Cathode assembly, X-ray tube and method for adjusting focused electron beam

Abstract

The invention relates to a cathode assembly, an X-ray tube and a control method for focusing an electron beam. The cathode assembly comprises a flat cathode and a focusing electrode, the flat cathode comprises a plurality of emission parts independently emitting electron beams, and the emission parts are circumferentially arranged around the center of the flat cathode; and the focusing electrode is arranged around the outer side of the flat cathode and is used for focusing the electron beams emitted by the emitting parts. The beam spot with a certain size can be formed by emitting the electron beams through the emitting parts, and when the size of the beam spot needs to be adjusted, the size of the electron beams emitted by the flat cathode can be adjusted by adjusting the number of the emitting parts emitting the electron beams or re-confirming the emitting parts emitting the electron beams. In addition, the tube current can be switched in real time by adjusting the number of the emitting parts emitting the electron beams or adjusting the size of the outgoing current of the emitting parts, the size of the beam spots of the electron beams and the size of the current are switched in real time, and the adjusting flexibility is high.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular to a cathode assembly, an X-ray tube and a method for adjusting a focused electron beam. Background Art

[0002] X-rays are widely used in the fields of industrial nondestructive testing, safety inspection, medical diagnosis and treatment. In particular, X-ray fluoroscopic imaging equipment made by the high penetration ability of X-rays plays an important role in all aspects of people's daily life. For example, CT (computed tomography) equipment can obtain high-definition three-dimensional stereoscopic graphics or slice images, which is an advanced high-end application. Under the existing cathode structure, the tube current of the X-ray tube is only adjusted by the cathode temperature, but due to the thermal inertia of the cathode, the tube current cannot be switched in real time; under the requirements of medical imaging with multiple focal spot sizes, the focusing device set around the electron beam channel is adjusted, which is limited by the performance of the focusing device and can only be fixed to several specific focal spot sizes, making it insufficiently flexible in complex imaging applications. In summary, the cathode structure design in the existing X-ray tube makes it insufficient in real time and flexibility when controlling the tube current and adjusting the focal spot. Summary of the invention

[0003] Based on this, it is necessary to provide a cathode assembly to address the technical problem that the cathode structure design in the existing X-ray tube has insufficient real-time performance and flexibility when controlling the tube current and adjusting the focus.

[0004] A cathode assembly, comprising:

[0005] A flat cathode, comprising a plurality of emitting portions that independently emit electron beams, wherein the plurality of emitting portions are arranged circumferentially around the center of the flat cathode;

[0006] A focusing electrode is arranged around the outer circumference of the flat cathode, and the focusing electrode is arranged at a first preset acute angle with the direction in which the flat cathode emits electron beams. The focusing electrode is used to focus the electron beams emitted by each of the emitting parts.

[0007] In one embodiment, the focusing electrode includes a plurality of independent focusing electrodes, and each of the focusing electrodes corresponds to each of the emitting parts one by one.

[0008] In one of the embodiments, the cathode assembly further includes an auxiliary electrode, which is disposed in a matching hole surrounded by each of the emitting parts, and the auxiliary electrode is used to cooperate with each of the focusing electrodes to control the electron beam emission of the corresponding emitting part.

[0009] In one of the embodiments, the radial dimension of the auxiliary electrode gradually decreases along the emission direction of the electron beam.

[0010] In one embodiment, adjacent sides of any adjacent emitting portions are parallel.

[0011] In one of the embodiments, an emitting surface of each emitting portion forms a second preset acute angle with an emitting direction of the electron beam.

[0012] The present invention also provides an X-ray tube, which can solve at least one of the above technical problems.

[0013] An X-ray tube comprises an anode assembly, a focusing deflection structure and the above-mentioned cathode assembly, wherein the anode assembly and the cathode assembly are arranged at intervals along the emission direction of the electron beam, the focusing deflection structure is arranged between the anode assembly and the cathode assembly, and the focusing deflection structure is used to cooperate with the focusing electrode to focus the electron beam emitted by the flat cathode on the anode assembly.

[0014] The present invention also provides a method for controlling a focused electron beam, which can solve at least one of the above technical problems.

[0015] A method for controlling a focused electron beam, using the cathode assembly described above for control, comprises the following steps:

[0016] Determining at least one target emitting portion of the flat cathode according to the position and size of the desired target focal point;

[0017] Providing a first electric potential to each of the target emission parts;

[0018] A second potential is provided to the focusing electrode, wherein the second potential is less than or equal to the first potential, so as to focus the electron beams emitted from each of the target emission portions.

[0019] In one embodiment, the focusing electrode includes a plurality of independent focusing electrodes, each of which corresponds to the configuration of each of the emitting parts; in the step of providing the focusing electrode with a second potential, the second potential being less than or equal to the first potential, so as to focus the electron beam emitted by each of the target emitting parts, the method specifically includes:

[0020] The focusing electrode corresponding to the target emission portion is provided with the corresponding second electric potential.

[0021] In one embodiment, the cathode assembly further includes an auxiliary electrode, and the auxiliary electrode is disposed in a matching hole formed by each of the emitting parts; the method further includes:

[0022] A third potential is provided to the auxiliary electrode.

[0023] In one embodiment, after the step of providing the auxiliary electrode with a third potential, the method further comprises:

[0024] The difference between the second electric potential of the focusing electrode corresponding to at least one of the target emitting portions and the third electric potential of the auxiliary electrode is adjusted to move the electron beam emitted by the at least one of the target emitting portions.

[0025] In one embodiment, after the step of providing the auxiliary electrode with a third potential, the method further comprises:

[0026] The difference between the second electric potential of the focusing electrode corresponding to at least one of the target emission portions and the third electric potential of the auxiliary electrode is periodically changed.

[0027] In one embodiment, there are multiple target emission parts, and in the step of providing the third potential to the auxiliary electrode, the method further includes:

[0028] Adjusting the third electric potential to within a first preset range;

[0029] The second electric potential of the focusing electrode corresponding to one of the target emission portions in the emission state is adjusted to be equal to the third electric potential, so that the target emission portion changes from the emission state to the emission suppression state; the second electric potential of the focusing electrode corresponding to one of the target emission portions in the emission suppression state is adjusted to be greater than the third electric potential of the auxiliary electrode, so that the target emission portion changes from the emission suppression state to the emission state, so as to realize the electron source emission switching.

[0030] In one embodiment, in the step of providing the auxiliary electrode with a third potential, the method further comprises:

[0031] Adjusting the third electric potential to within a second preset range;

[0032] Adjusting the second electric potential of the focusing electrode corresponding to one of the target emitting portions to be equal to the third electric potential of the auxiliary electrode;

[0033] The second potential of the focusing electrode and the third potential of the auxiliary electrode corresponding to the target emission portion are synchronously adjusted within the second preset range to ensure that the second potential and the third potential are always equal to adjust the intensity of the electron beam emitted by the target emission portion.

[0034] In one embodiment, the method further comprises:

[0035] Acquiring current information of electron beams emitted by each of the target emitting parts;

[0036] Determine the target emitting part to be failed according to the current information of the electron beam emitted by each target emitting part;

[0037] At least one of adjusting the second potential, adjusting the current of the target emission unit, and re-determining the target emission unit is adopted.

[0038] Beneficial effects:

[0039] The cathode assembly provided by the embodiment of the present invention includes a flat cathode and a focusing electrode, wherein the flat cathode includes a plurality of emitting parts that independently emit electron beams, and the plurality of emitting parts are arranged circumferentially around the center of the flat cathode; the focusing electrode is arranged around the outer periphery of the flat cathode, and the side of the focusing electrode facing the flat cathode is arranged at a first preset acute angle with the direction of the electron beam emitted by the flat cathode, and the focusing electrode is used to focus the electron beams emitted by each emitting part. In the present application, the flat cathode includes a plurality of emitting parts that can independently emit electron beams, and the emitting parts independently emit electron beams to form a beam spot of a certain size on the anode. When the size of the beam spot needs to be adjusted, the size of the electron beam emitted by the flat cathode can be adjusted by adjusting the number of emitting parts that emit electron beams, or reconfirming the emitting parts that emit electron beams, so as to adjust the size of the focus. In addition, the tube current size can be switched in real time by adjusting the number of emitting parts that emit electron beams or adjusting the size of the current drawn by the emitting parts. Compared with the prior art that requires adjustment by cathode temperature and the focus size is limited by the performance of the focusing device, the present application can switch the size and current of the electron beam spot in real time, and the adjustment flexibility is high.

[0040] The present invention also provides an X-ray tube, comprising an anode assembly, a focusing deflection structure and the above-mentioned cathode assembly, wherein the anode assembly and the cathode assembly are arranged at intervals along the emission direction of the electron beam, the focusing deflection structure is arranged between the anode assembly and the cathode assembly, and the focusing deflection structure is used to cooperate with the focusing electrode to focus the electron beam emitted by the flat cathode on the anode assembly. The X-ray tube can achieve at least one of the above-mentioned technical effects.

[0041] The present invention also provides a method for controlling a focused electron beam, which uses the above cathode assembly for control, and includes the following steps: determining at least one target emitting portion of the flat cathode according to the position and size of the desired target focus; providing a first potential to each target emitting portion; providing a second potential to the focusing electrode, the second potential being less than or equal to the first potential, so that the electron beam emitted by each target emitting portion is focused. The method can achieve at least one of the above technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of a cathode assembly provided in accordance with an embodiment of the present invention.

[0043] Figure 2 A schematic diagram of a flat cathode in a cathode assembly provided in one embodiment of the present invention.

[0044] Figure 3 A cross-sectional view of a cathode assembly provided in accordance with an embodiment of the present invention.

[0045] Figure 4 for Figure 2 First schematic diagram of the deformation of the flat cathode.

[0046] Figure 5 for Figure 2 Second schematic diagram of the deformation of the middle flat cathode.

[0047] Figure 6 for Figure 2 The third schematic diagram of the deformation of the middle flat cathode.

[0048] Figure 7 A schematic diagram of a cathode assembly provided according to another embodiment of the present invention.

[0049] Figure 8 for Figure 7 Deformation diagram of the cathode assembly.

[0050] Fig. 9 A schematic diagram of adding an auxiliary cathode to a cathode assembly provided in another embodiment of the present invention.

[0051] Fig.10 A cross-sectional view of a cathode assembly provided in another embodiment of the present invention with an auxiliary cathode added.

[0052] Fig.11 A schematic diagram of a cathode assembly provided in accordance with another embodiment of the present invention.

[0053] Fig.12 A cross-sectional view of a cathode assembly according to another embodiment of the present invention.

[0054] Fig.13 A schematic diagram of adding an auxiliary cathode to a cathode assembly provided in yet another embodiment of the present invention.

[0055] Fig.14 A cross-sectional view of a cathode assembly provided in accordance with another embodiment of the present invention with an auxiliary cathode added thereto.

[0056] Fig.15 A schematic diagram of an X-ray tube provided according to an embodiment of the present invention.

[0057] Figure Number:

[0058] 100-flat cathode; 110-emitting part; 111-first emitting part; 112-second emitting part; 113-third emitting part; 114-fourth emitting part; 120-second preset acute angle; 130-first gap; 140-second gap; 150-metal substrate; 160-third gap; 170-matching hole; 200-focusing electrode; 210-focusing pole; 211-first focusing pole; 212-second focusing pole; 213-third focusing pole; 214-fourth focusing pole; 220-first preset acute angle; 300-auxiliary electrode; 400-anode assembly; 410-target plate; 411-first plane; 412-second plane; 420-bearing; 500-focusing deflection structure; 600-tube core; 610-pipeline; 700-electron beam. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0060] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0061] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0062] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0064] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0065] See also Figure 1 , Figure 2 and Figure 3 , Figure 1 A schematic diagram of a cathode assembly provided in one embodiment of the present invention; Figure 2 A schematic diagram of a flat cathode in a cathode assembly provided in one embodiment of the present invention; Figure 3 A cross-sectional view of a cathode assembly provided in one embodiment of the present invention. The cathode assembly provided in one embodiment of the present invention comprises a flat cathode 100 and a focusing electrode 200, wherein the flat cathode 100 comprises a plurality of emitting portions 110 that independently emit electron beams 700, and the plurality of emitting portions 110 are arranged circumferentially around the center of the flat cathode 100; the focusing electrode 200 is arranged around the periphery of the flat cathode 100, and the focusing electrode 200 is arranged at a first preset acute angle 220 with respect to the direction in which the electron beam 700 is emitted from the flat cathode 100 on one side facing the flat cathode 100, and the focusing electrode 200 is used to focus the electron beams 700 emitted by each emitting portion 110.

[0066] The cathode assembly in the present application is applied to an X-ray tube. The X-ray tube also includes an anode target disk. A first potential is provided to each emitting unit 110, a second potential is provided to each focusing electrode 200, so as to form an electric field in cooperation with the anode, and a corresponding current is provided to each emitting unit 110, so that each emitting unit 110 can independently emit an electron beam 700. The second potential is less than or equal to the first potential, so that the electron beam 700 emitted by each emitting unit 110 is focused on the anode target disk.

[0067] Specifically, in the present application, the flat cathode 100 includes a plurality of emitting parts 110 that can independently emit electron beams. Each emitting part 110 independently emits an electron beam 700, and a beam spot of a certain size can be formed on the anode. When the size of the beam spot needs to be adjusted, the size of the electron beam 700 emitted by the flat cathode 100 can be adjusted by adjusting the number of emitting parts 110 that emit the electron beam 700, or reconfirming the emitting part 110 that emits the electron beam 700, so as to adjust the size of the focus. In addition, the tube current size can be switched in real time by adjusting the number of emitting parts that emit the electron beam 700 or adjusting the size of the current drawn by the emitting part 110. Compared with the prior art method that requires adjustment by cathode temperature and the focus size is limited by the performance of the focusing device, the present application can switch the size and current of the electron beam spot in real time, and has high adjustment flexibility. Among them, the focusing electrode 200 is used to make the electron beam 700 emitted by each emitting part 110 perform Pierce focusing to ensure the uniformity of the electron beam spot.

[0068] Among them, when it is necessary to adjust the size of the beam spot, the potential change of the focusing electrode 200 can be combined with adjusting the number of emitting parts 110 that emit the electron beam 700, or re-confirming the emitting parts 110 that emit the electron beam 700, to adjust the size of the electron beam 700 emitted by the flat cathode 100, so as to adjust the size of the beam spot where the electron beam 700 hits the anode target disk, thereby achieving further adjustment of the focus size, so as to achieve a continuous change from an ultra-small focus to an ultra-large focus when the electron beam 700 emitted by the flat cathode 100 hits the anode target disk 410, thereby improving the adaptability of the cathode assembly.

[0069] It should be noted that the transmitting units 110 in the present application are insulated from each other and are controlled individually.

[0070] It should be noted that the instructions are attached Figure 2For example, the planar cathode 100 is composed of four independent emitters 110, wherein the current of each emitter 110 is independently controlled. When an ultra-small focus is required, only one of the four emitters 110 needs to be emitted; when a small focus is required, only any two of the four emitters 110 need to be emitted; when a large focus is required, any three of the four emitters 110 need to be emitted; when an ultra-large focus is required, the four emitters 110 emit simultaneously. This emission method can make the current amplitude of each emitter 110 not much different, thereby increasing the service life of the planar cathode 100. At the same time, a small number of emitters 110 correspond to a small focus, and a large number of emitters 110 correspond to a large focus, which can make the field amplitude difference required for beam control smaller, which is conducive to beam stability; and the independent control of multiple emitters 110 can ensure that when a single emitter 110 or part of the emitters 110 fails, it can be replaced by other emitters 110 or a combination of other emitters 110 to ensure performance continuity.

[0071] The materials of the emitting parts 110 are the same, which may be tungsten or other materials doped with a certain proportion of tungsten.

[0072] It should be noted that the focusing strength of the focusing electrode 200 can be adjusted by adjusting the size of the first preset acute angle 220, that is, the smaller the first preset acute angle 220 is, the stronger the focusing is, and the larger the first preset acute angle 220 is, the weaker the focusing is.

[0073] Further, there is a gap between any adjacent emitting parts 110. Specifically, there is a first gap 130 between any two adjacent emitting parts 110, and there is a second gap 140 between any emitting parts 110 arranged opposite to each other. In the present application, when multiple emitting parts 110 are used in combination, the first gap 130 and the second gap 140 can be designed according to the distribution of the beam spot envelope of the focus.

[0074] Furthermore, the flat cathode 100 further includes an insulating base (not shown) and a metal substrate 150. The metal substrate 150 is insulated from each emitting portion 110. Each emitting portion 110 is fixed to the insulating base through the insulating material passing through the metal substrate 150, and the focusing electrode 200 is fixed to the insulating base through the insulating material. Among them, the metal substrate 150 has a corresponding surface parallel to the outer surface of each emitting portion 110 on one side close to each emitting portion 110, which improves the stability of each emitting portion 110 being fixed relative to the metal substrate 150. In addition, there is a third gap 160 between the metal substrate and each emitting portion 110, so as to facilitate heat dissipation of the emitting portion 110.

[0075] See also Figure 2 , Figure 4 , Figure 5 and Figure 6 , Figure 4 for Figure 2A first schematic diagram of a deformation of the flat cathode 100 is shown. Figure 5 for Figure 2 A second schematic diagram of a deformation of the flat cathode 100 is shown. Figure 6 for Figure 2 The third schematic diagram of the deformation of the flat cathode 100. In one embodiment, each emitting portion 110 may be fan-shaped, triangular, etc., and the number of emitting portions 110 may be three, four, etc., as long as each emitting portion 110 is arranged circumferentially around the center of the flat cathode 100 and can independently emit the electron beam 700. In other embodiments, each emitting portion 110 may also be other shapes.

[0076] Furthermore, in this embodiment, the emitting parts 110 are evenly spaced around the center of the flat cathode 100, so that the size of the beam spot can be adjusted by controlling the number of emitting parts 110 emitting the electron beam 700 or re-confirming the emitting parts 110 emitting the electron beam 700. Preferably, the shapes of the emitting parts 110 are the same.

[0077] See also Figure 7 , Figure 7 A schematic diagram of a cathode assembly according to another embodiment of the present invention. In one embodiment, the focusing electrode 200 includes a plurality of independent focusing electrodes 210 , and each focusing electrode 210 corresponds to each emitting portion 110 .

[0078] Specifically, each independent focusing electrode 210 corresponds to an independent emitting unit 110, and the position, shape and control of each focusing electrode 210 correspond to the corresponding emitting unit 110 one by one. By adjusting the voltage of each focusing electrode 210 on each focusing electrode 200, the focusing of the electron beam 700 emitted by the corresponding emitting unit 110 can be controlled, so that the continuity and range of the beam spot size adjustment can be further increased in combination with adjusting the number of target emitting units or re-determining the target emitting units, and the adaptability of the flat cathode 100 can be improved. Among them, each focusing electrode 210 is insulated.

[0079] See also Figure 7 and Figure 8 , Figure 8 for Figure 7 Deformation diagram of the cathode assembly. In one embodiment, each focusing electrode 210 is matched with the corresponding emitting portion 110, so that the structure of the cathode assembly is more compact. In the explanation of Appendix 8, each emitting portion 110 in this embodiment is rectangular, and the corresponding focusing electrodes 210 are also rectangular, so as to be matched with the corresponding emitting portion 110.

[0080] See also Fig. 9 and Fig.10 , Fig. 9A schematic diagram of adding an auxiliary cathode to a cathode assembly provided in another embodiment of the present invention. Fig.10 A cross-sectional view of a cathode assembly provided in another embodiment of the present invention with an auxiliary cathode added. In one embodiment, the cathode assembly further includes an auxiliary electrode 300, which is disposed in a matching hole 170 formed by each emitting portion 110, and the auxiliary electrode 300 is used to cooperate with each focusing electrode 210 to control the emission of the electron beam 700 of the corresponding emitting portion 110.

[0081] Specifically, by providing the third potential to the auxiliary electrode 300, the auxiliary electrode 300 can cooperate with each focusing electrode 210 to control the emitting unit 110 corresponding to each focusing electrode 210, so as to further control the focusing degree of the electron beam 700 emitted by each emitting unit 110, thereby improving the adaptability of the cathode assembly. Among them, by adjusting the potential difference between the auxiliary electrode 300 and the focusing electrode 210 and adjusting the potential size of the auxiliary electrode 300, the real-time switching of the tube current intensity, the adjustment of the spot size and position, and the fly focus can be achieved, further improving the adaptability of the cathode assembly.

[0082] In other embodiments, when the focusing electrode 200 is a whole, an auxiliary electrode 300 may also be arranged in the matching hole 170 surrounded by each emitting part 110. The auxiliary electrode 300 is used to cooperate with the focusing electrode 200 to realize the control of each emitting part 110, so as to further control the focusing degree of the electron beam 700 emitted by each emitting part 110 and improve the adaptability of the cathode assembly.

[0083] In one embodiment, the auxiliary electrode 300 is located at the center of the flat cathode 100 .

[0084] In one embodiment, the shape of the auxiliary electrode 300 is adapted to the shape of each emitting portion 110 , so that the structure of the cathode assembly is more compact.

[0085] See also Fig.13 and Fig.14 , Fig.13 A schematic diagram of adding an auxiliary cathode to a cathode assembly provided in yet another embodiment of the present invention. Fig.14 A cross-sectional view of a cathode assembly with an auxiliary cathode added to another embodiment of the present invention is provided. In one embodiment, the radial dimension of the auxiliary electrode 300 is gradually reduced along the emission direction of the electron beam 700, thereby reducing the electron beam 700 emitted by the emission unit 110 from hitting the auxiliary electrode 300, thereby improving the reliability of the cathode assembly. Fig.13 For example, the radial dimension of the end of the auxiliary electrode 300 away from the metal substrate 150 is smaller than the radial dimension of the end of the auxiliary electrode 300 close to the metal substrate 150 .

[0086] See also Figure 2 , Figure 4 , Figure 5 , Figure 6 and Figure 8 In one embodiment, the adjacent sides of any adjacent emitting parts 110 are parallel, so that the emitting surface of each emitting part 110 can form a complete plane, thereby facilitating the adjustment of the envelope distribution of the beam spot at the focus and improving the reliability of the flat cathode 100.

[0087] See also Fig.11 and Fig.12 , Fig.11 A schematic diagram of a cathode assembly provided in accordance with another embodiment of the present invention. Fig.12 A cross-sectional view of a cathode assembly provided in yet another embodiment of the present invention. In one embodiment, the emission surface of each emission portion 110 forms a second preset acute angle 120 with the emission direction of the electron beam 700 .

[0088] Specifically, the instructions are attached Fig.11 For example, the four emitting parts 110 form a spherical Pierce cathode structure, thereby achieving better laminar beam focusing. The second preset acute angle 120 is between 4° and 45°, and the smaller the second preset acute angle 120 is, the greater the focusing intensity is. Preferably, the first preset acute angle 220 is equal to the second preset acute angle 120.

[0089] See also Figure 1 and Fig.15 , Fig.15 Schematic diagram of an X-ray tube provided by an embodiment of the present invention. The embodiment of the present invention also provides an X-ray tube, comprising an anode assembly 400, a focusing deflection structure 500 and the above-mentioned cathode assembly, wherein the anode assembly 400 and the cathode assembly are arranged at intervals along the emission direction of the electron beam 700, the focusing deflection structure 500 is arranged between the anode assembly 400 and the cathode assembly, and the focusing deflection structure 500 is used to cooperate with the focusing electrode 200 to focus the electron beam 700 emitted by the flat cathode 100 on the anode assembly 400.

[0090] Specifically, the focusing deflection structure 500 is used to cooperate with the focusing electrode 200 to achieve focusing of the electron beam 700 emitted by each emission unit 110, so that when the potential of each focusing electrode 210 changes, it does not affect the focusing of the electron beam 700 on the anode assembly 400, thereby increasing the adjustment range of the potential of the focusing electrode 210 and improving the reliability and adaptability of the X-ray tube. In the present application, the size of the beam spot on the anode assembly 400 can achieve continuous changes from ultra-small focus to ultra-large focus, further improving the adaptability of the X-ray tube.

[0091] The focusing deflection structure 500 can be realized by an electric field or a magnetic field. When the focusing deflection structure 500 is a magnetic field structure, the focusing deflection structure 500 can be a quadruple iron for further shaping the beam spot, and it can also integrate a guide iron for focusing the beam spot; when the focusing deflection structure 500 is an electric field structure, the focusing of the beam spot can be completed by designing a metal structure with a certain shape and voltage distribution.

[0092] See also Fig.15 In one embodiment, the anode assembly 400 includes a target plate 410, the target plate 410 includes a first plane 411 and a second plane 412 connected to each other, the second plane 412 circumferentially surrounds the outer side of the first plane 411, a preset inclination angle is formed between the second plane 412 and the first plane 411, and the electron beam 700 emitted by the flat cathode 100 is focused on the second plane 412.

[0093] Specifically, the second plane 412 forms a certain inclination with the first plane 411 for line focusing projection of the electron beam 700. The preset inclination is generally between 7° and 10°. The electron beam 700 bombards the edge of the target disk 410, i.e., the second plane 412, to generate X-rays for medical imaging diagnosis.

[0094] See also Fig.15 In one embodiment, the X-ray tube further includes a tube core 600 and a bearing 420, wherein the bearing 420 is mounted on the tube core 600 and connected to the target plate 410, and the bearing 420 is configured to drive the target plate 410 to rotate around the center line of the first plane 411 by rotating.

[0095] Specifically, the cathode assembly and the target plate 410 are installed in the tube core 600, and the bearing 420 is used to drive the target plate 410 to rotate around the center line of the first plane 411 to achieve heat dissipation of the target plate 410. The tube core 600 is generally made of metal, ceramic or glass to ensure that the inside of the X-ray tube is in a vacuum environment.

[0096] Furthermore, the tube core 600 has a pipe 610 corresponding to the second plane 412, the inlet of the pipe 610 is located between the anode assembly 400 and the cathode assembly, and the focusing deflection structure 500 is located on both sides of the inlet of the pipe 610, so that the electron beam 700 emitted by the flat cathode 100 enters the pipe 610 from the inlet of the pipe 610 under the cooperation of the focusing electrode 200 and the focusing deflection structure 500, and hits the second plane 412. The setting of the pipe 610 can block a part of the electron beam 700 away from the focus center, and reduce the interference with the focus on the target plate 410.

[0097] See also Figure 1 , Figure 4 and Figure 6The embodiment of the present invention further provides a method for controlling the focused electron beam 700, which is controlled by the cathode assembly described above, and includes the following steps:

[0098] S10, determining at least one target emitting portion of the flat cathode 100 according to the position and size of the desired target focus;

[0099] S20 provides a first electric potential to each target emission unit;

[0100] S30 provides a second potential to the focusing electrode 200, the second potential being less than or equal to the first potential, so as to focus the electron beams 700 emitted from each target emission portion.

[0101] Specifically, in the present application, the flat cathode 100 includes a plurality of emitting parts 110 that independently emit electron beams 700. According to the position and size of the desired target focus, the emitting part 110 that emits the electron beam 700 is determined to be the target emitting part. A first potential is provided to each target emitting part, and a second potential is provided to the focusing electrode 200 to form an electric field in cooperation with the anode, and a corresponding current is provided to each target emitting part, so that each target emitting part can independently emit the electron beam 700, thereby forming a target focus on the target disk 410.

[0102] When the size or position of the target focus changes, at least one of adjusting the second potential of the focusing electrode 210, adjusting the number of the target emitting parts, or re-determining the target emitting parts can be performed.

[0103] It should be noted that when the emitting unit 110 emits the electron beam 700 , it is necessary to pass current through the emitting unit 110 to reach a desired cathode temperature.

[0104] See also Figure 7 and Figure 8 In one embodiment, in S30, the control method of focusing the electron beam 700 further includes:

[0105] A corresponding second electric potential is provided to the focusing electrode 210 corresponding to the target emitting portion. Specifically, the focusing electrode 200 includes a plurality of independent focusing electrodes 210, each focusing electrode 210 corresponds to the setting of each emitting portion 110 one by one, and by adjusting the electric potential of each focusing electrode 210 on each focusing electrode 200, the focusing condition of the electron beam 700 emitted by the corresponding emitting portion 110 can be individually controlled, so that it can be combined with adjusting the number of target emitting portions or re-determining the target emitting portion, further increasing the continuity and range of the beam spot size adjustment and improving the adaptability.

[0106] See also Fig. 9 and Fig.10 In one embodiment, the control method of the focused electron beam 700 further includes:

[0107] S40 provides a third potential to the auxiliary electrode 300. Specifically, by providing the third potential to the auxiliary electrode 300, the auxiliary electrode 300 can cooperate with each focusing electrode 210 to control the emitting unit 110 corresponding to each focusing electrode 210, thereby further controlling the focusing degree of the electron beam 700 emitted by each emitting unit 110, thereby improving the adaptability of the cathode assembly.

[0108] Among them, this application is attached to the specification Fig. 9 For example, the flat cathode 100 includes four emitting parts 110, namely, a first emitting part 111, a second emitting part 112, a third emitting part 113 and a fourth emitting part 114, and the focusing electrode 200 includes four corresponding focusing electrodes 210, namely, a first focusing electrode 211, a second focusing electrode 212, a third focusing electrode 213 and a fourth focusing electrode 214. The first emitting part 111 and the third emitting part 113 are arranged opposite to each other in the vertical direction, and the second emitting part 112 and the fourth emitting part 114 are arranged opposite to each other in the horizontal direction.

[0109] For the sake of convenience of description, this embodiment is described by taking the first emission unit 111 and the first focusing electrode 211 as examples, but is not limited thereto. When the third potential of the auxiliary electrode 300 is equal to the second potential of the first focusing electrode 211, and is lower than the first potential of the first emission unit 111 to a certain extent, the emission of the electron beam 700 of the first emission unit 111 is cut off, and the potential of the auxiliary electrode 300 is not higher than the potential when the emission of the emission unit 110 is cut off, which is defined as the first preset range. When the potentials of the auxiliary electrode 300 and the first focusing electrode 211 are gradually increased synchronously, the first emission unit 111 will gradually emit current; when the potentials of the auxiliary electrode 300 and the first focusing electrode 211 are increased synchronously to a certain value, the first emission unit 111 reaches the maximum emission current, that is, the emission unit 110 can normally emit the electron beam 700. Among them, the potential interval of the auxiliary electrode 300 corresponding to the emission current of the emission unit 110 from the beginning of the emission current to the maximum emission current is defined as the second preset range.

[0110] When the third electric potential of the auxiliary electrode 300 is not equal to the second electric potential of the first focusing electrode 211, and when the second electric potential of the first focusing electrode 211 is greater than the third electric potential of the auxiliary electrode 300, the beam spot emitted by the first emitting unit 111 toward the target disk 410 is offset toward the first focusing electrode 211; when the second electric potential of the first focusing electrode 211 is less than the third electric potential of the auxiliary electrode 300, the beam spot emitted by the first emitting unit 111 toward the target disk 410 is offset toward the auxiliary electrode 300.

[0111] See also Fig. 9 In one embodiment, after S40, the control method of the focused electron beam 700 further includes:

[0112] S50 adjusts the difference between the second potential of the focusing electrode 210 corresponding to at least one target emission portion and the third potential of the auxiliary electrode 300 .

[0113] As can be seen from the above, the difference between the second potential of the focusing electrode 210 corresponding to the target emission part and the third potential of the auxiliary electrode 300 is adjusted so that the beam spot on the target disk 410 can move. When there is only one target emission part, the beam spot can move along the arrangement direction of the auxiliary electrode 300 and the focusing electrode 210 corresponding to the target emission part, so that the position of the target focus can be adjusted, and the adaptability of the cathode assembly is improved.

[0114] Among them, the instructions are attached Fig. 9 For example, when the number of target emitting parts is one, and it is the first emitting part 111, when the difference between the second potential of the first focusing electrode 211 and the third potential of the auxiliary electrode 300 is adjusted, the position of the beam spot emitted by the first emitting part 111 can be adjusted in the vertical direction. When the number of target emitting parts is multiple, the second potentials of multiple corresponding focusing electrodes 210 in the target emitting part can be adjusted according to the position of the target focus to achieve the adjustment of the target beam spot position. The specific implementation method is the same as when the number of target emitting parts is one, and the difference is only in the number, so it will not be repeated.

[0115] See also Fig. 9 In one embodiment, in S50, the control method of focusing the electron beam 700 further includes:

[0116] The difference between the second potential of the focusing electrode 210 corresponding to at least one target emission portion and the third potential of the auxiliary electrode 300 is periodically changed.

[0117] Specifically, when the number of target emitting units is one, and is the first emitting unit 111, when the difference between the second potential of the first focusing electrode 211 and the third potential of the auxiliary electrode 300 is periodically changed, the position of the beam spot emitted by the first emitting unit 111 can be periodically adjusted in the vertical direction, thereby achieving a small-distance flying focus in the vertical direction, that is, achieving a small-distance flying focus in the arrangement direction of the second focusing electrode 212 and the auxiliary electrode 300, so as to realize dynamic adjustment of the position of the beam spot and improve the adaptability of the cathode assembly.

[0118] It should be noted that when there are multiple target emitting parts, the magnitude of the second potential of multiple corresponding focusing electrodes 210 in the target emitting parts can be periodically changed to achieve the adjustment of the target beam spot position and a small distance flying focus.

[0119] See also Fig. 9 In one embodiment, after S40, the control method of the focused electron beam 700 further includes:

[0120] S41 adjusts the third potential to within a first preset range;

[0121] S42 adjusts the second electric potential of the focusing electrode 210 corresponding to a target emission portion in an emission state to be equal to the third electric potential, so that the target emission portion changes from the emission state to the emission suppression state; adjusts the second electric potential of the focusing electrode 210 corresponding to a target emission portion in an emission suppression state to be greater than the third electric potential of the auxiliary electrode 300, so that the target emission portion changes from the emission suppression state to the emission state, so as to realize the electron source emission switching.

[0122] Specifically, the instructions are attached Fig. 9 For example, when there are two target emission parts, namely the first emission part 111 and the third emission part 113, the third potential of the auxiliary electrode 300 is within the first preset range, the second potential of the first focusing electrode 211 is equal to the third potential, and the second potential of the third focusing electrode 213 is greater than the third potential. At this time, the emission of the electron beam 700 of the first emission part 111 is cut off, that is, it is in a suppressed state, and the third emission part 113 emits the electron beam 700, that is, it is in an emission state. The second potential of the third focusing electrode 213 is adjusted to be equal to the third potential, and the second potential of the first focusing electrode 211 is adjusted to be greater than the third potential. At this time, the emission of the electron beam 700 of the third emission part 113 is cut off, that is, it is in a suppressed state, and the first emission part 111 emits the electron beam 700, that is, it is in an emission state, thereby realizing the switching of the electron source emission of the first emission part 111 and the third emission part 113, realizing the long-distance flying focus of the beam spot in the vertical direction, thereby realizing the long-distance flying focus on the basis of a small change in the beam trajectory, and ensuring the safety and stability and reliability of the beam.

[0123] The two target emission parts may be other, and the electron source switching between the second emission part 112 and the fourth emission part 114 may be realized by controlling the auxiliary electrode 300 and the second focusing electrode 212 to control the emission current of the second emission part 112, and the auxiliary electrode 300 and the fourth focusing electrode 214 to control the emission current of the fourth emission part 114. That is, the target emission part may be any two emission parts 110, and the present application may realize the flying focus between any two combined emission parts 110, so as to realize the dynamic adjustment of the beam spot at any position on the target disk 410, and further improve the adaptability of the cathode assembly.

[0124] It should be noted that, in this embodiment, just for the convenience of description, there can be multiple target emission parts. When there are multiple target emission parts, the third potential of the auxiliary electrode 300 can be adjusted to within the first preset range, the second potential of the focusing electrode 210 corresponding to multiple or one target emission parts can be adjusted to be equal to the third potential of the auxiliary electrode 300, and the second potential of the focusing electrode 210 corresponding to one or more target emission parts can be adjusted to be greater than the third potential; the second potential of the focusing electrode 210 corresponding to at least one target emission part in the emission state is adjusted to be equal to the third potential of the auxiliary electrode 300, and the second potential of the focusing electrode 210 corresponding to at least one target emission part in the emission suppression state is adjusted to be greater than the third potential of the auxiliary electrode 300, so as to realize the emission switching of multiple electron sources, improve the range of dynamic adjustment of the beam spot at any position on the target disk 410, and further improve the adaptability of the cathode assembly.

[0125] Among them, the setting of the electron source emission switching implemented in the present application, compared with the method of realizing the electron source emission switching by stopping the power supply to the emission part 110 to cool it in the prior art, can realize the current switching in microsecond level in this embodiment, which is of great significance for reducing the patient dose and balancing the dose during multi-energy radiation.

[0126] It should be noted that in the present embodiment, the general electric flying focus function can be realized by periodically changing the potential difference between the focusing electrode 200 and the auxiliary electrode 300, and the third flying focus mode in addition to electric flying focus and magnetic flying focus can be realized by controlling the switching of the emission and suppression of the electron beam 700 of the two emitting parts 110. By combining the periodic change of the potential difference between the focusing electrode 210 and the auxiliary electrode 300 and the switching of the electron source emission, long-distance flying focus can be realized on the basis of ensuring that the electron trajectory of each emitting part 110 changes very little, which can better ensure the safety and stability and reliability of the beam.

[0127] See also Fig. 9 In one embodiment, between S41 and S42, the control method of the focused electron beam 700 further includes:

[0128] The second potential of the focusing electrode 210 corresponding to one target emitting part is adjusted to be equal to the third potential of the auxiliary electrode 300, so that the target emitting part is in an emission suppression state; the second potential of the focusing electrode 210 corresponding to another target emitting part is adjusted to be greater than the third potential, so that the target emitting part is in an emission state. That is, it is ensured that among the target emitting parts, at least one emitting part 110 is in an emission suppression state, and at least one emitting part 110 is in an emission state.

[0129] See also Fig. 9 In one embodiment, after S40, the method further includes:

[0130] adjusting the third electric potential to within a second preset range;

[0131] Adjusting the second potential of the focusing electrode 210 corresponding to a target emission portion to be equal to the third potential of the auxiliary electrode 300;

[0132] The second potential of the focusing electrode corresponding to the target emission portion and the third potential of the auxiliary electrode 300 are synchronously adjusted within a second preset range to ensure that the second potential and the third potential are always equal, so as to adjust the intensity of the electron beam 700 emitted by the target emission portion.

[0133] Specifically, when the second potential of the focusing electrode 210 corresponding to the target emission portion is equal to the third potential of the auxiliary electrode 300 within the second preset range, the target emission portion can emit a portion of the electron beam 700, and as the second potential and the third potential increase synchronously, the tube current increases, and as the second potential and the third potential decrease synchronously, the tube current decreases. It should be noted that the second potential and the third potential of the auxiliary electrode 300 are always equal.

[0134] This embodiment is described by taking the target emission unit as the first emission unit 111 as an example. When the second potential of the first focusing electrode 211 is adjusted to be equal to the third potential of the auxiliary electrode 300 and is within the second preset range, the first emission unit 111 emits part of the electron beam. When the second potential of the first focusing electrode 211 and the third potential of the auxiliary electrode 300 are adjusted synchronously, the number of electron beams emitted by the first emission unit 111 can be adjusted, and then the intensity of the tube current drawn by the first emission unit 111 can be adjusted. That is, in this application, the magnitude of the drawn tube current is accurately controlled in real time through the focusing electrode 200 and the auxiliary electrode 300, thereby achieving real-time and accurate regulation of the dose. This method will play a huge role in reducing ineffective doses, dose balance of dual-energy scanning, and faster dose change rates.

[0135] It should be noted that this embodiment only takes the first emitting unit 111 as an example. In other embodiments, the target emitting unit may be other, and the number may be two or more, thereby further expanding the range of adjusting the intensity of the flat cathode lead-out tube current.

[0136] It should be noted that, since the auxiliary electrode 300 and the focusing electrode 210 usually operate at the kilovolt level during normal operation, it can be understood that the potentials of the auxiliary electrode 300 and the focusing electrode 210 are allowed to differ by a few volts or more than ten volts, and it is also considered that the potentials of the auxiliary electrode 300 and the focusing electrode 210 are equal.

[0137] See also Fig. 9 In one embodiment, the control method of the focused electron beam 700 further includes:

[0138] Acquire current information of the electron beam 700 emitted by each target emission part;

[0139] Determine the failed target emission part according to the current information of the electron beam 700 emitted by each target emission part;

[0140] At least one of the following methods is adopted: adjusting the second electric potential of the focusing electrode, adjusting the current of the target emitting portion, and re-determining the target emitting portion.

[0141] Specifically, after the target emission unit fails, the size or current of the target focus will change. When the tube current changes, the current of the target emission unit can be adjusted. When the size of the beam spot changes, the target emission unit can be re-determined, or the second potential of the focusing electrode 210 can be adjusted to achieve the same function and ensure performance continuity. Fig. 9 For example, when the target emitting unit is the first emitting unit 111, when the current obtained by the first emitting unit 111 is 0, the first emitting unit 111 cannot emit the electron beam 700, and the first emitting unit 111 fails, so that the spot size on the target disk 410 is different from the target focus. Then, current can be provided to the second emitting unit 112 and the fourth emitting unit 114, so that the fourth emitting unit 114 and the second emitting unit 112 emit the electron beam 700 to adjust the size of the beam spot, so as to achieve the same function and ensure performance continuity.

[0142] This embodiment is described by taking the first transmitting unit 111, the second transmitting unit 112 and the fourth transmitting unit 114 as examples, but is not limited thereto. That is, in this application, by independently controlling multiple transmitting units 110, it can be ensured that the same function can still be achieved by combining other transmitting units 110 when a certain transmitting unit 110 fails, thereby improving adaptability and reliability.

[0143] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0144] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A cathode assembly, characterized in that: The cathode assembly comprises: A flat cathode (100) comprising a plurality of emitting portions (110) for independently emitting electron beams, wherein the plurality of emitting portions (110) are circumferentially arranged around the center of the flat cathode (100); A focusing electrode (200) is arranged around the outer periphery of the flat cathode (100), and the focusing electrode (200) is arranged at a first preset acute angle (220) with respect to the direction in which the flat cathode (100) emits electron beams. The focusing electrode (200) is used to focus the electron beams emitted by each of the emitting units (110).

2. The cathode assembly according to claim 1, characterized in that The focusing electrode (200) comprises a plurality of independent focusing electrodes (210), and each of the focusing electrodes (210) corresponds to each of the emitting parts (110) in a one-to-one manner.

3. The cathode assembly according to claim 2, characterized in that The cathode assembly also includes an auxiliary electrode (300), which is arranged in a matching hole (170) surrounded by each of the emitting parts (110), and the auxiliary electrode (300) is used to cooperate with each of the focusing electrodes (210) to control the electron beam emission of the corresponding emitting part (110).

4. The cathode assembly according to claim 3, characterized in that Along the emission direction of the electron beam, the radial dimension of the auxiliary electrode (300) gradually decreases.

5. The cathode assembly according to any one of claims 1 to 4, characterized in that: Adjacent sides of any adjacent emitting parts (110) are parallel.

6. The cathode assembly according to claim 5, characterized in that The emission surface of each emission portion (110) forms a second preset acute angle (120) with the emission direction of the electron beam.

7. An X-ray tube, characterized in that: The X-ray tube comprises an anode assembly (400), a focusing deflection structure (500), and a cathode assembly according to any one of claims 1 to 6, wherein the anode assembly (400) and the cathode assembly are arranged at intervals along the emission direction of the electron beam, the focusing deflection structure (500) is arranged between the anode assembly (400) and the cathode assembly, and the focusing deflection structure (500) is used to cooperate with the focusing electrode (200) so that the electron beam emitted by the flat cathode (100) is focused on the anode assembly (400).

8. A method for controlling a focused electron beam, characterized in that: The cathode assembly according to any one of claims 1 to 6 is used for control, comprising the following steps: Determining at least one target emitting portion of the flat cathode (100) according to the position and size of the desired target focus; Providing a first electric potential to each of the target emission parts; A second potential is provided to the focusing electrode (200), wherein the second potential is less than or equal to the first potential, so as to focus the electron beams emitted from each of the target emission parts.

9. The method for controlling a focused electron beam according to claim 8, characterized in that: The focusing electrode (200) comprises a plurality of independent focusing electrodes (210), each of the focusing electrodes (210) corresponding to the arrangement of each of the emitting parts (110) one by one; in the step of providing the focusing electrode (200) with a second potential, the second potential being less than or equal to the first potential, so as to focus the electron beam emitted by each of the target emitting parts, the method specifically comprises: The focusing electrode (210) corresponding to the target emission portion is provided with the corresponding second electric potential.

10. The method for controlling a focused electron beam according to claim 9, characterized in that: The cathode assembly further comprises an auxiliary electrode (300), wherein the auxiliary electrode (300) is arranged in a matching hole (170) formed by each of the emitting parts (110); the method further comprises: A third potential is provided to the auxiliary electrode (300).

11. The method for controlling a focused electron beam according to claim 10, characterized in that: After the step of providing the auxiliary electrode (300) with a third potential, the method further comprises: The difference between the second electric potential of the focusing electrode (210) corresponding to at least one of the target emission parts and the third electric potential of the auxiliary electrode (300) is adjusted to move the electron beam emitted by the at least one target emission part.

12. The method for controlling a focused electron beam according to claim 10, characterized in that: After the step of providing the auxiliary electrode (300) with a third potential, the method further comprises: The difference between the second electric potential of the focusing electrode (210) corresponding to at least one of the target emission parts and the third electric potential of the auxiliary electrode (300) is periodically changed.

13. The method for controlling a focused electron beam according to any one of claims 10 to 12, characterized in that: There are at least two target emission parts, and in the step of providing the auxiliary electrode (300) with a third potential, the method further comprises: Adjusting the third electric potential to within a first preset range; The second electric potential of the focusing electrode (210) corresponding to one of the target emission parts in the emission state is adjusted to be equal to the third electric potential, so that the target emission part changes from the emission state to the emission suppression state; the second electric potential of the focusing electrode (210) corresponding to one of the target emission parts in the emission suppression state is adjusted to be greater than the third electric potential of the auxiliary electrode (300), so that the target emission part changes from the emission suppression state to the emission state, so as to realize the electron source emission switching.

14. The method for controlling a focused electron beam according to any one of claims 10 to 12, characterized in that: In the step of providing the auxiliary electrode (300) with a third potential, the method further comprises: Adjusting the third electric potential to within a second preset range; adjusting the second electric potential of the focusing electrode (210) corresponding to one of the target emission parts to be equal to the third electric potential of the auxiliary electrode (300); The second electric potential of the focusing electrode (210) corresponding to the target emission portion and the third electric potential of the auxiliary electrode (300) are synchronously adjusted within the second preset range to ensure that the second electric potential and the third electric potential are always equal, so as to adjust the intensity of the electron beam emitted by the target emission portion.

15. The method for controlling a focused electron beam according to any one of claims 10 to 14, characterized in that: The method further comprises: Acquiring current information of electron beams emitted by each of the target emitting parts; Determine the failed emission part according to the current information of the electron beam emitted by each target emission part; At least one of the following methods is adopted: adjusting the second electric potential of the focusing electrode (210), adjusting the current of the target emission part, and re-determining the target emission part.

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