Magnetic quadrupole lens, X-ray bulb tube and method for focusing and femtofocusing electron beams

Abstract

The invention discloses a magnetic quadrupole lens, an X-ray bulb tube and a method for focusing and femtofocusing an electron beam. The magnetic quadrupole lens comprises a frame iron core; the four magnetic pole assemblies are arranged on the inner periphery of the frame iron core and used for generating a focusing magnetic field for focusing the electron beams and a femtofocus magnetic field for performing femtofocus on the electron beams. The magnetic pole assembly comprises a main pole arranged on the inner periphery of the frame iron core and extending towards the center of the frame iron core; the first focusing coil sleeves the main pole and is used for generating a first focusing magnetic field for focusing the electron beam; and the first femtofocus coil sleeves the main pole and is used for generating a first femtofocus magnetic field for performing femtofocus on the electron beam. Wherein the first femtofocus coil is closer to the frame core than the first focus coil.

Description

Technical Field

[0001] This application relates to the field of vacuum electronic medical device technology, and in particular to a magnetic quadrupole lens, an X-ray tube, and a method for focusing and fusing an electron beam. Background Technology

[0002] In an X-ray tube, the magnetic quadrupole lens is a key component for focusing the electron beam. The performance of the magnetic quadrupole lens directly affects the accuracy and efficiency of the electron beam bombarding the target, and thus determines the quality of the generated X-rays.

[0003] Figure 1 A schematic diagram of a conventional magnetic quadrupole lens in the prior art is shown. (Reference) Figure 1 As shown, a traditional magnetic quadrupole lens typically includes four pole posts, four focusing coils nested on the pole posts, an iron core, four fly-focal coils located in the yoke of the iron core, and a drift tube. However, during assembly, the yoke of the iron core in a traditional magnetic quadrupole lens has a gap, and two fly-focal coils are positioned across this gap. Because the gaps on both sides of the yoke are not the same size after assembly, the magnetic energy loss is uneven, and the magnetic field distribution in the drift region deviates significantly from theoretical calculations.

[0004] Furthermore, these poles need to be precisely assembled and fixed around the drift tube, and each pole must be strictly perpendicular to the outer surface of the drift tube to ensure the generation of a symmetrical and uniform focusing magnetic field. However, due to manufacturing errors in the drift tube nested with the magnetic quadrupole lens, and because the drift tube requires high-temperature processing, its outer surface is no longer circular. This makes it difficult to keep the four poles perpendicular to the outer surface of the drift tube after assembly, thus compromising the quality of the generated X-rays.

[0005] There is currently no effective solution to the technical problem in the prior art where the structure of the magnetic quadrupole lens in the X-ray tube affects the X-ray quality. Summary of the Invention

[0006] This disclosure provides a magnetic quadrupole lens, an X-ray tube, and a method for focusing and defocusing an electron beam, to at least solve the technical problem in the prior art where the structure of the magnetic quadrupole lens in an X-ray tube affects the X-ray quality.

[0007] According to a first aspect of this application, a magnetic quadrupole lens is provided, comprising: a frame core; and four magnetic pole assemblies disposed on the inner periphery of the frame core for generating a focusing magnetic field for focusing an electron beam and a fly-focus magnetic field for fly-focusing the electron beam. The magnetic pole assemblies include: a main pole post disposed on the inner periphery of the frame core and extending toward the center of the frame core; a first focusing coil sleeved on the main pole post for generating a first focusing magnetic field for focusing the electron beam; and a first fly-focus coil sleeved on the main pole post for generating a first fly-focus magnetic field for fly-focusing the electron beam. The first fly-focus coil is closer to the frame core than the first focusing coil.

[0008] According to a second aspect of this application, an X-ray tube is provided, including an electron beam generator and an anode target disk, and further including the aforementioned magnetic quadrupole lens disposed between the electron beam generator and the anode target disk.

[0009] According to a third aspect of this application, a method for focusing an electron beam is provided, comprising: passing the electron beam through the magnetic quadrupole lens described above; applying a current of the same magnitude to each of the first focusing coils of the magnetic quadrupole lens, wherein the current polarities of adjacent first focusing coils are opposite, thereby generating a rectangularly distributed first focusing magnetic field in a rectangular region at the center of the magnetic quadrupole lens; and focusing the electron beam using the rectangularly distributed magnetic field.

[0010] According to a fourth aspect of this application, a method for fogging an electron beam is provided, comprising: passing the electron beam through a magnetic quadrupole lens as described above; applying a current of the same magnitude to each of the first fogging coils of the magnetic quadrupole lens, wherein the current polarity is the same between the first focusing coils of adjacent first pairs of magnetic pole assemblies, and the current polarity is the same between the first focusing coils of adjacent second pairs of magnetic pole assemblies, and the current polarity is opposite between the first focusing coils of the first pairs of magnetic pole assemblies and the second pairs of magnetic pole assemblies, thereby generating a uniform magnetic field in a first direction between the first pairs of magnetic pole assemblies and the second pairs of magnetic pole assemblies; and fogging the electron beam using the uniform magnetic field, such that the electron beam foggs in a second direction perpendicular to the first direction.

[0011] In this application, the frame core of the magnetic quadrupole lens includes two identical and completely symmetrical semi-annular magnetic dipole cores, and four symmetrically distributed magnetic pole assemblies are arranged on the inner circumference of the frame core. Each magnetic pole assembly is provided with a main pole post, and the main pole post extends towards the center of the frame core.

[0012] Therefore, since the main pole posts 121~124 are located on the inner periphery of the frame core 101 and extend toward the center of the frame core 101, the main pole posts 121~124 can be perpendicular to the outer surface of the drift tube nested in the magnetic quadrupole lens 10.

[0013] Furthermore, unlike existing technologies where four fly-focal coils are positioned on the iron core yoke, with two of them bridging the gaps in the yoke, this application features a first focusing coil and a second fly-focal coil on each main pole, generating a focusing magnetic field and a fly-focal magnetic field to achieve focusing and fly-focaling of the electron beam. This avoids uneven magnetic energy loss, which could lead to a greater discrepancy between the drift region's magnetic field distribution and theoretical calculations.

[0014] In summary, the magnetic quadrupole lens provided in this application can avoid affecting the quality of X-rays. This solves the technical problem in the prior art where the structure of the magnetic quadrupole lens in an X-ray tube affects the quality of X-rays.

[0015] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments of this application in conjunction with the accompanying drawings. Attached Figure Description

[0016] The following sections will describe some specific embodiments of this application in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic diagram of the structure of a conventional magnetic quadrupole lens in the prior art; Figure 2 This is a schematic diagram of the structure of a magnetic quadrupole lens according to an embodiment of this application; Figure 3 This is a schematic diagram of the focusing portion of a magnetic quadrupole lens according to an embodiment of this application; Figure 4 This is a schematic diagram of the flying focal portion in a magnetic quadrupole lens according to an embodiment of this application; Figure 5 This is a schematic diagram of the structure of an X-ray tube according to an embodiment of this application; Figure 6 This is a focusing structure diagram of a magnetic quadrupole lens according to an embodiment of this application; Figure 7 This is a schematic diagram of the focusing equivalent magnetic field distribution principle of a magnetic quadrupole lens according to an embodiment of this application; Figure 8 This is a magnetic field distribution diagram of the drift region of the focusing structure according to the embodiments of this application; Figure 9 This is a flying focal length structure diagram of a magnetic quadrupole lens in the Z direction according to an embodiment of this application; Figure 10 This is a magnetic field distribution diagram of the drift region of the fly-foil structure in the Z direction according to the embodiments of this application; Figure 11 This is a flying focal length structure diagram of a magnetic quadrupole lens in the X direction according to an embodiment of this application; and Figure 12 This is a magnetic field distribution diagram of the drift region of the fly-foil structure in the X direction according to the embodiments of this application. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] To enable those skilled in the art to better understand the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present disclosure.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Figure 2This is a schematic diagram of the structure of a magnetic quadrupole lens according to an embodiment of this application. According to a first aspect of this embodiment, a magnetic quadrupole lens 10 is provided, comprising: a frame core 101; and four magnetic pole assemblies 111-114 disposed on the inner periphery of the frame core 101, for generating a focusing magnetic field for focusing an electron beam and a fly-focus magnetic field for fly-focusing the electron beam. The magnetic pole assemblies 111-114 include: main pole posts 121-124 disposed on the inner periphery of the frame core 101 and extending toward the center of the frame core 101; first focusing coils 151-154 sleeved on the main pole posts 121-124 for generating a first focusing magnetic field for focusing the electron beam; and first fly-focus coils 161-164 sleeved on the main pole posts 121-124 for generating a first fly-focus magnetic field for fly-focusing the electron beam. The first fly-focus coils 161-164 are closer to the frame core 101 than the first focusing coils 151-154.

[0022] Specifically, refer to Figure 2 As shown, in the magnetic quadrupole lens 10, four magnetic pole components 111-114 are arranged on the inner periphery of the frame core 101. The four magnetic pole components 111-114 are used to generate a focusing magnetic field for focusing the electron beam and a fly-focusing magnetic field for fly-focusing the electron beam.

[0023] Furthermore, the magnetic pole assembly 111-114 includes main pole posts 121-124, first focusing coils 151-154, and first fly-focal coils 161-164. The main pole posts 121-124 are disposed on the inner periphery of the frame core 101 and extend towards the center of the frame core 101; the first focusing coils 151-154, used to generate the first focusing magnetic field, are sleeved on the main pole posts 121-124; and the first fly-focal coils 161-164, used to generate the first fly-focal magnetic field, are sleeved on the main pole posts 121-124. Moreover, the first fly-focal coils 161-164 are closer to the frame core 101 than the first focusing coils 151-154.

[0024] Therefore, the magnetic quadrupole lens 10 provided in this application can generate a focusing magnetic field and a fly-focusing magnetic field, realizing the focusing and fly-focusing operations of the electron beam. Furthermore, it avoids the problem of uneven magnetic energy loss, which would lead to a greater difference between the magnetic field distribution in the drift region and theoretical calculations.

[0025] Furthermore, since the main pole posts 121-124 are located on the inner periphery of the frame core 101 and extend toward the center of the frame core 101, they can be perpendicular to the outer surface of the drift tube nested in the magnetic quadrupole lens 10, thereby avoiding affecting the quality of X-rays.

[0026] As described in the background section, in an X-ray tube, the magnetic quadrupole lens is a key component for focusing the electron beam. The performance of the magnetic quadrupole lens directly affects the accuracy and efficiency of the electron beam bombarding the target, thus determining the quality of the generated X-rays. A traditional magnetic quadrupole lens typically includes four poles, four focusing coils nested on the poles, an iron core, four fly-focal coils located in the yoke of the iron core, and a drift tube. However, during the assembly process of a traditional magnetic quadrupole lens, a gap is left in the yoke of the iron core, and two fly-focal coils are positioned across this gap. Because the gaps on both sides of the yoke of the iron core are not uniform after assembly, uneven magnetic energy loss occurs, increasing the difference between the magnetic field distribution in the drift region and theoretical calculations. Furthermore, these poles need to be precisely assembled and fixed around the drift tube, and each pole must be strictly perpendicular to the outer surface of the drift tube to ensure a symmetrical and uniform focusing magnetic field. However, due to manufacturing errors in the drift tube nested within the magnetic quadrupole lens, and because the drift tube requires high-temperature processing, its outer surface is no longer circular. This makes it difficult to keep the four poles perpendicular to the outer surface of the drift tube after assembly, thus compromising the quality of the generated X-rays.

[0027] In view of this, in this application, the frame core of the magnetic quadrupole lens includes two identical and completely symmetrical semi-annular magnetic dipole cores, and four symmetrically distributed magnetic pole assemblies are arranged on the inner circumference of the frame core. Each magnetic pole assembly is provided with a main pole post, and the main pole post extends toward the center of the frame core. Therefore, since the main pole posts 121-124 are arranged on the inner circumference of the frame core 101 and extend toward the center of the frame core 101, the main pole posts 121-124 can be perpendicular to the outer surface of the drift tube nested in the magnetic quadrupole lens 10. Furthermore, unlike the prior art where four flyfocus coils are arranged in the yoke of the core, and two of the flyfocus coils are connected across the gap of the core yoke, in this application, each main pole post is fitted with a first focusing coil and a second flyfocus coil, which can generate a focusing magnetic field and a flyfocus magnetic field to realize the focusing and flyfocusing operation of the electron beam. Thus, the uneven magnetic energy loss is avoided, which leads to an increase in the difference between the magnetic field distribution in the drift region and the theoretical calculation. In summary, the magnetic quadrupole lens provided in this application can avoid affecting the quality of X-rays. This solves the technical problem in the prior art where the structure of the magnetic quadrupole lens in an X-ray tube affects the quality of X-rays.

[0028] Optionally, the magnetic pole assembly 111~114 further includes: a first sub-pole post 131~134 and a second sub-pole post 141~144 disposed on the inner periphery of the frame core 101; a second focusing coil 171~174 sleeved on the first sub-pole post 131~134 for generating a second focusing magnetic field that works in conjunction with the first focusing magnetic field to focus the electron beam; and a second fly-focus coil 181~184 sleeved on the second sub-pole post 141~144 for generating a second fly-focus magnetic field that works in conjunction with the first fly-focus magnetic field to fly-focus the electron beam.

[0029] Specifically, refer to Figure 2 As shown, the inner circumference of the frame core 101 is provided with a first sub-pole post 131~134 and a second sub-pole post 141~144. The second focusing coil 171~174, fitted on the first sub-pole post 131~134, is used to generate a second focusing magnetic field that works in conjunction with the first focusing magnetic field to focus the electron beam; and the second fly-focus coil 181~184, fitted on the second sub-pole post 141~144, is used to generate a second fly-focus magnetic field that works in conjunction with the first fly-focus magnetic field to fly-focus the electron beam.

[0030] Therefore, the second focusing magnetic field generated by the first sub-electrodes 131-134 can work in conjunction with the first focusing magnetic field generated by the main electrodes 121-124 to focus the electron beam. Furthermore, the second fly-focus magnetic field generated by the second sub-electrodes 141-144 can work in conjunction with the first fly-focus magnetic field generated by the main electrodes 121-124 to fly-focus the electron beam. Thus, the magnetic quadrupole lens 10 provided in this application can generate more focal spot sizes and increase the fly-focus distance. Simultaneously, the first and second sub-electrodes 131-134 provide support for the main electrodes 121-124, ensuring that the main electrodes 121-124 are perpendicular to the outer surface of the drift tube, thereby guaranteeing the quality of the generated X-rays.

[0031] Optionally, in the same magnetic pole assembly 111~114: the main pole post 121~124 intersects with the first auxiliary pole post 131~134 and the second auxiliary pole post 141~144, and the first auxiliary pole post 131~134 is symmetrically arranged with respect to the main pole post 121~124 and the second auxiliary pole post 141~144.

[0032] Specifically, refer to Figure 2 As shown, in the same magnetic pole assembly 111~114, the first auxiliary pole post 131~134 and the second auxiliary pole post 141~144 intersect on the main pole post 121~124, and with the main pole post 121~124 as the axis of symmetry, the first auxiliary pole post 131~134 and the second auxiliary pole post 141~144 are symmetrically arranged on both sides of the main pole post 121~124.

[0033] Therefore, the first and second auxiliary pole posts 131-134 and 141-144 can weaken the edge effects of the first focusing magnetic field and the first fly-focal magnetic field generated by the main pole posts 121-124, thus improving uniformity. Furthermore, they can provide symmetrical support for the main pole posts 121-124, preventing the introduction of asymmetric distortion.

[0034] Optionally, the included angle between the main pole posts 121-124 of adjacent magnetic pole assemblies 111-114 is 90°; the included angle between the first auxiliary pole posts 131-134 and the corresponding main pole posts 121-124 is 40°-60°; and the included angle between the second auxiliary pole posts 141-144 and the corresponding main pole posts 121-124 is 40°-60°.

[0035] Specifically, refer to Figure 2 As shown, the included angle between the main pole posts 121-124 of adjacent magnetic pole assemblies 111-114 is 90°, the included angle between the first auxiliary pole posts 131-134 and the corresponding main pole posts 121-124 is 40°-60°, and the included angle between the second auxiliary pole posts 141-144 and the corresponding main pole posts 121-124 is 40°-60°.

[0036] For example, the angle between the main pole post 121 of the magnetic pole assembly 111 and the main pole post 122 of the magnetic pole assembly 112 is 90°. The angle between the first auxiliary pole post 131 and the corresponding main pole post 121 is 40°~60°; the angle between the second auxiliary pole post 141 and the corresponding main pole post 121 is 40°~60°.

[0037] Therefore, the second focusing magnetic field generated by the first auxiliary poles 131-134 and the second femtofocus magnetic field generated by the second auxiliary poles 141-144 can weaken the edge effects of the first focusing magnetic field and the first femtofocus magnetic field generated by the main poles 121-124. Simultaneously, this structure avoids interference with the main poles 121-124 during assembly, ensuring that the main poles 121-124 are perpendicular to the outer surface of the drift tube, thereby guaranteeing the quality of the generated X-rays.

[0038] Optionally, the frame core 101 is composed of a first core 102 and a second core 103, wherein the first core 102 and the second core 103 are semi-circular and their openings face each other, and wherein the first magnetic pole assembly 111 and the second magnetic pole assembly 112 of the four magnetic pole assemblies 111 to 114 are disposed on the first core 102 to form a first magnetic diode lens unit; and the third magnetic pole assembly 113 and the fourth magnetic pole assembly 114 of the four magnetic pole assemblies 111 to 114 are disposed on the second core 103 to form a second magnetic diode lens unit symmetrically arranged with respect to the first magnetic diode lens unit.

[0039] Specifically, refer to Figure 2As shown, the frame core 101 includes a semi-circular shape with an opening opposite to the first core 102 and the second core 103. Furthermore, the four magnetic pole assemblies 111-114 disposed on the frame core 101 include a first magnetic pole assembly 111, a second magnetic pole assembly 112, a third magnetic pole assembly 113, and a fourth magnetic pole assembly 114.

[0040] Furthermore, in the magnetic quadrupole lens 10, the first magnetic diode lens unit includes: a first iron core 102, and a first magnetic pole assembly 111 and a second magnetic pole assembly 112 disposed on the first iron core 102; the second magnetic diode lens unit includes: a second iron core 103, and a third magnetic pole assembly 113 and a fourth magnetic pole assembly 114 disposed on the second iron core 103. The first and second magnetic diode lens units are symmetrically arranged.

[0041] Therefore, the symmetrically arranged first and second magnetic diode lens units can avoid asymmetrical interference.

[0042] Optionally, the main poles 121-124, the first auxiliary poles 131-134, and the second auxiliary poles 141-144 are all flat cuboid structures and are made of DT4 pure iron material.

[0043] Specifically, the main pole posts 121-124, the first auxiliary pole posts 131-134, and the second auxiliary pole posts 141-144 are all flat cuboid structures, and are all made of DT4 pure iron material with high magnetic permeability and low coercivity. This improves magnetic energy conversion efficiency, reduces losses, and enables precise magnetic field control.

[0044] Optionally, the first focusing coil 151~154 and the second focusing coil 171~174 have the same number of turns, length and thickness, and are both hollow cuboid coils, with the coil material being an oxygen-free copper ring coated with insulating material; and the first fly-coil coil 161~164 and the second fly-coil coil 181~184 have the same number of turns, length and thickness, and are both hollow cuboid coils, with the coil material being an oxygen-free copper ring coated with insulating material.

[0045] Specifically, the first focusing coils 151-154 on the main poles 111-114 and the second focusing coils 171-174 on the first auxiliary poles 121-124 have the same number of turns, length, and thickness, and are all hollow cuboid coils. The first fly-foil coils 161-164 on the main poles 111-114 and the second fly-foil coils 181-184 on the second auxiliary poles 141-144 have the same number of turns, length, and thickness, and are all hollow cuboid coils. All of the above coils are made of oxygen-free copper rings with a surface-coated insulating material.

[0046] This avoids the generation of asymmetric magnetic field components in the magnetic pole components 111~114.

[0047] Optionally, the magnetic pole assembly 111~114 further includes: a first sub-pole post 131~134 disposed on the inner periphery of the frame core 101; and a second focusing coil 171~174 sleeved on the first sub-pole post 131~134, for generating a second focusing magnetic field that cooperates with the first focusing magnetic field to focus the electron beam.

[0048] Specifically, Figure 3 A schematic diagram of the focusing portion in a magnetic quadrupole lens according to an embodiment of this application is shown. (Reference) Figure 3 As shown, the inner periphery of the magnetic pole assemblies 111-114 is provided with first auxiliary pole posts 131-134. Among them, the second focusing coils 171-174 sleeved on the first auxiliary pole posts 131-134 are used to generate a second focusing magnetic field to focus the electron beam in conjunction with the first focusing magnetic field.

[0049] Therefore, the second focusing magnetic field generated by the first auxiliary pole pieces 131-134 can work in conjunction with the first focusing magnetic field generated by the main pole pieces 121-124 to focus the electron beam. Thus, the magnetic quadrupole lens 10 provided in this application can generate more focal spot sizes, achieve more adjustments to the focal spot size, and thereby achieve more gradually varying focus.

[0050] Optionally, the magnetic pole assembly 111~114 further includes: a second auxiliary pole post 141~144 disposed on the inner periphery of the frame core 101; and a second fly-focus coil 181~184 sleeved on the second auxiliary pole post 141~144, for generating a second fly-focus magnetic field that cooperates with the first fly-focus magnetic field to fly-focus the electron beam.

[0051] Specifically, Figure 4 A schematic diagram of the flying focal length portion in a magnetic quadrupole lens according to an embodiment of this application is shown. (Reference) Figure 4 As shown, a second auxiliary pole post 141-144 is provided on the inner periphery of the magnetic pole assembly 111-114. Among them, a second fly-focus coil 181-184 is sleeved on the second auxiliary pole post 141-144, which is used to generate a second fly-focus magnetic field to perform fly-focusing of the electron beam in conjunction with the first fly-focus magnetic field.

[0052] Therefore, the second flyfocus magnetic field generated by the second auxiliary pole pieces 141-144 can work in conjunction with the first flyfocus magnetic field generated by the main pole pieces 121-124 to flyfocus the electron beam. Thus, the magnetic quadrupole lens 10 provided in this application can increase the flyfocus distance and achieve a longer flyfocus range.

[0053] According to a second aspect of this application, an X-ray tube 20 is provided, including an electron beam generator 210 and an anode target disk 220, and also including the aforementioned magnetic quadrupole lens 10, disposed between the electron beam generator 210 and the anode target disk 220.

[0054] Specifically, Figure 5 A schematic diagram of the structure of an X-ray tube according to an embodiment of this application is shown. (Reference) Figure 5 As shown, the X-ray tube 20 includes an electron beam generator 210, an anode target disk 220, and a magnetic quadrupole lens 10. The magnetic quadrupole lens 10 is disposed between the electron beam generator 210 and the anode target disk 220. The electron beam generator 210 emits an electron beam; the magnetic quadrupole lens 10 focuses and defocuses the electron beam, controlling its trajectory. Thus, the electron beam, focused and defocused by the magnetic quadrupole lens 10, bombards the anode target disk 220, thereby generating X-rays.

[0055] According to a third aspect of this application, a method for focusing an electron beam is provided, comprising: passing the electron beam through the magnetic quadrupole lens 10 described above; applying the same magnitude of current to each of the first focusing coils 151-154 of the magnetic quadrupole lens 10, wherein the current polarities of adjacent first focusing coils 151-154 are opposite, thereby generating a rectangularly distributed first focusing magnetic field in a rectangular region at the center of the magnetic quadrupole lens 10; and focusing the electron beam using the rectangularly distributed magnetic field.

[0056] Specifically, Figure 6 A focusing structure diagram of a magnetic quadrupole lens according to an embodiment of this application is shown. Figure 7 A schematic diagram illustrating the focusing equivalent magnetic field distribution principle of a magnetic quadrupole lens according to an embodiment of this application is shown. (Reference) Figure 6 As shown, the four magnetic pole components 111-114 in the magnetic quadrupole lens 10 include main pole posts 121-124, first auxiliary pole posts 131-134, and second auxiliary pole posts 141-144. The main pole posts 121-124 are fitted with first focusing coils 151-154 and first flyfocus coils 161-164; the first auxiliary pole posts 131-134 are fitted with second focusing coils 171-174; and the second auxiliary pole posts 141-144 are fitted with second flyfocus coils 181-184. Furthermore, the current polarities of adjacent first focusing coils 151-154 are opposite.

[0057] For a magnetic field with a vertical quadrupole moment (i.e., four magnetic pole assemblies 111~114), its equimagnetic potential surface equation is xy = constant. (See reference) Figure 7As shown, the magnetic field lines originate from the N pole (i.e., the North Pole) and return to the S pole (i.e., the South Pole). The four main pole posts 121-124 are symmetrically arranged, and the magnetic field is zero along the axial direction. Within the aperture of the above structure, the magnetic field is linearly distributed. That is: ; .

[0058] Transforming the above formula, we get: ; .

[0059] Where G is the magnetic field gradient (unit: Tesla / meter, T / m), representing the rate of change of the magnetic field along the spatial direction. The component of the magnetic field in the X direction (unit: Tesla, T); This represents the component of the magnetic field in the Y direction (unit: Tesla, T).

[0060] The formula for calculating the magnetic field gradient G generated by the coil is as follows: .

[0061] Where G is the magnetic field gradient (unit: Tesla / meter, T / m). I is the permeability in vacuum (unit: Henry / meter, H / m). I is the excitation current intensity through the coil (unit: Ampere, A). N is the number of turns of the coil. a is the radius of the coil (unit: meter, m).

[0062] For positive particles, we have: ; .

[0063] in, This represents the force exerted on a positive particle in the X direction. Let q be the force exerted on the positive particle in the Y direction. Let q be the charge of the positive particle (unit: coulomb, C), and q > 0. The velocity component of a positive particle in the Z direction (unit: m / s). The magnetic field gradient is located in the X direction. Let be the magnetic field gradient in the Y direction.

[0064] During the focusing of the electron beam by the magnetic quadrupole lens 10, firstly, the currents of the first and second femtofocus coils 161-164 are set to 0. Then, with each of the first focusing coils 151-154 having 100 turns, the same current (I=4A) is applied to them. Furthermore, the current polarities are opposite between adjacent first focusing coils 151-154.

[0065] Optionally, the same current is applied to each of the second focusing coils 171-174 of the magnetic quadrupole lens 10, wherein the polarity of the current in the second focusing coils 171-174 is the same as the polarity of the current in the first focusing coils 151-154 of the same magnetic pole assembly, thereby generating a second focusing magnetic field that works in conjunction with the first focusing magnetic field to focus the electron beam.

[0066] Specifically, Figure 8 A magnetic field distribution diagram of the drift region of the focusing structure according to an embodiment of this application is shown. (Reference) Figure 7 and Figure 8 As shown, during the focusing of the electron beam by the magnetic quadrupole lens 10, the number of turns of the second focusing coils 171-174 is the same as that of the first flyfocus coils 161-164, both being 100. The same magnitude of current (I=4A) is applied to the second focusing coils 171-174. Furthermore, the polarity of the current in the second focusing coils 171-174 is the same as the polarity of the current in the first focusing coils 151-154, which are composed of the same magnetic pole assembly, generating a second focusing magnetic field that coordinates with the first focusing magnetic field to focus the electron beam.

[0067] At this time, the adjacent magnetic pole components 111-114 have opposite polarities. A rectangularly distributed first focusing magnetic field is generated in the rectangular region at the center of the magnetic quadrupole lens 10, thereby enabling the electron beam to be focused using the rectangularly distributed magnetic field.

[0068] According to a fourth aspect of this application, a method for fogging an electron beam is provided, comprising: passing the electron beam through the magnetic quadrupole lens 10 described above; applying a current of the same magnitude to each of the first fogging coils 161-164 of the magnetic quadrupole lens 10, wherein the current polarity is the same between the first fogging coils 161-164 of adjacent first pair of magnetic pole assemblies, and the current polarity is the same between the first fogging coils 161-164 of adjacent second pair of magnetic pole assemblies, and the current polarity is opposite between the first fogging coils 161-164 of the first pair of magnetic pole assemblies and the second pair of magnetic pole assemblies, thereby generating a uniform magnetic field in a first direction between the first pair of magnetic pole assemblies and the second pair of magnetic pole assemblies; and fogging the electron beam using the uniform magnetic field, such that the electron beam fogs in a second direction perpendicular to the first direction.

[0069] Specifically, the magnetic quadrupole lens 10 includes four magnetic pole assemblies 111-114, and the same magnitude of current is applied to each of the first flyfocus coils (161-164) of the four magnetic pole assemblies 111-114. The current polarity is the same between the first flyfocus coils 161-164 of adjacent first pairs of magnetic pole assemblies, the current polarity is the same between the first flyfocus coils 161-164 of adjacent second pairs of magnetic pole assemblies, and the current polarity is opposite between the first flyfocus coils 161-164 of the first and second pairs of magnetic pole assemblies.

[0070] For example, the first flyjord coil 161 of magnetic pole assembly 111 and the first flyjord coil 162 of magnetic pole assembly 112 have the same current polarity; the first flyjord coil 163 of magnetic pole assembly 113 and the first flyjord coil 164 of magnetic pole assembly 114 have the same current polarity; and the first flyjord coil 161 and the first flyjord coil 162 have opposite current polarities to the first flyjord coil 163 and the first flyjord coil 164.

[0071] Optionally, the same magnitude of current is applied to each of the second flyfocus coils 181-184 of the magnetic quadrupole lens 10, wherein the polarity of the current in the second flyfocus coils 171-174 is the same as the polarity of the current in the first flyfocus coils 161-164 of the same magnetic pole assembly, thereby generating a second flyfocus magnetic field that coordinates with the first flyfocus magnetic field to flyfocus the electron beam.

[0072] Specifically, Figure 9 A flying focal length structure diagram in the Z direction of a magnetic quadrupole lens according to an embodiment of this application is shown. Figure 10 A magnetic field distribution diagram of the drift region of the fly-foil structure in the Z direction according to an embodiment of this application is shown. Figure 11 A flying focal length structure diagram of a magnetic quadrupole lens in the X direction according to an embodiment of this application is shown. Figure 12 A magnetic field distribution diagram of the drift region of the flyfoil structure in the X direction according to an embodiment of this application is shown.

[0073] refer to Figure 9 and Figure 10As shown, during the process of focusing the electron beam in the Z direction using the magnetic quadrupole lens 10, firstly, the currents of the first focusing coils 151-154 and the second focusing coils 171-174 are set to 0. Then, with the number of turns of both the first focusing coils 161-164 and the second focusing coils 181-184 being 20, the same current (I=3A) is applied to the first focusing coils 161-164 and the second focusing coils 181-184. Furthermore, the current polarity is the same between the first focusing coils 161 and 162; the current polarity is the same between the first focusing coils 163 and 164; and the current polarity is opposite between the first focusing coils 161 and 162 and between the first focusing coils 163 and 164. Furthermore, the polarity of the current in the second fly-focus coils 181-184 is the same as the polarity of the current in the first fly-focus coils 161-164 with the same magnetic pole assembly, thereby generating a second fly-focus magnetic field that works in conjunction with the first fly-focus magnetic field to fly-focus the electron beam.

[0074] This generates a uniform magnetic field in the first direction (i.e., the X direction) between the first pair of magnetic pole components 111, 112 and the second pair of magnetic pole components 113, 114, thereby enabling the electron beam to be focused in the second direction (i.e., the Z direction) perpendicular to the first direction, thus achieving the deflection of the electron beam in the Z direction.

[0075] Similarly, refer to Figure 10 and Figure 11 As shown, during the process of focusing the electron beam in the X direction using the magnetic quadrupole lens 10, firstly, the currents of the first focusing coils 151-154 and the second focusing coils 171-174 are set to 0. Then, with the number of turns of both the first focusing coils 161-164 and the second focusing coils 181-184 being 20, the same current (I=3A) is applied to the first focusing coils 161-164 and the second focusing coils 181-184. Furthermore, the current polarity is the same between the first focusing coils 161 and 164; the current polarity is the same between the first focusing coils 162 and 163; and the current polarity is opposite between the first focusing coils 161 and 164 and between the first focusing coils 162 and 163. Furthermore, the polarity of the current in the second fly-focus coils 181-184 is the same as the polarity of the current in the first fly-focus coils 161-164 with the same magnetic pole assembly, thereby generating a second fly-focus magnetic field that works in conjunction with the first fly-focus magnetic field to fly-focus the electron beam.

[0076] Thus, a uniform magnetic field is generated in the first direction (i.e., the Z direction) between the first pair of magnetic pole components 111, 114 and the second pair of magnetic pole components 112, 113, thereby enabling the electron beam to be focused in the second direction (i.e., the X direction) perpendicular to the first direction, thereby achieving the deflection of the electron beam in the X direction.

[0077] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0078] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0079] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0080] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A magnetic quadrupole lens (10), characterized in that, include: Frame core (101); as well as Four magnetic pole assemblies (111~114) disposed on the inner periphery of the frame core (101) are used to generate a focusing magnetic field for focusing the electron beam and a fly-focusing magnetic field for fly-focusing the electron beam. The magnetic pole assembly (111~114) includes: The main pole post (121~124) is disposed on the inner periphery of the frame core (101) and extends toward the center of the frame core (101). The first focusing coil (151~154) sleeved on the main pole post (121~124) is used to generate the first focusing magnetic field for focusing the electron beam; as well as The first fly-focus coil (161-164), fitted onto the main pole post (121-124), is used to generate a first fly-focus magnetic field for fly-focusing the electron beam, wherein... The first fly-focus coil (161~164) is closer to the frame core (101) than the first focusing coil (151~154).

2. The magnetic quadrupole lens (10) according to claim 1, characterized in that, The magnetic pole assembly (111~114) also includes: The first auxiliary pole (131~134) and the second auxiliary pole (141~144) are disposed on the inner periphery of the frame core (101). A second focusing coil (171-174) fitted onto the first sub-pole post (131-134) is used to generate a second focusing magnetic field that coordinates with the first focusing magnetic field to focus the electron beam; and The second fly-focus coil (181-184) fitted onto the second sub-pole post (141-144) is used to generate a second fly-focus magnetic field that works in conjunction with the first fly-focus magnetic field to fly-focus the electron beam.

3. The magnetic quadrupole lens (10) according to claim 2, characterized in that, In the same magnetic pole assembly (111~114): The main pole (121~124) intersects with the first secondary pole (131~134) and the second secondary pole (141~144), and the first secondary pole (131~134) is symmetrically arranged with respect to the main pole (121~124) and the second secondary pole (141~144).

4. The magnetic quadrupole lens (10) according to claim 3, characterized in that, The included angle between the main pole posts (121~124) of adjacent magnetic pole assemblies (111~114) is 90°; The angle between the first secondary pole post (131~134) and the corresponding primary pole post (121~124) is 40°~60°; and The angle between the second auxiliary pole (141~144) and the corresponding main pole (121~124) is 40°~60°.

5. The magnetic quadrupole lens (10) according to claim 2, characterized in that, The frame core (101) is composed of a first core (102) and a second core (103), wherein the first core (102) and the second core (103) are semi-circular with their openings facing each other, and wherein... The first magnetic pole assembly (111) and the second magnetic pole assembly (112) of the four magnetic pole assemblies (111~114) are disposed on the first iron core (102) to form a first magnetic diode lens unit; and The third magnetic pole assembly (113) and the fourth magnetic pole assembly (114) of the four magnetic pole assemblies (111~114) are disposed on the second iron core (103) to form a second magnetic diode lens unit symmetrically arranged with the first magnetic diode lens unit.

6. The magnetic quadrupole lens (10) according to claim 2, characterized in that, The main pole (121~124), the first auxiliary pole (131~134) and the second auxiliary pole (141~144) are all flat cuboid structures and are made of DT4 pure iron material.

7. The magnetic quadrupole lens (10) according to claim 2, characterized in that, The first focusing coil (151~154) and the second focusing coil (171~174) have the same number of turns, length, and thickness, and are both hollow cuboid coils. The coil material is an oxygen-free copper ring with an insulating material coated on its surface; and The first flycoil coil (161~164) and the second flycoil coil (181~184) have the same number of turns, length and thickness. They are both hollow cuboid coils, and the coil material is an oxygen-free copper ring with an insulating material coated on the surface.

8. The magnetic quadrupole lens (10) according to claim 1, characterized in that, The magnetic pole assembly (111~114) also includes: The first auxiliary pole post (131~134) is disposed on the inner periphery of the frame core (101); and The second focusing coil (171~174) is fitted onto the first sub-pole post (131~134) and is used to generate a second focusing magnetic field that works in conjunction with the first focusing magnetic field to focus the electron beam.

9. The magnetic quadrupole lens (10) according to claim 1, characterized in that, The magnetic pole assembly (111~114) also includes: The second auxiliary pole (141~144) is disposed on the inner periphery of the frame core (101); and The second fly-focus coil (181-184) fitted onto the second sub-pole post (141-144) is used to generate a second fly-focus magnetic field that works in conjunction with the first fly-focus magnetic field to fly-focus the electron beam.

10. An X-ray tube (20), comprising an electron beam generator (210) and an anode target disk (220), characterized in that, It also includes a magnetic quadrupole lens (10) as described in any one of claims 1 to 9, disposed between the electron beam generator (210) and the anode target disk (220).

11. A method for focusing an electron beam, characterized in that, include: The electron beam is passed through the magnetic quadrupole lens (10) according to any one of claims 1 to 9. The same current is applied to each of the first focusing coils (151~154) of the magnetic quadrupole lens (10), wherein the current polarities of adjacent first focusing coils (151~154) are opposite, thereby generating a rectangularly distributed first focusing magnetic field in the rectangular region at the center of the magnetic quadrupole lens (10). as well as The electron beam is focused using the rectangularly distributed magnetic field.

12. The method according to claim 11, characterized in that, Also includes: Apply the same current to each of the second focusing coils (171~174) of the magnetic quadrupole lens (10), wherein the polarity of the current in the second focusing coils (171~174) is the same as the polarity of the current in the first focusing coils (151~154) of the same magnetic pole assembly, thereby generating a second focusing magnetic field that works in conjunction with the first focusing magnetic field to focus the electron beam.

13. A method for foveating an electron beam, characterized in that, include: The electron beam is passed through the magnetic quadrupole lens (10) according to any one of claims 1 to 9. The same current is applied to each of the first fly-focal coils (161-164) of the magnetic quadrupole lens (10), wherein the current polarity is the same between the first fly-focal coils (161-164) of adjacent first pair of magnetic pole assemblies, and the current polarity is the same between the first fly-focal coils (161-164) of adjacent second pair of magnetic pole assemblies, and the current polarity is opposite between the first fly-focal coils (161-164) of the first pair of magnetic pole assemblies and the second pair of magnetic pole assemblies, thereby generating a uniform magnetic field in a first direction between the first pair of magnetic pole assemblies and the second pair of magnetic pole assemblies; as well as The electron beam is focused using the uniform magnetic field, so that the electron beam is focused in a second direction perpendicular to the first direction.

14. The method according to claim 13, characterized in that, Also includes: Apply the same current to each of the second flyfocus coils (181~184) of the magnetic quadrupole lens (10), wherein the polarity of the current in the second flyfocus coils (171~174) is the same as the polarity of the current in the first flyfocus coils (161~164) of the same magnetic pole assembly, thereby generating a second flyfocus magnetic field that coordinates with the first flyfocus magnetic field to flyfocus the electron beam.

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