electron beam emission unit according to the above [1] or [2], wherein the mesh portion is formed of a high-melting-point metal." According to the electron beam emission unit according to [3], the mesh portion has a smaller thermal expansion coefficient than when the mesh portion is formed of a metal other than a high-melting-point metal, so deformation of the mesh portion due to thermal expansion can be suppressed, and the electron beam emission characteristics can be stabilized.

[0010] The electron beam emission unit of the present invention may be [4] "the electron beam emission unit according to the above [3], wherein the high-melting-point metal is titanium." According to the electron beam emission unit according to [4], deformation of the mesh part due to thermal expansion can be more reliably suppressed.

[0011] The electron beam emission unit of the present invention may be [5] "the electron beam emission unit according to any one of the above [1] to [4], wherein the holding part is made of stainless steel." According to the electron beam emission unit according to [5], the workability of the holding part is improved, so that the protrusion can be easily formed.

[0012] The electron beam emission unit of the present invention may be [6] "the electron beam emission unit according to any one of [1] to [5] above, further comprising: a second electrode that causes the electrons emitted from the electron emitter to travel toward the first electrode; and at least one support that supports the first electrode relative to the second electrode, the support having an insulating portion and a first metal portion joined to the insulating portion, and the support supporting the first electrode relative to the second electrode with the first metal portion held by one of the first electrode and the second electrode." According to the electron beam emission unit described in [6], the electrons emitted from the electron emitter are caused to travel toward the first electrode by the second electrode, thereby increasing the amount of electrons passing through the multiple through holes. Furthermore, since the support has an insulating portion, the first electrode can be supported relative to the second electrode while ensuring electrical insulation between the first electrode and the second electrode. Furthermore, since the first metal portion is held by one of the first electrode and the second electrode, the support is less susceptible to wear, thereby suppressing the generation of foreign matter due to wear of the support.

[0013] The electron beam emission unit of the present invention may be [7] "the electron beam emission unit according to the above [6], wherein the support further has a second metal part joined to the insulating part while being electrically insulated from the first metal part, and the support supports the first electrode relative to the second electrode while the second metal part is held by the other of the first electrode and the second electrode." According to the electron beam emission unit according to [7], the second metal part is joined to the insulating part while being electrically insulated from the first metal part, so that the second metal part is held by the other of the first electrode and the second electrode, and electrical insulation between the first electrode and the second electrode can be ensured. Furthermore, because the second metal part is held by the other of the first electrode and the second electrode, the support is less susceptible to wear, and the generation of foreign matter due to wear of the support can be suppressed.

[0014] The electron beam emission unit of the present invention may be [8] "the electron beam emission unit according to the above [6] or [7], wherein the insulating section is arranged in a position that is not visible from the electron emitting section." According to the electron beam emission unit according to [8], electrons emitted from the electron emitting section are prevented from reaching the insulating section of the support. This makes it possible to prevent discharge caused by charging of the insulating section.

[0015] The electron beam emission unit of the present invention may be [9] "the electron beam emission unit according to any one of [1] to [8] above, wherein the electron emitting section is a filament extending along a second direction intersecting the first direction, the electron passing region is an elongated region having the second direction as its longitudinal direction, and the at least one protrusion is a first protrusion and a second protrusion located on both sides of the electron passing region in a third direction intersecting the first and second directions when viewed from the first direction, and each of the first protrusion and the second protrusion extends along the second direction." In the electron beam emission unit according to [9], deformation of the mesh section and the holder due to the influence of thermal expansion of each other can be suppressed, thereby reducing the amount of deformation of the mesh section due to thermal expansion and thereby suppressing uneven deformation of the mesh section. Furthermore, since the first protrusion and the second protrusion extend along the second direction on both sides of the electron passing region in the third direction, an electric field in which electrons passing through the electron passing region travel along a predetermined trajectory can be more reliably formed.

[0016] The electron beam emission unit of the present invention may be the electron beam emission unit described in [9] above,

[10] wherein "the holding section further includes a frame section having an elongated opening with the second direction as its longitudinal direction, the first protrusion section includes a first opposing section facing the second protrusion section in the third direction and a first connection section connecting the first opposing section and the frame section, the second protrusion section includes a second opposing section facing the first protrusion section in the third direction and a second connection section connecting the second opposing section and the frame section, and the mesh section is sandwiched between the frame section and the first opposing section and the second opposing section with the electron passing region overlapping the opening when viewed from the first direction." The electron beam emission unit described in

[10] can suppress interference between electrons passing through the electron passing region and the holding section, while suppressing misalignment of the mesh section with respect to the holding section.

[0017] The electron beam emission unit of the present invention may be

[11] "the electron beam emission unit according to the above

[10] , wherein one end of the mesh part in the third direction faces the first opposing part on the outside of the first opposing part, and the other end of the mesh part in the third direction faces the second opposing part on the outside of the second opposing part." According to the electron beam emission unit according to

[11] , movement of the mesh part along the third direction is restricted, so that it is possible to more reliably suppress displacement of the mesh part with respect to the holding part.

[0018] The electron beam emission unit of the present invention may be

[12] "the electron beam emission unit according to any one of the above [9] to

[11] , further comprising a terminal unit having terminals electrically connected to the mesh portion and the holding portion, wherein one end of the mesh portion in the second direction and one end of the holding portion in the second direction are fixed to the terminal unit." The electron beam emission unit according to

[12] can easily apply a predetermined potential to the first electrode from the outside via the terminal unit. Furthermore, by adopting a configuration in which the mesh portion other than one end is not fixed to the holding portion, it is possible to suppress deformation of the mesh portion and the holding portion, which expand due to thermal expansion, particularly along the second direction, while being affected by each other's thermal expansion.

[0019] The electron beam irradiation device of the present invention is

[13] "an electron beam irradiation device comprising the electron beam emission unit according to any one of [6] to [8] above and a housing that houses the electron emitter and the second electrode, wherein the first electrode is disposed outside the housing, and the insulating part is disposed in a position that is not visible from outside the housing." According to the electron beam irradiation device described in

[13] , for example, even if the insulating part is charged when electrons emitted from the electron emitter reach the insulating part, it is possible to prevent a discharge path from being formed between the insulating part and the outside of the housing. Therefore, it is possible to prevent discharge caused by charging of the insulating part. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide an electron beam emission unit capable of suppressing changes in the emission characteristics of an electron beam, and an electron beam irradiation apparatus including such an electron beam emission unit. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view of an electron beam irradiation device according to an embodiment. [Figure 2] FIG. 2 is a perspective view of the internal structure of the electron beam irradiation device shown in FIG. [Figure 3] FIG. 2 is a cross-sectional view of the electron beam irradiation device taken along line III-III shown in FIG. [Figure 4] 2 is a perspective view of an electron beam emission unit provided in the electron beam irradiation apparatus shown in FIG. 1. FIG. [Figure 5] 5 is a cross-sectional view of the electron beam emission unit taken along line VV shown in FIG. 4. FIG. [Figure 6] 6 is a perspective cross-sectional view of the electron beam emission unit taken along line VI-VI shown in FIG. 4. FIG. [Figure 7] 5A and 5B are a plan view and a perspective view of the mesh portion shown in FIG. 4. [Figure 8] 5A and 5B are a plan view and a perspective view of the holding portion shown in FIG. 4. [Figure 9] FIG. 5 is a perspective view of the holding portion shown in FIG. 4. [Figure 10] FIG. 10 is a perspective cross-sectional view of a modified electron beam emission unit. [Figure 11] 11A and 11B are a plan view and a perspective view of the mesh portion shown in FIG. 10. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted. [Configuration of electron beam irradiation equipment]

[0023] As shown in FIGS. 1 to 3, the electron beam irradiation device 10 includes an electron beam emission unit 1, a housing 11, a window 12, a storage section 13, a pair of holding members 14 and 15, and a power supply section 16. The electron beam emission unit 1 is a long unit that emits an electron beam EB. In this embodiment, the longitudinal direction of the electron beam emission unit 1 is referred to as the Y-axis direction (second direction), the direction perpendicular to the Y-axis direction is referred to as the Z-axis direction (first direction), and the direction perpendicular to both the Y-axis direction and the Z-axis direction is referred to as the X-axis direction (third direction). The electron beam irradiation device 10 is used for applications such as printing, sterilization, and modification, for example.

[0024] The housing 11 houses the electron beam emission unit 1. The housing 11 is a cylindrical vacuum vessel having a centerline parallel to the Y-axis direction. The window portion 12 is airtightly attached to a flange portion 111 that defines an opening 11a in the housing 11. The opening 11a is an elongated opening with its longitudinal direction in the Y-axis direction, and faces the electron beam emission unit 1 in the Z-axis direction. A connection port 112 is provided on the opposite side of the housing 11 from the opening 11a to which a pipe for evacuating the space within the housing 11 is connected.

[0025] The window portion 12 has a support member 121, a window foil 122, and a pressing member 123. The support member 121 is attached to the flange portion 111. The window foil 122 is arranged on the surface (atmosphere side) of the support member 121 so as to cover a plurality of through holes formed in the support member 121. The window foil 122 is made of a material (e.g., beryllium, titanium, or aluminum) that is highly transparent to the electron beam EB and is formed into a film shape with its longitudinal direction in the Y-axis direction and its thickness direction in the Z-axis direction, and defines a vacuum space in cooperation with the housing 11 and the support member 121. The pressing member 123 is a frame-shaped member with an opening. The pressing member 123 is arranged on the surface of the window foil 122 opposite the support member 121 so as not to overlap with the plurality of through holes formed in the support member 121 when viewed from the Z-axis direction. The pressing member 123 is made of a metal material (e.g., a material containing copper) with high thermal conductivity and is formed in a frame shape with its longitudinal direction in the Y-axis direction and its thickness direction in the Z-axis direction. The area between the support member 121 and the window foil 122 is airtightly sealed by fastening the support member 121 and the pressing member 123 to each other with fastening members (not shown) such as bolts.

[0026] The housing 13 is an elongated member whose longitudinal direction is the Y-axis direction, and houses the electron beam emission unit 1 inside the housing 11. The housing 13 is supported within the housing 11 while being insulated from the housing 11. The cross-sectional shape of the housing 13 perpendicular to the Y-axis direction is C-shaped, opening toward the window 12. The pair of holding members 14 and 15 are cylindrical members each having a center line parallel to the Y-axis direction, and hold both ends of the housing 13 within the housing 11. The holding member 14 is attached to a power supply unit 16. The holding member 15 is attached to the inner surface of the housing 11 via an insulating member (not shown). One end of the housing 11 in the Y-axis direction is hermetically sealed by the power supply unit 16. The other end of the housing 11 in the Y-axis direction is hermetically sealed by an opening / closing unit 113. In the electron beam irradiation device 10, the electron beam emission unit 1 can be inserted into or removed from the housing portion 13 by opening the cover 114 of the opening / closing portion 113.

[0027] The housing 11, the housing 13, and the pair of holding members 14, 15 are each made of a conductive material such as metal. The housing 11 is at ground potential. The housing 13 and the pair of holding members 14, 15 are at cathode potential. The housing 13 functions as an enclosing electrode that surrounds the electron beam extraction unit 1 and stabilizes the electric field within the housing 13. The electron beam extraction unit 1 is supplied with a high voltage from a power supply unit 16. Wiring for supplying a high voltage to the electron beam extraction unit 1 is connected to the power supply unit 16. [Configuration of electron beam extraction unit]

[0028] 3 to 5, the electron beam emission unit 1 includes an electron emitter 2, a first electrode 3, a second electrode 4, a frame 5, a power supply line 6, a plurality of connecting members 7, and a plurality of supports 8. The electron emitter 2 is housed in a housing 13 and extends in the Y-axis direction inside the housing 13. In the electron beam emission unit 1, the electron emitter 2 is a filament extending along the Y-axis direction. The filament is made of a material containing tungsten, for example, and emits electrons when heated by passing current through it.

[0029] The first electrode 3 is a grid electrode that adjusts the trajectory of electrons emitted as the electron beam EB. The first electrode 3 is an elongated member whose longitudinal direction is in the Y-axis direction and faces the electron emitter 2 in the Z-axis direction. The first electrode 3 is arranged outside the housing 13 so as to cover the opening of the housing 13. The first electrode 3 has a mesh portion 31 and a holding portion 32. The mesh portion 31 has a plurality of through holes 31a formed therein that allow electrons emitted from the electron emitter 2 to pass along the Z-axis direction. The plurality of through holes 31a are arranged two-dimensionally along a plane perpendicular to the Z-axis direction. The holding portion 32 has a frame portion 33, a first protrusion 34, and a second protrusion 35. The holding portion 32 holds the mesh portion 31.

[0030] The second electrode 4 is a cathode electrode that causes electrons emitted from the electron emitter 2 in a direction different from the direction toward the first electrode 3 to travel toward the first electrode 3. The second electrode 4 is housed in the housing 13. The second electrode 4 is an elongated member with its longitudinal direction in the Y-axis direction, and is located on the opposite side of the window 12 from the first electrode 3. The cross-sectional shape of the second electrode 4 perpendicular to the Y-axis direction is U-shaped, opening toward the window 12. The second electrode 4 surrounds the electron emitter 2 on three sides so that the electron emitter 2 and the first electrode 3 remain facing each other when viewed from the Y-axis direction. An opening 4a of the second electrode 4 is defined by both sides of the second electrode 4 in the X-axis direction.

[0031] The frame 5 is disposed on the opposite side of the second electrode 4 from the window portion 12. The frame 5 is an elongated member with its longitudinal direction in the Y-axis direction. The cross section of the frame 5 perpendicular to the Y-axis direction is U-shaped and opens on the window portion 12 side. The power supply line 6 extends in the Y-axis direction inside the frame 5. The power supply line 6 is protected by the frame 5. The second electrode 4 and the frame 5 are connected to each other by a plurality of connecting members 7. A guide portion 5a is provided on the bottom of the frame 5. The guide portion 5a fits into a protrusion 13a provided on the inner surface of the housing portion 13, thereby positioning the frame 5 with respect to the housing portion 13.

[0032] The connecting member 7 is a member that secures the second electrode 4 and the frame 5 to each other. Multiple connecting members 7 are arranged along the Y-axis direction. The connecting member 7 has a first portion 71 and a second portion 72. The first portion 71 is fixed to the second electrode 4 with a screw S1 while covering both sides of the second electrode 4 in the X-axis direction and both sides of the frame 5 in the X-axis direction, and is fixed to the frame 5 with a screw S2. The second portion 72 is connected to the first portion 71 along the Y-axis direction and is, for example, formed integrally with the first portion 71. The second portion 72 covers both sides of the second electrode 4 in the X-axis direction. The second portion 72 is provided with multiple spheres 72a and multiple holding portions 72b. Each holding portion 72b holds the sphere 72a so that the sphere 72a can rotate relative to the second portion 72. As a result, when the electron beam emission unit 1 is slid and accommodated in the accommodation section 13, the spheres 72a rotate while contacting the inner surface of the accommodation section 13, so that the electron beam emission unit 1 can be easily slid.

[0033] The multiple supports 8 are members that support the first electrode 3 relative to the second electrode 4. The supports 8 are attached to the first electrode 3 and the connecting member 7. In the electron beam extraction unit 1, multiple support members 73, which are members separate from the connecting member 7, are fixed to the second electrode 4, and some of the multiple supports 8 are attached to the first electrode 3 and the supporting members 73. In the electron beam extraction unit 1, multiple pairs of connecting members 7 and supporting members 73 are arranged at approximately equal intervals along the Y-axis direction. This allows the first electrode 3 to be stably supported relative to the second electrode 4. The supporting members 73 are not fixed to the frame 5.

[0034] The electron beam emission unit 1 further includes a terminal unit 9. The terminal unit 9 is attached to one end of the second electrode 4 in the Y-axis direction. The terminal unit 9 has a plurality of terminals 91 to 93 and a conductive member 94. Power is supplied to the electron emitter 2 via the terminal 91. A predetermined potential is applied to the second electrode 4 and the housing 13 via a terminal 92. A predetermined potential is applied to the first electrode 3 via a terminal 93. The terminal unit 9 holds the terminals 91 to 93 while the terminals are electrically insulated from each other. Power is supplied to the terminals 91 to 93 from the outside via a power supply unit 16 (see FIG. 2 ). The terminal 91 is connected to one end of a power supply line 6. The other end of the power supply line 6 is connected to a fixing member 96, which will be described later. The terminal 93 is electrically connected to the first electrode 3 via the conductive member 94.

[0035] The electron beam emission unit 1 further includes a pair of fixing members 95 and 96 and a rotation restriction member 97. The pair of fixing members 95 and 96 fix the position of the electron emitter 2 inside the second electrode 4. The pair of fixing members 95 and 96 are fixed to both ends of the second electrode 4 in the Y-axis direction. One end of the electron emitter 2 in the Y-axis direction is fixed to the fixing member 95, and the other end of the electron emitter 2 in the Y-axis direction is fixed to the fixing member 96. The rotation restriction member 97 restricts rotation of the electron beam emission unit 1 about an axis parallel to the Y-axis direction. The rotation restriction member 97 is attached to the other end of the second electrode 4 in the Y-axis direction. For example, the rotation restriction member 97 has a groove (not shown) that fits into a protrusion (not shown) provided on the accommodation portion 13, thereby restricting rotation of the electron beam emission unit 1.

[0036] 6 to 8, the mesh portion 31 of the first electrode 3 has a main body portion 311 and end portions 312, 313. The main body portion 311 and the end portions 312, 313 are each an elongated portion with the Y-axis direction as the longitudinal direction.

[0037] The main body 311 is a rectangular plate-shaped portion extending along a plane perpendicular to the Z-axis direction. The main body 311 includes an electron passing region 311a that occupies most of the main body 311 in the Y-axis direction. The electron passing region 311a is an elongated region with its longitudinal direction in the Y-axis direction. A plurality of through holes 31a are formed in the electron passing region 311a. Each of the plurality of through holes 31a has the same shape and the same size. When viewed from the Z-axis direction, the shape of each through hole 31a is, for example, hexagonal. The plurality of through holes 31a are uniformly formed in the electron passing region 311a. A plurality of through holes 31a are not formed at either end of the main body 311 in the Y-axis direction.

[0038] The end portions 312 and 313 are located on both sides of the electron passing region 311a in the X-axis direction. The end portion 312 is one end portion of the mesh portion 31 in the X-axis direction and is a rectangular plate-like portion extending along a plane perpendicular to the X-axis direction. The end portion 312 extends from the main body portion 311 toward the opposite side from the electron emitter 2 in the Z-axis direction. For example, the end portion 312 extends from one end of the main body portion 311 in the X-axis direction toward the opposite side from the electron emitter 2 in the Z-axis direction. The end portion 313 is the other end portion of the mesh portion 31 in the X-axis direction and is a rectangular plate-like portion extending along a plane perpendicular to the X-axis direction. The end portion 313 extends from the main body portion 311 toward the opposite side from the electron emitter 2 in the Z-axis direction. For example, the end portion 313 extends from the other end of the main body portion 311 in the X-axis direction toward the opposite side from the electron emitter 2 in the Z-axis direction. The cross-sectional shape of the mesh portion 31 perpendicular to the Y-axis direction is U-shaped and opens toward the window portion 12. The mesh portion 31 configured as described above is formed integrally by, for example, bending a plate-shaped member.

[0039] The holding portion 32 of the first electrode 3 has a frame portion 33, a first protruding portion 34, and a second protruding portion 35. The frame portion 33, the first protruding portion 34, and the second protruding portion 35 are each an elongated portion whose longitudinal direction is the Y-axis direction.

[0040] The frame portion 33 is a rectangular plate-shaped portion in which an opening 33a is formed, and extends along a plane perpendicular to the Z-axis direction. The opening 33a is an elongated opening with its longitudinal direction in the Y-axis direction, and is formed over most of the frame portion 33. The frame portion 33 faces the electron emitter 2 in the Z-axis direction. The frame portion 33 includes a surface 33b on the opposite side to the electron emitter 2.

[0041] The first protrusion 34 and the second protrusion 35 are located on both sides of the opening 33a in the X-axis direction. The first protrusion 34 and the second protrusion 35 each protrude to the opposite side from the electron emitting portion 2 in the Z-axis direction.

[0042] The first protrusion 34 includes a first opposing portion 341 facing the second protrusion 35 in the X-axis direction and a first connecting portion 342 connecting the first opposing portion 341 and the frame portion 33. The first opposing portion 341 is a rectangular plate-like portion extending along a plane perpendicular to the X-axis direction. One end of the first opposing portion 341 in the Z-axis direction faces the surface 33b across the main body 311 of the mesh portion 31. The first connecting portion 342 connects the other end of the first opposing portion 341 in the Z-axis direction to one end of the frame portion 33 in the X-axis direction. The first connecting portion 342 is curved so as to convex outward. The shape of the area surrounded by the first protrusion 34 and the frame portion 33 when viewed from the Y-axis direction is, for example, a rounded right triangle. The shape of the area may also be a rounded rectangle, a substantially semicircular shape, or the like.

[0043] The second protrusion 35 includes a second opposing portion 351 facing the first protrusion 34 in the X-axis direction and a second connecting portion 352 connecting the second opposing portion 351 and the frame portion 33. The second opposing portion 351 is a rectangular plate-like portion extending along a plane perpendicular to the X-axis direction. One end of the second opposing portion 351 in the Z-axis direction faces the surface 33b across the main body 311 of the mesh portion 31. The second connecting portion 352 connects the other end of the second opposing portion 351 in the Z-axis direction to the other end of the frame portion 33 in the X-axis direction. The second connecting portion 352 is curved so as to convex outward. The shape of the area surrounded by the second protrusion 35 and the frame portion 33 when viewed from the Y-axis direction is, for example, a rounded right triangle. The shape of the area may also be a rounded rectangle, a substantially semicircular shape, or the like.

[0044] The first opposing portion 341 and the second opposing portion 351 face each other in the X-axis direction. Each of the first opposing portion 341, the first connecting portion 342, the second opposing portion 351, and the second connecting portion 352 is an elongated portion whose longitudinal direction is in the Y-axis direction. The holding portion 32 configured as described above is integrally formed by, for example, bending a plate-shaped member.

[0045] The mesh portion 31 and the holding portion 32 are formed separately from each other. The thermal expansion coefficient of the mesh portion 31 is smaller than that of the holding portion 32. In the electron beam extraction unit 1, the thermal expansion coefficient is preferably a linear expansion coefficient. The thermal expansion coefficient may be a volume expansion coefficient. The mesh portion 31 is formed, for example, from a high-melting-point metal. In this specification, a high-melting-point metal refers to a metal whose melting point is equal to or higher than the melting point of iron (1536°C). Examples of such high-melting-point metals include titanium and zirconium. In the electron beam extraction unit 1, the mesh portion 31 is formed from titanium. The melting point of titanium is approximately 1668°C. On the other hand, the holding portion 32 is formed, for example, from a metal with excellent workability. Examples of such metals include stainless steel and aluminum. In the electron beam extraction unit 1, the holding portion 32 is formed from stainless steel.

[0046] The mesh portion 31 is sandwiched between the frame portion 33 and the first and second opposing portions 341 and 351, with the electron passing region 311a overlapping the opening 33a when viewed from the Z-axis direction. Specifically, the mesh portion 31 is disposed on the surface 33b so that the main body portion 311 is in contact with the surface 33b. One end of the first opposing portion 341 in the Z-axis direction and one end of the second opposing portion 351 in the Z-axis direction are in contact with the main body portion 311. Here, the first opposing portion 341 and the second opposing portion 351 do not need to be in complete contact with the main body portion 311, and a clearance (gap) may exist between the first opposing portion 341 and the main body portion 311 and between the second opposing portion 351 and the main body portion 311.

[0047] When the mesh portion 31 is held by the holder 32, the first protrusion 34 and the second protrusion 35 are located outside the electron passing region 311a when viewed from the Z-axis direction. In other words, the first protrusion 34 and the second protrusion 35 are located in regions overlapping with the end portions 312 and 313, respectively, when viewed from the Z-axis direction, but do not overlap with the electron passing region 311a when viewed from the Z-axis direction. In the electron beam emission unit 1, the first protrusion 34 and the second protrusion 35 are located on both sides of the electron passing region 311a in the X-axis direction when viewed from the Z-axis direction. The first protrusion 34 and the second protrusion 35 protrude from the mesh portion 31 on the side opposite to the electron emitter 2. In particular, the first opposing portion 341 and the second opposing portion 351 extend in a direction perpendicular to the main body 311 of the mesh portion 31. The end 312 of the mesh portion 31 faces the first opposing portion 341 on the outside of the first opposing portion 341 (on the opposite side of the electron passing region 311a with respect to the first opposing portion 341). The end 313 of the mesh portion 31 faces the second opposing portion 351 on the outside of the second opposing portion 351 (on the opposite side of the electron passing region 311a with respect to the second opposing portion 351). Clearances (gaps) exist between the end portions 312 and 313 and the first opposing portion 341 and between the end portions 312 and 313 and the second opposing portion 351, respectively. The end portions 312 and 313 may be in contact with the first opposing portion 341 and the second opposing portion 351, respectively.

[0048] When viewed from the Z-axis direction, the electron passing region 311a and the opening 33a each overlap the opening 4a of the second electrode 4. The width of the electron passing region 311a and the opening 33a in the X-axis direction may be the same as the width of the opening 4a in the X-axis direction, or may be narrower than the width of the opening 4a. The distance between the first opposing portion 341 and the second opposing portion 351 in the X-axis direction may be the same as the width of the opening 4a in the X-axis direction, or may be shorter than the width of the opening 4a.

[0049] As shown in FIG. 5 , one end 314 of the mesh portion 31 in the Y-axis direction and one end 321 of the holding portion 32 in the Y-axis direction are fixed to the terminal unit 9. Specifically, the mesh portion 31 and the holding portion 32 are fixed to the terminal unit 9 as follows. As shown in FIGS. 7( a) and 7(b), the mesh portion 31 has an extension portion 316 extending along the Y-axis direction from one end of the main body portion 311 in the Y-axis direction. Two through holes 316a are provided in the extension portion 316. The extension portion 316 is included in the end 314 of the mesh portion 31. As shown in FIGS. 8(a) and 8(b), the holding portion 32 has an extension portion 323 extending along the Y-axis direction from one end of the frame portion 33 in the Y-axis direction. Two through holes 323a are provided in the extension portion 323. The extension portion 323 is included in the end 321 of the holding portion 32. The end 314 of the mesh portion 31 and the end 321 of the holding portion 32 are fixed to the conductive member 94 by a conductive screw S3 via the through-holes 316a and 323a. The end 314 of the mesh portion 31 and the end 321 of the holding portion 32 are pressed against the conductive member 94 by the screw S3 and are in contact with each other. The mesh portion 31, the holding portion 32, the conductive member 94, and the screw S3 are electrically connected to each other. The conductive member 94 is fixed to the terminal 93. In this way, a voltage input from the terminal 93 is applied to the mesh portion 31 and the holding portion 32 via the conductive member 94 and the screw S3, and a predetermined potential is applied. The mesh portion 31, except for the end 314, is not fixed to the holding portion 32. The holding portion 32, except for the end 321, is not fixed to the mesh portion 31. In particular, the other end 315 of the mesh portion 31 in the Y-axis direction and the other end 322 of the holding portion 32 in the Y-axis direction are not fixed to each other. Note that no through-holes 31a are formed in the ends 314 and 315, and no openings 33a are formed in the ends 321 and 322.

[0050] If the distance between the first opposing portion 341 and the second opposing portion 351 in the X-axis direction is L and the height from the surface 33b of the frame portion 33 to the apex of the first protrusion 34 (second protrusion 35) in the Z-axis direction is H, the distance L and the height H satisfy a relationship of, for example, L:H=2:1 to 10:1. This makes it possible to suppress loss of the electron beam EB. Here, loss means that the electron beam EB diverges and hits parts other than the window portion 12, such as the inner surface of the opening 11a of the housing 11. When the distance L and the height H satisfy the above relationship, an electric field that efficiently emits the electron beam EB can be formed.

[0051] The first connecting portion 342 has a curved portion 342a connected to the first opposing portion 341 and a curved portion 342b connected to the frame portion 33. The curved portions 342a and 342b correspond to both ends of the first connecting portion 342 in the X-axis direction. When viewed from the Y-axis direction, the curved portions 342a and 342b are curved so as to convex outward. Specifically, the curved portion 342a is curved so as to convex on the side opposite the electron passing region 311a in the Z-axis direction. The curved portion 342b is curved so as to convex on the side opposite the electron passing region 311a in the X-axis direction. The radius of curvature of the curved portion 342a is, for example, larger than the radius of curvature of the curved portion 342b. This makes it possible to form an electric field that efficiently emits the electron beam EB. In addition, it is possible to prevent the electric field from concentrating near the curved portion 342a, thereby preventing discharge from occurring.

[0052] The second connecting portion 352 has a curved portion 352a connected to the second opposing portion 351 and a curved portion 352b connected to the frame portion 33. The curved portions 352a and 352b correspond to both ends of the second connecting portion 352 in the X-axis direction. The curved portions 352a and 352b are curved so as to be convex outward when viewed from the Y-axis direction. Specifically, the curved portion 352a is curved so as to be convex on the side opposite the electron passing region 311a in the Z-axis direction. The curved portion 352b is curved so as to be convex on the side opposite the electron passing region 311a in the X-axis direction. The radius of curvature of the curved portion 352a is, for example, larger than the radius of curvature of the curved portion 352b. This makes it possible to form an electric field that efficiently emits the electron beam EB. In addition, it is possible to prevent the electric field from concentrating near the curved portion 352a, thereby preventing discharge from occurring.

[0053] As shown in FIGS. 6 and 9, the support 8 has an insulating portion 81, a first metal portion 82, and a second metal portion 83. The insulating portion 81 is a cylindrical portion. The insulating portion 81 is made of an insulating material such as Al2O3 (alumina). The first metal portion 82 has a head portion 82a and shaft portions 82b and 82c. The head portion 82a and the shaft portions 82b and 82c are arranged in this order along the Z-axis direction. The head portion 82a is the head portion of the support 8. The outer diameter D1 of the head portion 82a is larger than the outer diameter D2 of the shaft portion 82b and is the same as the outer diameter of the shaft portion 82c. In other words, the first metal portion 82 has a cylindrical shape with grooves formed on the side circumferential surface. The second metal portion 83 has a head portion 83a and a shaft portion 83b. A thread groove (not shown) is formed in the shaft portion 83b. The first metal portion 82 and the second metal portion 83 are each made of a metal such as Kovar (KOV). The first metal portion 82 is joined to the insulating portion 81, and the second metal portion 83 is joined to the insulating portion 81 while being electrically insulated from the first metal portion 82. In addition, the second metal portion 83 is joined to the insulating portion 81 while being physically separated from the first metal portion 82. Specifically, one end surface of the insulating portion 81 in the Z-axis direction is joined to the shaft portion 82c of the first metal portion 82. The other end surface of the insulating portion 81 in the Z-axis direction is joined to the head portion 83a of the second metal portion 83. The first metal portion 82 and the second metal portion 83 sandwich the insulating portion 81 in the Z-axis direction. The first metal portion 82 and the second metal portion 83 are electrically insulated from each other by the insulating portion 81.

[0054] A plurality of through holes 33c are formed in the frame portion 33. The plurality of through holes 33c are formed in the frame portion 33 on both sides of the opening 33a in the X-axis direction. The plurality of through holes 33c are formed along the Y-axis direction. Each through hole 33c is arranged in a region overlapping the first protrusion 34 or the second protrusion 35 when viewed from the Z-axis direction. Each through hole 33c includes a first through hole 33d and a second through hole 33e connected to the first through hole 33d. When viewed from the Z-axis direction, the first through hole 33d has a substantially circular shape. When viewed from the Z-axis direction, the second through hole 33e has a substantially elliptical shape with the Y-axis direction as the longitudinal direction. The outer diameter D3 of the first through hole 33d is larger than the outer diameter D1 of the head 82a of the first metal portion 82. The width W1 of the second through hole 33e in the X-axis direction is narrower than the outer diameter D1 of the head 82a of the first metal part 82 and is wider than the outer diameter D2 of the shaft part 82b of the first metal part 82. The width W2 of the second through hole 33e in the Y-axis direction is wider than the outer diameter D2 of the shaft part 82b of the first metal part 82.

[0055] The multiple supports 8 are located on both sides of the mesh portion 31 in the X-axis direction. The multiple supports 8 support the first electrode 3 relative to the second electrode 4, with the first metal portion 82 held by the first electrode 3 and the second metal portion 83 held by the second electrode 4. Specifically, the supports 8 support the first electrode 3 relative to the second electrode 4 as follows: First, the support 8 is fixed to the second electrode 4 by screwing the shaft portion 83b of the second metal portion 83 into the connecting member 7 or the support member 73. In this state, the head 82a of the first metal portion 82 is inserted into the first through-hole 33d. Then, by sliding the support 8 or the first electrode 3 along the Y-axis direction, the shaft portion 82b of the first metal portion 82 moves into the second through-hole 33e. As described above, because the width W1 of the second through hole 33e is narrower than the outer diameter D1 of the head 82a and wider than the outer diameter D2 of the shaft portion 82b, the head 82a contacts the surface of the frame portion 33 when the shaft portion 82b is positioned within the second through hole 33e. At this time, the head 82a is covered by the first protrusion 34 or the second protrusion 35. Because the widths W1 and W2 of the second through hole 33e are each wider than the outer diameter D2 of the shaft portion 82b, the support 8 is held by the first electrode 3 with play (gap) present between the periphery of the second through hole 33e and the shaft portion 82b. As a result, deformation of the first electrode 3 due to thermal expansion is absorbed by the play, preventing damage or excessive deformation of the first electrode 3. Furthermore, because the width W2 of the second through hole 33e is wider than the outer diameter D2 of the shaft portion 82b, even if the position of the support 8 moves relatively from the second through hole 33e toward the first through hole 33d as a result of the first electrode 3 expanding in the Y-axis direction due to thermal expansion, the first electrode 3 can be prevented from falling off the support 8. Note that the first metal portion 82 is not in contact with the second electrode 4, and the second metal portion 83 is not in contact with the first electrode 3. Therefore, the first electrode 3 and the second electrode 4 are electrically insulated by the insulating portion 81. The widths W2 of all the second through holes 33e may be the same. Alternatively, the widths W2 of the second through holes 33e located closer to the end 322 than to the end 321 may be wider in accordance with the amount of expansion of the frame portion 33 in the Y-axis direction due to thermal expansion.

[0056] As shown in FIGS. 3 and 6 , the insulating portion 81 is disposed at a position that is not visible from the electron emitter 2. That is, some member exists on a line segment connecting an arbitrary point in the insulating portion 81 and an arbitrary point in the electron emitter 2. The member existing on the line segment connecting an arbitrary point in the insulating portion 81 and an arbitrary point in the electron emitter 2 is preferably a conductive material such as a metal material. In the electron beam emission unit 1, the second electrode 4 exists on this line segment. That is, in the Z-axis direction, the end of the insulating portion 81 that is joined to the first metal portion 82 is located closer to the electron emitter 2 than the upper surface 4b of the second electrode 4, and the insulating portion 81 is not visible from the electron emitter 2. The insulating portion 81 may be disposed at a position that is not visible from outside the housing portion 13. That is, some member may exist on a line segment connecting an arbitrary point in the insulating portion 81 and an arbitrary point outside the housing portion 13. The member existing on the line segment connecting an arbitrary point in the insulating portion 81 and an arbitrary point outside the housing portion 13 is preferably a conductive material such as a metal material. For example, the accommodation section 13 or the first electrode 3 may be present on the line segment. The insulating section 81 may be disposed in a position that is not visible from the housing 11. In other words, some member may be present on the line segment connecting an arbitrary point in the insulating section 81 and an arbitrary point in the housing 11. It is preferable that the member present on the line segment connecting an arbitrary point in the insulating section 81 and an arbitrary point in the housing 11 is a conductive material such as a metal material. For example, the accommodation section 13 or the first electrode 3 may be present on the line segment.

[0057] In the electron beam emission unit 1 configured as above, a reference potential (cathode potential) of −several tens of kV to −several hundreds of kV (for example, −100 kV) is applied to the second electrode 4 and the housing portion 13 via the terminal 92. A voltage of +several tens of V to +150 V with respect to the reference potential is applied to the electron emitter 2 via the terminal 91, the power supply line 6, and the fixing member 96, thereby obtaining power for emitting electrons from the electron emitter 2. A voltage of +100 V to +300 V with respect to the reference potential is applied to the first electrode 3 via the terminal 93 and the conductive member 94, thereby creating a potential difference (approximately +several tens of V to +200 V) between the first electrode 3 and the electron emitter 2. This forms an electric field in which electrons emitted from the electron emitter 2 travel toward the first electrode 3 and electrons that have passed through the electron passing region 311a travel along a predetermined trajectory. In particular, since the same potential as that of the first electrode 3 is applied to each of the first opposing portion 341 and the second opposing portion 351, an electric field that moves electrons toward the window portion 12 is formed. [Action and effect]

[0058] In the electron beam emission unit 1, the first protrusion 34 and the second protrusion 35 are located outside the electron passing region 311a when viewed from the Z-axis direction and protrude from the mesh portion 31 on the opposite side from the electron emitter 2. Thus, when a predetermined potential is applied to the first electrode 3, an electric field is formed in which electrons passing through the electron passing region 311a travel along a predetermined trajectory. Furthermore, the mesh portion 31, in which a plurality of through-holes 31a are formed, and the holding portion 32, including the first protrusion 34 and the second protrusion 35, are formed separately from each other. This prevents deformation of the mesh portion 31 and the holding portion 32 due to the influence of thermal expansion, even if the first electrode 3 is heated by radiant heat from the electron emitter 2, for example. Therefore, the electron beam emission unit 1 prevents changes in the emission characteristics of the electron beam EB.

[0059] In the electron beam emission unit 1, when the electron emitter 2 becomes hot due to current flow, debris from the electron emitter 2 (e.g., debris generated by sublimation of a filament) may accumulate on the mesh portion 31. In this case, the debris may become oxides, and when the electron beam EB irradiates the oxide, which is an insulator, the oxide may become charged. Furthermore, when the mesh portion 31 itself is oxidized, oxides may be generated, and when the electron beam EB irradiates the oxide, the oxide may become charged. Such charging of the oxides may change the emission characteristics of the electron beam EB. However, in the electron beam emission unit 1, the mesh portion 31 and the holding portion 32 are formed separately from each other, so that the mesh portion 31 on which oxides have been generated can be easily replaced. Furthermore, the electron beam irradiation device 10 may repeatedly turn on and off the electron beam EB irradiation depending on its application. In this case, the first electrode 3 repeatedly undergoes thermal expansion and contraction, causing metal fatigue in the mesh portion 31. In the electron beam emission unit 1, the mesh portion 31 can be easily replaced before it is damaged due to metal fatigue.

[0060] The electron beam irradiation device 10 may irradiate the electron beam EB for a predetermined time depending on its application. The electron beam emission unit 1 can suppress deformation of the mesh portion 31 and the holding portion 32 due to the influence of thermal expansion of each other, thereby reducing the amount of deformation of the mesh portion 31 and the holding portion 32 within the predetermined time. This suppresses fluctuations in the dose of the electron beam EB within the predetermined time.

[0061] In the electron beam emission unit 1, the multiple through-holes 31a are formed in the electron passing region 311a, and are not formed at both ends of the main body 311 in the Y-axis direction. As a result of the existence of a solid portion in the mesh portion 31 where no through-holes 31a are provided, warping of the mesh portion 31 can be suppressed even if the first electrode 3 is heated by radiant heat from the electron emitter 2.

[0062] In the electron beam extraction unit 1, the thermal expansion coefficient of the mesh portion 31 is smaller than that of the holding portion 32. This makes it possible to suppress deformation of the mesh portion 31 due to thermal expansion, and to stabilize the extraction characteristics of the electron beam EB.

[0063] In the electron beam extraction unit 1, the mesh portion 31 is made of a high-melting-point metal. This reduces the thermal expansion coefficient of the mesh portion 31 compared to when the mesh portion 31 is made of a metal that is not a high-melting-point metal, making it possible to suppress deformation of the mesh portion 31 due to thermal expansion and to stabilize the extraction characteristics of the electron beam EB.

[0064] In the electron beam emission unit 1, the high melting point metal forming the mesh portion 31 is, for example, titanium, which can more reliably suppress deformation of the mesh portion 31 due to thermal expansion.

[0065] In the electron beam emission unit 1, the holder 32 is made of, for example, stainless steel, which improves the workability of the holder 32, making it possible to easily form the first protrusion 34 and the second protrusion 35.

[0066] The electron beam emission unit 1 includes a second electrode 4 that directs electrons emitted from the electron emitter 2 toward the first electrode 3, and a support 8 that supports the first electrode 3 relative to the second electrode 4. The support 8 has an insulating portion 81 and a first metal portion 82 joined to the insulating portion 81. The support 8 supports the first electrode 3 relative to the second electrode 4 with the first metal portion 82 held by the first electrode 3. This allows the electrons emitted from the electron emitter 2 to be directed toward the first electrode 3 by the second electrode 4, thereby increasing the amount of electrons passing through the multiple through holes 31a. Furthermore, because the support 8 has the insulating portion 81, the first electrode 3 can be supported relative to the second electrode 4 while ensuring electrical insulation between the first electrode 3 and the second electrode 4. Furthermore, because the first metal portion 82 is held by the first electrode 3, the support 8 is less susceptible to wear, thereby suppressing the generation of foreign matter due to wear of the support 8. This prevents discharge caused by charging of the foreign matter.

[0067] In the electron beam emission unit 1, the support 8 has a second metal portion 83 joined to the insulating portion 81 while being electrically insulated from the first metal portion 82, and the support 8 supports the first electrode 3 relative to the second electrode 4 with the second metal portion 83 held by the second electrode 4. As a result, the second metal portion 83 is joined to the insulating portion 81 while being electrically insulated from the first metal portion 82, and therefore, the second metal portion 83 is held by the second electrode 4, and electrical insulation between the first electrode 3 and the second electrode 4 can be ensured. Furthermore, since the second metal portion 83 is held by the second electrode 4, the support 8 is less susceptible to wear, and the generation of foreign matter due to wear of the support 8 can be suppressed. Therefore, discharge caused by charging of the foreign matter can be suppressed.

[0068] In the electron beam emission unit 1, the insulating section 81 is disposed at a position that is not visible from the electron emitting section 2. This prevents electrons emitted from the electron emitting section 2 from reaching the insulating section 81 of the support 8. This prevents discharge caused by charging of the insulating section 81 and a deterioration in the emission characteristics of the electron beam EB.

[0069] In the electron beam emission unit 1, the electron emitter 2 is a filament extending along the Y-axis direction, the electron passing region 311a is an elongated region with the Y-axis direction as its longitudinal direction, and the first protrusion 34 and the second protrusion 35 are located on both sides of the electron passing region 311a in the X-axis direction when viewed from the Z-axis direction, and each of the first protrusion 34 and the second protrusion 35 extends along the Y-axis direction. As described above, in the electron beam emission unit 1, the mesh portion 31 and the holding portion 32 can be prevented from being deformed due to the influence of thermal expansion of each other, thereby reducing the amount of deformation of the mesh portion 31 due to thermal expansion and thereby preventing the amount of deformation of the mesh portion 31 from becoming non-uniform. Furthermore, because the first protrusion 34 and the second protrusion 35 extend along the Y-axis direction on both sides of the electron passing region 311a in the X-axis direction, an electric field in which electrons passing through the electron passing region 311a travel along a predetermined trajectory can be more reliably formed.

[0070] The above-described effects are supplemented below. The electron beam irradiation device 10 is required to uniformly emit the electron beam EB in order to uniformly process the electron beam irradiation target. Therefore, in the electron beam emission unit 1, a plurality of through-holes 31a, each having the same shape and size, are uniformly formed in the electron passing region 311a. In the electron beam emission unit 1, the electron emitter 2, which is a filament, is heated to approximately 2000°C to emit electrons. When the filament is heated, the temperature of the surrounding components increases due to radiant heat from the filament. For example, the temperature of the first electrode 3 reaches approximately 350 to 400°C. The heated first electrode 3 expands along the Y-axis direction due to thermal expansion. One end of the first electrode 3 in the Y-axis direction is thermally connected to the conductive member 94 through physical contact therewith, and thus heat transfers from one end of the first electrode 3 to the conductive member 94 and the terminal 93 (terminal unit 9) to which the conductive member 94 is connected. Furthermore, both ends of the electron emitter 2 are thermally connected by physical contact with the fixing members 95 and 96, respectively, and heat transfers from both ends of the electron emitter 2 to the fixing members 95 and 96. As a result, the amount of radiant heat emitted from both ends of the electron emitter 2 is thought to be less than that from the center of the electron emitter 2. Therefore, the temperature of both ends of the first electrode 3 is thought to be lower than that of the center of the first electrode 3. As a result, the temperature of the first electrode 3 becomes non-uniform. Because the amount of deformation of the first electrode 3 changes depending on the temperature, the amount of deformation of each through-hole 31a becomes non-uniform. This causes non-uniformity in the aperture ratio in the electron passing region 311a, resulting in non-uniformity in the dose of the electron beam EB emitted from the electron beam irradiation device 10. However, in the electron beam emission unit 1, the mesh portion 31 and the holding portion 32 can be prevented from deforming due to the influence of each other's thermal expansion, thereby preventing non-uniformity in the aperture ratio in the electron passing region 311a. This makes it possible to prevent the dose of the electron beam EB from becoming non-uniform.

[0071] In the electron beam emission unit 1, the holding portion 32 includes a frame portion 33 having an elongated opening 33a with its longitudinal direction in the Y-axis direction, the first protrusion 34 includes a first opposing portion 341 facing the second protrusion 35 in the X-axis direction and a first connection portion 342 connecting the first opposing portion 341 and the frame portion 33, the second protrusion 35 includes a second opposing portion 351 facing the first protrusion 34 in the X-axis direction and a second connection portion 352 connecting the second opposing portion 351 and the frame portion 33, and the mesh portion 31 is sandwiched between the frame portion 33 and the first opposing portion 341 and the second opposing portion 351 with the electron passing region 311a overlapping the opening 33a when viewed from the Z-axis direction. This makes it possible to suppress interference between electrons passing through the electron passing region 311a and the holding portion 32 and to suppress misalignment of the mesh portion 31 with respect to the holding portion 32.

[0072] In the electron beam emission unit 1, one end 312 of the mesh portion 31 in the X-axis direction faces the first opposing portion 341 on the outside of the first opposing portion 341, and the other end 313 of the mesh portion 31 in the X-axis direction faces the second opposing portion 351 on the outside of the second opposing portion 351. This restricts movement of the mesh portion 31 along the X-axis direction, making it possible to more reliably suppress positional deviation of the mesh portion 31 with respect to the holder 32.

[0073] The electron beam emission unit 1 includes a terminal unit 9 having terminals 93 electrically connected to the mesh portion 31 and the holding portion 32, and one end 314 of the mesh portion 31 in the Y-axis direction and one end 321 of the holding portion 32 in the Y-axis direction are fixed to the terminal unit 9. This makes it easy to apply a predetermined potential to the first electrode 3 from outside via the terminal unit 9. Furthermore, by adopting a configuration in which the portions of the mesh portion 31 other than the end 314 are not fixed to the holding portion 32, it is possible to prevent the mesh portion 31 and the holding portion 32, which expand due to thermal expansion, particularly along the Y-axis direction, from being affected by each other's thermal expansion and deforming.

[0074] In the electron beam emission unit 1, the mesh portion 31 is not fixed to the holding portion 32 except for the end 314, and the holding portion 32 is not fixed to the mesh portion 31 except for the end 321. In particular, the end 315 of the mesh portion 31 and the end 322 of the holding portion 32 are not fixed to each other. By adopting such a configuration, it is possible to suppress deformation of the mesh portion 31 and the holding portion 32 that would otherwise elongate due to thermal expansion, particularly along the Y-axis direction, as described above.

[0075] The electron beam irradiation device 10 includes an electron beam emission unit 1 and a housing 13 that houses an electron emitter 2 and a second electrode 4. The first electrode 3 is disposed outside the housing 13, and the insulating part 81 may be disposed in a position that is not visible from outside the housing 13. For example, even if the insulating part 81 is charged when electrons emitted from the electron emitter 2 reach the insulating part 81, it is possible to prevent a discharge path from being formed between the insulating part 81 and the outside of the housing 13. Therefore, it is possible to prevent discharge caused by charging the insulating part 81. [Variations]

[0076] The present invention is not limited to the above-described embodiment. In the above-described embodiment, the end portions 312, 313 extend along the Z-axis direction. However, the end portions 312, 313 do not have to extend along the Z-axis direction. For example, as shown in FIG. 10 and FIGS. 11(a) and 11(b), the end portions 312, 313 may extend along the X-axis direction from both ends of the main body portion 311 in the X-axis direction. In this case, the cross-sectional shape of the mesh portion 31 perpendicular to the Y-axis direction is linear. In other words, the end portions 312, 313 are not bent along the Z-axis direction. This allows the mesh portion 31 to be easily formed.

[0077] In the electron beam emission unit 1 shown in FIG. 10 , the end 312 does not face the first opposing portion 341 in the X-axis direction, and the end 313 does not face the second opposing portion 351 in the X-axis direction. However, the end 312 faces the head 82a of the support 8 located on one side in the X-axis direction, and the end 313 faces the head 82a of the support 8 located on the other side in the X-axis direction. This restricts movement of the mesh portion 31 along the X-axis direction, thereby more reliably suppressing displacement of the mesh portion 31 with respect to the holding portion 32. In the electron beam emission unit 1 shown in FIG. 10 , clearances exist between the end portions 312 and 313 and the multiple supports 8, respectively. The end portions 312 and 313 may be in contact with the multiple supports 8, respectively.

[0078] In the electron beam emission unit 1, the holder 32 of the first electrode 3 has the first protrusion 34 and the second protrusion 35. However, the holder 32 of the first electrode 3 may have a single protrusion. In this case, the protrusion may be formed in a ring shape so as to surround the opening 33a of the frame 33.

[0079] In the electron beam emission unit 1, the mesh portion 31 is made of, for example, titanium, but the mesh portion 31 may be made of a metal with excellent workability (for example, stainless steel). In this case, the mesh portion 31 can be easily formed. Furthermore, the holding portion 32 is made of, for example, stainless steel, but the holding portion 32 may be made of a high-melting-point metal (for example, titanium). In this case, deformation of the holding portion 32 due to thermal expansion can be suppressed.

[0080] Although the electron beam irradiation device 10 includes the housing portion 13, the electron beam emission unit 1 may also include the housing portion 13. In this case, the support 8 may support the first electrode 3 with respect to the housing portion 13.

[0081] In the electron beam emission unit 1, the plurality of through holes 31a are formed in the electron passing region 311a, but the plurality of through holes 31a may be formed in a portion other than the electron passing region 311a. For example, the plurality of through holes 31a may be formed in both end portions of the main body portion 311 in the Y-axis direction, the end portions 312 and 313, the extension portion 316, etc. The entire mesh portion 31 may be formed in a mesh shape. [Explanation of symbols]

[0082] 1...electron beam emission unit, 2...electron emission portion, 3...first electrode, 4...second electrode, 33a...opening, 8...support, 9...terminal unit, 10...electron beam irradiation device, 13...accommodation portion, 31...mesh portion, 31a...through hole, 32...holding portion, 33...frame portion, 34...first protrusion portion, 35...second protrusion portion, 81...insulating portion, 82...first metal portion, 83...second metal portion, 93...terminal, 311a...electron passing region, 312, 313, 314, 321...end portion, 341...first opposing portion, 342...first connecting portion, 351...second opposing portion, 352...second connecting portion, EB...electron beam.

Claims

1. an electron emitting portion that emits electrons; a first electrode that adjusts the trajectory of the electrons emitted as an electron beam; The first electrode is a mesh portion having a plurality of through holes formed therein through which the electrons emitted from the electron emission portion pass along a first direction; a holding portion that holds the mesh portion and includes at least one protrusion that is located outside an electron passing region in which the plurality of through holes are formed in the mesh portion when viewed from the first direction and that protrudes from the mesh portion on a side opposite to the electron emission portion, The electron beam emission unit, wherein the mesh portion and the holding portion are formed separately from each other.

2. 2. The electron beam emission unit according to claim 1, wherein the mesh portion has a thermal expansion coefficient smaller than that of the holder portion.

3. 3. The electron beam emission unit according to claim 1, wherein the mesh portion is made of a high-melting-point metal.

4. 4. The electron beam emission unit according to claim 3, wherein the high melting point metal is titanium.

5. 3. The electron beam emission unit according to claim 1, wherein the holding portion is made of stainless steel.

6. a second electrode that causes the electrons emitted from the electron emission portion to travel toward the first electrode; at least one support supporting the first electrode relative to the second electrode; the support body has an insulating portion and a first metal portion joined to the insulating portion, 3. The electron beam emission unit according to claim 1, wherein the support supports the first electrode relative to the second electrode in a state in which the first metal portion is held by one of the first electrode and the second electrode.

7. the support body further includes a second metal portion joined to the insulating portion in a state of being electrically insulated from the first metal portion, 7. The electron beam emission unit according to claim 6, wherein the support supports the first electrode relative to the second electrode in a state in which the second metal portion is held by the other of the first electrode and the second electrode.

8. 7. The electron beam emission unit according to claim 6, wherein the insulating portion is arranged at a position that is not visible from the electron emitting portion.

9. the electron emission portion is a filament extending along a second direction intersecting the first direction, the electron passing region is an elongated region having a longitudinal direction in the second direction, the at least one protrusion is a first protrusion and a second protrusion located on both sides of the electron passing region in a third direction intersecting the first direction and the second direction when viewed from the first direction, 3. The electron beam emission unit according to claim 1, wherein the first protrusion and the second protrusion each extend along the second direction.

10. the holding portion further includes a frame portion having an elongated opening with the second direction as a longitudinal direction, the first protruding portion includes a first opposing portion facing the second protruding portion in the third direction and a first connecting portion connecting the first opposing portion and the frame portion, the second protruding portion includes a second opposing portion facing the first protruding portion in the third direction and a second connecting portion connecting the second opposing portion and the frame portion, 10. The electron beam emission unit according to claim 9, wherein the mesh portion is sandwiched between the frame portion and each of the first opposing portion and the second opposing portion, with the electron passing region overlapping the opening when viewed from the first direction.

11. one end of the mesh portion in the third direction faces the first opposing portion on the outer side of the first opposing portion, 11. The electron beam emission unit according to claim 10, wherein the other end of the mesh portion in the third direction faces the second opposing portion on the outside of the second opposing portion.

12. a terminal unit having terminals electrically connected to the mesh portion and the holding portion; 10. The electron beam emission unit according to claim 9, wherein one end of the mesh portion in the second direction and one end of the holding portion in the second direction are fixed to the terminal unit.

13. the electron beam emission unit according to claim 6; a housing portion that houses the electron emission portion and the second electrode, the first electrode is disposed outside the housing portion, The insulating section is disposed in a position that cannot be seen from outside the housing section.

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