electric field radiation device

Abstract

A field radiation device capable of obtaining a predetermined withstand voltage even when the amount of input from the emitter is small is provided. As an electric field radiation device, the device comprises a vacuum container (2) having a vacuum chamber (20), an emitter (30) having an electron generating part (33) located on one side in the axial direction of the vacuum chamber (20) and facing the other side in the axial direction of the vacuum chamber (20), a target (41) located on the other side of the vacuum chamber (20) and facing the emitter (30), a guard electrode (32) which is a tubular body provided on the outer side of the emitter (30), having one side fixed to the vacuum container (2) and an opening (310) on the other side, a support body (31) that moves the emitter (30) in the axial direction inside the guard electrode (32), and a field shield (1) which is composed of a conductor connected to the guard electrode (32) and disposed on one side of the edge portion (36) of the guard electrode, wherein the field shield (1) has an axial projection surface It is formed in a shape that partially overlaps with the opening (310) on the surface and divides the opening (310) into multiple regions.

Description

Technology Field

[0001] The present invention relates to a field radiation device applicable to various devices such as X-ray devices, electron tubes, and lighting devices. Background Technology

[0002] Conventional field emission devices are applied to various devices such as X-ray devices, electron tubes, and lighting devices. A field emission device has an emitter (an electron source such as carbon) and a target positioned opposite each other at a predetermined distance in a vacuum chamber of a vacuum vessel. The field emission device emits an electron beam from the emitter by applying a voltage between the emitter and the target (field emission). Then, by colliding with the target, this electron beam produces a desired function, such as the imaging resolution achieved by the external emission of X-rays.

[0003] The emitter in the field radiation device described in Patent Document 1 discloses a configuration in which a voltage is applied to the guard electrode while the electron generating part of the emitter and the guard electrode are separated from each other by operating a support part. By this, in Patent Document 1, at least the guard electrode within the vacuum chamber can be modified, and it becomes possible to obtain a desired withstand voltage in the field radiation device. Furthermore, the field radiation device described in Patent Document 1 enables miniaturization of the field radiation device by configuring the electron generating part and the guard electrode to be separated from each other by operating a support part as described above. Prior art literature

[0004] Japanese Patent Publication No. 6135827 The problem to be solved

[0005] However, when the lengthwise dimensions of the field radiation device are shortened as a result of miniaturizing the bellows or support (support part of the emitter), the amount of emitter inserted is insufficient. Consequently, even though the emitter is inserted to the maximum extent, if a sufficient voltage is applied during the modification process of the field radiation device, electrons are emitted in excess from the emitter and the emitter is damaged. If the voltage is set low to suppress damage to the emitter, there is a risk that the modification of the field radiation device will be insufficient and the desired withstand voltage cannot be obtained.

[0006] Therefore, the present invention is made in consideration of the above situation and aims to provide a field radiation device capable of obtaining a predetermined withstand voltage even when the input amount of the emitter is small. means of solving the problem

[0007] One embodiment of the present invention is an electric field radiation device comprising: a vacuum vessel having a vacuum chamber; an emitter having an electron generating part located on one side in the axial direction of the vacuum chamber and facing the other side in the axial direction of the vacuum chamber; a target located on the other side in the vacuum chamber and facing the emitter; a tube-shaped body provided on the outer side of the emitter, having a guard electrode with one side fixed to the vacuum vessel and an opening on the other side; a support body that moves the emitter in the axial direction inside the guard electrode; and a conductor connected to the guard electrode, and an electric field shield disposed on one side of the edge portion of the guard electrode, wherein the electric field shield is disposed partially overlapping with the opening on the axial projection plane and is formed in a shape that divides the opening into a plurality of regions.

[0008] In the above-described electric field radiation device, the electric field shield may be composed of one or more linear members fixed to the edge of the opening. In the above-described electric field radiation device, the electric field shield may be formed of linear members arranged in a grid shape. In the above-described electric field radiation device, the electric field shield may be formed in a plate shape having a plurality of through holes.

[0009] In the above-described field radiation device, the field shield may divide the electron generating portion to form an edge portion when the emitter moves to the other side and comes into contact with the guard electrode. In the above-described field radiation device, at the contact portion between the emitter and the support, at least one surface of the emitter or the support may be electrically insulating.

[0010] In the above-described field radiation device, the axial height of the field shield may be formed lower than the axial height of the electron generating part. In the above-described field radiation device, the field shield may be formed integrally with the guard electrode. Effects of the invention

[0011] According to the present invention, even when the input amount of the emitter is small, a predetermined withstand voltage can be obtained. Brief explanation of the drawing

[0012] FIG. 1 is an enlarged cross-sectional view of the electric field shielding structure of an electric field radiation device according to Embodiment 1. Figure 2 is a schematic plan view of the electric field shielding structure of Figure 1. FIG. 3 is a schematic cross-sectional view of the electric field shielding structure of Embodiment 1 when the emitter is inserted. FIG. 4 is a schematic cross-sectional view of the electric field shielding structure of Embodiment 1 during emitter extrusion. FIG. 5 is a schematic cross-sectional view showing an example of an electric field radiation device of Embodiment 1. FIG. 6 is a drawing showing a test specimen assuming a case without the electric field shielding structure of Embodiment 1. FIG. 7 is a drawing showing a test specimen assuming the case where the electric field shielding structure of Embodiment 1 is present. Figure 8 is a diagram showing the results of electronic analysis using the test specimens of Figures 6 and 7. FIG. 9 is a schematic plan view of the electric field shielding structure of an electric field radiation device according to embodiment 2. FIG. 10 is a schematic plan view of the electric field shielding structure of an electric field radiation device according to embodiment 3. FIG. 11 is a schematic cross-sectional view of a conventional emitter unit. Figure 12 is a schematic plan view of the emitter unit of Figure 11. Specific details for implementing the invention

[0013] Hereinafter, suitable embodiments of the present invention will be described using the embodiments and drawings with reference to the attached drawings. In addition, in each drawing, the same reference numerals are used for identical members or elements, and redundant descriptions are omitted or simplified.

[0014] [Embodiment 1]

[0015] FIG. 1 is an enlarged cross-sectional view of a field shielding structure of a field radiation device (10) according to embodiment 1. FIG. 2 is a schematic plan view of the field shielding structure of embodiment 1 shown in FIG. 1. FIG. 5 is also a schematic cross-sectional view showing an example of the field radiation device (10) of embodiment 1. The field shielding structure of one embodiment of the present invention shown in FIG. 1 and FIG. 2, etc. is applied to a field radiation device (10) including, for example, an X-ray device, an electron tube, a lighting device, etc.

[0016] Hereinafter, the field radiation device (10) of Embodiment 1 will be described with reference to the field radiation device (10) shown in FIG. 5. The field radiation device (10) in Embodiment 1 comprises a vacuum vessel (2), an emitter unit (3), and a target unit (4). In addition, the emitter unit (3) side shown in FIG. 5 is designated as the one side, and the target unit (4) side is designated as the other side. Furthermore, the direction from the one side to the other side is designated as the axial direction. In addition, the direction perpendicular (intersecting) to the axial direction is designated as the radial direction (transverse direction).

[0017] (Vacuum container (2))

[0018] The vacuum vessel (2) has a tube-shaped insulator (21) that extends in the axial direction. The insulator (21) insulates the emitter unit (3) and the target unit (4) from each other and forms a vacuum chamber (20) inside the vacuum vessel (2) (inner wall side). Additionally, the insulator (21) may be formed from an insulating material, such as ceramic, and may be capable of insulating the emitter unit (3) and the target unit (4) from each other and forming a vacuum chamber (20) inside as described above. The vacuum vessel (2) includes a cylindrical insulating member (21a) and an insulating member (21b) arranged in series. Additionally, the vacuum vessel (2) may be constructed by joining the two insulating members (21a, 21b) together by soldering, etc., with a grid electrode (22) interposed between them.

[0019] A grid electrode (22) extending in the diameter direction of the vacuum chamber (20) is provided between the emitter unit (3) and the target unit (4). The grid electrode (22) can be of various shapes as long as it is configured to interpose between the emitter unit (3) and the target unit (4) and to appropriately control the electron beam (L1) passing through the grid electrode (22). The grid electrode (22) is provided, for example, with an electrode portion (24) and an extraction terminal (25). The electrode portion (24) is, for example, a mesh-shaped electrode and extends in the diameter direction of the vacuum chamber (20). A passage hole (23) through which the electron beam (L1) passes is formed in the electrode portion (24). Additionally, the extraction terminal (25) penetrates the insulator (21) in the diameter direction and is connected to the electrode portion (24).

[0020] (Emitter unit (3))

[0021] The emitter unit (3) comprises an emitter (30), an emitter support (support body) (31), and a guard electrode (32).

[0022] The emitter (30) is provided with an electron generating part (33) at a position (region) axially opposite to the target (41) of the target unit (4). The electron generating part (33) generates electrons by applying voltage and emits an electron beam (L1). Furthermore, as shown in FIG. 5, the electron generating part (33) can be applied in various forms as long as it is capable of emitting an electron beam (L1) (radiator). For example, the electron generating part (33) may utilize materials formed by carbon nanotubes or carbon fibers. Additionally, for example, the electron generating part (33) may be composed of an emitter (30) formed by molding a material such as carbon into a bulk shape or depositing it in a thin film shape. Furthermore, in the electron generating part (33), it is preferable to make the surface on the side facing the target (41) of the target unit (4) concave or curved to facilitate the convergence of the electron beam (L1).

[0023] The emitter support (31) is movable (operable) in the axial direction on the inner side of the guard electrode (32) and supports the emitter (30) with the electron generating part (33) facing the target (41). For example, the base side of the emitter (30) (opposite side of the electron generating part (33)) is joined to the emitter support (31) by soldering or the like.

[0024] An operating unit (35) that operates the emitter support (31) via a bellows (34) that can be extended and retracted in the axial direction is connected (mounted) to the emitter support (31). By operating the operating unit (35), the bellows (34) is extended and retracted, and as a result, the emitter support (31) moves in the axial direction, and the emitter (30) also moves in conjunction with the emitter support (31) in the same direction. In addition, in Embodiment 1, the operating unit (35) is formed integrally with the emitter support (31) in a shape that partially extends from the opposite side of the emitter (30), but it is not limited to this and may be configured to be separate and detachable. In addition, at the contact portion between the emitter support (31) and the emitter (30), at least one surface of the emitter (30) or the emitter support (31) may be electrically insulating. For example, when the electron generating part (33) is formed with carbon nanotubes, the base side of the emitter (30) is formed with an insulator, thereby allowing the carbon nanotubes to be grown efficiently with the insulator as the base.

[0025] By appropriately manipulating the emitter support (31), the distance between the electron generating part (33) of the emitter (30) and the target (41) can be changed. For example, as shown in FIG. 1, if the electron generating part (33) is in a non-discharge position separated from the guard electrode (32) and the field radiation is suppressed, a desired modification treatment can be performed on the guard electrode (32), target (41), grid electrode (22), etc. As a modification treatment, for example, the surface of the guard electrode (32) can be melted and smoothed. In addition, the field radiation device (10) equipped with, for example, a manipulator (35) is easy to miniaturize compared to a conventional field radiation device equipped with a large-diameter exhaust pipe, and it is possible to reduce the number of manufacturing processes and product costs.

[0026] Here, the modification treatment of the guard electrode (32) of the field radiation device (10) is described below. First, the operating part (35) of the emitter support part (31) is operated to move the emitter (30) toward one side in the axial direction (the emitter unit (3) side, right side of FIG. 5). By doing so, the emitter (30) moves to a non-discharge position separated from the guard electrode (32), and the field radiation of the electron generating part (33) is suppressed. At this time, both the electron generating part (33) of the emitter (30) and the edge part (36) of the guard electrode (32) are in a non-contact state with each other. In this state, by applying a desired voltage appropriately between, for example, the guard electrode (32) and the grid electrode (22), discharge is repeated at the guard electrode (32), and the guard electrode (32) is modified.

[0027] After the modification process described above, the operating part (35) of the emitter support part (31) is operated again to move the emitter (30) from the non-discharge position toward the other side in the axial direction (target unit (4) side, left side in FIG. 5) and bring it into contact with the guard electrode (32) to a discharge position where field radiation of the electron generating part (33) is possible. At the discharge position, the electron generating part (33) of the emitter (30) and the edge part (36) of the guard electrode (32) are in contact with each other (for example, by the vacuum pressure of the vacuum container (2)) as shown in FIG. 4 or FIG. 5. At the discharge position, the electron generating part (33) of the emitter (30) and the guard electrode (32) are at the same potential. At the discharge position, if a desired voltage is applied between the emitter (30) and the target (41), for example, electrons are generated from the electron generating part (33) of the emitter (30) and an electron beam (L1) is emitted. The surface of the guard electrode (32) is modified by emitting electron beams (L1) from protrusions present on the surface of the guard electrode (32), thereby heating and melting the protrusions and smoothing them.

[0028] By the modification treatment described above, events such as flashover (generation of electrons) from the guard electrode (32) in the field radiation device (10) can be suppressed, and the amount of electron generation in the field radiation device (10) can be stabilized. In addition, the electron beam (L1) can be made into a converging electron flux, and the focus of the X-ray (L2) also becomes easier to converge, making it possible to obtain high projection resolution.

[0029] In addition, the emitter support (31) can be applied in various forms as long as it is capable of supporting the emitter (30) movably in the axial direction as described above. In addition, the emitter support (31) can be constructed using various materials and is not particularly limited, but for example, conductive metal materials such as stainless steel (SUS material, etc.), copper, or silver can be used.

[0030] As the bellows (34) can be extended axially as described above, various shapes can be applied, and, for example, a molded product made by appropriately processing a thin sheet metal material can be used. Additionally, the bellows (34) may be configured in a corrugated box shape that extends axially to surround the outer periphery of the emitter support (31) or the operating part (35), for example.

[0031] The guard electrode (32) is positioned facing the target (41) on one side of the vacuum chamber (20). The guard electrode (32) is a tubular electrode (tubular body) made of a metal material such as stainless steel (SUS material, etc.) and is positioned on the outer side of the electron generating part (33) of the emitter (30). Additionally, the guard electrode (32) has a flange-shaped edge portion (36) that extends toward the inner circumference. Furthermore, the guard electrode (32) has an opening (310) on the inner side of the flange-shaped edge portion (36). Additionally, the guard electrode (32) has a first receiving part (37) and a second receiving part (38) communicating with it. The first receiving part (37) accommodates the emitter (30) and the emitter support part (31). The second receiving portion (38) is located on one side of the first receiving portion (37) and accommodates the bellows (34) and the operating portion (35). Additionally, this second receiving portion (38) is fixed to the edge portion of the insulating member (21b) of the vacuum container (2) via the flange portion (39).

[0032] In addition, the guard electrode (32) is provided with an electric field shield (1) placed in the opening (310) of the edge portion (36). The electric field shield (1) in Embodiment 1 is formed of a conductor and functions to suppress electron emission from the emitter (30) by weakening the electric field applied to the emitter (30) when a high voltage is applied between the guard electrode (32) and the target (41) for modification treatment.

[0033] The electric field shield (1) is connected to the guard electrode (32) and is at the same potential as the guard electrode (32). Additionally, as shown in FIG. 2, the electric field shield (1) is positioned to partially overlap the opening (310) of the guard electrode (32) on an axial projection plane and is composed of a linear member, such as a wire or a wire. Furthermore, the electric field shield (1) is formed in a shape that divides the opening (310) of the guard electrode (32) in the radial direction.

[0034] By dividing the opening (310) in the radial direction, the opening (310) can be divided into multiple regions. Additionally, the electric field shield (1) may be made of a conductive metal material, for example, iron, stainless steel (SUS material, etc.), copper, silver, etc., but is not limited to this and various materials can be applied. It is preferable for the guard electrode (32) and the electric field shield (1) to match in material, but different conductive metal materials may be used. In Embodiment 1, the electric field shield (1) is made into one, and the opening (310) of the guard electrode (32) is divided into two regions. However, it is not limited to this, and one or more electric field shields (1) may be fixed to the opening (310) of the guard electrode (32) to divide the opening (310) into two or more regions.

[0035] In addition, the electric field shield (1) is not limited to conventional materials such as wires or strands, and a conductive metal material processed into a cross-sectional shape such as a cylinder, ellipse, flat shape, or approximately a rectangle shape may be used as the electric field shield (1). In this case, the electric field shield (1) is formed from a conductive metal material, similar to a wire or strand.

[0036] The electric field shield (1) is fixed (connected) to the edge (opening edge portion) of the opening (310) of the guard electrode (32). As shown in FIGS. 1 and 3, the electric field shield (1) is positioned on one side (emitter (30) side, lower side in FIGS. 1 and 3) of the edge portion (36) of the guard electrode (32). In Embodiment 1, as shown in FIG. 2, the electric field shield (1) is fixed in a state where one end of the electric field shield (1) is in contact with the opening edge portion, and the other end of the electric field shield (1) is fixed in a state where it is in contact with the opening edge portion located opposite to the one end of the electric field shield (1). By doing so, the opening (310) of the guard electrode (32) is divided in the radial direction by the electric field shield (1), and the area of ​​the opening (310) is divided into two. The method of fixing the electric field shield (1) to the opening edge of the guard electrode (32) can be any fixing method that prevents the electric field shield (1) from falling off. For example, the electric field shield (1) and the guard electrode (32) may be mechanically connected or joined, fixed by caulking or welding, or fixed by welding.

[0037] When fixing the electric field shield (1) to the opening edge portion at one end and the other end, if a wire or similar material is used, it is preferable to fix it with a predetermined tension. If the electric field shield (1) is fixed in a loose state, when it comes into contact with the electron generating portion (33) described later, the electron generating portion (33) cannot be pushed evenly, and the formation of the edge portion (33a) becomes insufficient, which may result in insufficient improvement of electron emission from the emitter (30). Additionally, although the electric field shield (1) is fixed to the opening edge portion of the guard electrode (32) as described above, the electric field shield (1) and the guard electrode (32) may be formed as a single unit.

[0038] (Target unit (4))

[0039] The target unit (4) is provided with a target (41) and a flange portion (42), as shown in FIG. 5. The target (41) is positioned on the other side of the vacuum chamber (20) opposite the electron generating portion (33) of the emitter (30).

[0040] The target (41) has an inclined surface (40) formed at a predetermined angle with respect to the axial direction on a portion facing the electron generating part (33) of the emitter (30). Then, X-rays (L2) are emitted by the electron beam (L1) colliding with this inclined surface (40). The X-rays (L2) are irradiated in a direction bent from the direction of irradiation of the electron beam (L1) (for example, the direction of the cross-section of the vacuum chamber (20) shown in FIG. 5). In addition, the target (41) can be applied in various shapes as long as it is capable of emitting X-rays (L2) when the electron beam (L1) emitted from the electron generating part (33) of the emitter (30) collides with it. The flange portion (42) is fixed to the edge portion of the insulating member (21a) of the vacuum vessel (2) as shown in FIG. 5.

[0041] (Effects of the operation of the present embodiment)

[0042] As described above, in the field radiation device (10) of embodiment 1, voltage is applied to the guard electrode (32) while the electron generating part (33) and the guard electrode (32) are separated from each other by operating the emitter support part (31) by the operating part (35). By doing so, at least the guard electrode (32) in the vacuum chamber (20) can be modified, and a desired withstand voltage is obtained in the field radiation device (10).

[0043] Here, as described above, if the electron generating unit (33) and the guard electrode (32) are configured to be separated from each other by the operation of the emitter support unit (31) by the operating unit (35), the field radiation device (10) can be miniaturized. In miniaturizing, it is possible to shorten the axial (length direction) dimensions of the field radiation device (10) and shorten the bellows (34) or the emitter support unit (31). However, as a result of shortening the bellows (34) or the emitter support unit (31), there is a possibility that the amount of input from the emitter (30) will be insufficient. Even if the amount of input from the emitter (30) is insufficient and the emitter (30) is fully input, if sufficient voltage is applied to the modification process of the field radiation device (10), electrons are emitted in excess from the emitter (30) and the emitter (30) is damaged. If the voltage is set low to suppress damage to the emitter (30), the modification of the field radiation device (10) is insufficient and there is a concern that the desired withstand voltage cannot be obtained.

[0044] Regarding this, as shown in FIG. 1 or FIG. 2, according to the electric field shielding structure in which an electric field shield (1) is placed in the opening (310) of the guard electrode (32), the electric field on the emitter surface is mitigated and electron emission from the emitter (30) is prevented. Therefore, in order to miniaturize the electric field radiation device (10), the axial dimensions of the electric field radiation device (10) are shortened, and even if the amount of input from the emitter (30) is reduced, it becomes possible to shield the electric field on the emitter surface. Below, the electric field shielding structure in Embodiment 1 will be explained with reference to FIG. 3 and FIG. 4.

[0045] FIG. 3 is a schematic cross-sectional view of the emitter (30) of the electric field shielding structure of Embodiment 1 at the insertion (non-discharge position). FIG. 4 is a schematic cross-sectional view of the emitter (30) of the electric field shielding structure of Embodiment 1 at the extrusion (discharge position).

[0046] As shown in FIG. 3, the electric field shield (1) is preferably fixed at approximately the center of the opening (310) of the guard electrode (32) (on the line passing through the radial center point of the opening (310)), but the position of fixation may be arbitrary. Additionally, as described above, the electric field shield (1) is positioned on one side (emitter (30) side, lower side in FIG. 3) of the edge portion (36) of the guard electrode (32). Specifically, as shown in FIG. 3, the electric field shield (1) is preferably fixed to the edge portion of the opening of the guard electrode (32) such that the side (36b) facing one side of the edge portion (36) is more prominent than the side (36a) facing the other side (upper side in FIG. 3) of the edge portion (36) of the guard electrode (32). Additionally, h1 represents the height (length) of the electric field shield (1) in the axial direction, and h2 represents the height of the electron generating part (33) in the axial direction. Also, if a wire or a wire with a round cross-sectional shape is used in the electric field shield (1), h1 is the diameter.

[0047] When the emitter (30) is extruded, as shown in FIG. 4, a part of the electron generating part (33) comes into contact with the side (36b) facing one side (lower side in FIG. 4) of the edge part (36) of the guard electrode (32), and the corresponding contact point of the electron generating part (33) is pushed. At this time, the electron generating part (33) also comes into contact with the electric field shield (1), and the contact point of the electron generating part (33) that is in contact with the electric field shield (1) is also pushed. When pushed by the electric field shield (1), a part of the electron generating part (33) is divided, and an edge part (33a) is formed in the electron generating part (33). By forming an edge portion (33a) in the electron generating portion (33), when the electron generating portion (33) generates electrons by applying voltage and emits an electron beam (L1), it becomes possible to improve the electron emission efficiency by the electric field concentration of the edge portion (33a).

[0048] In addition, in Embodiment 1, it is preferable to make the height (h1) of the electric field shield (1) lower (smaller) than the height (h2) of the electron generating part (33). That is, the heights of the electric field shield (1) and the electron generating part (33) are set so that h2 > h1. Here, for each height, as shown in FIG. 4, it is preferable to set each height so that when the emitter (30) is extruded, a part of the electric field shield (1) does not protrude beyond one end (edge ​​part (33a) side) of the electron generating part (33) (so that the electric field shield (1) is buried in the electron generating part (33)). As described above, in Embodiment 1, h2 > h1, and also, when the emitter (30) is pressed in, the heights of h1 and h2 are set so that the electric field shield (1) is hidden (buried) inside the electron generating part (33). By this, it becomes possible to avoid the influence on the emitted electron orbits given by the electric field shielding structure equipped with the electric field shield (1).

[0049] Below, the effect of the electric field shielding structure in Embodiment 1 will be explained with reference to FIGS. 6, 7, 8, 11, and 12. In order to verify the effect of the electric field shielding structure in Embodiment 1, an electronic analysis was performed by assuming the analysis surface (X) in the experimental model (test specimen) (5) shown in FIGS. 6 and 7 to be an electron emission part.

[0050] FIG. 6 is a drawing showing a test model assuming the case without the electric field shielding structure of Embodiment 1. FIG. 7 is a drawing showing a test model assuming the case with the electric field shielding structure of Embodiment 1. FIG. 8 is a drawing showing the results of an electronic analysis performed by the test model (5) shown in FIG. 6 and FIG. 7. The vertical axis of FIG. 8 represents the electric field strength E (V / m), and the horizontal axis of FIG. 8 represents the horizontal position (mm) of the analysis plane (X). In addition, in FIG. 8, "without shield" represents the analysis results from the test model (5) of FIG. 6, and "with shield" represents the analysis results from the test model (5) of FIG. 7.

[0051] FIG. 11 is a schematic cross-sectional view of the area around the opening of the guard electrode of a conventional emitter unit. FIG. 12 is a schematic plan view of the area around the opening of the guard electrode of the emitter unit of FIG. 11. The test model (5) of FIG. 6 is modeled after the area around the opening of the guard electrode of the emitter unit shown in FIG. 11 and FIG. 12. And the test model (5) of FIG. 7 is modeled after the area around the opening (310) of the guard electrode (32) of the emitter unit (3) of embodiment 1 shown in FIG. 1, FIG. 2, etc.

[0052] In the electronic analysis using the test model (5) of FIGS. 6 and FIGS. 7 described above, the electric field strength of the analysis surface is analyzed when 5 kV is applied in a vacuum between the anode (51) and the cathode (52), which are spaced 2 mm apart by a spacer (53). In addition, the opening (54) is modeled after the opening (310) of the guard electrode (32). In addition, in the test model (5) of FIG. 7, the electric field shield (50) is arranged as a conductor modeled after the electric field shield (1) of Embodiment 1, and the electric field shield structure is the same as Embodiment 1. In addition, the analysis surface (X) is positioned at a location 4 mm indented from the cathode surface (a location 4 mm lower from the cathode surface) as a simulation of the insertion of the emitter (30). Under the aforementioned conditions, the results of the analysis of electric field strength under the same conditions in each test model (5) are described below.

[0053] In the analysis results of the test model (5) of FIG. 7, which has an electric field shielding structure similar to Embodiment 1, the electric field strength near the center of the X-plane, where the electric field strength is strongest, is less than 1 / 3 compared to the analysis results when there is no electric field shielding structure. Therefore, the electric field shielding effect of the electric field shielding structure of Embodiment 1 can be confirmed.

[0054] As described above, by using the electric field shielding structure of Embodiment 1 in the electric field radiation device, the electric field applied to the emitter (30) during the modification process is weakened, thereby suppressing damage to the emitter (30) caused by electron emission from the emitter (30). By doing so, even if the desired amount of input to the emitter (30) is not achieved (the amount of input to the emitter (30) is reduced), it is possible to shield the electric field on the emitter surface, and a predetermined withstand voltage can be obtained by applying a sufficiently high voltage between the target (41) and the guard electrode (32) to perform the modification process.

[0055] [Embodiment 2]

[0056] FIG. 9 is a schematic plan view of the electric field shielding structure in the electric field radiation device (10) of Embodiment 2. In Embodiment 2, the configuration is the same as that of the electric field radiation device (10) of Embodiment 1, except that the electric field shield (1) is formed of wires or strands arranged in a grid shape (mesh shape). Therefore, detailed descriptions of the similarities are appropriately omitted.

[0057] In Embodiment 2, the electric field shield (1) is formed by weaving a linear member, such as a wire or a wire, as a conductor at predetermined intervals to form a grid shape. Any method of forming the electric field shield (1) is acceptable as long as the electric field shield (1) is woven in a grid shape. Additionally, the predetermined intervals may be any intervals, and for example, each wire or wire may be woven at equal or uneven intervals. Furthermore, when using wires and wires separately, they may be combined and woven in a grid shape. In this way, by making the electric field shield (1) into a grid shape, the strength (physical strength) of the electric field shield (1) constituting the electric field shield structure can be improved.

[0058] In addition, the diameter, number, and positional spacing of the wires or strands used to form the grid shape of the electric field shield (1) of embodiment 2 can be arbitrarily configured. By doing so, the electric field shield (1) can be formed according to the required output of the electric field radiation device (10).

[0059] Additionally, when fixing the electric field shield (1) of Embodiment 2 to the opening edge of the guard electrode (32), it may be configured to be detachable. In this case, multiple electric field shields (1) with different diameters, numbers, and positional spacings of the wires or strands used to form a grid shape may be prepared, and the electric field shields (1) may be exchanged according to the required output of the electric field radiation device (10). By doing so, it becomes possible to control the output of the electric field radiation device (10). Furthermore, the material of the electric field shield (1) in Embodiment 2 and the method of fixing it to the opening edge of the guard electrode (32) are the same as in Embodiment 1.

[0060] In addition, since the electric field shield (1) of Embodiment 2 is in the shape of a grid, the edge portion (33a) formed by pushing the electron generating part (33) by the introduction of the emitter (30) is formed more than in Embodiment 1. Therefore, when the electron generating part (33) generates electrons by applying voltage and emits an electron beam (L1), the electron emission efficiency can be improved compared to Embodiment 1 by the concentration of the electric field at the edge portion (33a).

[0061] As described above, by configuring the electric field shield (1) in a grid shape, in addition to the effect of Embodiment 1, the strength of the electric field shield (1) is increased, and the electron emission efficiency can be improved compared to Embodiment 1 by the concentration of the electric field of the multiple edge portions (33a).

[0062] [Embodiment 3]

[0063] FIG. 10 is a schematic plan view of the electric field shielding structure in the electric field radiation device (10) of Embodiment 3. In Embodiment 3, except that the electric field shield (1) is formed in a plate shape having a plurality of through holes, the configuration is the same as that of the electric field radiation device (10) of Embodiment 1; therefore, detailed descriptions of the similar points are appropriately omitted.

[0064] In Embodiment 3, the electric field shield (1) uses a conductor plate formed in the shape of a flat plate. In addition, a plurality of through holes are formed in the conductor plate in Embodiment 3. Furthermore, in addition to the conductor plate, a conductor foil may be used as the electric field shield (1) in Embodiment 3. By using the electric field shield (1) in the shape of a flat plate in this way, when the electric field shield (1) pushes against the electron generating unit (33) due to the introduction of the emitter (30), the emitter surface electric field becomes more uniform than in Embodiment 1. As the emitter surface electric field becomes uniform, the electron emission generated from the electron generating unit (33) becomes more stable than in Embodiment 1. That is, it becomes possible to reduce the deviation in the output of the electron generating unit (33).

[0065] In addition, since the electric field shield (1) in embodiment 3 has a plurality of through holes, the formed edge portion (33a) is formed more than in embodiment 1. Therefore, when the electron generating unit (33) generates electrons by applying voltage and emits an electron beam (L1), the electron emission efficiency can be improved compared to embodiment 1 by the concentration of the electric field in the edge portion (33a).

[0066] In addition, the multiple through holes in the electric field shield (1) of Embodiment 3 can be formed at arbitrary intervals, for example, at equal intervals or at uneven intervals. Also, the diameter of the through holes in the electric field shield (1) can be arbitrarily determined. For example, the diameter of each hole can be the same, or the diameter of each hole can be different. Also, although the shape of the through holes in the electric field shield (1) is round in Embodiment 3, it is not limited to this; the shape of the through holes can be approximately rectangular or polygonal. Furthermore, the number of through holes is determined by the size of the opening (310) of the guard electrode (32) and the diameter of the through holes. That is, the number of through holes in the electric field shield (1) can also be arbitrarily determined.

[0067] In this way, the diameter, spacing, shape, and number of through holes of the electric field shield (1) can be configured arbitrarily. By doing so, the electric field shield (1) can be formed according to the required output of the electric field radiation device (10). Additionally, when fixing the electric field shield (1) of Embodiment 3 to the opening edge of the guard electrode (32), it may be configured to be detachable. In this case, a plurality of electric field shields (1) with different diameters, spacing, shapes, and numbers of through holes, respectively or partially, can be prepared, and the electric field shield (1) can be exchanged according to the required output of the electric field radiation device (10). By doing so, it becomes possible to control the output of the electric field radiation device (10).

[0068] In addition, the outer circumference of the electric field shield (1) of Embodiment 3 is formed to be smaller than the outer circumference (outer diameter) of the opening (310) of the guard electrode (32). By doing so, it becomes possible to insert the electric field shield (1) into the inner side of the opening (310) of the guard electrode (32) and to fix the electric field shield (1) to the edge portion of the opening of the guard electrode (32) so that it is closer to the side facing one side (36b) than to the side facing the other side (36a) of the edge portion (36) of the guard electrode (32). In addition, the material of the electric field shield (1) in Embodiment 3 and the method of fixing to the edge portion of the opening of the guard electrode (32) are the same as in Embodiment 1.

[0069] As described above, by configuring the electric field shield (1) in a plate shape to form a plurality of through holes, the strength of the electric field shield (1) is increased in addition to the effect of Embodiment 1, and the electric field on the emitter surface becomes uniform, thereby reducing the deviation in the output of the electron generating part (33). In addition, the electron emission efficiency can be improved compared to Embodiment 1 by concentrating the electric field of the plurality of edge parts (33a).

[0070] Although preferred embodiments of the present invention have been described above, various improvements and design changes may be made to the present invention without departing from the spirit of the invention.

[0071] This application claims priority based on Japanese patent application No. 2021-187431 filed on November 17, 2021, and incorporates all contents described in said Japanese patent application. Explanation of the symbols

[0072] 1 : Electric field shield 30 : Emitter 31: Emitter support 32: Guard electrode 33: Electron generating part 36: Edge part 36a: The surface of the edge facing the other side 36b: The surface facing one side of the edge 310 : Opening

Claims

Claim 1 A vacuum vessel having a vacuum chamber; an emitter having an electron generating part located on one side in the axial direction of the vacuum chamber and facing the other side in the axial direction of the vacuum chamber; a target located on the other side in the vacuum chamber and facing the emitter; a cylindrical body provided on the outer periphery of the emitter, wherein the one side is fixed to the vacuum vessel and the guard electrode has an opening on the inner side of the edge portion of the other side; a support member that moves the emitter in the axial direction from the inner side of the guard electrode; and a conductor connected to the guard electrode, and an electric field shield disposed on one side of the opening on the edge portion of the guard electrode, wherein the electric field shield is disposed to partially overlap with the opening on the axial projection plane, and when the emitter is extruded to the other side in the axial direction by the support member, the opening is divided into a plurality of regions to form an edge portion on the electron generating part by pushing the electron generating part. Electric field radiation device. Claim 2 An electric field radiation device according to claim 1, characterized in that the electric field shield is composed of one or more linear members fixed to the edge portion of the opening. Claim 3 An electric field radiation device according to claim 2, wherein the electric field shield is formed of the linear members arranged in a grid shape. Claim 4 An electric field radiation device according to claim 1, wherein the electric field shield is formed in a plate shape having a plurality of through holes. Claim 5 An electric field radiation device according to any one of claims 1 to 4, characterized in that at least one surface of the emitter or the support is electrically insulating at the contact portion between the emitter and the support. Claim 6 An electric field radiation device according to any one of claims 1 to 4, characterized in that the axial height of the electric field shield is formed lower than the axial height of the electron generating part. Claim 7 An electric field radiation device according to any one of claims 1 to 4, wherein the electric field shield is formed integrally with the guard electrode. Claim 8 delete

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