Electron source, and electron gun and device using the same

Abstract

To provide an electron source capable of increasing electron current density and achieving a longer lifetime, and an electron gun and an electronic device using the same.SOLUTION: An electron source includes a support part made of metal and an electron emission part that is configured as a solid body made of metals including iridium and rare earth elements. The electron emission part is provided on the support part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an electron source, and an electron gun and device using the same. [Background technology]

[0002] Electron guns equipped with an electron source are used in devices such as X-ray generators, electron beam generators, electron beam type metal 3D printers, and electron microscopes (SEM and TEM). The electron source includes an electron emitter and a filament that heats the electron emitter. As such an electron source, for example, the electron source described in the following Patent Document 1 is known. This document describes a thermionic emission filament in which a second metal is coated on the surface of a first metal that serves as a bus of the filament wire, and the surface of the second metal coating is coated with a metal oxide such as thorium oxide or yttrium oxide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-259606 A Summary of the Invention [Problem to be solved by the invention]

[0004] In devices such as electron microscopes, an electron source capable of emitting a high-brightness electron beam is desired to improve resolution, and in order to emit a high-brightness electron beam, the electron source needs to emit a high electron current density. Also, it is desirable for the electron gun to have a long life. However, the electron source described in Patent Document 1 has room for improvement in terms of electron current density and life span. That is, in a thermionic emission filament, if the material coated on the surface of the second metal coating is thorium oxide or yttrium oxide, the filament has a very high melting point, and the heat during the manufacturing process, such as during coating, may adversely affect the filament, shortening the life of the electron source. Therefore, it is preferable to use metals containing iridium and rare earth elements, which have a relatively low melting point and high electron emission ability (high electron current density), for the electron emission section. On the other hand, when such metals are used, unlike the above-mentioned oxides, there is a possibility that deterioration of characteristics due to oxidation may occur, and in that case, the life of the electron source may be shortened.

[0005] An object of the present disclosure is to provide an electron source capable of increasing electron current density and extending the life span, and an electron gun and an electronic device using the same. [Means for solving the problem]

[0006] In order to solve the above problem, one aspect of the present disclosure provides an electron source comprising a support portion made of a metal and an electron emitting portion constituted by a solid body made of a metal containing iridium and a rare earth element, the electron emitting portion being provided on the support portion. According to the above-mentioned electron source, the solid body constituting the electron emission section provided on the support section is made of a metal containing iridium and a rare earth element. This metal has a low work function, so that electrons can be easily emitted from the electron emission section, and the electron current density can be increased. In addition, this metal has the following properties: Since the melting point is relatively low, there is little adverse effect on the support during manufacturing. Furthermore, since the electron emitter is made of a solid body, it is possible to reduce the surface area exposed to the surrounding atmosphere compared to when the electron emitter is made of a non-solid body such as a porous structure such as a sintered body, and the effect of oxidation is suppressed. As a result, the decrease in the electron emission ability of the electron emitter is suppressed. In this way, the electron source of the present disclosure can have a long life.

[0007] In the electron source, it is preferable that the support portion has a support wire, and the electron emission portion is provided so as to cover at least a portion of the support wire. In this case, since the electron emitter is provided so as to cover at least a part of the support wire of the support part, the electron emitter is less likely to fall off the support wire, and the life of the electron source can be extended. In addition, since the contact area between the support wire and the electron emitter is increased, the heating efficiency of the electron emitter by electrical heating of the support part can be improved.

[0008] In the electron source, it is preferable that the support portion has a support wire and a metal wire joined to and intersects with the support wire, and the electron emission portion is provided so as to cover at least a part of the tip of the metal wire. In this case, by arranging the electron emission portion so as to cover at least a portion of the tip of the metal wire, it becomes possible to adjust the size of the electron emission portion regardless of the thickness of the support wire, making it easier to adjust the area from which electrons are emitted from the electron emission portion.

[0009] In the electron source, the electron emitting portion is preferably spherical. In this case, since the electron emission portion is spherical, it is possible to increase the volume of the electron emission portion while reducing the surface area thereof, and therefore it is possible to include a larger amount of rare earth elements therein, thereby extending the life of the electron source.

[0010] It is preferable that the electron source further includes an alloy layer that bonds the electron emitting portion and the supporting portion and contains an alloy of iridium and a metal constituting the supporting portion. In this case, the alloy layer contains iridium contained in the electron emitting portion and the metal constituting the supporting portion, and the thermal expansion coefficient of the alloy layer is close to that of the electron emitting portion and is also close to that of the supporting portion. Therefore, even if the supporting portion and the electron emitting portion are heated by electrical heating of the supporting portion, and stress is applied between the supporting portion and the electron emitting portion due to the difference in thermal expansion coefficient between the supporting portion and the electron emitting portion, the stress is mitigated by the alloy layer. Therefore, it is possible to suppress the occurrence of cracks in the electron emitting portion.

[0011] In the electron source, the electron emitting portion preferably has a surface roughness Rz of 2 μm or less. By making the surface roughness Rz of the electron emitting portion 2 μm or less, the surface area of ​​the electron emitting portion can be made small, and the effect of oxidation of the electron emitting portion can be suppressed, thereby making it possible to extend the life of the electron source.

[0012] In the electron source, the metal constituting the supporting portion is preferably at least one selected from the group consisting of tungsten, iridium, and rhenium. In this case, since the metals constituting the supporting portion all have high melting points, deformation of the supporting portion can be suppressed even if the supporting portion is electrically heated to a temperature at which electrons are emitted from the electron emitting portion.

[0013] In the electron source, the rare earth element of the electron emitting portion may be at least one selected from the group consisting of cerium, lanthanum, and praseodymium.

[0014] In the electron source, it is preferable that the rare earth element is cerium, and the metal of the electron emitting portion includes at least one selected from the group consisting of Ir2Ce, Ir3Ce, Ir5Ce, and Ir7Ce2. In this case, the life of the electron emitting portion can be extended, and therefore the life of the electron source can be extended.

[0015] In the electron source, the rare earth element is lanthanum, and the metal of the electron emission portion is Ir2La, Ir3La, Ir5La, Ir7La2, and Ir 17 It is preferable that the compound contains at least one selected from the group consisting of La2. In this case, the life of the electron emitting portion can be extended, and therefore the life of the electron source can be extended.

[0016] Another aspect of the present disclosure provides an electron gun including the electron source described above. With this electron gun, when the electron source is heated, electrons are emitted from the electron emitting section and are output as an electron beam. At this time, the electron source can increase the electron current density, so that the electron gun can output a high-brightness electron beam that is easily converged.

[0017] Yet another aspect of the present disclosure provides a device including the electron gun described above. According to this device, the electron gun can emit a high-brightness electron beam, thereby improving the performance of the device. Effect of the Invention

[0018] According to the present disclosure, there is provided an electron source capable of increasing electron current density and extending the life span, and an electron gun and device using the same. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing an embodiment of a device according to the present disclosure. [Diagram 2] FIG. 2 is a partial cross-sectional front view showing the electron gun of FIG. [Diagram 3] FIG. 3 is an enlarged view showing a part of the electron source of FIG. 2. [Figure 4] FIG. 4 is a vertical cross-sectional view of a portion of the electron source of FIG. [Diagram 5] FIG. 4 is a longitudinal sectional view showing a portion of a second embodiment of an electron source according to the present disclosure. [Figure 6] FIG. 11 is a partially enlarged front view showing a part of a third embodiment of an electron source according to the present disclosure. [Figure 7] FIG. 11 is a longitudinal sectional view showing a portion of a third embodiment of an electron source according to the present disclosure. [Figure 8] 13 is a partially enlarged front view showing a part of a fourth embodiment of an electron source according to the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, preferred embodiments of the electron source, the electron gun, and the device of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having equivalent functions are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0021] Fig. 1 is a schematic diagram showing an embodiment of a device according to the present disclosure. The device 100 shown in Fig. 1 is an X-ray generator that generates X-rays XR, and includes an X-ray emitter 10 that emits X-rays XR, a power supply unit 20 connected to the X-ray emitter 10, and a vacuum pump 50 connected to the X-ray emitter 10.

[0022] The power supply unit 20 includes a power source 21 and a metal case 22 that houses the power source 21. The power source 21 is molded in the case 22 with an electrically insulating resin (for example, epoxy resin).

[0023] The X-ray emission unit 10 includes an electron gun 11 that emits an electron beam EB, and a cylindrical portion 12 that is connected to a case 22 and that houses the electron gun 11 and is made of metal (for example, stainless steel). The electron gun 11 is fixed to a neck portion 13 made of resin or the like within the cylindrical portion 12, and is electrically connected to a power source 21. The electron gun 11 is capable of emitting an electron beam EB by power supplied from the power source 21. A target 14 is fixed to the tip of the cylindrical portion 12, which converts the electron beam EB emitted from the electron gun 11 into X-rays XR and emits the X-rays. A partition plate 18 is installed inside the cylindrical portion 12, and an electron path 15 extends along a direction connecting the partition plate 18 and the target 14. A pair of cylindrical coil portions 16 and 17 that function as electromagnetic lenses are arranged around and along the electron path 15. The vacuum pump 50 is connected to the cylindrical portion 12 and is capable of evacuating the internal space of the cylindrical portion 12 to create a vacuum state.

[0024] In the device 100, when the inside of the cylindrical portion 12 is evacuated by the vacuum pump 50 and power is supplied from the power supply 21 to the electron gun 11, an electron beam EB is emitted from the electron gun 11. The electron beam EB passes through the electron path 15 while being focused and deflected by the coil portions 16 and 17, and is irradiated onto the target 14, which then emits X-rays XR.

[0025] The electron gun 11 will be described in detail with reference to Fig. 2 to Fig. 4. Fig. 2 is a partial cross-sectional front view showing the electron gun of Fig. 1, Fig. 3 is an enlarged view showing a part of the electron source of Fig. 2, and Fig. 4 is a vertical cross-sectional view of a part of the electron source of Fig. 3. 2, the electron gun 11 includes an electron source 30 and an electrode 40 disposed opposite the electron source 30. A voltage can be applied to the electron source 30 and the electrode 40 by a power source 21.

[0026] The electrode 40 has a beam passage opening 41 through which the electron beam EB emitted from the electron source 30 passes.

[0027] The electron source 30 includes a filament (supporting portion) 32 made of a filament wire (supporting wire) 32a, and an electron emitting portion 31 provided on the filament 32. The electron emitting portion 31 is configured of a solid body made of a metal containing iridium and rare earth elements. The solid body is a solid body having no voids, and is different from a porous structure such as a sintered body. The filament wire 32a is bent into a hairpin shape, and the electron emission portion 31 is provided at the bent portion of the filament wire 32a.

[0028] A power feed pin 34 is connected to each end of the filament 32, and the power feed pin 34 may penetrate a plate-shaped insulating support member 35 and be fixed to the insulating support member 35. The power feed pin 34 is made of a conductive material such as Kovar alloy (KOV), molybdenum, molybdenum rhenium alloy, or SUS. The insulating support member 35 is made of, for example, ceramic. The power feed pin 34 can be supplied with power.

[0029] 3, the electron emitter 31 is spherical. In this embodiment, the spherical shape refers to a shape in which, when the electron emitter 31 is observed two-dimensionally, the diameter of the arc described by the surface of the electron emitter 31 on the electron emission side is smaller than the diameter of the arc described by the bent portion of the filament wire 32a. 4, the electron emission portion 31 is provided so as to cover the filament wire 32a. In this embodiment, the electron emission portion 31 is provided so as to surround the entire periphery of the central region of the bent portion of the filament wire 32a. The alloy layer 33 contains an alloy of iridium and a metal constituting the filament wire 32a.

[0030] According to the electron source 30, the solid body constituting the electron emitter 31 provided on the filament 32 is made of a metal containing iridium and rare earth elements. This metal has a low work function, so that electrons are easily emitted from the electron emitter 31, and the electron current density can be increased. In addition, this metal has a relatively low melting point, so that the filament 32 is less adversely affected (e.g., damaged) during manufacture. Furthermore, by making the electron emitter 31 out of a solid body, it is possible to reduce the surface area exposed to the surrounding atmosphere compared to when the electron emitter 31 is made of a non-solid body such as a porous structure such as a sintered body, and the probability of contact between the electron emitter 31 and oxygen remaining in the tubular part 12 in a vacuum state, oxygen derived from water, and oxygen derived from carbon dioxide can be reduced, and the effect of oxidation by oxygen (e.g., deterioration of the electron emitter 31) is suppressed. In addition, the rare earth elements and the like are suppressed from escaping from the surface. As a result, the decrease in the electron emission ability of the electron emitter 31 is suppressed, and the electron source 30 can have a long life.

[0031] Furthermore, in the electron source 30, since the electron emitting portion 31 is spherical, the volume of the electron emitting portion 31 can be increased while reducing the surface area, and therefore a larger amount of rare earth elements can be contained inside. This allows the electron source 30 to have a longer life. In addition, since the electron emitting portion 31 is spherical, the area from which electrons are emitted from the electron emitting portion 31 can be restricted to a narrow range. In other words, electrons can be emitted from a minute area. This allows the electron source 30 to emit electrons that are easy to converge.

[0032] Furthermore, in the electron source 30, the filament 32 is made of a filament wire 32a, and the spherical electron emitting portion 31 is provided so as to cover the filament wire 32a, so that the electron emitting portion 31 is less likely to fall off the filament wire 32a, and the life of the electron source 30 can be extended. In addition, since the contact area between the filament wire 32a and the electron emitting portion 31 is increased, the heating efficiency of the electron emitting portion 31 due to the electrical heating of the filament 32 can be improved. In addition, even if the electron emitting portion 31 is spherical and the average distance from the surface that emits electrons to the filament wire 32a is extended, a local potential gradient is less likely to occur in the electron emitting portion 31 because the electron emitting portion 31 is made of a metal containing iridium and rare earth elements and has high electrical conductivity, and thus a decrease in the uniformity and temporal stability of electron emission can be suppressed.

[0033] The electron source 30 will now be described in more detail.

[0034] <Electron emission section> The electron emitting portion 31 is a portion that is heated by a filament 32 and emits electrons. The electron emitting portion 31 is made of a solid body made of a metal containing iridium and rare earth elements. More specifically, the electron emitting portion 31 is made by melting a metal containing iridium and rare earth elements and solidifying it at a desired position (in this embodiment, the bent portion of the filament wire 32a), and has a structure made of only metal (filled with metal) without having any space such as a hole inside.

[0035] The rare earth elements include cerium, lanthanum and praseodymium, which may be used alone or in combination of two or more. Here, it is preferable that the rare earth element is cerium, and the alloy of the electron emitting portion 31 is composed of at least one selected from the group consisting of Ir2Ce, Ir3Ce, Ir5Ce, and Ir7Ce2. In this case, the life of the electron emitting portion 31 can be extended, and therefore the life of the electron source 30 can be extended. In particular, the alloy of the electron emitting portion 31 is preferably composed of at least one selected from the group consisting of Ir2Ce, Ir3Ce, and Ir7Ce2. In this case, the electron emitting portion 31 is less likely to change over time, and a longer life is possible.

[0036] In addition, the rare earth element is lanthanum, and the alloy of the electron emitting portion 31 is Ir2La, Ir3La, Ir5La, Ir7La2, and Ir 17 La2. In this case as well, the life of the electron emitting portion 31 can be extended, and therefore the life of the electron source 30 can be extended.

[0037] The thermal expansion coefficient of the electron emitting portion 31 may be greater than the thermal expansion coefficient of the filament 32 or less than the thermal expansion coefficient of the filament 32 .

[0038] The surface roughness (maximum height roughness) Rz of the electron emitting portion 31 is not particularly limited and may be greater than 2 μm or less than 2 μm, but is preferably less than 2 μm. Note that the surface roughness Rz in this embodiment is a value excluding sporadic protrusions that are higher than the surroundings, and is a value that is satisfied in most regions of the electron emitting portion 31. By making the surface roughness Rz of the electron emitting portion 31 2 μm or less, the surface area of ​​the electron emitting portion 31 can be reduced, which suppresses the effect of oxidation of the electron emitting portion 31 and also suppresses the escape of rare earth elements from the electron emitting portion 31. This suppresses the decrease in the electron emission ability of the electron emitting portion 31, and enables the electron source 30 to have a longer life. The surface roughness Rz of the electron emitting portion 31 is more preferably 1 μm or less. The surface roughness Rz of the electron emitting portion 31 is a value measured by a three-dimensional optical surface shape / roughness measuring instrument (white light interferometer) (product name "nexview NX2", manufactured by Zygo Corporation).

[0039] The electron emitting portion 31 can be formed, for example, as follows. That is, first, an alloy compound of iridium and a rare earth element (for example, Ir7Ce2) prepared by an arc melting method is pulverized using a mortar and pestle to obtain an alloy compound powder. Next, the obtained alloy compound powder is sieved through a sieve having a predetermined mesh size (for example, 20 μm). Next, the sieved alloy compound powder is mixed with a resin such as polyvinylpyrrolidone (PVP) and a solvent such as ethanol so that the resin content is about 1 mass %, thereby coating the alloy compound powder with the resin and obtaining a resin-coated powder. Next, the obtained resin-coated powder is dispersed in pure water to obtain a powder dispersion. Next, the filament wire 32a welded to the power supply pin 34 is set in a vacuum chamber after the powder dispersion liquid is applied to the bent portion with a brush. Finally, for example, 10 -5 The filament wire 32a is heated by applying current in a high vacuum of 100 Pa or less to weld the alloy compound to the bent portion of the filament wire 32a. In this manner, the electron emission portion 31 is obtained. The above resin is believed to easily increase the surface tension of the powder dispersion liquid with respect to the filament wire 32a, which makes it easier to make the electron emitting portion 31 spherical.

[0040] <Filament> The filament 32 is made of a filament wire 32a, and the filament wire 32a is made of a metal. The metal is not particularly limited as long as it is a metal that does not melt when heated by electrical current up to a temperature at which electrons are emitted from the electron emitting portion 31, but a high-melting point metal is preferable as such a metal. A high-melting-point metal is a metal that has a melting point of 1800°C or higher. As the high melting point metal, for example, tungsten, iridium, molybdenum, tantalum and rhenium are preferable. These may be used alone or in combination of two or more. In this case, even if the filament 32 is heated by current application to a temperature at which electrons are emitted from the electron emitting portion 31, deformation of the filament 32 can be suppressed. As the high melting point metal, tungsten is preferable because it has a low thermal expansion coefficient and is particularly resistant to deformation when an electric current is passed through it.

[0041] The cross section of the filament wire 32a may be circular or rectangular, but is preferably circular from the viewpoint of enabling electron emission from a minute region.

[0042] <Alloy layer> As shown in FIG. 4, the electron source 30 preferably has an alloy layer 33 between the electron emitting portion 31 and the filament wire 32a, which bonds the electron emitting portion 31 and the filament wire 32a. The alloy layer 33 contains an alloy of iridium and a metal constituting the filament 32. That is, the alloy layer 33 contains the iridium contained in the electron emitting portion 31 and the metal constituting the filament 32, and the thermal expansion coefficient of the alloy layer 33 is close to that of the electron emitting portion 31 and also close to that of the filament 32. Therefore, even if the filament 32 and the electron emitting portion 31 are heated by energizing the filament 32 and a stress is applied between the filament 32 and the electron emitting portion 31 due to the difference in the thermal expansion coefficient between the filament 32 and the electron emitting portion 31, the stress is alleviated by the alloy layer 33. Therefore, it is possible to suppress the occurrence of cracks in the electron emitting portion 31. The alloy layer 33 may be a sintered body containing voids, or a solid body containing no voids. When the alloy layer 33 is a sintered body including voids, even if stress is applied to the alloy layer 33 during heating, the stress is easily absorbed and alleviated by the voids in the sintered body, and the occurrence of cracks in the electron emitting section 31 is further suppressed. As a result, the electron source 30 can further improve the temperature stability of the electron emitting section 31 during heating. When the alloy layer 33 is a sintered body containing voids, the alloy layer 33 can be formed by fixing iridium powder onto the filament 32 by sintering. If the alloy layer 33 is a solid body without voids, the surface area exposed to the surrounding atmosphere can be reduced, and the influence of oxidation can be suppressed. As a result, the deterioration of the electron emission ability of the electron emitter 31 is suppressed, and the life of the electron source 30 can be further extended.

[0043] The thickness of the alloy layer 33 is not particularly limited, but is preferably 10 μm or more, and more preferably 30 μm or more.

[0044] Next, a second embodiment of the electron source of the present disclosure will be described with reference to FIG. FIG. 5 is a vertical cross-sectional view showing a part of the second embodiment of the electron source of the present disclosure. As shown in FIG. 5, the electron source 130 of this embodiment differs from the electron source 30 of the first embodiment in that the filament 32 further includes a plate-shaped member 32b provided on the filament wire 32a, and the electron emission section 31 is provided in a layer on the plate-shaped member 32b opposite to the filament wire 32a. The plate-shaped member 32b is made of a metal, and is not particularly limited as long as it is a metal that does not melt even when heated by current flow up to a temperature at which electrons are emitted from the electron emission section 31, but a high-melting point metal is preferable as such a metal. Specific examples of the material are tungsten, iridium, molybdenum, tantalum, and rhenium. These may be used alone or in combination of two or more kinds. According to the electron source 130 of the present embodiment, it is easy to realize the electron emitting portion 31 with a uniform thickness. Therefore, it is possible to suppress unevenness depending on the position in the amount of electrons emitted from the electron emitting portion 31. In addition, since the electron emitting portion in the electron emitting portion 31 has a planar shape and a large area, it is possible to emit more electrons.

[0045] It is preferable that the electron source 130 further includes an alloy layer 33 between the electron emitter 31 and the metal wire 32c of the filament 32, which joins the electron emitter 31 and the metal wire 32c of the filament 32 and contains an alloy of iridium and the metal that constitutes the filament 32.

[0046] Next, a third embodiment of the electron source of the present disclosure will be described with reference to FIGS. FIG. 6 is a partially enlarged front view showing a part of the third embodiment of the electron source of the present disclosure, and FIG. 7 is a vertical sectional view showing a part of the third embodiment of the electron source of the present disclosure.

[0047] As shown in FIG. 6, the electron source 230 of this embodiment differs from the electron source 30 of the first embodiment in that the filament 32 further includes a metal wire 32c that is joined to the filament wire 32a in an intersecting manner, and the electron emission portion 31 is provided at the tip of the metal wire 32c (the end opposite to the base end side that is the joint with the filament wire 32a). According to the electron source 230 of this embodiment, by providing the electron emitting portion 31 at the tip of the metal wire 32c, it becomes possible to adjust the size of the electron emitting portion 31 regardless of the thickness of the filament wire 32a, and it becomes easier to adjust the area from which electrons are emitted from the electron emitting portion 31.

[0048] As shown in FIG. 7, it is preferable that the electron source 230 further includes an alloy layer 33 between the electron emitter 31 and the metal wire 32c of the filament 32, which joins the electron emitter 31 and the metal wire 32c of the filament 32 and contains an alloy of iridium and the metal constituting the filament 32.

[0049] The metal wire 32c may be made of the same metal as the filament wire 32a or a different metal, but is preferably made of the same metal. In this case, the thermal expansion coefficients of the filament wire 32a and the metal wire 32c are the same, so that even if the filament 32 expands due to electrical heating of the filament 32, stress is unlikely to be applied between the filament wire 32a and the metal wire 32c, and it is easy to prevent the filament wire 32a from falling off.

[0050] The cross-sectional area of ​​the metal wire 32c may be equal to or larger than the cross-sectional area of ​​the filament wire 32a, or may be smaller than the cross-sectional area of ​​the filament wire 32a, but is preferably smaller than the cross-sectional area of ​​the filament wire 32a. In this case, it is possible to make the electron emitting portion 31 smaller, and the area from which electrons are emitted from the electron emitting portion 31 can be restricted to a narrow range. In other words, electrons can be emitted from a minute area. Therefore, the electron source 230 can emit electrons that are easy to converge. Specifically, the cross-sectional area of ​​the metal wire 32c may be less than 1 time the cross-sectional area of ​​the filament wire 32a, but is preferably 0.5 times or less, and more preferably 0.3 times or less.

[0051] The metal wire 32c can be joined to the filament wire 32a by, for example, welding.

[0052] The shape of the electron emitting portion 31 is not particularly limited, and in this embodiment, the electron emitting portion 31 is spherical. In this embodiment, the spherical shape refers to a shape in which the electron emitting portion 31 is provided so as to surround the entire tip of the metal wire 32c with an arc surface.

[0053] The present disclosure is not limited to the above-described embodiment. For example, in the electron source 30 of the above-described embodiment, the electron emitting portion 31 is spherical, but as in the electron source 330 shown in FIG. 8, the electron emitting portion 31 may be formed in a film shape along the extension direction (surface shape) of the filament wire 32a.

[0054] It is preferable that the electron source 330 further includes an alloy layer 33 between the electron emitting portion 31 and the filament wire 32a of the filament 32, which joins the electron emitting portion 31 and the filament wire 32a of the filament 32 and contains an alloy of iridium and the metal constituting the filament 32.

[0055] The electron emitting portion 31 of the electron source 330 can be formed in the same manner as the electron emitting portion 31 of the electron source 30, except that the sieved alloy compound powder is not coated with resin. In addition, since the alloy compound powder is not coated with resin, the surface tension of the powder dispersion liquid with respect to the filament wire 32a is reduced, which is believed to make it easier for the electron emitting portion 31 to be in the form of a film. Furthermore, in the above embodiment, the electron gun 11 includes the electron source 30 and the electrode 40 , but the electron gun of the present disclosure does not necessarily need to include the electrode 40 .

[0056] The device of the present disclosure is not limited to the device of the above embodiment. For example, the device 100 of the above embodiment is an X-ray generator, but the device of the present disclosure is not particularly limited as long as it is a device equipped with an electron gun, and may be an electron beam generator, an electron beam type metal 3D printer, an electron microscope (SEM and TEM), etc.

[0057] The outline of this disclosure is as follows. [1] A support part made of metal; and an electron emission portion formed of a solid body made of a metal containing iridium and a rare earth element, The electron source, wherein the electron emission portion is provided on the support portion. [2] The support portion has a support wire, The electron source according to [1], wherein the electron emission portion is provided so as to cover at least a portion of the support wire. [3] The support portion has a support wire and a metal wire that crosses and is joined to the support wire, The electron source according to [1], wherein the electron emission portion is provided so as to cover at least a portion of the metal wire. [4] The electron source according to [2] or [3], wherein the electron emitting portion is spherical. [5] The electron source according to any one of [1] to [4], further comprising an alloy layer joining the electron emitting portion and the filament and containing an alloy of iridium and a metal constituting the filament. [6] The electron source according to any one of [1] to [5], wherein the surface roughness Rz of the electron emitting portion is 2 μm or less. [7] The electron source according to any one of [1] to [6], wherein the metal constituting the supporting portion is at least one selected from the group consisting of tungsten, iridium, and rhenium. [8] The electron source according to any one of [1] to [7], wherein the rare earth element of the electron emitting portion is at least one selected from the group consisting of cerium, lanthanum, and praseodymium. [9] The rare earth element is cerium; The electron source according to [8], wherein the alloy of the electron emitting portion is composed of at least one selected from the group consisting of Ir2Ce, Ir3Ce, Ir5Ce, and Ir7Ce2.

[10] The rare earth element is lanthanum; The alloy of the electron emitting portion is Ir2La, Ir3La, Ir5La, Ir7La2, and Ir 17 The electron source according to [8], which is composed of at least one selected from the group consisting of La2.

[11] An electron gun comprising the electron source according to any one of [1] to

[10] .

[12] A device comprising an electron gun according to

[11] . [Industrial Applicability]

[0058] The electron source of the present disclosure can be used in electron guns, X-ray generators, electron beam generators, electron beam type metal 3D printers, electron microscopes (SEM and TEM), and the like. [Explanation of symbols]

[0059] 100...device, 11...electron gun, 30, 130, 230, 330...electron source, 31...electron emission portion, 32...filament (support portion), 32a...filament wire (support wire), 32b...plate-shaped member, 32c...metal wire, 33...alloy layer, 40...electrode, EB...electron beam, XR...X-ray.

Claims

1. A support part made of metal; and an electron emission portion formed of a solid body made of a metal containing iridium and a rare earth element, The electron source, wherein the electron emission portion is provided on the support portion.

2. The support portion has a support wire, The electron source according to claim 1 , wherein the electron emitting portion is provided so as to cover at least a portion of the support wire.

3. The support portion includes a support wire and a metal wire that intersects and is joined to the support wire, The electron source according to claim 1 , wherein the electron emitting portion is provided so as to cover at least a part of the tip of the metal wire.

4. 4. The electron source according to claim 2, wherein the electron-emitting portion is spherical.

5. 4. The electron source according to claim 1, further comprising an alloy layer that bonds said electron emitting portion and said supporting portion and contains an alloy of iridium and a metal constituting said supporting portion.

6. 4. The electron source according to claim 1, wherein the surface roughness Rz of the electron emitting portion is 2 μm or less.

7. 4. The electron source according to claim 1, wherein the metal constituting the supporting portion is at least one selected from the group consisting of tungsten, iridium, and rhenium.

8. 4. The electron source according to claim 1, wherein the rare earth element of the electron emission portion is at least one selected from the group consisting of cerium, lanthanum, and praseodymium.

9. the rare earth element is cerium; The metal of the electron emission portion is Ir ２ Ce, Ir ３ Ce, Ir ５ Ce and Ir ７ C ２ The electron source according to claim 8 , comprising at least one selected from the group consisting of:

10. the rare earth element is lanthanum, The metal of the electron emission portion is Ir ２ La, Ir ３ La, Ir ５ La, Ir ７ La ２ and Ir １７ La ２ The electron source according to claim 8 , comprising at least one selected from the group consisting of:

11. An electron gun comprising the electron source according to claim 1 .

12. A device comprising the electron gun of claim 11.

Images