Field emission x-ray generator

Abstract

The present invention relates to a field emission X-ray generator. The field emission X-ray generator comprises: a tube-shaped insulating housing; an anode electrode arranged on one side of the insulating housing and having a target; a cathode electrode arranged on the other side of the insulating housing and having an electron emission source; a gate electrode arranged between the anode electrode and the cathode electrode; and an anode hood coupled to the anode electrode to surround the target and having a first hole through which electrons emitted from the electron emission source pass and a second hole through which X-rays generated from the target pass, wherein the outer surface of the anode hood may be arranged in a straight line with the outer surface of the anode electrode.

Description

Field emission X-ray generator

[0001] The present invention relates to a field emission X-ray generator. More specifically, it relates to a field emission X-ray generator that emits X-rays by colliding electrons emitted from an electron emission source on the cathode electrode side with a target on the anode electrode side.

[0002] The present invention was derived from the research project “Development of Intelligent Carry-on Baggage Security Screening Technology” conducted with support from the Ministry of Land, Infrastructure and Transport’s Land, Infrastructure and Transport Science and Technology Promotion Agency [Project Unique Number: 1615013162, Subproject Number: KA162822].

[0003] Conventional X-ray source devices use a tungsten hot cathode as an electron emitter to generate X-rays, and are structured to heat a tungsten filament with high voltage to emit electrons and collide the emitted electrons with a target on the anode electrode side to generate X-rays.

[0004] However, tungsten filament-based hot cathode X-ray source devices have high heat loss, consume a lot of power to generate electrons, and have extremely low X-ray emission efficiency because the generated electrons are randomly emitted from the tungsten surface, which has a spiral structure. In addition, a certain time interval is required for heating and cooling the tungsten filament, and it is difficult to emit X-rays in a pulse form, which has limited their use.

[0005] To solve the problems of the conventional hot cathode X-ray source, research on field emission X-ray generators using nanostructures such as carbon nanotubes (CNTs) as cold cathode electron emitters has been actively conducted recently. Unlike the conventional tungsten filament-based hot cathode X-ray source, the field emission X-ray generator uses an electric field emission mechanism for its electron emission.

[0006] Field emission X-ray generators have lower power consumption than tungsten filament-based hot cathode X-ray sources, and because the emitted electrons are emitted along the longitudinal direction of nanostructures such as carbon nanotubes, the electrons have excellent directional directionality toward the target on the anode electrode side, resulting in very high X-ray emission efficiency. In addition, it is easy to emit X-rays in pulse form through electric field control.

[0007] The conventional field emission X-ray generator (9) illustrated in FIG. 1 may include a housing (91) made of an insulating material, an anode electrode (92) covering one side of the housing (91), a cathode electrode (93) covering the other side of the housing (91), and a gate electrode (94) arranged at a predetermined distance from the cathode electrode (93) on one side of the cathode electrode (93).

[0008] A conventional field emission X-ray source is configured to have an electron emitter installed on a cathode electrode and a gate electrode installed adjacent thereto within an insulating housing, and to emit electrons from the electron emitter by an electric field formed between the gate electrode and the cathode electrode.

[0009] The gate electrode has a mesh shape or a metal plate shape with a plurality of holes arranged according to the arrangement of the electron emitter. When an electron beam emitted from the electron emitter passes through this mesh structure or a plurality of holes, the electrons are accelerated by the potential difference of tens to hundreds of kV formed between the anode electrode and the cathode electrode, and the electrons are struck by the X-ray target installed on the anode electrode side to emit X-rays. Meanwhile, one or more focusing electrodes may be added between the anode electrode (92) and the gate electrode (94) so ​​that the electron beam is focused onto one area of ​​the anode electrode. In order to operate the field emission X-ray generator, a positive gate voltage of tens to hundreds of kV difference is applied to the gate electrode based on the potential of the cathode electrode, and a positive acceleration voltage of tens to hundreds of kV difference is applied to the anode electrode. At this time, a voltage is applied to the focusing electrode to focus the electron beam, and the voltage applied to the focusing electrode can be changed depending on the operating conditions.

[0010] In a field emission X-ray generator having such a structure, a high potential difference is applied to the anode electrode (92), the cathode electrode (93), and the gate electrode (94), so insulation is important. In the case of a field emission X-ray generator such as this, a predetermined insulation distance is secured, but the gate electrode (94) formed of a conductive material is vulnerable to high voltage, so there is a risk of insulation breakdown, and near the target provided on the anode electrode, the insulating housing may be damaged or its durability may be reduced due to high voltage. In addition, there is a risk that the gate electrode (94) may be exposed to the outside between the anode electrode (92) and the cathode electrode (93), so the insulation performance may be reduced.

[0011] In addition, in the case of conventional field emission X-ray generators, some of the electrons that collide with the target and some of the X-rays emitted from the target may be backscattered in an undesirable direction. If these scattered electrons accumulate on the gate electrode, they may cause a change in the cathode-gate voltage, which reduces the performance of the field emission X-ray generator. If they accumulate on the housing, etc., they may cause arcing. In addition, the scattered X-rays may deteriorate image quality and cause unnecessary radiation exposure.

[0012] Accordingly, a field emission X-ray generator is required that can increase the insulation distance between the gate electrode and the anode electrode compared to a conventional field emission X-ray generator, is easy to manufacture, minimizes exposure of the cathode electrode, and prevents scattering of electrons and X-rays from the target.

[0013] The technology underlying this application is disclosed in Korean Patent Publication No. 10-2095268.

[0014] The present invention is intended to solve the problems of the above-mentioned prior art and to provide a field emission X-ray generating device capable of preventing electron and X-ray scattering from a target, including an anode hood.

[0015] The present invention is intended to solve the problems of the prior art described above, and to provide a field emission X-ray generator that increases the insulation distance between the gate electrode and the anode electrode compared to a conventional field emission X-ray generator.

[0016] The present invention is intended to solve the problems of the above-mentioned prior art, and to provide a field emission X-ray generator in which the cathode electrode and the gate electrode are modularized, thereby facilitating manufacturing.

[0017] The present invention is intended to solve the problems of the prior art described above, and to provide a field emission X-ray generator that minimizes the exposure of the cathode electrode to the outside of the insulating housing.

[0018] However, the technical tasks to be achieved by the embodiments of the present invention are not limited to the technical tasks described above, and other technical tasks may exist.

[0019] As a technical means for achieving the above-described technical task, a field emission X-ray generating device according to one embodiment of the present invention includes a tube-shaped insulating housing, an anode electrode provided with a target and disposed on one side of the insulating housing, a cathode electrode provided with an electron emission source and disposed on the other side of the insulating housing, a gate electrode provided between the anode electrode and the cathode electrode, and an anode hood coupled to the anode electrode and surrounding the target, the anode hood having a first hole through which electrons emitted from the electron emission source pass and a second hole through which X-rays generated from the target pass, wherein the anode hood may be provided such that an outer surface thereof is arranged in a straight line with an outer surface of the anode electrode.

[0020] The above-described problem-solving methods are merely exemplary and should not be construed as limiting the present invention. In addition to the exemplary embodiments described above, additional embodiments may be included in the drawings and detailed description of the invention.

[0021] According to the above-described means for solving the problem of the present invention, a field emission X-ray generating device capable of preventing electron and X-ray scattering from a target, including an anode hood, can be provided.

[0022] According to the above-described means for solving the problem of the present invention, the insulation distance between the gate electrode and the anode electrode can be increased compared to a conventional field emission X-ray generator.

[0023] According to the above-described means for solving the problem of the present invention, a field emission X-ray generating device can be provided in which the cathode electrode and the gate electrode are modularized and thus easy to manufacture.

[0024] According to the aforementioned means for solving the problem of the present invention, the effect of minimizing the exposure of the cathode electrode to the outside of the insulating housing can be achieved.

[0025] However, the effects that can be obtained from this center are not limited to the effects described above, and other effects may exist.

[0026] Figure 1 is a schematic perspective view of a conventional field emission X-ray generator.

[0027] Figure 2 is a schematic perspective view of a field emission X-ray generating device according to one embodiment of the present invention.

[0028] Figure 3 is a schematic cross-sectional view of a field emission X-ray generating device according to one embodiment of the present invention.

[0029] Figure 4 is a schematic enlarged view of the anode hood portion of a field emission X-ray generator according to one embodiment of the present invention.

[0030] FIG. 5 is a schematic enlarged view of the lower part of a field emission X-ray generator according to one embodiment of the present invention.

[0031] FIG. 6 is a schematic plan view of the lower portion of a field emission X-ray generator according to one embodiment of the present invention.

[0032] Below, with reference to the attached drawings, embodiments of the present invention are described in detail to facilitate easy implementation by those skilled in the art. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, irrelevant parts have been omitted for clarity, and similar reference numerals have been used throughout the specification to indicate similar elements.

[0033] Throughout this specification, when a part is said to be "connected" to another part, this includes not only the case where it is "directly connected," but also the case where it is "electrically connected" or "indirectly connected" with another element in between.

[0034] Throughout this specification, when it is said that a member is located “on,” “above,” “upper,” “lower,” “lower” or “lower” another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.

[0035] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0036] Terms such as "first~", "second~" may be used to indicate the same or substantially the same configuration in a different order, and may be interpreted as a configuration that is substantially the same as a configuration that is not indicated as "first", "second", etc.

[0037] In addition, terms related to direction or position (upper side, upper surface, lower side, etc.) in the description of the embodiment of the present invention are set based on the arrangement state of each component shown in the drawing.

[0038] In the present embodiment, the upper side or upper surface can be understood as the direction in which the anode electrode (20) is arranged with respect to the insulating housing (10) (12 o'clock direction in FIGS. 2 and 3), and the lower side or lower surface can be understood as the direction in which the cathode electrode (70) is arranged with respect to the insulating housing (10) (6 o'clock direction in FIGS. 2 and 3).

[0039] The present invention relates to a field emission X-ray generator. More specifically, it relates to a field emission X-ray generator that emits X-rays by colliding electrons emitted from an electron emission source on the cathode electrode side with a target on the anode electrode side.

[0040] Below, a field emission X-ray generator (1) according to a preferred embodiment of the present invention is described.

[0041] FIG. 2 is a schematic perspective view of a field emission X-ray generator according to an embodiment of the present invention. In addition, FIG. 3 is a schematic cross-sectional view of a field emission X-ray generator according to an embodiment of the present invention. In addition, FIG. 4 is a schematic enlarged view of an anode hood portion of a field emission X-ray generator according to an embodiment of the present invention. In addition, FIG. 5 is a schematic enlarged view of a lower portion of a field emission X-ray generator according to an embodiment of the present invention. Referring to FIGS. 2 to 5, a field emission X-ray generator (1) may include an insulating housing (10), an anode electrode (20), an anode hood (30), a target (40), a gate electrode (50), an insulating spacer (60), a cathode electrode (70), and an electron emission source (80).

[0042] The insulating housing (10) may be made of an insulating material such as ceramic, glass or silicon, and may be made of a material such as alumina ceramic, for example. As the insulating housing (10) is made of an insulating material, the anode electrode (20) and the cathode electrode (70) of the field emission X-ray generator (1) may be electrically insulated from each other. In addition, the interior of the insulating housing (10) may be maintained in a vacuum state or a near-vacuum state.

[0043] The insulating housing (10) may be extended into a tube shape whose one side and the other side are covered by the anode electrode (20) and the gate electrode (50) described later. That is, the insulating housing (10) may have a tube shape in which one side and the other side, in other words, the upper side and the other side, are open, and as described later, one side may be covered by the anode electrode (20) and the other side may be covered by the gate electrode (50). The insulating housing (10) may be an integrally extended tube.

[0044] In addition, a portion of the insulating housing (10) that allows X-rays to be emitted, specifically, a portion of the portion close to the anode electrode (20), can be formed to have a thinner thickness than other portions on the upper and lower sides as shown in FIG. 3, thereby filtering out unnecessary wavelengths from X-rays passing through the portion without a separate window or filter.

[0045] The anode electrode (20) can be arranged on one side of the insulating housing (10) in a form that covers the insulating housing (10). The anode electrode (20) forms a high potential difference of tens to hundreds of kV with respect to the cathode electrode (70) on which the electron emission source (80) described below is arranged, thereby serving as an accelerating electrode and at the same time serving as an X-ray target that emits X-rays by collision of electrons emitted from the electron emission source (80) and accelerated.

[0046] In addition, the anode electrode (20) may include an anode electrode body covering an insulating housing (10). The anode electrode body may be formed of various conductive metal materials, and may be formed of oxygen-free copper (OFHC), for example. It may be understood that the anode electrode body is advantageous in terms of heat diffusion when made of a metal material that can withstand high temperatures and has a thermal conductivity higher than that of the target (40), and advantageous in terms of bondability with the insulating housing (10) when the thermal expansion coefficient is similar to that of the insulating housing (10).

[0047] Referring to FIG. 3, the anode electrode (20) may include a heat dissipation structure (21) on the outside of the insulating housing (10). The heat dissipation structure (21) may be provided to increase the surface area of ​​the anode electrode (20) at a portion exposed to one side of the insulating housing (10). For example, the heat dissipation structure (21) may include a plurality of heat dissipation fins extended from the anode electrode body, but is not limited thereto.

[0048] Referring to FIGS. 3 and 4, the anode electrode (20) may extend into the insulating housing (10) and have a target (40) provided (arranged) on the end surface. In addition, the anode electrode (20) may include a rod-shaped end portion (23) that extends into the insulating housing (10) and has a step of a predetermined depth formed along the outer surface. That is, the end portion (23) may mean a portion having a step of a relatively small diameter compared to other portions on the lower side of the anode electrode (20). An anode hood (30) may be coupled to the anode electrode (20) by the step of the end portion (23).

[0049] The anode hood (30) may have a cylindrical shape or a similar shape that surrounds the target (40) and extends to the other side than the portion where the target (40) is placed. Specifically, the anode hood (30) may be provided in a tubular shape with one end fitted into the step and having the same thickness as the step of the distal end (23). For example, referring to FIG. 4, the diameter T1 of the anode electrode (20) may be 10 mm or more and less than 40 mm, and the thickness T2 of the anode hood (30) may be 1 mm or more and less than 3 mm. At this time, the end portion (23) of the anode electrode (20) may have a diameter obtained by subtracting a step corresponding to the thickness of the anode hood (30) from the diameter of the anode electrode (20), that is, 7 mm or more (when T1=10 (minimum value), T2=3 mm (maximum value)) and less than 39 mm (when T1=40 (maximum value), T2=1 mm (minimum value)). However, the present invention is not limited thereto.

[0050] Referring to FIG. 4, the anode hood (30) may be provided so that its end has a predetermined distance from the focal spot, which is the center of the target (40). For example, the distance T3 between the focal spot and the end of the anode hood (30) may be 5 mm or more and less than 15 mm. In other words, the anode hood (30) may surround the target (40) and extend downward from the target (40) to prevent scattering of electrons emitted from the electron emission source (80) and colliding with the target (40) and X-rays generated from the target (40). Such an anode hood (30) may be more effective when the tube voltage, which is the voltage difference between the cathode electrode (70) and the anode electrode (20), is 100 kV or more, for example, 150 kV or more.

[0051] More specifically, the higher the tube voltage, the more severe the scattering phenomenon of electrons or X-rays becomes. If scattered electrons at a high voltage level of 100 kV or higher in the tube voltage accumulate in the insulating housing, etc., not only will the insulation performance be significantly reduced, but arcing, etc. may also occur. In addition, X-rays scattered in an unwanted direction may cause unnecessary radiation exposure. Therefore, the anode hood (30) of the present invention is more effective when the tube voltage is 100 kV or higher, for example, 150 kV or higher, but is not limited thereto.

[0052] Referring to FIG. 4, the anode hood (30) may be fitted to the step of the end portion (23) of the anode electrode (20), so that the outer surface of the anode hood (30) may be arranged in a straight line with the outer surface of the anode electrode (20). In other words, arcing may be prevented by eliminating the outer step between the anode electrode (20) and the anode hood (30). In addition, the anode hood (30) may be made of the same material as the anode electrode (20), and for example, may be made of oxygen-free copper (OFHC), but is not limited thereto.

[0053] Referring to FIG. 4, the anode hood (30) may include a first hole (31) through which an electron beam (E, or electrons (E)) emitted from an electron emission source (80) is transmitted (passed) on the lower side (other side). The first hole (31) may be provided with a size equal to the size of the target (40) or may be provided with a size larger than the size of the target (40). In other words, the size T4 of the first hole (31) is defined as the size of the passage area of ​​the electron beam (E) and may be larger than the target size.

[0054] In addition, the anode hood (30) may include a second hole (33) through which X-rays generated from the target (40) are transmitted on the side. At this time, the size T5 of the second hole (33) is defined as the size of the X-ray transmission area and may be determined differently depending on the irradiation field of view (FOV). In addition, a window (33a) may be provided in the second hole (33). Specifically, the window (33a) may be provided in the second hole (33) to filter a specific wavelength range from the X-ray. The window (33a) may be made of one of beryllium (Be), aluminum (Al), magnesium (Mg), aluminum nitride (AlN), aluminum-beryllium alloy (AlBe), silicon oxide (SixOy), and titanium (Ti), or an alloy thereof, which have relatively high X-ray transmittance.

[0055] In general, some of the electrons colliding with the target and some of the X-rays generated from the target may be backscattered in an undesired direction. Accordingly, in a preferred embodiment, the anode hood (30) may block X-rays from being backscattered in an undesired direction, and the window (33a) through which the X-rays are transmitted may be formed of a beryllium material to filter out unnecessary wavelengths within the X-rays. However, the present invention is not limited thereto.

[0056] The target (40) is hit by an electron beam (E) emitted from an electron emission source (80), and can provide a target surface inclined with respect to the direction of travel of the electron beam (E). The target (40) can be surrounded by an anode hood (30). The target (40) can be made of any one of tungsten (W), copper (Cu), molybdenum (Mo), cobalt (Co), chromium (Cr), iron (Fe), silver (Ag), tantalum (Ta), and yttrium (Y), or an alloy thereof, which emits X-rays when hit by an accelerated electron beam (E).

[0057] The target (40) emits X-rays when hit by accelerated electrons, and when continuously hit by electron beams (E), the focus on the target (40) reaches a high temperature of about 2700°C or higher, and the entire anode electrode (20) reaches about 1700°C. In order to prevent focal spot fluctuations due to deformation even at such high temperatures, the target (40) may be formed of, for example, tungsten (W) having a high melting point of 3440°C.

[0058] The gate electrode (50) may be disposed between the anode electrode (20) and the cathode electrode (70). Specifically, the gate electrode (50) may cover the other side of the insulating housing (10) and may have an opening (41a) formed on one side thereof, for example, in the other direction. As described below, the cathode electrode (70) may be mounted on the gate electrode (50) inside the insulating housing via an insulating spacer (60) and communicate with the outside of the insulating housing (10) through the opening (41a). A portion of the gate electrode (50) may be disposed between the electron emission source (80) described below and the anode electrode (20) to form an electric field that initiates electron emission.

[0059] In one embodiment, the gate electrode (50) may be formed of the same material as the anode electrode (20), but is not limited thereto. For example, a portion of the gate electrode (50) may be formed of the same material as the anode electrode (20), and another portion may be formed of an iron-nickel-cobalt alloy called Kovar. Specifically, a portion forming the gate flange (433) may be formed of an iron-nickel-cobalt alloy called Kovar, and other portions of the gate electrode, such as the first gate portion (51) and the gate body (531), may be formed of oxygen-free copper.

[0060] The gate electrode (50) may include a first gate portion (51) covering the other side of the insulating housing (10), and a second gate portion (53) arranged inside a space formed by the insulating housing (10) and the first gate portion (51).

[0061] The first gate portion (51) may be formed to cover the lower side and the lower surface of the insulating housing (10). That is, it may be understood that the first gate portion (51) covers the other side of the insulating housing (10) and is exposed to the outside. The first gate portion (51) may have an opening (41a) formed in a downward direction. A gate voltage, i.e., a voltage that induces electron emission from the electron emission source (80), may be applied through the first gate portion (51).

[0062] Referring to a conventional field emission X-ray generator in which a gate electrode (94) illustrated in FIG. 1 is positioned between a cathode electrode (93) and an anode electrode (92), the housing (91) is vertically separated by the gate electrode (94), and the insulating distance between the anode electrode (92) and the gate electrode (94) is limited to the vertical distance between the anode electrode (92) and the gate electrode (94).

[0063] Compared to a conventional field emission X-ray generator (9), the gate electrode (50) of the present invention is provided such that the first gate portion (51) covers the lower side of the insulating housing (10), so that the upper end of the gate electrode (50) can move lower than the conventional gate electrode, and accordingly, the insulating distance between the upper end of the gate electrode (50) and the anode electrode (20) can be increased. In addition, since the insulating housing (10) is not separated vertically by the gate electrode (50) but is formed integrally, a phenomenon that causes a decrease in durability, such as ceramic puncture, which may occur at the joining portion, can be minimized.

[0064] The second gate portion (53) may be mounted on the first gate portion (51) within the insulating housing (10). The second gate portion (53) may substantially form an electric field within the space where the insulating housing (10) and the first gate portion (51) are formed. Referring to Fig. 5, the second gate portion (53) may include a gate body (531), a gate mesh (532), and a gate flange (433).

[0065] The gate body (531) is mounted on the first gate portion (51) and can extend upward from the first gate portion (51). The gate body (531) has a cylindrical shape and can be provided to accommodate an insulating spacer (60) therein and surround the insulating spacer.

[0066] The gate mesh (532) may be placed within the second gate portion (53). An electron beam (E) emitted from an electron emission source (80) may pass through the gate mesh (532). The gate mesh (532) may be a thin metal plate having a plurality of holes formed therein so that the electron beam (E) may pass through, or may be provided in the form of a metal mesh. The gate mesh (532) may have a circular cross-section so as to be seated on a mesh opening having a circular cross-section formed on one side of the cathode electrode.

[0067] In addition, the gate mesh (532) may be positioned apart from the electron emission source (80) toward the anode electrode (20). That is, the electron emission source (80) on the top of the cathode electrode (70) and the gate mesh (532) may be positioned to face each other with a certain distance between them. For example, the gate mesh (532) may be positioned apart from the electron emission source (80) by 0.1 mm, but is not limited thereto.

[0068] The gate flange (433) can perform focusing to concentrate an electron beam (E) passing through the gate mesh (532). The gate flange (433) may surround the gate mesh (532) and extend to one side beyond the portion where the gate mesh (532) is arranged.

[0069] Fig. 6 is a schematic plan view of the lower portion of the field emission X-ray generator according to one embodiment of the present invention. Referring to Fig. 6, the gate flange (433) can form a hollow (433a) through which an electron beam (E) passes through the gate mesh (532) and propagates. The hollow (433a) can have a cross-section of a predetermined shape extending in the vertical direction, and the cross-sectional shape of the hollow (433a) can vary depending on the voltage applied to the anode electrode (20) and the cathode electrode (70) and the desired X-ray emission amount. That is, it can be understood that the shape of the gate flange (433) is determined differently depending on the X-ray emission resulting from the focusing of the electron beam (E).

[0070] In a preferred embodiment, referring to FIG. 6, when the target (40) is inclined at an angle of 25 degrees (relative to the horizontal line in FIG. 3), the hollow formed by the gate flange (433) may have a square cross-section. In this case, the square cross-section may be understood as a square or rectangular cross-section. In addition, it is preferable to understand the concept as including a shape in which the four corners of the square cross-section are filleted, as illustrated in FIG. 6.

[0071] An insulating spacer (60) may be placed inside the second gate portion (53) on the first gate portion (51). The insulating spacer (60) may have a cylindrical shape and may be made of an insulating material. For example, the insulating spacer (60) may be formed of a material that is the same as the insulating housing (10) or has excellent thermal behavior.

[0072] Referring to FIGS. 3 and 5, the cathode electrode (70) may be disposed on the other side of the insulating housing (10), and specifically, may be mounted on an insulating spacer (60) extending from the gate electrode (50) to one side inside the insulating housing (10). In addition, the cathode electrode (70) may be provided to communicate with the outside of the insulating housing (10) through an opening (41a) formed in the first gate portion (51). Since the cathode electrode (70) is disposed inside the insulating housing (10) to be insulated from the gate electrode (50), and the gate electrode (50) is exposed to the outside through the opening (41a), the occurrence of insulation breakdown or arcing can be minimized. The cathode electrode (70) may be made of substantially the same material as the gate electrode (50) and the anode electrode (20), for example, oxygen-free copper.

[0073] Also, referring to FIG. 5, the cathode electrode (70) may be disposed on the other side of the insulating housing (10) to face the anode electrode (20). The cathode electrode (70) may include a cathode electrode body (61) disposed on an insulating spacer (60), an extension portion (62) extending downward (the other side) from the cathode electrode body (61), and an extension portion (63) extending to the outside of the insulating spacer (60) via the insulating spacer (60). An upwardly recessed ring-shaped mounting groove may be formed between the cathode electrode body (61) and the extension portion (63) to allow the cathode electrode (70) to be mounted on the insulating spacer (60). Also, according to one embodiment, the extension portion (62) may be formed such that a voltage is applied to the cathode electrode (70) through an end thereof.

[0074] Referring to FIG. 5, an electron emission source (80) may be provided on the cathode electrode (70). In other words, the electron emission source (80) may be placed on the cathode electrode (70), and the electron emission source (80) may be provided on a separate substrate and coupled to the cathode electrode (70), or may be formed directly on the surface of the cathode electrode (70). The electron emission source (80) may utilize a plurality of nanostructures, such as carbon nanotubes. In the case of an electron emission source (80) utilizing carbon nanotubes, a plurality of carbon nanotubes may be directly grown on the surface of the substrate or cathode electrode (70) using a chemical vapor deposition (CVD) method, or may be formed by applying a carbon nanotube paste and then firing it.

[0075] In a preferred embodiment, the electron emission source (80) may be a carbon nanotube, and by emitting electrons in a current-controlled manner rather than in a thermionic manner, the on / off of the field emission X-ray generator (1) can be easily controlled through the gate voltage applied to the gate electrode (50), and can be implemented in a compact structure.

[0076] In addition, since the electron emitter (80) is formed of a nano-structure such as a carbon nanotube, heat generated on the cathode electrode (70) side can be minimized. Accordingly, the anode electrode (20) may have a heat dissipation structure (21) that increases the surface area of ​​the anode electrode (20) in a portion exposed to one side of the insulating housing (10), while the cathode electrode (70) may be provided so as not to have a heat dissipation structure that increases the surface area of ​​the cathode electrode (70) in a portion exposed to one side of the insulating housing (10).

[0077] Again, referring to FIGS. 2 and 3, a field emission X-ray generator (1) according to one embodiment of the present invention may have an anode electrode (20) exposed on the upper side (one side) of an insulating housing (10) and a gate electrode (50) exposed on the lower side (the other side). A cathode electrode (70) may be mounted on the gate electrode (50) inside the insulating housing (10) via an insulating spacer (60) and may be provided to communicate with the outside through an opening formed in the gate electrode (50).

[0078] In addition, the cathode electrode (70) mounted on the insulating spacer (60) may be surrounded by the second gate portion (53), and the second gate portion (53) may be surrounded by the first gate portion (51). The space between the first gate portion (51) and the second gate portion (53) may be understood as being substantially in a vacuum state as the internal space of the insulating housing (10), and the space between the gate electrode body (431) of the second gate portion (53) and the insulating spacer (60) and cathode electrode (70) therein may also be understood as being substantially in a vacuum state.

[0079] In addition, conventionally, the housing (91) had to be divided into upper and lower parts by the gate electrode (94) so ​​that the housing (91) could be used in multiple stages, but in the present invention, the gate electrode (50), the cathode electrode (70), and the insulating spacer (60) are modularized and can be combined with a single insulating housing (10), so that the cathode module including the gate electrode (50) and the cathode electrode (70) can be easily combined with the insulating housing, thereby improving manufacturability.

[0080] In addition, the field emission X-ray generator (1) according to one embodiment of the present invention includes an anode hood (30) at the end portion of the anode electrode (20) where the target (40) is positioned, thereby preventing electron and X-ray scattering at the target (40). The anode hood (30) is provided with the same thickness as the step of the anode electrode (20), so that an external step due to the coupling between the anode electrode (20) and the anode hood (30) does not exist, thereby preventing an arcing phenomenon.

[0081] The above description of the present invention is provided for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0082] The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. Tubular insulating housing; An anode electrode disposed on one side of the insulating housing and equipped with a target; A cathode electrode disposed on the other side of the insulating housing and equipped with an electron emitter; A gate electrode disposed between the anode electrode and the cathode electrode; An anode hood coupled to the anode electrode and surrounding the target, the anode hood having a first hole through which electrons emitted from the electron emission source pass and a second hole through which X-rays generated from the target pass; Includes, A field emission X-ray generator, wherein the anode hood is provided so that its outer surface is aligned in a straight line with the outer surface of the anode electrode.

2. In paragraph 1, A window provided in the second hole above to filter a specific wavelength range from the X-rays, A field emission X-ray generator further comprising:

3. In paragraph 1, The anode electrode includes a rod-shaped terminal portion extending into the insulating housing, having the target provided on the terminal surface, and having a step of a predetermined depth formed along the outer surface. The above anode hood is a field emission X-ray generator having a tube phenomenon in which one end is fitted into the step and is formed with the same thickness as the step.

4. In paragraph 1, A field emission X-ray generator, wherein the anode hood is made of the same material as the anode electrode.

5. In paragraph 1, A field emission X-ray generating device, wherein the first hole is provided with a size equal to or larger than the size of the target.

6. In paragraph 1, A field emission X-ray generator, wherein the anode hood is provided such that the end thereof has a distance of 5 mm or more and less than 15 mm from the focal spot, which is the center of the target.

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