Electron source, and electron gun and device using same

Abstract

This electron source comprises: a support part that is formed from a metal; and an electron emission part that is constituted from a solid body formed from a metal containing iridium and a rare earth element. In the electron source, the electron emission part is provided to the support part.

Description

Electron source, electron gun and device using the same

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

[0002] Electron guns equipped with an electron source are used in devices such as X-ray generators, electron beam generators, electron beam metal 3D printers, and electron microscopes (SEM and TEM). The electron source includes an electron emitter and a filament for heating the electron emitter. One such electron source is known from Patent Document 1. This document describes a thermionic electron-emitting filament in which a first metal serving as a bus bar of the filament wire is coated with a second metal, and the surface of the second metal coating is coated with a metal oxide such as thorium oxide or yttrium oxide.

[0003] Japanese Patent Application Laid-Open No. 2005-259606

[0004] In devices such as electron microscopes, electron sources capable of emitting high-brightness electron beams are desirable for improving resolution. To emit high-brightness electron beams, the electron source must have a high electron current density. Furthermore, electron guns are also desired to have a long life. However, the electron source described in Patent Document 1 leaves room for improvement in terms of electron current density and life. Specifically, if the material coated on the surface of the second metal coating in a thermionic emission filament is thorium oxide or yttrium oxide, its melting point is so high that heat during the manufacturing process, such as during coating, can adversely affect the filament, potentially 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) compared to the above oxides, for the electron emitter. However, unlike the above oxides, using such metals can lead to degradation of characteristics due to oxidation, which can shorten the life of the electron source.

[0005] An object of the present disclosure is to provide an electron source that can increase electron current density and have a long life, and an electron gun and device that use the same.

[0006] To solve the above-mentioned problems, one aspect of the present disclosure provides an electron source comprising a metal support and an electron emitter formed of a solid body made of a metal containing iridium and a rare earth element, with the electron emitter being mounted on the support. According to this electron source, the solid body constituting the electron emitter mounted on the support is made of a metal containing iridium and a rare earth element. This metal has a low work function, which facilitates electron emission from the electron emitter and increases the electron current density. Additionally, this metal has a relatively low melting point, which minimizes adverse effects on the support during manufacturing. Furthermore, by forming the electron emitter as a solid body, the surface area exposed to the ambient atmosphere can be reduced compared to electron emitters formed of non-solid bodies, such as porous structures such as sintered bodies, thereby minimizing the effects of oxidation. As a result, the electron emitter's electron emission capability is prevented from deteriorating. In this way, the electron source of the present disclosure can achieve a long life.

[0007] In the electron source, it is preferable that the support portion has a support wire, and the electron emitter is provided so as to cover at least a portion of the support wire. In this case, by providing the electron emitter so as to cover at least a portion of the support wire of the support portion, the electron emitter is less likely to fall off the support wire, thereby extending the life of the electron source. Furthermore, 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 portion 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 the support wire so as to intersect with the support wire, and the electron emitter is provided so as to cover at least a part of the tip of the metal wire. In this case, by providing the electron emitter so as to cover at least a part of the tip of the metal wire, it becomes possible to adjust the size of the electron emitter regardless of the thickness of the support wire, and it becomes easier to adjust the area from which electrons are emitted from the electron emitter.

[0009] In the electron source, it is preferable that the electron-emitting portion is spherical. In this case, since the electron-emitting portion is spherical, the volume of the electron-emitting portion can be increased while the surface area thereof is reduced, and therefore a larger amount of rare earth elements can be contained therein. This results in a longer life of the electron source.

[0010] Preferably, the electron source further includes an alloy layer bonding the electron emitter and the support and containing an alloy of iridium and a metal constituting the support. In this case, the alloy layer contains the iridium contained in the electron emitter and the metal constituting the support, and the thermal expansion coefficient of the alloy layer is close to that of the electron emitter and also close to that of the support. Therefore, even if the support and the electron emitter are heated by electrical heating of the support, and stress is applied between the support and the electron emitter due to the difference in thermal expansion coefficients between the support and the electron emitter, the stress is alleviated by the alloy layer. Therefore, cracks can be prevented from occurring in the electron emitter.

[0011] In the electron source, it is preferable that the surface roughness Rz of the electron emitting portion is 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 reduced, and the influence of oxidation of the electron emitting portion can be suppressed. This makes 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 all of the metals constituting the supporting portion have high melting points, deformation of the supporting portion can be suppressed even when the supporting portion is heated by electrical current 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 element selected from the group consisting of cerium, lanthanum, and praseodymium.

[0014] In the electron source, the rare earth element is cerium, and the metal of the electron emission portion is Ir ２ Ce, Ir３ Ce, Ir ５ Ce and Ir ７ Ce ２ 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 Ir ２ La, Ir ３ La, Ir ５ La, Ir ７ La ２ and Ir １７ La ２ 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 above-described electron source. With this electron gun, electrons are emitted from the electron emitting portion when the electron source is heated, and the electrons are emitted as an electron beam. At this time, the electron source can increase the electron current density, so that the electron gun can emit a high-brightness electron beam that is easily converged.

[0017] According to yet another aspect of the present disclosure, there is provided a device including the above-described electron gun, which enables the electron gun to emit a high-brightness electron beam, thereby improving the performance of the device.

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

[0019] Fig. 1 is a schematic configuration diagram showing an embodiment of a device of the present disclosure; Fig. 2 is a partially cross-sectional front view showing the electron gun of Fig. 1; Fig. 3 is an enlarged view showing a portion of the electron source of Fig. 2; Fig. 4 is a longitudinal cross-sectional view showing a portion of the electron source of Fig. 3; Fig. 5 is a partially enlarged front view showing a portion of a second embodiment of an electron source of the present disclosure; Fig. 6 is a partially enlarged front view showing a portion of a third embodiment of an electron source of the present disclosure; Fig. 7 is a longitudinal cross-sectional view showing a portion of a third embodiment of an electron source of the present disclosure; Fig. 8 is a partially enlarged front view showing a portion of a fourth embodiment of an electron source of the present disclosure;

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

[0021] Fig. 1 is a schematic diagram showing the configuration of 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 supply 21 and a metal case 22 that houses the power supply 21. The power supply 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 metal (e.g., stainless steel) cylindrical portion 12 that is connected to a case 22 and houses the electron gun 11. 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 supply 21. The electron gun 11 is capable of emitting the electron beam EB using power supplied from the power supply 21. A target 14 that converts the electron beam EB emitted from the electron gun 11 into X-rays XR and emits the X-rays XR is fixed to the tip of the cylindrical portion 12. A partition plate 18 is installed within 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 coils 16 and 17 that function as electromagnetic lenses are arranged around the electron path 15 and along the electron path 15. A vacuum pump 50 is connected to the cylindrical portion 12, which can evacuate the interior space of the cylindrical portion 12 to create a vacuum.

[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 Figures 2 to 4. Figure 2 is a partial cross-sectional front view showing the electron gun of Figure 1, Figure 3 is an enlarged view showing a part of the electron source of Figure 2, and Figure 4 is a vertical cross-sectional view of a part of the electron source of Figure 3. As shown in Figure 2, the electron gun 11 includes an electron source 30 and an electrode 40 arranged opposite the electron source 30. A voltage can be applied to the electron source 30 and the electrode 40 by a power supply 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 (support portion) 32 made of a filament wire (support wire) 32a, and an electron-emitting portion 31 provided on the filament 32. The electron-emitting portion 31 is configured as a solid body made of a metal containing iridium and rare earth elements. The solid body is a solid body without voids, and differs from a porous structure such as a sintered body. The filament wire 32a is bent into a hairpin shape, and the electron-emitting 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. Power can be supplied to the power feed pin 34.

[0029] As shown in Fig. 3, the electron emitting portion 31 is spherical. In this embodiment, the spherical shape refers to a shape in which, when the electron emitting portion 31 is observed two-dimensionally, the diameter of the arc described by the electron emitting surface of the electron emitting portion 31 is smaller than the diameter of the arc described by the bent portion of the filament wire 32a. As shown in Fig. 4, the electron emitting portion 31 is provided so as to cover the filament wire 32a. In this embodiment, the electron emitting 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 the metal that constitutes 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, which facilitates electron emission from the electron emitter 31 and increases the electron current density. Additionally, this metal has a relatively low melting point, which minimizes adverse effects on the filament 32 (e.g., damage to the filament 32) during manufacturing. Furthermore, the electron emitter 31 being made of a solid body reduces the surface area exposed to the ambient atmosphere compared to electron emitter 31 made of a non-solid body, such as a porous structure like a sintered body. This reduces the probability of contact between the electron emitter 31 and oxygen remaining in the vacuum-sealed cylindrical portion 12, oxygen derived from water, and oxygen derived from carbon dioxide, thereby suppressing the effects of oxygen-induced oxidation (e.g., deterioration of the electron emitter 31). Furthermore, the rare earth elements and other elements are prevented from escaping from the surface. As a result, the electron emitter 31's electron emission capability is prevented from decreasing, enabling the electron source 30 to have a longer 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, allowing a larger amount of rare earth elements to be contained therein. 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 limited to a narrow range. In other words, electrons can be emitted from a very small area. Therefore, the electron source 30 can 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, thereby extending the life of the electron source 30. Also, 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 by electrical heating of the filament 32 can be improved. Furthermore, 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, the electron-emitting portion 31 is made of a metal containing iridium and rare earth elements and has high conductivity, so that a local potential gradient is less likely to occur in the electron-emitting portion 31, and deterioration 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 Emitting Section> The electron emitting section 31 is a section that emits electrons when heated by the filament 32. The electron emitting section 31 is configured as a solid body made of a metal containing iridium and rare earth elements. More specifically, the electron emitting section 31 is formed 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 that does not have any spaces such as voids inside and is made up of only metal (filled with metal).

[0035] The rare earth elements include cerium, lanthanum, and praseodymium. These may be used alone or in combination of two or more. Here, when the rare earth element is cerium and the alloy of the electron emitting portion 31 is Ir ２ Ce, Ir ３ Ce, Ir ５ Ce and Ir ７ Ce ２ In this case, the life of the electron emitting section 31 can be extended, and therefore the life of the electron source 30 can be extended. In particular, the alloy of the electron emitting section 31 is preferably Ir ２ Ce, Ir３ Ce and Ir ７ Ce ２ In this case, the electron-emitting portion 31 is less likely to change over time, and the life of the electron source 30 can be extended.

[0036] The rare earth element is lanthanum, and the alloy of the electron emitting portion 31 is Ir ２ La, Ir ３ La, Ir ５ La, Ir ７ La ２ and Ir １７ La ２ 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.

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

[0038] The surface roughness (maximum height roughness) Rz of the electron-emitting region 31 is not particularly limited and may be greater than or equal to 2 μm, but is preferably 2 μm or less. Note that the surface roughness Rz in this embodiment is a value excluding sporadic protrusions that are higher than the surrounding area, and is a value that is substantially satisfied over most of the electron-emitting region 31. By making the surface roughness Rz of the electron-emitting region 31 2 μm or less, the surface area of ​​the electron-emitting region 31 can be reduced, suppressing the effects of oxidation of the electron-emitting region 31 and preventing rare-earth elements from escaping from the electron-emitting region 31. This suppresses a decrease in the electron-emitting ability of the electron-emitting region 31 and enables the electron source 30 to have a longer life. The surface roughness Rz of the electron-emitting region 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: First, an alloy compound of iridium and a rare earth element (e.g., Ir ７ Ce ２ ) is pulverized using a mortar and pestle to obtain an alloy compound powder. Next, the obtained alloy compound powder is sieved through a sieve with a predetermined mesh size (e.g., 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 coated with the powder dispersion liquid using a brush at its bent portion, and then set in a vacuum chamber. Finally, for example, 10 －５ The filament wire 32a is heated by applying an electric current in a high vacuum of 100 Pa or less, and the alloy compound is welded to the bent portion of the filament wire 32a, thereby obtaining the electron emitting portion 31. It is considered that the resin easily increases the surface tension of the powder dispersion liquid with respect to the filament wire 32a, thereby making it easier to form the electron emitting portion 31 into a spherical shape.

[0040] <Filament> The filament 32 is made of a filament wire 32a, which is made of a metal. The metal is not particularly limited as long as it does not melt when heated by electrical current to a temperature at which electrons are emitted from the electron-emitting portion 31. However, a high-melting-point metal is preferable. A high-melting-point metal is a metal having a melting point of 1800°C or higher. Examples of high-melting-point metals include tungsten, iridium, molybdenum, tantalum, and rhenium, with tungsten, iridium, and rhenium being more preferable. These metals may be used alone or in combination of two or more. In this case, deformation of the filament 32 can be suppressed even when heated by electrical current to a temperature at which electrons are emitted from the electron-emitting portion 31. Tungsten is preferable as a high-melting-point metal because it has a low thermal expansion coefficient and is particularly resistant to deformation when electrical current is applied.

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

[0042] <Alloy Layer> As shown in FIG. 4 , the electron source 30 preferably has an alloy layer 33 between the electron emitter 31 and the filament wire 32a, bonding the electron emitter 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 emitter 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 emitter 31 and also close to that of the filament 32. Therefore, even if the filament 32 and the electron emitter 31 are heated by electrical heating of the filament 32, and stress is applied between the filament 32 and the electron emitter 31 due to the difference in thermal expansion coefficients between the filament 32 and the electron emitter 31, the stress is alleviated by the alloy layer 33. Therefore, the occurrence of cracks in the electron emitter 31 can be suppressed. The alloy layer 33 may be a sintered body containing voids or a solid body without voids. If the alloy layer 33 is a sintered body containing 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, further suppressing the occurrence of cracks in the electron emitter 31. As a result, the temperature stability of the electron emitter 31 during heating of the electron source 30 can be further improved. Note that, when the alloy layer 33 is a sintered body containing voids, the alloy layer 33 can be formed by sintering and fixing iridium powder onto the filament 32. If the alloy layer 33 is a solid body without voids, the surface area exposed to the ambient atmosphere can be reduced, suppressing the effects of oxidation. 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 longer life.

[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 according to the present disclosure will be described with reference to FIG. 5 . FIG. 5 is a longitudinal cross-sectional view showing a portion of the second embodiment of the electron source according to the present disclosure. As shown in FIG. 5 , the electron source 130 according to the present embodiment differs from the electron source 30 according to the first embodiment in that the filament 32 further includes a plate-like member 32b attached to the filament wire 32a, and the electron emitter 31 is provided in a layer on the plate-like member 32b opposite the filament wire 32a. The plate-like member 32b is made of a metal, and is not particularly limited as long as it does not melt when heated by electrical current up to a temperature at which the electron emitter 31 emits electrons. However, a high-melting-point metal is preferable as such a metal. Specific examples of suitable materials include tungsten, iridium, molybdenum, tantalum, and rhenium. These may be used alone or in combination. The electron source 130 according to the present embodiment facilitates the realization of an electron emitter 31 with a uniform thickness. This reduces positional variations in the amount of electrons emitted from the electron emitter 31. Furthermore, since the electron emitting portion 31 has a planar shape and a large surface 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 emitting portion 31 and the metal wire 32c of the filament 32, which joins the electron emitting portion 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 Fig. 6 and Fig. 7. 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 cross-sectional view showing a part of the third embodiment of the electron source of the present disclosure.

[0047] 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 joined to the filament wire 32a so as to intersect therewith, and the electron emitter 31 is provided at the tip of the metal wire 32c (the end opposite to the base end which is the joint with the filament wire 32a). According to the electron source 230 of this embodiment, by providing the electron emitter 31 at the tip of the metal wire 32c, it becomes possible to adjust the size of the electron emitter 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 emitter 31.

[0048] As shown in Figure 7, it is preferable that the electron source 230 further includes an alloy layer 33 between the electron emitting portion 31 and the metal wire 32c of the filament 32, which joins the electron emitting portion 31 and the metal wire 32c of the filament 32 and contains an alloy of iridium and the metal that constitutes 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 filament wire 32a and the metal wire 32c have the same thermal expansion coefficient, so even if the filament 32 expands due to electrical heating of the filament 32, stress is less likely to be applied between the filament wire 32a and the metal wire 32c, making it easier to prevent the metal wire 32c from falling off the filament wire 32a.

[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, the electron emitter 31 can be made smaller, and the area from which electrons are emitted from the electron emitter 31 can be limited to a narrow range. In other words, electrons can be emitted from a very small area. This allows the electron source 230 to emit electrons that are easily focused. 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 emitter 31 is not particularly limited, and in this embodiment, it is spherical. In this embodiment, the spherical shape refers to a shape in which the electron emitter 31 is provided so as to surround the entire tip of the metal wire 32 c with an arcuate 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 emitter 31 is spherical. However, as in an electron source 330 shown in FIG. 8 , the electron emitter 31 may be formed in a film shape along the extending direction (surface shape) of the filament wire 32 a.

[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 that constitutes the filament 32.

[0055] The electron emitter 31 of the electron source 330 can be formed in the same manner as the electron emitter 31 of the electron source 30, except that the sieved alloy compound powder is not coated with resin. It is considered that not coating the alloy compound powder with resin reduces the surface tension of the powder dispersion liquid with respect to the filament wire 32a, making it easier to form the electron emitter 31 into 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 need to include the electrode 40.

[0056] Furthermore, 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 metal 3D printer, an electron microscope (SEM and TEM), or the like.

[0057] The present disclosure is outlined as follows. [1] An electron source comprising: a supporting portion made of 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 supporting portion. [2] The electron source according to [1], wherein the supporting portion has a support wire, and the electron emitting portion is provided so as to cover at least a portion of the support wire. [3] The electron source according to [1], wherein the supporting portion has a support wire and a metal wire joined to the support wire so as to intersect with the support wire, and the electron emitting 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, the alloy layer 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 electron emitting portion has a surface roughness Rz of 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, and the alloy of the electron-emitting portion is Ir ２ Ce, Ir ３ Ce, Ir ５ Ce and Ir ７ Ce ２

[10] The electron source according to [8], wherein the rare earth element is lanthanum, and the alloy of the electron emission portion is Ir ２ La, Ir ３ La, Ir ５ La, Ir ７ La ２ and Ir １７ La ２

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

[10] .

[12] A device comprising the electron gun according to

[11] .

[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.

[0059] 100...device, 11...electron gun, 30, 130, 230, 330...electron source, 31...electron emitting 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. 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.

2. The electron source according to claim 1, wherein 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.

3. An electron source according to claim 1, wherein the support portion has a support wire and a metal wire joined to the support wire so as to cross the support wire, and the electron emission portion is provided so as to cover at least a portion of the tip of the metal wire.

4. The electron source according to claim 2 or 3, wherein said electron emitting portion is spherical.

5. An electron source according to any one of claims 1 to 3, further comprising an alloy layer joining said electron emitting portion and said supporting portion, said alloy layer containing an alloy of iridium and a metal constituting said supporting portion.

6. An electron source according to any one of claims 1 to 3, wherein the surface roughness Rz of the electron emitting portion is 2 µm or less.

7. The electron source according to any one of claims 1 to 3, 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 claims 1 to 3, wherein the rare earth element of the electron emission portion is at least one element selected from the group consisting of cerium, lanthanum and praseodymium.

9. The rare earth element is cerium, and 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, and 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 an electron source according to any one of claims 1 to 3.

12. A device comprising an electron gun according to claim 11.

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