HK1195665B - Cathode control multi-cathode distributed x-ray apparatus and ct device having said apparatus - Google Patents

Description

Cathode-controlled multi-cathode distributed X-ray device and CT equipment with the same

Technical Field

The present invention relates to a device for generating distributed X-rays, and in particular to a cathode-controlled multi-cathode distributed X-ray device which generates X-rays whose focal positions are changed in a predetermined sequence by arranging multiple independent hot cathodes in an X-ray light source device and controlling the cathodes, and a CT device having the X-ray device.

Background Art

An X-ray light source refers to a device that generates X-rays. It typically consists of an X-ray tube, a power supply and control system, and auxiliary devices such as cooling and shielding. The core of the X-ray tube is the X-ray tube. An X-ray tube typically consists of a cathode, an anode, and a glass or ceramic housing. The cathode is a directly heated spiral tungsten filament. During operation, an electric current passes through it, heating it to an operating temperature of approximately 2000K, generating a thermally emitted electron beam. The cathode is surrounded by a metal cover with a slotted front end that focuses the electrons. The anode is a tungsten target embedded in the end face of a copper block. During operation, a high voltage of hundreds of thousands of volts is applied between the anode and cathode. The electrons generated by the cathode are accelerated by the electric field and fly toward the anode, where they strike the target surface, generating X-rays.

X-rays have a wide range of applications in industrial nondestructive testing, safety inspections, medical diagnosis, and treatment. In particular, X-ray fluoroscopic imaging devices, leveraging the high penetrating power of X-rays, play a vital role in everyday life. Early versions of these devices were film-based, two-dimensional fluoroscopic imaging devices. Current advancements include digital, multi-view, high-resolution stereoscopic imaging devices, such as computed tomography (CT), which can produce high-definition three-dimensional images or slices, representing advanced, high-end applications.

In CT equipment (including industrial flaw detection CT, luggage security CT, and medical diagnostic CT), an X-ray source is typically placed on one side of the object being inspected, and a detector that receives the X-rays is placed on the other side. As X-rays pass through the object, their intensity varies depending on the object's thickness, density, and other information. The intensity of the X-rays received by the detector contains structural information about the object from a specific viewing angle. By rotating the X-ray source and detector around the object, structural information from different viewing angles can be obtained. Using a computer system and software algorithms, this information is reconstructed to produce a 3D image of the object. Current CT equipment fixes the X-ray source and detector on a circular slip ring that surrounds the object. Each rotation produces an image of a thickness section of the object, called a slice. The object then moves along its thickness, producing a series of slices. These slices, combined, provide the object's detailed 3D structure. Therefore, in existing CT equipment, in order to obtain image information from different perspectives, the position of the X-ray source must be changed. Therefore, the X-ray source and detector need to move on slip rings. To increase inspection speed, the movement speed of the X-ray source and detector is usually very high. Due to the high-speed movement of the X-ray source and detector on the slip ring, the overall reliability and stability of the equipment are reduced. In addition, the CT inspection speed is also limited by the movement speed. Although the latest generation of CT in recent years uses circumferentially arranged detectors, which can prevent the detectors from moving, the X-ray source still needs to move on the slip ring. In addition, multiple rows of detectors can be added to move the X-ray source once a circle to obtain multiple slice images, thereby increasing the CT inspection speed. However, this does not fundamentally solve the problems caused by movement on the slip ring. Therefore, a CT system needs an X-ray source that can generate multiple perspectives without moving its position.

In addition, to increase inspection speed, the electron beam generated by the cathode of the X-ray source usually bombards the anode tungsten target continuously for a long time at high power. However, since the target area is very small, heat dissipation of the target also becomes a big problem.

To address the reliability, stability, and inspection speed issues associated with slip rings in existing CT equipment, as well as the heat resistance of the anode target, several methods have been proposed in existing patent literature. For example, rotating target X-ray sources can address the anode target overheating issue to a certain extent. However, their structure is complex, and the target point generating X-rays remains at a fixed position relative to the overall X-ray source. For example, some technologies, in order to achieve multiple viewing angles from a stationary X-ray source, closely arrange multiple independent traditional X-ray sources around a circumference, replacing the moving X-ray source. While this approach also achieves multiple viewing angles, it is costly, and the distance between targets at different viewing angles is large, resulting in poor imaging quality (stereoscopic resolution). Furthermore, Patent Document 1 (US4926452) proposes a light source and method for generating distributed X-rays. The anode target has a large area, alleviating the target overheating issue. Furthermore, the target point position varies along the circumference, enabling multiple viewing angles. Although Patent Document 1 employs scanning deflection of an accelerated high-energy electron beam, which presents challenges such as difficult control, inconsistent target position, and poor repeatability, it remains an effective method for generating a distributed light source. Furthermore, Patent Document 2 (US20110075802) and Patent Document 3 (WO2011/119629) propose a light source and method for generating distributed X-rays. The anode target has a large area, alleviating the problem of target overheating. Furthermore, the target points are dispersed and fixed in an array arrangement, enabling multiple viewing angles. Furthermore, carbon nanotubes are used as cold cathodes, arranged in an array. Field emission is controlled by voltage between the cathode and grid electrodes, allowing each cathode to emit electrons sequentially, bombarding the target points on the anode in a corresponding order, creating a distributed X-ray source. However, this method suffers from complex production processes and limited emission capacity and lifespan of the carbon nanotubes.

Summary of the Invention

The present invention is proposed to solve the above-mentioned problems. Its purpose is to provide a cathode-controlled multi-cathode distributed X-ray device that can generate multiple viewing angles without moving the light source and is conducive to simplifying the structure, improving system stability and reliability, and improving inspection efficiency.

The present invention provides a cathode-controlled multi-cathode distributed X-ray device, characterized by comprising: a vacuum box, which is sealed on all sides and has a high vacuum inside; a plurality of cathodes, each of which is independent of each other and arranged in a linear array and installed at one end of the interior of the vacuum box, and each cathode has a cathode filament, a cathode surface connected to the cathode filament, and filament leads extending from both ends of the cathode filament; a plurality of focusing current limiting devices, which are arranged in a linear array in a one-to-one correspondence with the cathodes and installed in the middle of the vacuum box near the cathodes, and the focusing current limiting devices are connected to each other; an anode, which is made of metal and installed at the other end of the interior of the vacuum box end, and is parallel to the focusing current limiting device in the length direction and forms a predetermined angle with the focusing current limiting device in the width direction; a power supply and control system, comprising a cathode power supply, a focusing current limiting device power supply connected to the mutually connected focusing current limiting devices, an anode high-voltage power supply, and a control device for performing integrated logical control of each power supply; a pluggable high-voltage connecting device, for connecting the anode and the anode high-voltage power supply, installed on the side of the vacuum box near the anode end; a plurality of pluggable cathode power supply connecting devices, for connecting the cathode and the cathode power supply, installed on the side of the vacuum box near the cathode end.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the cathode further comprises: a cathode shell, which surrounds the cathode filament and the cathode surface, and is provided with a beam opening at a position corresponding to the center of the cathode surface, a planar structure is provided at the outer edge of the beam opening, and an inclined surface is provided at the outer edge of the planar structure; a cathode shield, which surrounds the other surfaces of the cathode shell except the surface provided with the beam opening on the outside of the cathode shell, and the filament lead passes through the cathode shell and the cathode shield and is led out to the pluggable cathode power supply connection device.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the cathode housing and the cathode shield are in the shape of a cuboid, and the cathode surface and the beam opening corresponding to the center of the cathode surface are both rectangular.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the cathode housing and the cathode shield are in a rectangular parallelepiped shape, and the cathode surface and the beam opening corresponding to the center of the cathode surface are circular.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the cathode housing and the cathode shield are rectangular parallelepiped, the cathode surface is spherical arc-shaped, and the beam opening corresponding to the center of the cathode surface is circular.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the vacuum box is made of glass or ceramic.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the vacuum box is made of metal, and the inner wall of the vacuum box maintains a sufficient insulation distance from the multiple cathodes, the focusing current limiting device, and the anode.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the pluggable high-voltage connection device is internally connected to the anode and externally extends out of the vacuum box and is tightly connected to the vacuum box wall to form a vacuum sealing structure.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, each of the pluggable cathode power supply connection devices is connected to the filament lead of the cathode inside the vacuum box, extends out of the vacuum box, and is tightly connected to the vacuum box wall to form a vacuum sealing structure.

The cathode-controlled multi-cathode distributed X-ray device provided by the present invention also has: a vacuum power supply included in the power supply and control system; a vacuum device installed on the side wall of the vacuum box, using the vacuum power supply to work and maintain a high vacuum in the vacuum box.

The cathode-controlled multi-cathode distributed X-ray device provided by the present invention further comprises: a shielding and collimating device installed on the outside of the vacuum box, and a long strip opening corresponding to the anode is opened at the available X-ray outlet position.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the shielding and collimating devices are made of lead material.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the focusing current limiting device includes: an electric field balancing surface, which is made of metal and has a current limiting hole in its center; a focusing electrode, which is made of metal and is cylindrical, and its tip is facing the beam opening of the cathode, and the size of the current limiting hole is smaller than or equal to the center hole of the focusing electrode.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the multiple cathodes are arranged in a straight line, and the multiple focusing current limiting devices are also arranged in a straight line.

In the cathode-controlled multi-cathode distributed X-ray device provided by the present invention, the multiple cathodes are arranged in an arc shape, and the multiple focusing current limiting devices are also arranged in an arc shape corresponding to the multiple cathodes. The anode is a conical arc and is arranged in the order of the cathodes, the focusing current limiting devices, and the anodes. The plane where the outer edge arc of the anode is located is a third plane parallel to the first plane where the multiple cathodes are located and the second plane where the multiple focusing current limiting devices are located. The distance between the inner edge of the anode and the focusing current limiting device is farther than the distance between the outer edge of the anode and the focusing current limiting device.

The present invention provides a CT device, which is equipped with the cathode-controlled multi-cathode distributed X-ray device as described above.

The cathode-controlled multi-cathode distributed X-ray device of the present invention comprises multiple independent cathodes, multiple focusing current limiting devices, an anode, a vacuum box, a pluggable high-voltage connection device, multiple pluggable cathode power supply connection devices, a power supply, and a control system. The cathodes, focusing current limiting devices, and anodes are installed within the vacuum box, while the high-voltage connection device and cathode power supply connection device are mounted on the vacuum box wall, forming an integral sealed structure with the vacuum box. The cathodes generate electrons under the action of heat from the cathode filament. Typically, the focusing current limiting device has a negative voltage of hundreds of volts relative to the cathodes, confining the electrons within the cathodes. The control system, in accordance with the set control logic, causes each cathode power supply to sequentially deliver a kilovolt-level negative high-voltage pulse to each cathode. Upon receiving the negative high-voltage pulse, the electrons within the cathodes rapidly fly toward the focusing current limiting device, where they are focused into a small spot beam. These electrons then pass through the current limiting aperture and enter the high-voltage accelerating electric field between the focusing current limiting device and the anode. There, they are accelerated by an electric field of tens to hundreds of kilovolts, gaining energy and ultimately bombarding the anode, generating X-rays. Since there are multiple independent cathode arrays arranged, the positions where the electron beams are generated and the X-rays generated by bombarding the anodes are also arranged in corresponding arrays.

In the cathode-controlled multi-cathode distributed X-ray device of the present invention, X-rays with focal positions that change periodically in a certain order are generated in a light source device. The present invention adopts a hot cathode source, which has the advantages of large emission current and long life compared to other designs; multiple independent cathodes are arranged in a linear array, each cathode is independent and is controlled by an independent cathode power supply, which is convenient and flexible; the focusing current limiting devices corresponding to each cathode are arranged in a straight line and interconnected, and are at a stable small negative voltage potential, which is easy to control; there is a certain distance between the cathode and the focusing current limiting device, which is easy to process and produce; the design of a long large anode effectively alleviates the problem of anode overheating, which is conducive to increasing the power of the light source; the cathodes can be arranged in a straight line to form a linear distributed X-ray device as a whole, or the cathodes can be arranged in an arc shape to form an arc distributed X-ray device as a whole, which is flexible in application. Compared with other distributed X-ray light source devices, the present invention has large current, small target, uniform target position distribution and good repeatability, high output power, simple structure, and convenient control.

The distributed X-ray light source of the present invention is applied to CT equipment, and multiple viewing angles can be generated without moving the light source, so the slip ring movement can be omitted, which is conducive to simplifying the structure, improving system stability and reliability, and improving inspection efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a cathode-controlled multi-cathode distributed X-ray device according to the present invention.

FIG2 is a schematic diagram of the structure of an independent cathode in the present invention.

FIG3 is a schematic diagram of the structure of a focusing current limiting device in the present invention.

FIG4 is a schematic diagram of the structure of a rectangular cathode in the present invention, (A) is a side view, and (B) is a top view.

FIG5 is a schematic diagram showing a partial side structure of a distributed X-ray device using a rectangular cathode according to the present invention.

FIG6 is a schematic diagram showing the relative positional relationship among the cathode, the focusing current limiting device and the anode in an embodiment of the present invention.

FIG. 7 is a schematic diagram showing the structure of a distributed X-ray device arranged in an arc shape.

Description of reference numerals:

1, 11, 12, 13, 14, 15 cathode

2, 21, 22, 23, 24, 25 Focusing current limiting device

3 Anode

4 Vacuum box

5. Pluggable high-voltage connection device

6, 61, 62, 63, 64, 65 Pluggable cathode power connection device

7 Power supply and control system

8 Vacuum device

9 Shielding and collimation devices

E electron beam

X-ray

C The angle between the anode and the focusing current limiting device.

DETAILED DESCRIPTION

Hereinafter, the present invention will be described with reference to the accompanying drawings.

Figure 1 is a schematic diagram of a cathode-controlled multi-cathode distributed X-ray device according to the present invention. As shown in Figure 1 , the cathode-controlled multi-cathode distributed X-ray device according to the present invention comprises multiple cathodes 1 (at least two, hereinafter specifically referred to as cathodes 11, 12, 13, 14, 15, ...), multiple focus current limiting devices 2 corresponding to the multiple cathodes 1 (hereinafter specifically referred to as focus current limiting devices 21, 22, 23, 24, 25, ...), an anode 3, a vacuum box 4, a pluggable high-voltage connection device 5, multiple pluggable cathode power supply connection devices 6, and a power supply and control system 7.

Multiple cathodes 1, multiple focusing current limiting devices 2, and anodes 3 are installed inside the vacuum box 4. Multiple cathodes 1 are arranged in a straight line. Each of the multiple focusing current limiting devices 2 corresponds to each cathode 1 and is also arranged in a straight line. These two straight lines are parallel to each other and are parallel to the surface of the anode 3. The pluggable high-voltage connection device 5 and the pluggable cathode power supply connection device 6 are installed on the box wall of the vacuum box 4, forming an overall sealed structure with the vacuum box 4.

Furthermore, the cathode 1 is used to generate electrons and is mounted at one end (herein defined as the lower end, see FIG1 ) within the vacuum box 4 . FIG2 shows a structure of the cathode 1, comprising a cathode filament 101; a cathode surface 102; a cathode housing 103; a cathode shield 104; and filament leads 105. As shown in FIG2 , the cathode surface 102 and the cathode filament 101 are connected together and surrounded by the cathode housing 103. A beam aperture is provided at the center of the cathode surface 102 on the cathode housing 103. The cathode shield 104 surrounds the outer surface of the cathode housing 103, except for the surface with the beam aperture. The filament leads 105 extend from both ends of the cathode filament 101 and pass through the cathode housing 103 and the cathode shield 104. The cathode filament 101 is typically made of tungsten, and the cathode surface 102 is typically made of a material with strong thermal electron emission capability, such as barium oxide, scandate, or lanthanum hexaboride. The cathode housing 103 is made of metal and is electrically connected to one end of the cathode filament 101. A planar structure is designed around the outer edge of the beam opening on the surface of the cathode housing 103 where the beam opening is located, facilitating electric field concentration at and around the beam opening. An inclined surface is provided along the outer edge of this planar structure to facilitate a smooth transition of the electric field between adjacent cathodes. The cathode shield 104 is made of an insulating, high-temperature resistant material, such as ceramic, to provide mechanical strength protection and insulation between adjacent cathodes. Two openings are provided at the bottom of the cathode shield 104 for passage of two filament leads 105. However, the openings for passage of the two filament leads 105 are not limited to being located at the bottom of the cathode shield 104; they can be located in a position that allows passage of the filament leads 105. When the cathode is working, under the action of the cathode power supply, the cathode filament 101 heats the cathode surface 102 to 1000-2000°C, generating a large number of electrons on the cathode surface 102. Usually, the electric field at the beam opening of the cathode housing 103 is negative, and the electrons are confined within the cathode housing 103. If the power supply and control system 7 causes the cathode power supply to generate a negative high-voltage pulse, usually negative 2kV-10kV, for example, negative 5kV, the electric field at the beam opening becomes positive, and the electrons are emitted from the beam opening to become an emission electron beam E. The emission current density can reach several A/ ^cm2 .

In addition, the focusing and current limiting device 2 is used to focus the electron beam and limit its size. It is installed inside the vacuum box 4, close to the cathode 1. Figure 3 shows a structure of a single focusing and current limiting device 2. The focusing and current limiting device 2 consists of a focusing electrode 201, a current limiting hole 202 and an electric field equalization surface 203. The focusing and current limiting device 2 is an all-metal structure. The focusing electrode 201 is made of metal and is cylindrical. In addition, its tip is facing the beam opening of the cathode 1. The electric field converges from the beam opening on the upper surface of the cathode shell 103 and the surrounding plane to the tip of the focusing electrode 201 of the focusing and current limiting device 2, forming a focusing electric field, which produces a focusing effect on the electron beam emitted from the cathode 1. In addition, the electric field equalization surface 203 is made of metal, and the current limiting hole 202 is located at its center. The size of the current limiting hole 202 is less than or equal to the size of the central hole of the cylindrical focusing electrode 201. The electron beam enters the focusing current limiting device 2 through the central hole of the focusing electrode 201 and performs a brief forward drift motion. When reaching the current limiting hole 202, the electrons at the edge and with poor forward directivity are blocked by the current limiting structure around the current limiting hole 202 (that is, the portion of the electric field balancing surface 203 other than the current limiting hole 202). Therefore, only the electron beam with good forward directivity and concentrated in a small size range passes through the current limiting hole 202 and enters the high-voltage electric field between the focusing current limiting device 2 and the anode 3. Here, it is preferred that the central axis of the current limiting hole 202 is the same as the central axis of the focusing electrode 201, thereby enabling the electron beam with better forward directivity to pass through the current limiting hole 202 and enter the high-voltage electric field between the focusing current limiting device 2 and the anode 3. The electric field equalization surface 203 of the focusing current limiting device 2, which faces the anode 3, is a plane that is parallel to the surface of the anode 3 in the longitudinal direction (i.e., the left-right direction in Figures 1 and 3). This forms a high-voltage electric field between the focusing current limiting device 2 and the anode 3, with electric lines of force parallel to each other and perpendicular to the anode 3. A negative voltage -V is applied to the focusing current limiting device 2 by its power supply, which is used to form a reverse electric field at the beam opening of the cathode housing 103 (i.e., the electric field at the beam opening is negative), thereby limiting the thermal electrons on the cathode surface 102 from escaping the cathode housing 103.

Furthermore, the structure of the focusing and current limiting device 2 has been described above. However, the structure of the focusing and current limiting device 2 is not limited thereto. As long as it can perform both focusing and current limiting functions, other structures are also possible. For example, the electric field balancing surfaces 203 of multiple focusing and current limiting devices 2 may be integrally formed, and current limiting holes 202 may be formed at predetermined intervals. This can reduce the number of steps required to manufacture the focusing and current limiting device 2 and the X-ray device, thereby reducing manufacturing costs.

Furthermore, the cathode 1 can have a square outer surface and a circular inner surface, i.e., the cathode housing 103 and cathode shield 104 are rectangular parallelepipeds, the cathode surface 102 is circular, and the beam opening on the upper surface of the cathode housing 103 is circular. Furthermore, to achieve a better focusing effect for the electrons generated by the cathode surface 102, the cathode surface 102 is typically machined into a spherical arc shape. The diameter of the cathode surface 102 is typically several millimeters to tens of millimeters, for example, a diameter of 4 mm, and the diameter of the beam opening of the cathode housing 103 is typically several millimeters, for example, a diameter of 2 mm. The corresponding focusing electrode 201 of the focusing and current limiting device 2 is cylindrical, and the current limiting hole 202 is also circular. Typically, the diameter of the focusing electrode 201 is comparable to the diameter of the beam opening of the cathode housing 103. For example, the inner diameter of the focusing electrode 201 is 1.5 mm, and the diameter of the current limiting hole 202 is 1 mm. The distance from the focusing electrode 201 to the current limiting hole 202 of the focusing and current limiting device 2 is typically several millimeters, for example, a distance of 4 mm.

Furthermore, the cathode preferably has an internal and external rectangular structure. That is, the cathode housing 103 and cathode shield 104 are rectangular, and the cathode surface 102 and the beam opening corresponding to the center of the cathode surface 102 are both rectangular. The linear arrangement of the multiple cathodes 1 is oriented along the narrow side of each cathode (the width of the rectangle), while the direction perpendicular to the arrangement of the cathodes 1 is the wide side (the length of the rectangle). Figure 4 shows a rectangular cathode configuration, with (A) a side view and (B) a top view. The cathode surface 102 is rectangular, preferably a cylindrical arc surface, which facilitates further convergence of the electron beam along the narrow side. Typically, the arc surface has a length of several to more than ten millimeters and a width of several millimeters, for example, a length of 10 mm and a width of 3 mm. Regarding the dimensions of the beam opening on the top surface of the cathode housing 103, the width W is preferably 2 mm and the length D is preferably 8 mm. In addition, the focusing electrode 201 of the corresponding focusing current limiting device 2 is a rectangular cylindrical shape and the current limiting hole 202 is a rectangle, and multiple focusing current limiting devices 2 are arranged linearly according to the arrangement of multiple cathodes 1. Preferably, the inner hole size of the focusing electrode 201 is 8 mm long and 1.5 mm wide, and the size of the current limiting hole 202 is preferably 8 mm long and 1 mm wide. Preferably, the distance from the focusing electrode 201 to the current limiting hole 202 is 4 mm.

Furthermore, the anode 3 is a long metal strip mounted at the other end (here defined as the upper end, see FIG1 ) inside the vacuum chamber 4. It is parallel to the focusing current limiting device 2 in the length direction and forms a small angle with the focusing current limiting device 2 in the width direction. The anode 3 is completely parallel to the focusing current limiting device 2 in the length direction (as shown in FIG1 ). A positive high voltage is applied to the anode 3, typically ranging from tens to hundreds of kV, typically 180 kV, thereby forming a parallel high-voltage electric field between the anode 3 and the focusing current limiting device 2. The electron beam passing through the current limiting aperture 202 is accelerated by the high-voltage electric field, moving along the direction of the electric field and ultimately bombarding the anode 3, thereby generating X-rays. Furthermore, the anode 3 is preferably made of high-temperature-resistant tungsten metal.

In addition, Figure 5 shows a partial side view of a distributed X-ray device using a rectangular cathode 1 (herein, the left-right direction in the figure is the width direction, and the direction perpendicular to the paper is the length direction, which is the direction in which the cathodes 1 are arranged linearly). Figure 6 schematically illustrates the relative positional relationship between the cathode 1, the focusing current limiting device 2, and the anode 3, with (A) indicating the width direction and (B) indicating the length direction. As shown in Figures 5 and 6, the width direction of the anode 3 forms a small angle C with the focusing current limiting device 2. The X-rays generated by the electron beam bombarding the anode 3 are most intense in the direction at a 90-degree angle to the incident electron beam, and this direction becomes the direction in which the rays can be used. The anode 3 is tilted at a predetermined small angle C relative to the focusing and current limiting device 2, usually a few degrees to more than ten degrees, which is beneficial to the emission of X-rays. On the other hand, a wider electron beam (here, the width of the electron beam is denoted as T), for example, an electron beam with T=8mm is projected onto the anode 3. However, from the perspective of the emission direction of the X-rays, the generated ray focus H is smaller, for example, H=1mm, which is equivalent to reducing the focus size.

The vacuum box 4 is a sealed, hollow shell with a high vacuum interior. The shell is preferably made of an insulating material such as glass or ceramic, but can also be made of metal materials such as stainless steel. Furthermore, the walls of the vacuum box 4 maintain a sufficient insulation distance from the cathode 1, focusing current limiting device 2, and anode 3. Inside the vacuum box 4, multiple cathodes 1 are mounted at its lower end and arranged in a straight line. In the middle, near the cathodes 1, multiple focusing current limiting devices 2 are mounted in an array. Each focusing current limiting device 2 corresponds to a cathode 1 and is also arranged in a straight line. The electric field equalization surfaces 203 of adjacent focusing current limiting devices 2 are connected to form a plane. A long, rectangular anode 3 is mounted at the upper end. The anode 3, focusing current limiting device 2, and cathode 1 are parallel to each other in their lengthwise direction. The space inside the vacuum box 4 is sufficient for the electron beam to move in the electric field without any obstruction. The high vacuum within the vacuum box 4 is achieved by baking and exhausting the electrons in a high-temperature exhaust furnace, with a vacuum level typically better than ^10-5 Pa.

In addition, a pluggable high-voltage connector 5 is used to connect the anode 3 to the cable of the high-voltage power supply and is installed on the side of the vacuum box 4 near one end of the anode 3. The pluggable high-voltage connector 5 is internally connected to the anode 3 and externally extends outside the vacuum box 4 and is tightly connected to the box wall of the vacuum box 4 to form a vacuum-tight structure.

The pluggable cathode power supply connection device 6 (also collectively referred to as pluggable cathode power supply connection devices 61, 62, 63, 64, 65, etc.) is used to connect the cathode 1 to the cathode power supply and is installed on the side of the vacuum box 4 near one end of the cathode 1. The pluggable cathode power supply connection devices 6 have the same number and arrangement as the cathodes 1. Each cathode power supply connection device 6 is connected to the filament lead 105 of the cathode 1 inside the vacuum box 4 and extends outside the vacuum box 4 to tightly connect to the box wall of the vacuum box 4, forming a vacuum-sealed structure.

The power supply and control system 7 provides the necessary power and operational control for each component of the cathode-controlled multi-cathode distributed X-ray device. This system includes: multiple cathode power supplies (PS1, PS2, PS3, PS4, PS5, etc.) for cathode 1; a focus current limiting device power supply (-V) for focus current limiting device 2; an anode high-voltage power supply (+H.V.) for anode 3; and a control device. The control device performs comprehensive logical control of each power supply, thereby ensuring the normal operation of the entire system. It also provides an external control interface and a human-machine interface. Typically, the control system can be programmed to program and automatically adjust the output filament current and cathode negative high-voltage pulse magnitude of each cathode power supply through negative feedback, thereby achieving consistent X-ray intensity after the electron beam generated by each cathode is accelerated and impacts the target. Furthermore, the control system can be programmed to determine the operating sequence of each cathode based on the order in which the negative high-voltage pulses are output by each cathode power supply. This can include sequential operation of individual cathodes (e.g., 1st → 2nd → 3rd → 4th → 5th → ...), or sequential operation of multiple intermittent cathodes (e.g., (1st, 5th, 9th) → (2nd, 6th, 10th) → (3rd, 7th, 11th) → ...), among other programming schemes. Furthermore, while the cathode power supplies used to power the cathodes are multiple in the aforementioned embodiment (i.e., multiple cathode power supplies PS1, PS2, PS3, PS4, PS5, ...), it is also possible to have a single cathode power supply divided into multiple paths to power each cathode separately.

Furthermore, the cathode-controlled multi-cathode distributed X-ray device may also include a vacuum device 8. The vacuum device 8 is installed on the side wall of the vacuum box 4 and works under the action of a vacuum power supply to maintain a high vacuum inside the vacuum box 4. Usually, when the distributed X-ray device is working, the electron beam bombards the anode 3, so that the anode 3 will heat up and release a small amount of gas. In the present invention, the vacuum device 8 can be used to quickly extract this part of the gas to maintain a high vacuum degree inside the vacuum box 4. In addition, it is preferred that the vacuum device 8 uses a vacuum ion pump. Accordingly, the power supply and control system 7 of the cathode-controlled multi-cathode distributed X-ray device also includes a power supply Vacc PS for powering the vacuum device 8.

Furthermore, the cathode-controlled multi-cathode distributed X-ray device may further include a shielding and collimating device 9. The shielding and collimating device 9 is installed on the outside of the vacuum box 4 and is used to shield unnecessary X-rays. A long strip opening corresponding to the anode 3 is opened at the available X-ray outlet position. At this opening, a portion is provided along the X-ray emission direction to limit the X-rays to the required application range in the length direction, width direction, and vertical direction in Figure 5 (refer to Figure 5). In addition, the shielding and collimating device 9 is preferably made of lead.

It should be noted that in the cathode-controlled multi-cathode distributed X-ray device described above, the multiple cathodes 1 can be arranged in a linear or arc-shaped arrangement to meet different application requirements. Figure 7 is a schematic diagram of the structure of an arc-shaped cathode-controlled multi-cathode distributed X-ray device, with (A) being a perspective view and (B) being an end view. From top to bottom, the multiple cathodes 1 are arranged in an arc shape in a first plane, and the corresponding multiple focusing current limiting devices 2 are arranged in an arc shape in a second plane parallel to the first plane. In terms of vertical positional relationship, each focusing current limiting device 2 corresponds to each cathode 1. Furthermore, a conical arc-shaped anode 3 is arranged below the focusing current limiting device 2, parallel to the first plane in the arc direction, and radially forming a predetermined angle C with the first plane. Angle C is typically several to more than ten degrees, and the anode is tilted downward along its inner edge (as shown in Figure 7(B)). That is, the inner edge of the anode 3 is farther from the focusing current limiting device 2 than the outer edge of the anode 3. An electron beam is emitted from cathode 1, focused and limited by focusing and current-limiting device 2, then enters the space between the focusing and current-limiting device and the anode. Accelerated by a high-voltage electric field, it strikes anode 3, forming a series of arc-shaped focal spots 31, 32, 33, 34, 35, and so on on anode 3. The useful X-rays are directed toward the center of the arc. Arc-shaped distributed X-ray devices emit X-rays directed toward the center of the arc, making them suitable for applications requiring a circular arrangement of radiation sources.

(System composition)

As shown in Figures 1 to 7, the cathode-controlled multi-cathode distributed X-ray device of the present invention comprises multiple cathodes 1, multiple focusing current limiting devices 2, an anode 3, a vacuum box 4, a pluggable high-voltage connection device 5, multiple pluggable cathode power connection devices 6, and a power supply and control system 7. Furthermore, it may further comprise a vacuum device 8 and a shielding and collimation device 9. Multiple cathodes 1 are arranged in a linear array and mounted at the lower end of the vacuum box 4, with each cathode 1 being independent of the others. Multiple focusing current limiting devices 2 are mounted in the middle of the vacuum box 4, near the cathodes 1. The focusing current limiting devices 2 correspond one-to-one with the cathodes 1 and are also arranged in a linear array. All the focusing current limiting devices 2 are interconnected. A long strip of anode 3 is mounted at the upper end of the vacuum box 4. The array of cathodes 1, the array of focusing current limiting devices 2, and the anodes 3 are parallel to one another. A pluggable high-voltage connection device 5 is mounted on the upper end of the vacuum box 4. It is internally connected to the anode 3 and externally connectable to a high-voltage cable. Multiple pluggable cathode power supply connection devices 6 are mounted on the lower end of the vacuum box 4. These pluggable cathode power supply connection devices 6 are internally connected to the cathode 1 and externally connectable to each cathode power supply via a cable. A vacuum device 8 is mounted on the side wall of the vacuum box 4. The power supply and control system 7 includes multiple modules, including cathode power supplies PS1, PS2, PS3, PS4, PS5, ..., a focusing current limiting device power supply -V, a vacuum power supply Vacc PS, an anode high-voltage power supply +H.V., and a control device. These modules are connected to the cathodes 1, the focusing current limiting devices 2, the vacuum device 8, the anode 3, and other components via power and control cables.

(Working Principle)

In a cathode-controlled multi-cathode distributed X-ray device, under the control of the power supply and control system 7, multiple cathode power supplies PS1, PS2, PS3, PS4, PS5, ..., the focusing current limiting device power supply -V., the vacuum power supply Vacc PS, and the anode high-voltage power supply +H.V., among others, begin operating according to a pre-set program. The cathode power supplies power the cathode filament 101, which heats the cathode surface 102 to a very high temperature, generating a large amount of thermally emitted electrons. The focusing current limiting device power supply -V. applies a negative voltage of 200V to the interconnected focusing current limiting devices 2, creating a reverse electric field at the beam opening of each cathode 1, limiting the thermal electrons on the cathode surface 102 from escaping the cathode housing 103. The anode high-voltage power supply +H.V. provides a positive voltage of 160kV to the anode 3, forming a positive high-voltage electric field between the array of focusing current limiting devices 2 and the anode 3. At time 1, the power supply and control system 7 controls the cathode power supply PS1 to generate a 2 kV negative high-voltage pulse and supplies it to the cathode 11. The overall voltage of the cathode 11 drops in a pulsed manner, causing the electric field between the cathode 11 and the focusing current limiting device 21 to instantly change to a positive electric field. The thermal electrons in the cathode shell of the cathode 11 are emitted from the beam opening and fly toward the focusing electrode of the focusing current limiting device 21. During their movement, the thermal electrons are focused and become a small-sized electron beam. Most of them enter the central hole of the focusing electrode and reach the current limiting hole after a short drift motion. The edge electrons with poor forward direction are blocked by the current limiting structure around the current limiting hole. Only the electrons concentrated in a small size range and moving forward in a uniform manner pass through the current limiting hole, enter the positive high-voltage electric field, and are accelerated to gain energy. They eventually bombard the anode 3 and generate X-rays. The focal position of the X-rays is the projection of the line connecting the cathode surface 102 of the cathode 11, the focusing electrode 201 of the focusing current limiting device 21, and the current limiting hole 202 on the anode 3, i.e., the focal point 31. Moment 2: Similar to Moment 1, the power supply and control system 7 controls the cathode power supply PS2 to generate a 2 kV negative high-voltage pulse and supplies it to the cathode 12. The overall voltage of the cathode 12 drops in a pulsed manner, causing the electric field between the cathode 12 and the focusing current limiting device 22 to instantly change to a positive electric field. The thermal electrons in the cathode shell of the cathode 12 are emitted from the beam opening and fly toward the focusing electrode of the focusing current limiting device 22. During the movement, the thermal electrons are focused and become a small-sized electron beam. Most of them enter the central hole of the focusing electrode and reach the current limiting hole after a short drift motion. The edge electrons with poor forward direction are blocked by the current limiting structure around the current limiting hole. Only the electrons concentrated in a small size range and moving forward in a uniform manner pass through the current limiting hole, enter the positive high-voltage electric field, and are accelerated to gain energy. They eventually bombard the anode 3 and generate X-rays. The focus position of the X-rays is the projection of the line connecting the cathode surface 102 of the cathode 12, the focusing electrode 201 of the focusing current limiting device 22, and the current limiting hole 202 on the anode 3, that is, the focus 32. Similarly, at time 3, cathode 13 receives a pulsed negative high voltage, generating an electron beam. This electron beam is focused and current-limited by focusing and current-limiting device 23, entering the high-voltage electric field and being accelerated. It strikes anode 3, generating X-rays at focal position 33. At time 4, the focus is at position 34; at time 5, the focus is at position 35, and so on, until the last cathode emits a beam and the last focal position is reached, completing a working cycle. In the next cycle, X-rays are generated again, sequentially from focal positions 31, 32, 33, 34, and so on.

The gas released by the anode 3 when bombarded by the electron beam is evacuated in real time by the vacuum device 8, maintaining a high vacuum within the vacuum chamber 4 and facilitating long-term stable operation. The shielding and collimation device 9 shields X-rays from unwanted directions, allows X-rays in useful directions to pass through, and confines the X-rays to a predetermined range. In addition to controlling the various power supplies and driving the various components to coordinate operations according to pre-set programs, the power supply and control system 7 can also receive external commands through the communication interface and human-machine interface, modify and set key system parameters, update programs, and perform automatic control adjustments.

In addition, the cathode-controlled multi-cathode distributed X-ray device of the present invention can be applied to a CT device, thereby obtaining a CT device that can generate multiple viewing angles without moving the X-ray device.

(Effect)

The present invention provides a cathode-controlled multi-cathode distributed X-ray device, which generates X-rays in a light source device with a periodic change in focus position according to a predetermined sequence. The present invention uses a hot cathode source, which has the advantages of large emission current and long life compared to other designs; multiple independent cathodes are arranged in a linear array, and each cathode is independent and controlled by an independent cathode power supply, which is convenient and flexible; the focusing current limiting devices corresponding to each cathode are arranged in a straight line and interconnected, at a stable small negative voltage potential, which is easy to control; there is a large distance between the cathode and the focusing current limiting device, which is easy to process and produce; the design of a long large anode effectively alleviates the problem of anode overheating and is conducive to increasing the power of the light source; the cathodes can be arranged in a straight line to form a linear distributed X-ray device as a whole, or the cathodes can be arranged in an arc shape to form an arc distributed X-ray device as a whole, which is flexible in application. Compared with other distributed X-ray light source devices, the present invention has a large current and a small target, the target position distribution is uniform and repeatable, the output power is high, the structure is simple, and the control is convenient. In addition, when the distributed X-ray light source of the present invention is applied to CT equipment, multiple viewing angles can be generated without moving the light source. Therefore, the slip ring movement can be omitted, which is conducive to simplifying the structure, improving system stability and reliability, and improving inspection efficiency.

While the present invention has been described above, it is not limited thereto and should be understood that various modifications can be made within the scope of the present invention. For example, the anode is not limited to the anode used in the above-described embodiment; any anode capable of forming multiple target locations and providing excellent heat dissipation can be used in the present invention. Furthermore, the cathode is not limited to the cathode structure used in the embodiments of the present invention; any cathode capable of emitting X-rays can be used in the present invention.

Claims (15)

1. A cathode-controlled multi-cathode distributed X-ray device, characterized in that it comprises: Vacuum box, sealed on all sides and with a high vacuum inside; Multiple cathodes are installed independently and in a linear array at one end inside the vacuum box. Each cathode has a cathode filament, a cathode surface connected to the cathode filament, and filament leads extending from both ends of the cathode filament. Multiple focusing and current limiting devices are arranged in a linear array corresponding to the cathode and installed in the middle of the vacuum box near the cathode, and each focusing and current limiting device is interconnected. The anode, made of metal, is installed at the other end inside the vacuum box and is parallel to the focusing and current limiting device in the length direction and forms a predetermined angle with the focusing and current limiting device in the width direction; The power supply and control system includes a cathode power supply, a focusing current limiting device power supply connected to an interconnected focusing current limiting device, an anode high voltage power supply, and a control device for comprehensive logic control of each power supply. A pluggable high-voltage connection device for connecting the anode and the anode high-voltage power supply is installed on the side of the vacuum box near the anode end; and Multiple pluggable cathode power supply connection devices, used to connect the cathode and the cathode power supply, are installed on the side of the vacuum box near the cathode end. The focusing and current-limiting device includes: an electric field equalization surface made of metal with a current-limiting orifice in its center; and a focusing electrode made of metal and cylindrical in shape, with its tip facing the beam opening of the cathode. The size of the flow-limiting orifice is less than or equal to the center hole of the focusing electrode. 2. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1, characterized in that, The cathode further comprises: a cathode housing surrounding the cathode filament and the cathode surface, and having a beam opening at a position corresponding to the center of the cathode surface; a planar structure along the outer edge of the beam opening; and a chamfer along the outer edge of the planar structure; and a cathode shield surrounding the cathode housing on the outside of the cathode housing, excluding the surface with the beam opening. The filament lead passes through the cathode housing and the cathode shield and is led out to the pluggable cathode power connection device. 3. The cathode-controlled multi-cathode distributed X-ray device as described in claim 2, characterized in that, The cathode housing and the cathode shield are rectangular in shape, and the cathode surface and the beam opening corresponding to the center of the cathode surface are both rectangular. 4. The cathode-controlled multi-cathode distributed X-ray device as described in claim 2, characterized in that, The cathode housing and the cathode shield are rectangular in shape, and the cathode surface and the beam opening corresponding to the center of the cathode surface are circular. 5. The cathode-controlled multi-cathode distributed X-ray device as described in claim 2, characterized in that, The cathode housing and the cathode shield are rectangular in shape, the cathode surface is a spherical arc, and the beam opening corresponding to the center of the cathode surface is circular. 6. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, The vacuum box is made of glass or ceramic. 7. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, The vacuum box is made of metal. 8. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, The pluggable high-voltage connection device is internally connected to the anode and externally extends out of the vacuum box, tightly connected to the wall of the vacuum box, together forming a vacuum-sealed structure. 9. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, Each of the pluggable cathode power connection devices is connected inside the vacuum box to the filament lead of the cathode, extends out of the vacuum box, and is tightly connected to the vacuum box wall to form a vacuum-sealed structure. 10. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, It also includes: a vacuum power supply, included within the power supply and control system; and a vacuum device, installed on the side wall of the vacuum chamber, which operates using the vacuum power supply to maintain a high vacuum inside the vacuum chamber. 11. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, It also features a shielding and collimation device installed on the outside of the vacuum box, with an elongated opening at the available X-ray exit position corresponding to the anode. 12. The cathode-controlled multi-cathode distributed X-ray device as described in claim 11, characterized in that, The shielding and collimation device uses lead material. 13. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, The plurality of cathodes are arranged in a straight line, and the plurality of focusing and current-limiting devices are also arranged in a straight line accordingly. 14. The cathode-controlled multi-cathode distributed X-ray device as described in claim 1 or 2, characterized in that, The plurality of cathodes are arranged in an arc shape, and the plurality of focusing and current-limiting devices are also arranged in an arc shape corresponding to the plurality of cathodes. The anode is a conical arc shape, and the cathode, the focusing current limiting device and the anode are arranged in sequence. The plane containing the outer arc of the anode is a third plane parallel to the first plane containing the plurality of cathodes and the second plane containing the plurality of focusing current limiting devices. The distance between the inner edge of the anode and the focusing current limiting device is greater than the distance between the outer edge of the anode and the focusing current limiting device. 15. A CT scanner, characterized in that, The device comprises a cathode-controlled multi-cathode distributed X-ray apparatus as described in any one of claims 1 to 14.