HK1195665A - 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 same

Technical Field

The present invention relates to an apparatus for generating distributed X-rays, and more particularly, to a cathode-controlled multi-cathode distributed X-ray apparatus and a CT apparatus having the same, which generate X-rays with focal positions shifted in a predetermined order by arranging a plurality of independent hot cathodes and controlling the cathodes in one X-ray light source device.

Background

An X-ray source is a device that generates X-rays, and is generally composed of an X-ray tube, a power supply and control system, auxiliary devices such as a cooling and shielding device, and the core of the X-ray source is the X-ray tube. X-ray tubes are typically constructed with a cathode, anode, glass or ceramic envelope. The cathode is a directly-heated spiral tungsten wire, and is heated to the working temperature of about 2000K through current to generate electron beams for thermal emission when working, and the cathode is surrounded by a metal cover with a slot at the front end, and the metal cover enables electrons to be focused. The anode is a tungsten target embedded on the end face of the copper block, when the cathode works, hundreds of thousands of volts of high voltage are applied between the anode and the cathode, electrons generated by the cathode are accelerated to move under the action of an electric field, fly to the anode and impact the target surface, and thus X rays are generated.

X-rays have wide applications in the fields of industrial nondestructive testing, safety inspection, medical diagnosis and treatment, etc. In particular, a fluoroscopic X-ray imaging apparatus which is made by utilizing a high transmission capability of X-rays plays an important role in the aspect of daily life of people. The device is a film type planar perspective imaging device in the early days, the current advanced technology is a digital, multi-view and high-resolution stereo imaging device, such as ct (computed tomography), which can obtain high-definition three-dimensional stereo images or slice images, and is an advanced high-end application.

In a CT apparatus (including an industrial inspection CT, a baggage security inspection CT, a medical diagnosis CT, etc.), an X-ray source is usually disposed on one side of an object to be inspected, and a detector for receiving X-rays is disposed on the other side of the object to be inspected. If the X-ray source and the detector are switched around the detected object, the structural information of different view angle directions can be obtained. The information is structurally reconstructed by using a computer system and a software algorithm, so that a stereoscopic image of the detected object can be obtained. In the current CT apparatus, an X-ray source and a detector are fixed on a circular slip ring surrounding an object to be examined, and each time the X-ray source and the detector move one turn in operation, an image of a thickness section of the object to be examined is obtained, which is called a slice, and the object to be examined moves in the thickness direction to obtain a series of slices, which together are a three-dimensional fine three-dimensional structure of the object to be examined. Therefore, in the conventional CT apparatus, the position of the X-ray source is changed to obtain image information of different view angles, and therefore, the X-ray source and the detector need to move on the slip ring, and in order to increase the inspection speed, the movement speed of the X-ray source and the detector is usually very high. The reliability and stability of the whole device are reduced due to the high-speed movement of the X-ray source and the detector on the slip ring, and in addition, the examination speed of CT is limited due to the limitation of the movement speed. Although the latest generation of CT in recent years uses detectors arranged in a circle so that the detectors do not move, the X-ray source still needs to move on a slip ring, and in addition, a plurality of rows of detectors can be added so that the X-ray source moves for a circle to obtain a plurality of slice images so as to improve the CT inspection speed, however, the problem caused by the movement on the slip ring is not fundamentally solved. Therefore, there is a need for an X-ray source in a CT apparatus that is capable of producing multiple views without moving position.

In addition, in order to increase the inspection speed, the electron beam generated by the cathode of the X-ray source usually continuously bombards the anode tungsten target with high power for a long time, but the heat dissipation of the target point becomes a big problem because the area of the target point is small.

In order to solve the reliability, stability and inspection speed problems caused by the slip ring in the existing CT apparatus and the heat resistance of the anode target, some methods are provided in the existing patent documents. Such as a rotating target X-ray source, can solve the problem of overheating of the anode target to some extent, but its structure is complex and the target point for generating X-rays is still a defined target point position relative to the X-ray source as a whole. For example, in some techniques, in order to realize multiple views of a stationary X-ray source, a plurality of independent conventional X-ray sources are arranged closely on a circle to replace the movement of the X-ray source, which can also realize multiple views, but the cost is high, and the target point spacing of different views is large, and the imaging quality (stereo resolution) is poor. Further, in patent document 1 (US 4926452), a light source and a method of generating distributed X-rays are proposed, an anode target has a large area, the problem of overheating of the target is alleviated, and the target point position varies along the circumference, and a plurality of viewing angles can be generated. Although patent document 1 is a scanning deflection method for obtaining an accelerated high-energy electron beam, which has the problems of great control difficulty, no separation of target positions, and poor repeatability, it is still an effective method for generating a distributed light source. In addition, for example, patent document 2 (US 20110075802) and patent document 3 (WO 2011/119629) propose a light source and a method for generating distributed X-rays, the anode target has a large area, the problem of overheating of the target is alleviated, and the target points are distributed and fixed and arranged in an array, so that a plurality of viewing angles can be generated. In addition, carbon nanotubes are used as cold cathodes, the cold cathodes are arrayed, and field emission is controlled by using voltage between cathode grids, so that each cathode is controlled to emit electrons in sequence, targets are bombarded on anodes in corresponding sequence positions, and the distributed X-ray source is formed. However, the method has the disadvantages of complex production process and low emission capability and service life of the carbon nano tube.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a cathode-controlled multi-cathode distributed X-ray apparatus which can generate a plurality of viewing angles without moving a light source, and is advantageous in simplifying a structure, improving system stability, reliability, and improving inspection efficiency.

The present invention provides a cathode-controlled multi-cathode distributed X-ray device, comprising: the periphery of the vacuum box is sealed, and the inside of the vacuum box is in high vacuum; a plurality of cathodes, each of which is independent of each other and is arranged in a linear array at one end of the inside of the vacuum box, and each of which has a cathode filament, a cathode surface connected with the cathode filament, and filament leads led out from both ends of the cathode filament; the focusing current limiting devices and the cathodes are arranged in a linear array in a one-to-one correspondence mode and are arranged at the positions, close to the cathodes, of the middle part in the vacuum box, and the focusing current limiting devices are connected with one another; the anode is made of metal, is arranged at the other end in the vacuum box, is parallel to the focusing current limiting device in the length direction, and forms an included angle of a preset angle with the focusing current limiting device in the width direction; the power supply and control system is provided with a cathode power supply, a focusing current limiting device power supply connected with the mutually connected focusing current limiting devices, an anode high-voltage power supply and a control device for carrying out comprehensive logic control on each power supply; the pluggable high-voltage connecting device is used for connecting the anode with the anode high-voltage power supply and is arranged on the side surface of the vacuum box close to one end of the anode; and the pluggable cathode power supply connecting devices are used for connecting the cathode and the cathode power supply and are arranged on the side surface of the vacuum box close to one end of the cathode.

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

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, the cathode shell and the cathode shield are cuboid, and the surface of the cathode and the beam opening corresponding to the center of the surface of the cathode are rectangular.

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, the cathode shell and the cathode shield are cuboid, and the surface of the cathode and the beam opening corresponding to the center of the surface of the cathode are circular.

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, the cathode shell and the cathode shield are cuboid, the surface of the cathode is in a spherical arc shape, and the beam opening corresponding to the center of the surface of the cathode is in a circular shape.

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

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

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, the inner part of the pluggable high-voltage connecting device is connected with the anode, the outer part of the pluggable high-voltage connecting device extends out of the vacuum box and is tightly connected with the wall of the vacuum box, and a vacuum sealing structure is formed together.

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, each pluggable cathode power supply connecting device is connected with the filament lead of the cathode in the vacuum box, and the outer part of the pluggable cathode power supply connecting device extends out of the vacuum box and is tightly connected with the wall of the vacuum box to form a vacuum sealing structure together.

The cathode-controlled multi-cathode distributed X-ray device according to the present invention further includes: a vacuum power supply included within the power and control system; and the vacuum device is arranged on the side wall of the vacuum box and works by utilizing the vacuum power supply to maintain high vacuum in the vacuum box.

The cathode-controlled multi-cathode distributed X-ray device according to the present invention further includes: and the shielding and collimating device is arranged outside the vacuum box, and is provided with a long strip-shaped opening corresponding to the anode at the position of an available X-ray outlet.

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, the shielding and collimating device uses a 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 equalizing face made of metal and having a current limiting hole at a center thereof; the focusing electrode is made of metal and is cylindrical, the tip end of the focusing electrode is opposite to the beam opening of the cathode, and the size of the current limiting hole is smaller than or equal to the size of the central hole of the focusing electrode.

In the cathode-controlled multi-cathode distributed X-ray device provided by the invention, the plurality of cathodes are arranged in a linear manner, and the plurality of focusing current limiting devices are also arranged in a linear manner.

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

The present invention provides a CT apparatus including the cathode-controlled multi-cathode distributed X-ray device described above.

The cathode-controlled multi-cathode distributed X-ray device provided by the invention is provided with a plurality of independent cathodes, a plurality of focusing current-limiting devices, an anode, a vacuum box, a pluggable high-voltage connecting device, a plurality of pluggable cathode power supply connecting devices, a power supply and a control system. The cathode, the focusing current limiting device and the anode are arranged in the vacuum box, and the high-voltage connecting device and the cathode power supply connecting device are arranged on the wall of the vacuum box and form an integral sealing structure together with the vacuum box. The cathode generates electrons under the heating action of the cathode filament, and the focusing current limiting device usually has a negative voltage of the order of hundreds of volts with respect to the cathode, so that the electrons are limited in the cathode. The control system enables each cathode power supply to sequentially supply a kilovolt negative high-voltage pulse to each cathode according to the set control logic, electrons in the cathode receiving the negative high-voltage pulse quickly fly to the focusing current limiting device, are focused into small spot beam current, pass through the current limiting hole, enter a high-voltage accelerating electric field area between the focusing current limiting device and the anode, are accelerated by an electric field of dozens to hundreds of kilovolts, obtain energy, and finally bombard the anode to generate X rays. Because a plurality of independent cathode arrays are arranged, the generation position of the electron beam and the X-ray generated by bombarding the anode are correspondingly arranged in the arrays.

In the cathode-controlled multi-cathode distributed X-ray apparatus of the present invention, X-rays whose focal positions are periodically changed in a certain order are generated in one light source device. The invention adopts the hot cathode source, and has the advantages of large emission current and long service life compared with other designs; a plurality of independent cathodes are arranged to form a linear array, each cathode is independent and is controlled by an independent cathode power supply, and the device is convenient and flexible; the focusing current limiting devices corresponding to each cathode are arranged in a straight line and are mutually connected, are at a stable small negative voltage potential and are easy to control; a certain distance is reserved between the cathode and the focusing current limiting device, so that the processing and the production are easy; the design of the long strip-shaped large anode is adopted, so that the problem of overheating of the anode is effectively relieved, and the power of a light source is improved; the cathodes can be linearly arranged and integrally form a linear distributed X-ray device, and can also be arranged in an arc shape and integrally form an arc-shaped distributed X-ray device, so that the application is flexible. Compared with other distributed X-ray light source devices, the X-ray source device has the advantages of large current, small target point, uniform target point position distribution, good repeatability, high output power, simple structure and convenience in control.

The distributed X-ray light source is applied to CT equipment, and a plurality of visual angles can be generated without moving the light source, so that the movement of a slip ring can be omitted, the structure is simplified, the stability and the reliability of a system are improved, and the inspection efficiency is improved.

Drawings

Fig. 1 is a schematic view of a cathodically controlled multi-cathode distributed X-ray apparatus of the present invention.

Fig. 2 is a schematic diagram of the structure of an independent cathode in the present invention.

Fig. 3 is a schematic view showing a structure of a focusing current limiting device according to the present invention.

Fig. 4 is a schematic view of the structure of a rectangular cathode in the present invention, wherein (a) is a side view and (B) is a top view.

Fig. 5 is a schematic diagram of a partial side view of a distributed X-ray device using a rectangular cathode according to the present invention.

Fig. 6 is a schematic diagram illustrating a relative positional relationship between a cathode, a focus current limiting device, and an anode according to an embodiment of the present invention.

Fig. 7 is a schematic diagram showing the structure of a distributed X-ray device of a circular arc type arrangement.

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 connecting device

6. 61, 62, 63, 64, 65 pluggable cathode power supply connection device

7 power supply and control system

8 vacuum device

9 shielding and collimating device

E electron beam current

X X ray

The C anode and the focusing current limiting device form an included angle.

Detailed Description

The present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic view of a cathodically controlled multi-cathode distributed X-ray apparatus of the present invention. As shown in fig. 1, the cathode-controlled multi-cathode distributed X-ray device of the present invention includes a plurality of cathodes 1 (at least two of which will be hereinafter also referred to as cathodes 11, 12, 13, 14, 15, … …), a plurality of focusing current limiting devices 2 corresponding to the plurality of cathodes 1 (hereinafter also referred to as focusing current limiting devices 21, 22, 23, 24, 25, … …), an anode 3, a vacuum box 4, a pluggable high-voltage connection device 5, a plurality of pluggable cathode power supply connection devices 6, and a power supply and control system 7.

The plurality of cathodes 1, the plurality of focusing current limiting devices 2 and the anodes 3 are arranged inside the vacuum box 4, the plurality of cathodes 1 are arranged on a straight line, each of the plurality of focusing current limiting devices 2 corresponds to each cathode 1 respectively and is also arranged into a straight line, the two straight lines are parallel to each other and are parallel to the surface of the anodes 3, and the pluggable high-voltage connecting device 5 and the pluggable cathode power supply connecting device 6 are arranged on the box wall of the vacuum box 4 and form an integral sealing structure with the vacuum box 4.

Further, the cathode 1 for generating electrons is installed at one end (defined herein as a lower end, see fig. 1) inside the vacuum box 4. In addition, a structure of the cathode 1 is shown in fig. 2, including: a cathode filament 101; a cathode surface 102; a cathode casing 103; a cathode shield 104; filament legs 105. As shown in fig. 2, the cathode surface 102 is connected with the cathode filament 101 and they are surrounded by the cathode housing 103, beam openings are provided in the cathode housing 103 at positions corresponding to the center of the cathode surface 102, on the outside of the cathode housing 103,except for the faces provided with the beam openings, the other faces are surrounded by a cathode shield 104, and filament leads 105 are led out from both ends of the cathode filament 101 and pass through the cathode case 103 and the cathode shield 104. The cathode filament 101 is usually a tungsten filament, and the cathode surface 102 is usually made of a material having a high ability to emit electrons thermally, and for example, barium oxide, scandate, lanthanum hexaboride, or the like can be used. The cathode shell 103 is made of metal material and is electrically connected with one end of the cathode filament 101, a plane structure is designed on the outer edge of the beam opening on the surface of the cathode shell 103, which is provided with the beam opening, so that the electric field at the beam opening and around the beam opening is concentrated, and an inclined surface is arranged on the outer edge of the plane structure, so that the electric field between adjacent cathodes is in smooth transition. The cathode shield 104 is made of an insulating high-temperature-resistant material, and can be made of, for example, ceramic, for protecting the mechanical strength of the cathode and insulating the adjacent cathodes, and two openings for passing the two filament leads 105 are formed in the bottom of the cathode shield 104. However, the openings through which the two filament leads 105 pass are not limited to the bottom of the cathode shield 104, and may be provided at positions through which the filament leads 105 can pass. When the cathode works, under the action of a cathode power supply, the cathode filament 101 heats the cathode surface 102 to 1000-2000 ℃, the cathode surface 102 generates a large amount of electrons, the electric field at the beam opening of the cathode shell 103 is usually negative, the electrons are limited in the cathode shell 103, if the power supply and control system 7 enables the cathode power supply to generate a negative high-voltage pulse, usually negative 2-10 kV, for example negative 5kV, the electric field at the beam opening becomes a positive electric field, the electrons are emitted from the beam opening to become an emitted electron beam E, and the emitted current density can reach several A/cm²。

Further, a focusing current limiter 2 for focusing the electron beam current and limiting the size thereof is installed inside the vacuum chamber 4 near the cathode 1. Fig. 3 shows one configuration of a single focusing current limiting device 2. The focusing current-limiting device 2 is composed of a focusing electrode 201, a current-limiting hole 202 and an electric field equalization surface 203. The focusing current limiting device 2 is of an all-metal construction. The focusing electrode 201 is made of metal and is cylindrical, and the tip end of the focusing electrode faces the beam opening of the cathode 1, and an electric field converges from the beam opening on the upper surface of the cathode housing 103 and the surrounding plane to the tip end of the focusing electrode 201 of the focusing current limiting device 2, so that a focusing electric field is formed, and a focusing effect is generated on the electron beam emitted from the cathode 1. Furthermore, the field-equalizing surface 203 is made of metal, with the flow-restricting orifice 202 in the center thereof. The size of the current-limiting hole 202 is smaller than or equal to the size of the central hole of the tubular focusing electrode 201, the electron beam enters the focusing current-limiting device 2 through the central hole of the focusing electrode 201, and performs transient forward drift motion, when reaching the current-limiting hole 202, electrons with poor forward directionality at the edge are blocked by the current-limiting structure (i.e., the part of the electric field equalization surface 203 except the current-limiting hole 202) around the current-limiting hole 202, and therefore, only the electron beam with good forward directionality and concentrated in a small size range enters a high-voltage electric field between the focusing current-limiting device 2 and the anode 3 through the current-limiting hole 202. Here, the central axis of the current-limiting hole 202 is preferably the same as the central axis of the focusing electrode 201, and thus, the electron beam having better forward directivity can be made 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 equalizing surface 203 of the focusing current limiting device 2 opposite to the anode 3 is a plane parallel to the surface of the anode 3 in the length direction (i.e., the left-right direction in fig. 1 and 3) so as to form a high-voltage electric field having electric lines of force parallel to each other and perpendicular to the anode 3 between the focusing current limiting device 2 and the anode 3. The focusing current limiting device 2 is applied with a negative voltage-V by the power supply of the focusing current limiting device for forming a reverse electric field at the beam aperture of the cathode housing 103 (i.e. the electric field at the beam aperture is negative), thereby limiting the hot electrons at the cathode surface 102 from flying out of the cathode housing 103.

Further, although the structure of the focusing current limiter 2 has been described above, the structure of the focusing current limiter 2 is not limited to this, and other structures may be employed as long as the focusing and current limiting functions are achieved, for example, a plurality of electric field equalizing surfaces 203 of the focusing current limiters 2 are formed integrally, and the current limiting holes 202 are formed at predetermined intervals. Thus, the number of processes for manufacturing the focusing current limiting device 2 and the X-ray device can be reduced, and the manufacturing cost can be reduced.

The cathode 1 may have a structure with an outer square and an inner circle, that is, the cathode can 103 and the cathode shield 104 are rectangular parallelepiped, the cathode surface 102 is circular, and the beam opening on the upper surface of the cathode can 103 is circular. In addition, in order to achieve a better convergence effect of electrons generated from the cathode surface 102, the cathode surface 102 is generally processed into a spherical arc shape. The diameter of the cathode surface 102 is typically a few mm to ten mm, e.g. 4mm in diameter, and the diameter of the beam opening of the cathode housing 103 is typically a few mm, e.g. 2mm in diameter. The corresponding focusing electrode 201 of the focusing current limiting device 2 is cylindrical and the current limiting hole 202 is also circular, and generally, the diameter of the focusing electrode 201 is equivalent to the diameter of the beam current opening of the cathode housing 103, for example, the diameter of the inner hole of the focusing electrode 201 is 1.5mm, and the diameter of the current limiting hole 202 is 1 mm. The distance from the focusing pole 201 of the focusing flow restriction 2 to the flow restriction orifice 202 is typically a few mm, for example a distance of 4 mm.

Preferably, the cathode has an inner and outer rectangular configuration, that is, the cathode housing 103 and the cathode shield 104 are rectangular parallelepiped and the cathode surface 102 and the beam opening corresponding to the center of the cathode surface 102 are rectangular. The plurality of cathodes 1 are linearly arranged in a direction of a narrow side (width of a rectangle) of a single cathode, and in a direction perpendicular to the arrangement direction of the cathodes 1 in a direction of a wide side (length of a rectangle). Fig. 4 shows a structure of a rectangular cathode, where (a) is a side view and (B) is a top view. The cathode surface 102 is rectangular, preferably a cylindrical arc, which facilitates further convergence of the electron beam stream in the direction of the narrow side. Typically the arc has a length of a few mm to a dozen mm and a width of a few mm, for example a length of 10mm and a width of 3 mm. Regarding the dimensions of the beam aperture in the upper surface of the cathode housing 103, the width W is preferably 2mm and the length D is preferably 8 mm. In addition, the focusing electrode 201 of the corresponding focusing current limiting device 2 is in a rectangular parallelepiped shape and the current limiting hole 202 is in a rectangular shape, and a plurality of focusing current limiting devices 2 are arranged in a corresponding line according to the arrangement of the plurality of cathodes 1, preferably, the inner hole size of the focusing electrode 201 is 8mm long and 1.5mm wide, preferably, the size of the current limiting hole 202 is 8mm long and 1mm wide, and preferably, the distance from the focusing electrode 201 to the current limiting hole 202 is 4 mm.

Further, the anode 3 is a long strip of metal, is installed at the other end (defined herein as an upper end, see fig. 1) of the inside of the vacuum box 4, 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 fig. 1), a positive high voltage, usually several tens kV to several hundreds kV, typically 180kV, is applied to the anode 3, so that a parallel high voltage electric field is formed between the anode 3 and the focusing current limiting device 2, and the electron beam passing through the current limiting hole 202 is accelerated by the high voltage electric field, moves along the electric field direction, and finally bombards the anode 3, thereby generating X-rays. In addition, the anode 3 is preferably made of a high-temperature-resistant metal tungsten material.

Fig. 5 shows a partial side structure of a distributed X-ray device using a rectangular cathode 1 (here, the left-right direction in the drawing is defined as the width direction, and the direction perpendicular to the paper is defined as the longitudinal direction, that is, the direction in which the cathodes 1 are linearly arranged). Fig. 6 schematically shows the relative positional relationship among the cathode 1, the focus current limiter 2, and the anode 3, where (a) indicates the width direction and (B) indicates the length direction. As shown in fig. 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 bombardment of the anode 3 by the electron beam have the maximum intensity in the direction forming an angle of 90 degrees with the incident electron beam, and the direction becomes the usable direction of the rays. The anode 3 is inclined at a predetermined small angle C, typically several degrees to ten and several degrees, with respect to the focusing current limiting device 2, which is advantageous for the emission of X-rays, and on the other hand, a wider electron beam (here, the width of the electron beam is denoted as T) such as an electron beam with T =8mm is projected onto the anode 3, but the resulting radiation focus H is small, such as H =1mm, as viewed in the emission direction of the X-rays, which corresponds to a reduction in the focus size.

The vacuum box 4 is a hollow casing sealed at its periphery, and has a high vacuum inside, and the casing is preferably made of an insulating material, for example, glass, ceramic, or the like, but may be made of a metal material such as stainless steel. The vacuum box 4 has box wall, cathode 1, focusing current limiter 2 and anode3 maintain a sufficient insulation distance. In the interior of the vacuum box 4, a plurality of cathodes 1 are installed at the lower end thereof and arranged in a straight line, in the middle, a plurality of focusing current limiting devices 2 are installed close to the array of the cathodes 1, each focusing current limiting device 2 corresponds to the position of the cathode 1 and is also arranged in a straight line, in addition, the electric field equalizing surfaces 203 of the adjacent focusing current limiting devices 2 are connected with each other to form a plane, the long strip-shaped anode 3 is installed at the upper end, and in addition, the anode 3, the focusing current limiting devices 2 and the cathodes 1 are parallel to each other in the length 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 in the vacuum box 4 is obtained by baking and exhausting in a high-temperature exhaust furnace, and the vacuum degree is generally better than 10^-5Pa。

In addition, a pluggable high-voltage connection device 5 for connecting the anode 3 to a cable of a high-voltage power supply is installed on the side surface of the vacuum box 4 near one end of the anode 3. The inner part of the pluggable high-voltage connecting device 5 is connected with the anode 3, the outer part of the pluggable high-voltage connecting device extends out of the vacuum box 4 and is tightly connected with the box wall of the vacuum box 4, and a vacuum sealing structure is formed together.

The pluggable cathode power supply connection device 6 (the pluggable cathode power supply connection devices 61, 62, 63, 64, and 65 … … are also collectively referred to as the pluggable cathode power supply connection device 6) is used to connect the cathode 1 and the cathode power supply, and is attached to the side surface 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 mode as the cathodes 1, and each cathode power supply connection device 6 is connected with the filament lead 105 of the cathode 1 in the vacuum box 4, and the outside of the cathode power supply connection device extends out of the vacuum box 4 to be tightly connected with the box wall of the vacuum box 4 to form a vacuum sealing structure together.

The power supply and control system 7 provides the required power supply and operation control for the various components of the cathode-controlled multi-cathode distributed X-ray apparatus. The power supply and control system 7 comprises: a plurality of cathode power supplies PS1, PS2, PS3, PS4, PS5, … … for supplying power to the cathode 1; a focusing current limiting device power supply-v for supplying power to the focusing current limiting device 2; an anode high voltage power supply + h.v. for powering the anode 3; and a control device and the like. The control device carries out comprehensive logic control on each power supply, thereby controlling the normal work of the whole system and providing an external control interface and a man-machine operation interface. Typically, the magnitude of the filament current output from each cathode power supply and the magnitude of the negative high voltage pulse of the cathode can be programmed and automatically adjusted by negative feedback through the programming of the control system, so as to achieve the consistency of the intensity of the generated X-rays after the electron beam current generated by each cathode is accelerated and hit, and the operating timing of each cathode can be determined according to the sequence of the negative high voltage pulse output from each cathode power supply through the programming of the control system, and the operating timing can be determined by a single cathode (for example, 1 st → 2 nd → 3 rd → 4 th → 5 th → … …), or by a plurality of cathodes in intervals (for example, (1 st, 5 th, 9) → (2 nd, 6 th, 10 th) → (3 rd, 7 th, 11 th) → … …). In addition, although the cathode power source for supplying power to the cathode is provided in plural (i.e., plural cathode power sources PS1, PS2, PS3, PS4, PS5, and … …) in the above-described embodiment, one cathode power source may be divided into plural paths and supply power to each cathode.

Furthermore, the cathode-controlled multi-cathode distributed X-ray device may further include a vacuum device 8. The vacuum device 8 is installed on a sidewall of the vacuum box 4, and operates under the action of a vacuum power supply for maintaining a high vacuum in the vacuum box 4. In general, when the distributed X-ray device is in operation, the electron beam bombards the anode 3, so that the anode 3 may generate heat and release a small amount of gas, and in the present invention, the vacuum device 8 can be used to rapidly extract the gas, thereby maintaining a high vacuum degree inside the vacuum box 4. Further, the vacuum apparatus 8 preferably uses a vacuum ion pump. Correspondingly, the power supply and control system 7 of the cathode-controlled multi-cathode distributed X-ray device further comprises a power supply Vacc PS for powering the vacuum device 8.

Furthermore, the cathode-controlled multi-cathode distributed X-ray device may further comprise a shielding and collimating device 9. The shielding and collimating device 9 is installed outside the vacuum box 4 to shield unnecessary X-rays, and a long-sized opening corresponding to the anode 3 is opened at an available X-ray exit position, and a portion for limiting the X-rays to a desired application range in a longitudinal direction, a width direction, and an up-down direction in fig. 5 is provided at the opening along an X-ray emitting direction (refer to fig. 5), and further, it is preferable that the shielding and collimating device 9 is made of a lead material.

It should be noted that, in the cathode-controlled multi-cathode distributed X-ray device, the plurality of cathodes 1 may be arranged in a linear manner, but may also be arranged in an arc manner, so as to meet different application requirements. Fig. 7 is a schematic view of the structure of a circular arc cathode-controlled multi-cathode distributed X-ray device, where (a) is a perspective view and (B) is an end view. In order from the top down, the plurality of cathodes 1 are arranged in a circular arc shape in a first plane, the corresponding plurality of focusing current limiting devices 2 are arranged in a circular arc shape in a second plane parallel to the first plane, and the respective focusing current limiting devices 2 are in one-to-one correspondence with the respective cathodes 1 in the up-down positional relationship. Further, the anode 3 of a conical arc shape is disposed below the focusing current limiting device 2 in parallel with the first plane in the arc direction, and forms a predetermined angle C with the first plane in the radial direction, the angle C being usually several degrees to ten and several degrees, and the inclination direction being such that the inside edge of the anode is inclined downward (as shown in fig. 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 is from the focusing current limiting device 2. The electron beam is emitted from the cathode 1, enters between the focusing current limiting device and the anode after being focused and limited by the focusing current limiting device 2, is accelerated by a high-voltage electric field to bombard the anode 3, and a series of circularly arranged focuses 31, 32, 33, 34, 35 and … … formed on the anode 3 point to the center of a circular arc by the emitting direction of X rays. Emergent X rays of the arc-shaped distributed X-ray device all point to the circle center of the arc, and the device can be applied to occasions needing circular arrangement of the ray sources.

(System composition)

As shown in fig. 1 to 7, the cathode-controlled multi-cathode distributed X-ray device of the present invention includes a plurality of cathodes 1, a plurality of focusing current limiting devices 2, an anode 3, a vacuum box 4, a pluggable high-voltage connection device 5, a plurality of pluggable cathode power connection devices 6, and a power supply and control system 7, and may further include a vacuum device 8 and a shielding and collimating device 9. A plurality of cathodes 1 are arranged into a linear array and are arranged at the lower end inside a vacuum box 4, each cathode 1 is independent, a plurality of focusing current limiting devices 2 are arranged at the positions, close to the cathodes 1, of the middle part inside the vacuum box 4, the focusing current limiting devices 2 are in one-to-one correspondence with the cathodes 1 and are also arranged into a linear array, all the focusing current limiting devices 2 are connected with each other, a long strip-shaped anode 3 is arranged at the upper end inside the vacuum box 4, and the array of the cathodes 1, the array of the focusing current limiting devices 2 and the anode 3 are parallel to each other. Pluggable high-voltage connection device 5 is installed on the upper end of vacuum box 4, and its inside links to each other with positive pole 3, and the outside can connect high-voltage cable, and a plurality of pluggable negative pole power supply connection device 6 are installed at vacuum box 4 lower extreme, and pluggable negative pole power supply connection device 6 is inside to link to each other with negative pole 1, and outside accessible cable junction is to every negative pole power. The vacuum device 8 is mounted on the side wall of the vacuum box 4. The power supply and control system 7 includes a plurality of modules such as a plurality of 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., a control device, and is respectively connected to a plurality of cathodes 1, a plurality of focusing current limiting devices 2, a vacuum device 8, an anode 3, and the like through power cables and control cables.

(working principle)

In the cathode-controlled multi-cathode distributed X-ray apparatus, a plurality of cathode power supplies PS1, PS2, PS3, PS4, PS5, … …, a focus current limiting apparatus power supply-v., a vacuum power supply Vacc PS, an anode high-voltage power supply + h.v., and the like are respectively started to operate according to a set program under the control of the power supply and control system 7. The cathode power supply powers the cathode filament 101, and the cathode filament 101 heats the cathode surface 102 to a very high temperature, generating a large number of thermally emitted electrons; a power supply of the focusing current limiting device-V applies a negative voltage of 200V to the mutually connected focusing current limiting devices 2, and a reverse electric field is formed at the beam opening of each cathode 1 to limit the thermal electrons on the cathode surface 102 from flying out of the cathode shell 103. The anode high-voltage power supply + h.v. supplies a positive high voltage of 160kV to the anode 3, and a positive high-voltage electric field is formed between the array of the focusing current limiting devices 2 and the anode 3. Time 1: the power supply and control system 7 controls the cathode power supply PS1 to generate a 2kV negative high-voltage pulse and provide it to the cathode 11, the whole voltage of the cathode 11 falls in a pulse mode, so that the electric field between the cathode 11 and the focusing current-limiting device 21 is instantly changed into a positive electric field, the thermal electrons in the cathode shell of the cathode 11 are emitted from the beam opening and fly to the focusing electrode of the focusing current-limiting device 21, the thermal electrons are focused during the movement process and become small-sized electron beams, most of the thermal electrons enter the central hole of the focusing electrode and reach the current-limiting hole after the transient drifting movement, the marginal electrons with poor forward directionality are blocked by the current-limiting structure around the current-limiting hole, only the electrons concentrated in the small-sized range and forward in the positive high-voltage electric field pass through the current-limiting hole and are accelerated to obtain energy, and finally bombard the anode 3 to generate X-rays, the focal position of the X-rays is, The projection of the connecting line of the focusing electrode 201 and the flow restriction hole 202 of the focusing flow restriction device 21 on the anode 3, namely the focal point 31. Time 2: similar to the time 1, the power supply and control system 7 controls the cathode power supply PS2 to generate a negative high voltage pulse of 2kV and provide it to the cathode 12, the overall voltage of the cathode 12 falls in a pulse manner, so that the electric field between the cathode 12 and the focusing current limiting device 22 is instantaneously converted into a positive electric field, thermal electrons in the cathode shell of the cathode 12 are emitted from the beam opening and fly to the focusing electrode of the focusing current limiting device 22, the thermal electrons are focused during the movement process and become small-sized electron beams, most of the thermal electrons enter the central hole of the focusing electrode, after a short drift movement, the thermal electrons reach the current limiting hole, the marginal and poor-forward-directionality electrons are blocked by the current limiting structure around the current limiting hole, only the electrons concentrated in a small-sized range and forward uniformly pass through the current limiting hole, enter the positive high voltage electric field and are accelerated to obtain energy, and finally bombard the anode 3, the focal point of the X-ray is the projection of the connecting line of 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, i.e. the focal point 32. Similarly, at the time 3, the cathode 13 obtains a negative pulse high voltage to generate an electron beam, the electron beam is focused and limited by the focusing current limiting device 23, enters a high-voltage electric field area to be accelerated and bombard the anode 3 to generate X rays, and the focal position is 33; focal position 34 at time 4; focal position 35 at time 5; … … until the last cathode emits a beam current, resulting in the last focal position, completing a duty cycle. In the next cycle, the sequential generation of X-rays from the focal spot positions 31, 32, 33, 34, … … is repeated.

The gas released when the anode 3 is bombarded by the electron beam is pumped away by the vacuum device 8 in real time, so that high vacuum is maintained in the vacuum box 4, and the long-time stable operation is facilitated. The shielding and collimating device 9 shields the X-rays in the useless direction, lets the X-rays in the usable direction pass through, and confines the X-rays to a predetermined range. The power supply and control system 7 can control each power supply to drive each component to work coordinately according to a set program, and can receive external commands through a communication interface and a human-computer interface, modify and set key parameters of the system, update the program and perform automatic control and adjustment.

Further, the cathode-controlled multi-cathode distributed X-ray device of the present invention can be applied to a CT apparatus, and thus, a CT apparatus capable of generating a plurality of view angles without moving the X-ray device can be obtained.

(Effect)

The invention provides a cathode-controlled multi-cathode distributed X-ray device, which generates X-rays in a light source device, wherein the X-rays periodically change focal positions according to a preset sequence. The invention adopts the hot cathode source, and has the advantages of large emission current and long service life compared with other designs; a plurality of independent cathodes are arranged to form a linear array, and each cathode is independent and is controlled by adopting an independent cathode power supply, so that the device is convenient and flexible; the focusing current limiting devices corresponding to each cathode are arranged in a straight line and are mutually connected, and are at stable small negative voltage potential and easy to control; the cathode and the focusing current limiting device have a larger distance, so that the processing and the production are easy; the design of the long strip-shaped large anode is adopted, so that the problem of overheating of the anode is effectively relieved, and the power of a light source is improved; the cathodes can be linearly arranged and integrally form a linear distributed X-ray device, and can also be arranged in an arc shape and integrally form an arc-shaped distributed X-ray device, so that the application is flexible. Compared with other distributed X-ray light source devices, the distributed X-ray light source device has the advantages of large current, small target point, uniform target point position distribution, good repeatability, high output power, simple structure and convenience in control. In addition, under the condition that the distributed X-ray light source is applied to the CT equipment, a plurality of visual angles can be generated without moving the light source, so that the movement of a slip ring can be omitted, the structure is simplified, the stability and the reliability of the system are improved, and the inspection efficiency is improved.

As described above, the present invention has been explained, but the present invention is not limited to this, and it should be understood that various modifications can be made within the spirit of the present invention. For example, the anode is not limited to the anode used in the above-described embodiment, and any anode that can form a plurality of target positions and has excellent heat dissipation can be applied to the present invention, and the cathode is not limited to the cathode structure applied in the embodiment of the present invention, and any cathode that can emit X-rays can be applied to the present invention.

Claims (16)

1. A cathode-controlled multi-cathode distributed X-ray device is characterized by comprising:

the periphery of the vacuum box is sealed, and the inside of the vacuum box is in high vacuum;

a plurality of cathodes, each of which is independent of each other and is arranged in a linear array at one end of the inside of the vacuum box, and each of which has a cathode filament, a cathode surface connected with the cathode filament, and filament leads led out from both ends of the cathode filament;

the focusing current limiting devices and the cathodes are arranged in a linear array in a one-to-one correspondence mode and are arranged at the positions, close to the cathodes, of the middle part in the vacuum box, and the focusing current limiting devices are connected with one another;

the anode is made of metal, is arranged at the other end in the vacuum box, is parallel to the focusing current limiting device in the length direction, and forms an included angle of a preset angle with the focusing current limiting device in the width direction;

the power supply and control system is provided with a cathode power supply, a focusing current limiting device power supply connected with the mutually connected focusing current limiting devices, an anode high-voltage power supply and a control device for carrying out comprehensive logic control on each power supply;

the pluggable high-voltage connecting device is used for connecting the anode with the anode high-voltage power supply and is arranged on the side surface of the vacuum box close to one end of the anode; and

and the pluggable cathode power supply connecting devices are used for connecting the cathode and the cathode power supply and are arranged on the side surface of the vacuum box close to one end of the cathode.

2. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1,

the cathode further has: the cathode shell surrounds the cathode filament and the cathode surface, a beam opening is arranged at the position corresponding to the center of the cathode surface, a plane structure is arranged on the outer edge of the beam opening, and an inclined plane is arranged on the outer edge of the plane structure; a cathode shield surrounding the cathode case except for a surface provided with the beam opening, on the outer side of the cathode case,

the filament lead is led out to the pluggable cathode power supply connection device through the cathode shell and the cathode shield.

3. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the cathode shell and the cathode shield are cuboid in shape, and the beam opening holes on the surface of the cathode and corresponding to the center of the surface of the cathode are rectangular.

4. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the cathode shell and the cathode shield are cuboid in shape, and the beam open holes on the surface of the cathode and corresponding to the center of the surface of the cathode are circular.

5. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the cathode shell and the cathode shield are cuboid, the cathode surface is in a spherical arc shape, and the beam opening corresponding to the center of the cathode surface is in a circular shape.

6. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the vacuum box is made of glass or ceramic.

7. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the vacuum box is made of a metal material.

8. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the inner part of the pluggable high-voltage connecting device is connected with the anode, the outer part of the pluggable high-voltage connecting device extends out of the vacuum box and is tightly connected with the wall of the vacuum box, and a vacuum sealing structure is formed together.

9. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

each pluggable cathode power supply connecting device is connected with the filament lead of the cathode in the vacuum box, extends out of the vacuum box and is tightly connected with the wall of the vacuum box to form a vacuum sealing structure.

10. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

further comprising: a vacuum power supply included within the power and control system; and the vacuum device is arranged on the side wall of the vacuum box and works by utilizing the vacuum power supply to maintain high vacuum in the vacuum box.

11. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

further comprising: and the shielding and collimating device is arranged outside the vacuum box, and is provided with a long strip-shaped opening corresponding to the anode at the position of an available X-ray outlet.

12. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 11,

the shielding and collimating device uses lead material.

13. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the focusing current limiting apparatus includes: an electric field equalizing face made of metal and having a current limiting hole at a center thereof; a focusing electrode which is made of metal and is cylindrical, the tip end of the focusing electrode is opposite to the beam opening of the cathode,

the size of the flow limiting hole is smaller than or equal to the central hole of the focusing pole.

14. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the plurality of cathodes are arranged in a linear fashion, and the plurality of focusing current limiting devices are correspondingly arranged in a linear fashion.

15. The cathodically controlled multi-cathode distributed X-ray apparatus of claim 1 or 2,

the cathodes are arranged in an arc shape, and the focusing current limiting devices are also arranged in an arc shape corresponding to the cathodes,

the anode is in a conical arc shape, the cathode, the focusing current limiting device and the anode are sequentially arranged, the plane where the arc of the outer edge of the anode is located is a third plane parallel to the first plane where the plurality of cathodes are located and the second plane where the plurality of focusing current limiting devices are located, and 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.

16. A CT apparatus is characterized in that a CT scanner is provided,

the cathode-controlled multi-cathode distributed X-ray device according to any one of claims 1 to 15.