HK1204201B - X-ray device and ct equipment provided with same - Google Patents

Description

X-ray device and CT apparatus having the same

Technical Field

The present invention relates to an apparatus for generating distributed X-rays, and more particularly, to an external hot cathode distributed X-ray apparatus in which a plurality of independent hot cathode electron emission units are externally arranged in one X-ray light source device and X-rays whose focal positions are changed in a predetermined order are generated using grid control or cathode control, and a CT device having the same.

Background

Generally, 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 device and a 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 a high-temperature state through current to generate a heat-emitted electron beam current during working, 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, high voltage is applied between the anode and the cathode, electrons generated by the cathode fly to the anode in an accelerated motion under the action of an electric field and impact the target surface, and therefore 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, and 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 the existing CT apparatus, 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, which results in the decrease of the reliability and stability of the whole apparatus, and in addition, the inspection speed of the CT is also limited due to the limitation of the movement speed. 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 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 spot spacing between 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 an external hot cathode distributed X-ray device that 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, and a CT apparatus having the external hot cathode distributed X-ray device.

In order to achieve the above object, the present invention provides an external hot cathode distributed X-ray device including: the periphery of the vacuum box is sealed, and the inside of the vacuum box is in high vacuum; a plurality of electron emission units, each of which is independent and arranged in a linear array mounted on a sidewall of the vacuum box; an anode installed at a middle position inside the vacuum box, and parallel to an arrangement direction of the electron emission units in a length direction and forming an included angle of a predetermined angle with an installation plane of the electron emission units in a width direction; a power supply and control system having a high voltage power supply connected to the anode, an emission control device connected to each of the plurality of electron emission units, and a control system for controlling the respective power supplies, the electron emission units having: heating the filament; a cathode connected to the heating filament; filament leads led out from two ends of the heating filament; an insulating support surrounding the heating filament and the cathode; a focusing electrode disposed on the top end of the insulating support so as to be located above the cathode; and the connecting fixing piece is arranged above the focusing electrode and is connected with the box wall of the vacuum box in a sealing way, and the filament lead passes through the insulating support and is connected with the emission control device.

In addition, the external hot cathode distributed X-ray device according to the present invention further includes: the high-voltage power supply connecting device is used for connecting the anode with a cable of the high-voltage power supply and is arranged on the side wall of one end, close to the anode, of the vacuum box; the emission control device connecting device is used for connecting the heating filament and the emission control device; 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.

Further, in the external hot cathode distributed X-ray device according to the present invention, the electron emission unit further includes: a grid mounted between the cathode and the focus electrode and proximate to the cathode; and the grid lead is connected with the grid, penetrates through the insulating support and is connected with the emission control device.

Further, in the external hot cathode distributed X-ray device according to the present invention, the electron emission unit further includes: the focusing section is arranged between the focusing pole and the connecting and fixing piece; and a focusing device disposed so as to surround the focusing segment.

In addition, the external hot cathode distributed X-ray device according to the present invention further includes: a focusing power supply included within the power supply and control system; and the focusing device connecting device is used for connecting the focusing device and the focusing power supply.

In addition, in the external hot cathode distributed X-ray device of the present invention, the electron emission units are mounted in two rows on two opposite sidewalls of the vacuum box.

Further, in the external hot cathode distributed X-ray device of the present invention, the vacuum box is made of glass or ceramic.

Further, in the external hot cathode distributed X-ray device of the present invention, the vacuum box is made of a metal material.

In addition, in the external hot cathode distributed X-ray device of the present invention, the plurality of electron emission units are arranged in a linear shape or a piecewise linear shape.

In addition, in the external hot cathode distributed X-ray device of the present invention, the plurality of electron emission units are arranged in a circular arc shape or a segmented circular arc shape.

In addition, in the external hot cathode distributed X-ray device of the present invention, the arrangement intervals of the plurality of electron emission units are uniform.

In addition, in the external hot cathode distributed X-ray device of the present invention, the arrangement intervals of the plurality of electron emission units are non-uniform.

Furthermore, the invention provides a CT apparatus, characterized in that the X-ray source used is an external hot cathode distributed X-ray device as described above.

According to the present invention, there is provided an external hot cathode distributed X-ray device for generating X-rays with focal positions periodically changed in a certain order in a light source apparatus. The electron emission unit adopts the hot cathode, and has the advantages of large emission current and long service life compared with other designs; the electron emission units are independently fixed on the vacuum box, and a small two-pole or three-pole electron gun can be directly used, so that the technology is mature, the cost is low, and the application is flexible; 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 electron emission units can be linearly arranged and integrally form a linear type distributed X-ray device, and can also be annularly arranged and integrally form an annular type distributed X-ray device, so that the application is flexible; by the design of the focusing electrode, and the design of the external focusing means, the electron beam can achieve a very small focus. 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, convenience in control and low cost.

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 the structure of an external hot cathode distributed X-ray device of the present invention.

Fig. 2 is a schematic view of the positional relationship of the anode and the electron emission unit in the present invention.

Fig. 3 is a schematic diagram of the structure of an electron emission unit in the present invention.

Fig. 4 is a schematic diagram of the structure of a transmission control unit in the present invention.

Fig. 5 is a schematic diagram of the structure of an electron emission unit having a gate electrode and a focusing means in the present invention.

Fig. 6 is a schematic diagram of the structure of an emission control unit with gate control in the present invention.

Fig. 7 is a schematic view of the structure of another electron emission unit in the present invention.

Fig. 8 is a plan view of the structure of a cylindrical electron-emitting unit in the present invention, (a) is a case of a circular gate hole, and (B) is a case of a rectangular gate hole.

Fig. 9 is a plan view of the structure of a rectangular parallelepiped electron-emitting unit in the present invention, (a) is a case of a circular gate hole, and (B) is a case of a rectangular gate hole.

Fig. 10 is a schematic structural view of the cathode in the present invention, (a) is a planar circular cathode, (B) is a planar rectangular cathode, (C) is a spherical arc cathode, and (D) is a cylindrical arc cathode.

Fig. 11 is a schematic structural view of the grid of the present invention, (a) is a planar grid, (B) is a spherical grid, and (C) is a U-groove grid.

Fig. 12 is a schematic diagram of the autofocus using the control of the grid according to the present invention.

Fig. 13 is a schematic view showing the structure of a linear type double-row oppositely arranged external hot cathode distributed X-ray device according to the present invention, wherein (a) is a view showing the positional relationship among an electron emission unit, an anode and a vacuum box, and (B) is a view showing the positional relationship among the electron emission unit and the anode.

Fig. 14 is a schematic diagram of the structure of an external hot cathode distributed X-ray device in a circular arc type double-row opposite arrangement in the invention.

Fig. 15 is a schematic diagram of the main structure of a two-dimensional distributed X-ray device of the present invention.

Fig. 16 is a bottom view of the anode structure of the two-dimensional distributed X-ray device in the present invention.

Fig. 17 is a schematic diagram of an electron emission cell array in which gates are separated from cathodes in the present invention, (a) is a side view, (B) is a top view of each gate independent control pattern, and (C) is a top view of each gate interconnection and cathode control pattern.

Fig. 18 is a distributed X-ray device of the present invention with filaments connected in series.

Fig. 19 is a schematic diagram of the structure of a curved array distributed X-ray device of the present invention.

Fig. 20 is an end view schematic of the structure of a curved array distributed X-ray device of the present invention.

Fig. 21 is a schematic diagram of a different structure of an anode in the present invention.

Fig. 22 is a schematic view of the arrangement relationship of the electron emission unit and the anode of the ring type distributed X-ray device in the present invention.

Description of reference numerals:

1 Electron emission Unit

2 anode

3 vacuum box

4 high-voltage power supply connecting device

5 transmitting control device connecting device

6 focusing device connecting device

7 power supply and control system

8 vacuum device

E electron beam current

X X ray

Center of O-shaped arc

101 heating filament

102 cathode

103 insulating support

104 focus pole

105 connecting fixing piece

106 filament leads

107 grid

108 gate lead

109 focusing segment

110 focusing device

701 control system

702 high voltage power supply

703 emission control device

704 focusing power supply

70301 negative high voltage module

70302 DC module

70303 high-voltage isolation transformer

70304 negative voltage module

70305 positive voltage module

70306 switch module

801 vacuum pump

802 vacuum valve.

Detailed Description

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

Fig. 1 is a schematic view of the structure of an external hot cathode distributed X-ray device of the present invention. As shown in fig. 1, the external hot cathode distributed X-ray device of the present invention includes a plurality of electron emission units 1 (at least two, hereinafter also referred to as electron emission units 11, 12, 13, 14, … … specifically), an anode 2, a vacuum box 3, a high-voltage power supply connection device 4, an emission control device connection device 5, and a power supply and control system 7. Further, the electron emission unit 1 is composed of a heating filament 101, a cathode 102, an insulating support 103, a focusing electrode 104, a connection fixture 105, a filament lead 106, and the like. The anode 2 is installed in the middle inside the vacuum box 3, and the electron emission unit 1 and the high voltage power connection device 4 are installed on the box wall of the vacuum box 3 and constitute an integral sealing structure with the vacuum box 3.

Fig. 2 is a schematic diagram showing the relative positional relationship between the anode 2 and the electron emission unit 1 of the external hot cathode distributed X-ray device of the present invention. As shown in fig. 2, the plurality of electron emission units 1 are arranged in a straight line, the anode 2 is in the shape of a long bar corresponding to the arrangement of the electron emission units 1, and the anode 2 is parallel to the straight line formed by arranging the plurality of electron emission units 1 in the length direction, and the surface of the anode 2 facing the electron emission units 1 and the surface of the electron emission units 1 facing the anode 2 form an angle of a predetermined angle in the width direction.

The electron emission unit 1 is used for generating electron beam current according to requirements, is arranged on the side wall of the vacuum box 3, forms a sealing structure with the side wall of the vacuum box 3 through the connecting fixing piece 105, is wholly positioned outside the vacuum box 3, and can enter the inside of the vacuum box 3 through an opening in the middle of the connecting fixing piece 105. Further, one structure of the electron emission unit 1 is shown in fig. 3, and the electron emission unit 1 includes a heating filament 101, a cathode 102, an insulating support 103, a focusing electrode 104, a connection fixture 105, and a filament lead 106. The cathode 102 is connected to the heating filament 101, the heating filament 101 is usually made of tungsten, and the cathode 102 is usually made of a material having a strong ability to emit electrons thermally, such as barium oxide, scandate, lanthanum hexaboride, or the like. An insulating support 103 surrounds the heating filament 101 and the cathode 102, corresponding to a part of the housing of the electron emission unit 1, and is made of an insulating material, typically ceramic. The filament lead 106 is led out to the outside of the electron emission unit 1 through the insulating support 103, and a sealing structure is provided between the filament lead 106 and the insulating support 103. A focusing electrode 104 is mounted on the upper end of the insulating support 103, the focusing electrode 104 being of a nose-cone design with an opening in the middle and the center of the opening being aligned above and below the center of the cathode 102. The connecting fixture 105 is used to connect the electron emission unit 1 with the vacuum box 3 in a sealing manner, and is usually a knife flange, and has an opening in the middle for allowing the electron beam current E to enter the vacuum box 3 from the electron emission unit 1. The insulating support 103, the focusing electrode 104, and the connecting fixture 105 are closely coupled together so that the other portions of the electron emission unit 1 except for the central opening of the connecting fixture 105 form a vacuum sealed structure.

Further, the power supply and control system 7 includes a control system 701, a high-voltage power supply 702, an emission control device 703, and the like. The high voltage power supply 702 is connected to the anode 2 through a high voltage power supply connection 4 mounted on the cartridge wall of the vacuum cartridge 3. The emission control device 703 is connected to the filament leads 106 of the respective electron emission units 1 through the emission control device connecting means 5, respectively, and generally has the same number of emission control units as the number of electron emission units 1. In fig. 4, a structure of a transmission control unit is shown, and a transmission control device 703 includes a plurality of transmission control units, each of which includes a negative high voltage module 70301, a low voltage direct current module 70302, and a high voltage isolation transformer 70303. The negative high-voltage module 70301 is configured to generate a negative high-voltage pulse under the control of the control system 701, and an output of the negative high-voltage pulse is connected to a primary side of the high-voltage isolation transformer 70303; the low voltage dc module 70302 is used to generate current for heating the heating filament 106, and its output is connected to the low voltage terminals of the two sets of parallel secondary sides of the high voltage isolation transformer 70303, and is output to the filament lead 106 from the high voltage terminals of the two sets of parallel secondary sides through the transformer winding. The emission control means connecting means 5 are generally cables with connectors, the number of which is the same as the number of the electron emission units 1. The control system 701 controls the operating states of the high-voltage power supply 702 and the emission control device 703.

In addition, the vacuum box 3 is a cavity shell with sealed periphery, the inside of the vacuum box is high vacuum, and the shell can be made of insulating materials such as glass or ceramic. A plurality of electron emission units 1 are mounted on a sidewall of the vacuum box 3 (see fig. 1), the electron emission units 1 are arranged in a line, and an elongated anode 2 is mounted inside (see fig. 1), the anode 2 being parallel to the arrangement direction of the electron emission units 1 in the length direction. The space inside the vacuum box 3 is sufficient for the electron beam to move in the electric field without any obstruction. The high vacuum in the vacuum box 3 is obtained by baking and exhausting in a high-temperature exhaust furnace, and the vacuum degree is generally better than 10^-3Pa, recommended vacuum degree of better than 10^-5Pa 。

In addition, the casing of the vacuum box 3 is preferably made of metal, in the case of using metal material, the electron emission unit 1 is connected with the wall of the vacuum box 3 through the connecting fixture 105 thereof in a knife flange sealing manner, the anode 2 is fixedly installed in the vacuum box 3 by using an insulating support material, and a sufficient distance is maintained between the anode 2 and the casing of the vacuum box 3, so that high-pressure sparking is not generated.

The high-voltage power supply connection device 4 is used to connect the anode 2 to the cable of the high-voltage power supply 702, and is attached to the side wall of the vacuum box 3. The high voltage power supply connection means 4 is typically a conical ceramic structure with a metal column inside, one end of which is connected to the anode 2 and the other end of which is tightly connected to the box wall of the vacuum box 3, together forming a vacuum seal structure. The metal post inside the high voltage power connection 4 is used to electrically connect the anode 2 to the cable connector of the high voltage power supply 702. The high-voltage power supply connection device 4 and the cable connector are usually designed to be pluggable.

In addition, in the external hot cathode distributed X-ray device of the present invention, the electron emission unit 1 may further include a gate electrode 107 and a gate lead 108. In fig. 5, a structure of an electron emission unit 1 having a gate electrode and a focusing device is shown. As shown in fig. 5, a grid 107 is disposed between the cathode 102 and the focusing electrode 104, next to the cathode 102, the grid 107 is generally a mesh structure, the outer shape is generally the same as the cathode 102, a grid lead 108 is connected to the grid 107 and led out to the outside of the electron emission unit 1 through an insulating support 103, the grid lead 108 is hermetically connected to the insulating support 103, and the grid lead 108 is connected to an emission control device 703 through an emission control device connecting device 5.

In addition, in the external hot cathode distributed X-ray device of the present invention, the emission control unit of the emission control device 703 may further include a negative bias module 70304, a positive bias module 70305, and a selection switch 70306. A structure of an emission control unit with gate control is shown in fig. 6. As shown in fig. 6, the negative high voltage module 70301 is used to generate a negative high voltage, the output of which is connected to the primary side of the high voltage isolation transformer 70303; the mains supply is connected to the low-voltage terminals of the two sets of parallel secondary sides of the high-voltage isolation transformer 70303, and outputs power suspended at high voltage from the high-voltage terminals of the two sets of parallel secondary sides through the transformer windings, and the power is supplied to the dc module 70302, the negative bias module 70304 and the positive bias module 70305, respectively. The direct current module 70302 generates current for supplying power and heating to the heating filament 101; the negative bias block 70304 and the positive bias block 70305 generate a negative voltage and a positive voltage respectively and output to two input terminals of the selection switch 70306, and the selection switch 70306 selects a voltage to output to the gate lead 108 and finally to the gate 107 under the action of the control device 701.

In addition, in the external hot cathode distributed X-ray device of the present invention, the electron emission unit 1 may further include a focusing section 109 and a focusing device 110. As shown in fig. 5, the focusing segment 109 is connected between the focusing pole 104 and the connecting fixture 105, the focusing pole 104, the focusing segment 109 and the connecting fixture 105 may be an integral body formed by machining a metal piece, or three metal parts may be connected together by welding, the focusing device 110 is installed outside the focusing segment 109, and the focusing device 110 is generally a focusing coil. The focusing device 110 is connected to a focusing power supply 704 through a focusing device connecting device 6, the focusing device 110 is driven by the focusing power supply 704 to operate, and the operation state of the focusing power supply 704 is controlled by a power supply and control system 7. Correspondingly, the external hot cathode distributed X-ray device further comprises a focusing device connecting device 6, and the power supply and control system 7 further comprises a focusing power supply 704.

In addition, the external hot cathode distributed X-ray device of the present invention may further include a vacuum device 8 and a vacuum power supply 705, the vacuum device 8 includes a vacuum pump 801 and a vacuum valve 802, and the vacuum device 8 is mounted on a sidewall of the vacuum box 3. The vacuum pump 801 operates by the vacuum power source 705 for maintaining a high vacuum in the vacuum box 3. Generally, when the external hot cathode distributed X-ray device is in operation, electron beam bombards the anode 2, the anode 2 generates heat and releases a small amount of gas, and the vacuum pump 801 is used to rapidly pump out the gas, so as to maintain a high vacuum degree inside the vacuum box 3. The vacuum pump 801 preferably uses a vacuum ion pump. The vacuum valve 802 is typically an all-metal vacuum valve that can withstand high temperature baking, such as an all-metal manual gate valve. The vacuum valve 802 is normally in a closed state. Correspondingly, the power supply and control system 7 of the external hot cathode distributed X-ray device further comprises a vacuum power supply (Vacc PS) 705 of the vacuum device 8.

In addition, electron-emitting units of other structures can also be used in the present invention. Fig. 7 is a schematic view of the structure of another electron emission unit that can be used in the present invention. As shown in fig. 7, the electron emission unit 1 is composed of a heating filament 101A, a cathode 102A, a grid 103A, an insulating support 104A, a connection fixture 109A, and the like.

The electron emission unit 1 is configured as an integral sealing structure with the wall of the vacuum box 3 by the connection fixture 109A, but is not limited thereto, and may be mounted in other ways as long as the electron emission unit 1 can be mounted on the box wall of the vacuum box 3 and the entirety thereof is outside the vacuum box 3 (that is, the cathode terminal (including the heating filament 101A, the cathode 102A, and the grid 103A) of the electron emission unit 1 and the lead terminal (including the filament lead 105A, the grid lead 108A, and the connection fixture 109A) of the electron emission unit 1 are outside the vacuum box 3). The electron emission unit 1 includes a heating filament 101A, a cathode 102A, a grid 103A, an insulating support 104A, a filament lead 105A, and a connection fixture 109A, and the grid 103A is composed of a grid frame 106A, a grid 107A, and a grid lead 108A. The cathode 102A is connected to the heating filament 101A, the heating filament 101A is usually a tungsten filament, and the cathode 102A is usually made of a material having a strong ability to emit electrons thermally, for example, barium oxide, scandate, lanthanum hexaboride, or the like. The insulating support 104A surrounds the heating filament 101A and the cathode 102A, corresponds to a case of the electron emission unit 1, and employs an insulating material, typically ceramic. The filament lead 105A is led out to the lower end of the electron emission unit 1 through the insulating support 104A (but not limited thereto, as long as it is led out to the outside of the electron emission unit 1), and a sealing structure is provided between the filament lead 105A and the insulating support 104A. The gate electrode 103A is mounted on the upper end of the insulating support 104A (i.e., disposed on the opening of the insulating support 104A) and is opposed to the cathode 102A, preferably with the gate electrode 103A aligned up and down with the center of the cathode 102A. In addition, the gate 103A includes a gate frame 106A, a grid 107A, and a gate lead 108A, where the gate frame 106A, the grid 107A, and the gate lead 108A are all made of metal, and generally, the gate frame 106A is made of stainless steel material, the grid 107A is made of molybdenum material, and the gate lead 108A is made of kovar (alloy) material. The gate lead 108A is led out to the lower end of the electron emission unit 1 through the insulating support 104A (but not limited thereto, as long as it is led out to the outside of the electron emission unit 1), and a sealing structure is between the gate lead 108A and the insulating support 104A. The filament lead 105A and the gate lead 108A are connected to the emission control device 703.

Further, specifically, regarding the structure of the gate electrode 103A, the main body thereof is a metal plate (for example, stainless material) or a gate frame 106A, an opening is formed in the middle of the gate frame 106A, the shape of the opening may be square or circular or the like, a wire mesh (for example, molybdenum material) or a grid 107A is fixed at the position of the opening, and a lead (for example, kovar material) or a gate lead 108A is led out from a certain position of the metal plate, so that the gate electrode 103A can be connected to a potential. The gate electrode 103A is located directly above the cathode electrode 102A, the center of the opening of the gate electrode 103A is aligned with the center of the cathode electrode 102A (i.e., vertically on a vertical line), the shape of the opening corresponds to the shape of the cathode electrode 102A, and the size of the opening is generally smaller than the area of the cathode electrode 102A. However, the structure of the gate electrode 103A is not limited to the above structure as long as an electron beam can pass through the gate electrode 103A. In addition, the gate electrode 103A and the cathode electrode 102A are fixed in relative position by an insulating support member 104A.

Further, specifically, with regard to the structure of the connecting fixture 109A, it is recommended that its main body is a circular knife-edge flange, an opening is formed in the middle, the shape of the opening may be square or circular, etc., the position of the opening is connected with the upper end outer edge of the insulating support 104A in a sealing manner, such as welding, the outer edge of the knife-edge flange is formed with screw holes, the electron emission unit 1 can be fixed on the wall of the vacuum box 3 by bolting, and the knife-edge thereof is connected with the wall of the vacuum box 3 in a vacuum sealing manner. This is a flexible structure that is easy to disassemble, and when one of the plurality of electron emission units 1 fails, it can be flexibly replaced. It should be noted that the function of the connecting fixture 109A is to achieve a sealed connection between the insulating support 104A and the vacuum box 3, and there may be various flexible ways, such as welding via metal flange transition, or glass high-temperature melting sealing connection, or welding with metal after ceramic metallization.

Further, the electron emission unit 1 may have a cylindrical structure, that is, the insulating support 104A has a cylindrical shape, and the cathode 102A, the gate frame 106A, and the grid 107A may have a circular shape or a rectangular shape at the same time. Fig. 8 is a plan view of a cylindrical electron-emitting unit 1, in which (a) shows a structure in which the cathode 102A, the gate frame 106A, and the grid 107A are simultaneously circular, and (B) shows a structure in which the cathode 102A, the gate frame 106A, and the grid 107A are simultaneously rectangular. In addition, in the case of a circular cathode, it is generally preferable to form the surface of the cathode 102A into a spherical arc shape (as shown in fig. 10C) in order to achieve a better convergence effect of electrons generated on the surface of the cathode 102A. The diameter of the surface of the cathode 102A is typically several mm, for example, 2mm, and the diameter of the opening of the grid 107A mounted on the grid holder 106A is typically several mm, for example, 1 mm. Further, the distance from the gate electrode 103A to the surface of the cathode electrode 102A is usually a few tenths of mm to a few mm, for example, 2 mm. In addition, for a rectangular cathode, in order to achieve a better convergence effect of electrons generated on the surface of the cathode 102A, a cylindrical arc shape is generally preferred, which is favorable for further converging the electron beam flow in the narrow side direction. The arc surface is typically several mm to several tens of mm in length and several mm in width, for example 10mm in length and 2mm in width. Accordingly, the grid 107A is rectangular, preferably 1mm wide and 10mm long. Fig. 10 shows four configurations, i.e., a planar circle, a planar rectangle, a spherical arc, and a cylindrical arc, of the cathode 102A.

Further, the electron emission unit 1 may also be a rectangular parallelepiped structure, that is, the insulating support 104A is a rectangular parallelepiped, and the cathode 102A, the gate frame 106A, and the grid 107A may be simultaneously circular or simultaneously rectangular. Fig. 9 is a plan view of a rectangular parallelepiped electron-emitting unit 1, in which (a) shows a structure in which a cathode 102A, a gate frame 106A, and a grid 107A are simultaneously circular, and (B) shows a structure in which the cathode 102A, the gate frame 106A, and the grid 107A are simultaneously rectangular. It should be noted that the diagonal lines in fig. 8 and 9 are for the convenience of distinguishing the different components, and do not show the cross section.

Further, specifically, as for the structure of the grid 107A, as shown in fig. 11, it may be a plane type, a spherical type, or a U-groove type, and a spherical type is preferred because the spherical grid will provide a better focusing effect for the electron beam.

In addition, if the emission control device 703 changes the state of only one gate of the adjacent electron emission units, and only one of the adjacent electron emission units emits electrons at the same time to form an electron beam, the electric fields on both sides of the gate of the electron emission unit have an effect of auto-focusing on the electron beam. As shown in fig. 12, the direction of electron movement (the direction of the reverse power line) is indicated by an arrow between the electron emission unit 1 and the anode 2. In fig. 12, the anode 2 is at a high voltage +160kV, and the arrows of the large electric field between the electron emission unit 1 and the anode 2 are all directed from the electron emission unit 1 to the anode 2, that is, as long as the electron emission unit 1 emits the electron beam, the electron beam moves toward the anode 2. Considering the local electric field state of the surface of the electron emission unit 1, in the adjacent electron emission units 12, 13, 14, the voltage of the gate electrode 103A of the electron emission unit 13 is changed from-500V to +2000V, the electron emission unit 13 enters the electron emission state, the voltage of the gate electrodes 103A of the adjacent electron emission units 12 and 14 is still-500V, if there is electron emission in the electron emission units 12, 14, electrons move from the gate electrodes 103A of the electron emission units 12 and 14 to the gate electrode 103A of the electron emission unit 13, but since there is no electron emission in the electron emission units 12, 14, the electron beam emitted from the electron emission unit 13 is squeezed by the effect of the electric field directed from the electron emission unit 13 to the adjacent electron emission units 12 and 14, and thus, has an automatic focusing effect.

It should be noted that the external hot cathode distributed X-ray device of the present invention operates in a high vacuum state, and the method for obtaining and maintaining the high vacuum state may be: the anode 2 is installed in the vacuum box 3, the high-voltage power supply connecting device 4 and the vacuum device 8 are hermetically connected on the wall of the vacuum box 3, and the connection part of the electron emission unit on the side wall of the vacuum box 3 is sealed by a blind flange, so that the vacuum box 3 integrally forms a sealing structure; then the structure is placed in a vacuum furnace to be baked and degassed, and the vacuum valve 802 is connected with an external vacuum pumping system for removing gas adsorbed by the material of each part; then, in a normal-temperature clean environment, nitrogen is injected into the vacuum box 3 from the vacuum valve 802 to form a protective environment, and then the blind flange at the joint of the electron emission units is opened and the electron emission units are installed one by one; after all the electron emission units are installed, the vacuum valve 802 is connected with an external vacuum pumping system for pumping air, and baking and exhausting are carried out again to ensure that the inside of the vacuum box 3 is in high vacuum; the activation of the cathode of each electron emission unit can be carried out in the baking exhaust process; after the baking and exhausting are finished, the vacuum valve 802 is closed to keep the interior of the vacuum box 3 in high vacuum; in the working process of the external hot cathode distributed X-ray device, a small amount of gas released by the anode is pumped by the vacuum pump 801 to maintain high vacuum inside the vacuum box 3. When one electron emission unit is damaged or needs to be replaced when the service life of the electron emission unit is up, nitrogen is injected into the vacuum box 3 from the vacuum valve 802 to form protection; in the shortest time, the electron emission unit needing to be replaced is disassembled, and a new electron emission unit is installed; the vacuum valve 802 is connected with an external vacuum pumping device to pump vacuum to the vacuum box 3; when the inside of the vacuum box 3 reaches the high vacuum again, the vacuum valve 802 is closed, so that the inside of the vacuum box 3 is kept at the high vacuum.

In addition, it should be noted that in the external hot cathode distributed X-ray device of the present invention, the electron emission units 1 may be arranged on one side wall of the vacuum box 3, or may be arranged simultaneously in the same extending direction on two opposite side walls of the vacuum box 3. Fig. 13 shows a structure of a linear double-row externally-mounted hot cathode distributed X-ray device, in which (a) is a diagram of a positional relationship between the electron emission unit 1, the anode 2, and the vacuum box 3, and (B) is a diagram of a positional relationship between the electron emission unit 1 and the anode 2. As shown in fig. 13 (a), the plurality of electron emission units 1 are arranged in two rows on two opposite side walls of the vacuum box 3, respectively, and the anode 2 is arranged in the middle inside the vacuum box 3. As shown in fig. 13 (B), the surfaces of the anode 2 opposite to the two rows of electron emission units 1 are both inclined surfaces, an electron beam current E generated by the electron emission units 1 is accelerated by an electric field between the electron emission units 1 and the anode 2, and bombards the inclined surfaces of the anode 2 to generate X-rays, and the emission direction of the useful X-rays is the inclined direction of the inclined surfaces of the anode 2. Since the two rows of electron emission units 1 are arranged oppositely, the anode 2 has two inclined surfaces, and the X-rays generated by the two inclined surfaces are emitted in the same direction.

In addition, it should be noted that the external hot cathode distributed X-ray device of the present invention may be arranged in a linear manner or in an arc manner, so as to meet different application requirements. Fig. 14 is a schematic diagram showing a positional relationship between the electron emission unit 1 and the anode 2 of the arc-shaped external hot cathode distributed X-ray device of the present invention. Two rows of electron emission units 1 are arranged along the circumference and are respectively arranged on two opposite side surfaces of the vacuum box 3, the two side surfaces are mutually parallel, the extension direction of the arrangement of the electron emission units 1 is an arc line, and the size of the arranged radian can be determined according to the requirement. The anode 2 is arranged in the middle of the vacuum box 3, namely in the middle of the two rows of opposite electron emission units 1, the surfaces of the anode 2 facing the two rows of electron emission units 1 are all inclined planes, and the inclined directions of the two inclined planes point to the center O of the circular arc. The electron beam current E is emitted from the upper surface of the electron emission unit 1, is accelerated by a high-voltage electric field between the anode 2 and the electron emission unit 1, and finally bombards the anode 2, two rows of circularly arrayed series X-ray target points are formed on two inclined surfaces of the anode 2, and the emergent direction of useful X-rays points to the center of a circular arc. The vacuum box 3 of the arc-shaped external hot cathode distributed X-ray device is also arc-shaped or called ring-shaped, corresponding to the arrangement of the electron emission units 1 and the shape of the anode 2. Emergent X rays of the arc-shaped distributed X-ray device all point to the circle center of the arc, and the method can be applied to the condition that the ray sources are required to be circularly arranged.

In addition, it should be noted that, in the external hot cathode distributed X-ray device, the arrangement of each electron emission unit may be a straight line, or may be a segmented straight line such as an L-shape or a U-shape, and further, the arrangement of each electron emission unit may be an arc, or may be a segmented arc, for example, a curve formed by connecting arc segments with different diameters, or a combination of a straight line segment and an arc segment.

In addition, it should be noted that, in the external hot cathode distributed X-ray device of the present invention, the arrangement pitch of the electron emission units may be uniform or non-uniform.

In addition, in the present invention, the electron emission units can be arranged so as to be distributed in a two-dimensional array, and thus a two-dimensional array distributed X-ray apparatus can be obtained. As shown in fig. 15 and 16, the two-dimensional array distributed X-ray device has a plurality of electron emission units 1 (at least four, hereinafter also referred to as electron emission units 11a, 12a, 13a, 14a, … …, electron emission units 11b, 12b, 13b, 14b, … …), the electron emission units may be any of the electron emission units described above, and the anode 2 is composed of an anode plate 201 and a plurality of targets 202 mounted on the anode plate 201 and arranged corresponding to the electron emission units 1, but the anode 2 is not limited to this structure, and an anode commonly used in the art may be used. Further, a plurality of electron emission units 1 are arranged in a two-dimensional arrangement on one side wall of the vacuum box 3, and are parallel to the plane on which the anode plate 201 is located. Further, as described above, the electron emission unit 1 is entirely outside the vacuum box 3, and the anode 2 is disposed inside the vacuum box 3.

A schematic structural view of the spatial arrangement of the electron emission unit 1 and the anode 2 is shown in fig. 15 (here, the illustration of the vacuum box 3 is omitted). The electron emission units 1 are arranged in two rows on one plane (i.e., one sidewall of the vacuum box 3), and the electron emission units 1 of the front and rear rows are staggered (see fig. 15), but it is not limited thereto, even if the electron emission units of the front and rear rows are not staggered with each other. The targets 202 on the anode 2 correspond to the electron emission units 1 one by one, the top surfaces of the targets 202 point to the electron emission units 1, and a line connecting the centers of the electron emission units 1 and the centers of the targets 202 is perpendicular to the plane of the anode plate 201, and the line is also a motion path of an electron beam current E emitted by the electron emission units 1. The electrons bombard the target to generate X-rays, the exit direction of the useful X-rays is parallel to the plane of the anode plate 201, and the useful X-rays are parallel to each other.

One configuration of the anode 2 is shown in fig. 16. The anode 2 includes: an anode plate 201; a plurality of targets 202 distributed in a two-dimensional array. The anode plate 201 is a flat plate made of a metal material, and preferably a high temperature resistant metal material, which is completely parallel to the plane formed by the upper surface of the electron emission unit 1, and when a positive high voltage, usually several tens kV to several hundreds kV, typically, for example, 180kV, is applied to the anode 2, so that a parallel high voltage electric field is formed between the anode plate 201 and the electron emission unit 1. The targets 202 are mounted on the anode plate 201 at positions arranged in a manner to correspond to the positions of the electron emission units 1, respectively, and the surfaces of the targets 202 are usually made of a high-temperature-resistant heavy metal material such as tungsten or a tungsten alloy. The target 202 is a circular frustum structure, the height is usually several mm, for example 3mm, the bottom surface with larger diameter is connected with the anode plate 201, the diameter of the top surface is smaller, usually several mm, for example 2mm, the top surface is not parallel to the anode plate 201, and a small included angle of several degrees to ten and several degrees is usually formed, so that useful X-rays generated by electron targeting can be conveniently emitted. All targets 202 are arranged in such a manner that the top surface inclination direction is uniform, that is, the emission direction of all useful X-rays is uniform. The structural design of the target is equivalent to a small bulge growing on the anode plate 201, and the local electric field distribution on the surface of the anode plate 201 is changed, so that the electron beam has an automatic focusing effect before bombarding the target, the target spot is reduced, and the image quality is favorably improved. In the design of the anode, the anode plate 201 is made of common metal, and only the surface of the target 202 is made of tungsten or tungsten alloy, thereby reducing the cost.

Further, in the present invention, the electron emission unit may be a structure in which the gate electrode and the cathode electrode are separated. An array of electron emitting cells with separate gates and cathodes is shown in fig. 17. In fig. 17, the flat grid 9 is composed of an insulating skeleton plate 901, a grid plate 902, a grid 903, and a grid lead 904. As shown in the figure, a grid plate 902 is disposed on an insulating skeleton plate 901, a grid 903 is disposed at a position of an opening formed on the grid plate 902, and a gate lead 904 is led out from the grid plate 902. The cathode array 10 is composed of a plurality of cathode structures closely arranged, each cathode structure is composed of a filament 1001, a cathode 1002, and an insulating support 1004. The flat grid 9 is above the cathode array 10 and the distance between the two is small, typically a few mm, for example 3 mm. The grid structures formed by the grid plate 902, the grids 903, and the grid leads 904 correspond to the cathode structures one to one, and the circle center of each grid 903 and the circle center of each cathode 1002 coincide two by two when viewed in the vertical direction.

Further, as shown in fig. 17 (B), in the present invention, the gate structure may be a structure in which each gate lead is independently drawn and state control is independently performed by the gate control device. Each cathode 1002 of the cathode array 10 may be at the same potential, for example, grounded, and each gate is switched between two states of minus several hundred volts and plus several thousand volts, for example, between-500V and +2000V, so as to control the operation state of each electron emission unit, for example, when a certain gate is-500V at a certain time, the electric field between the gate and the corresponding cathode is a negative electric field, electrons emitted from the cathode are confined on the surface of the cathode, when the gate voltage becomes +2000V at the next time, the electric field between the gate and the corresponding cathode becomes a positive electric field, electrons emitted from the cathode move toward the gate and pass through the grid, are emitted into the accelerating electric field between the gate and the anode, are accelerated and finally bombard the anode, and generate X-rays at the corresponding target position.

As shown in fig. 17 (C), the grid may be formed by connecting grid leads in parallel, and the grid leads may be at the same potential, and the filament power supply may control the operating state of each electron emission unit. For example, all grids are at-500V, each cathode filament is led out independently, the voltage difference between two end points of each cathode filament is constant, and the overall voltage of each cathode is switched between two states of 0V and-2500V. At a certain moment, the cathode is at 0V potential, a negative field is between the grid and the cathode, the electrons emitted from the cathode are confined on the surface of the cathode, at the next moment, the voltage of the cathode becomes-2500V, the electric field between the grid and the corresponding cathode becomes a positive field, the electrons emitted from the cathode move towards the grid and pass through the grid, are emitted into the accelerating electric field between the grid and the anode, obtain acceleration and finally bombard the target, generating X-rays at the corresponding target position.

Further, in the two-dimensional distributed X-ray device of the present invention, the filament leads of the respective electron emission units may be individually connected to the respective output terminals of the filament power supply, or may be connected in series and then integrally connected to one output terminal of the filament power supply. A schematic diagram of the series connection of the filament legs of an electron emitting unit to the filament power supply is shown in fig. 18. In a system in which filament leads of an electron emission unit are connected in series, the cathodes are usually at the same potential, and each grid lead needs to be led out independently, so that the working state of the electron emission unit is controlled by a grid control device.

Further, in the present invention, the array of electron emission units may be two rows or a plurality of rows.

In addition, in the invention, the target of the anode can be in a circular frustum structure, a cylindrical structure, a square frustum structure, a multi-prism structure, other polygonal bulges, other irregular bulges and other structures.

In addition, in the present invention, the top surface of the target of the anode may be a flat surface, a slant surface, a spherical surface, or other irregular surface.

In addition, in the present invention, the two-dimensional array arrangement of the electron emission units may be in various combinations such that both directions are linear extensions, one direction is linear extension and the other direction is arc extension, one direction is linear extension and the other direction is piecewise linear extension, and one direction is linear extension and the other direction is piecewise arc extension.

In addition, in the present invention, the two-dimensional array arrangement of the electron emission units may be uniform in interval between the two directions, may be uniform in interval between each direction and nonuniform in interval between the two directions, may be uniform in interval between one direction and nonuniform in interval between the other direction, or may be nonuniform in interval between the two directions.

In the present invention, the electron emission units may be arranged so as to be distributed in a curved array, and thus a curved array distributed X-ray apparatus can be obtained. Fig. 19 is a schematic structural diagram of a curved array distributed X-ray device of the present invention. Fig. 20 is an end view of the internal structure of the curved array distributed X-ray device of the present invention. Fig. 21 is a schematic view of a different structure of the anode of the present invention.

As shown in the figure, a plurality of electron emission units 1 (at least four, hereinafter also referred to specifically as electron emission units 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b, … …) are arrayed in a plurality of rows on a curved surface along an axis direction facing an axis O, and further, an anode 2 is arranged on the axis O of the curved surface. Further, as described above, the electron emission unit 1 is mounted on the case wall of the vacuum case 3 and is entirely outside the vacuum case 3, and the anode 2 is mounted inside the vacuum case.

In addition, the curved surface includes a cylindrical surface and a torus. Fig. 20 is a schematic end view showing the internal structure of a curved array distributed X-ray device of the present invention, and specifically, a schematic view showing the internal structure of a cylindrical array distributed X-ray device is shown in fig. 20. The electron emission units 1 are arrayed in a plurality of rows in the axial direction on a cylindrical surface, and the upper surface (electron emission surface) of the electron emission unit 1 faces the axis O. The anode 2 is arranged on the axis O of the cylinder. Generally, the electron emission units 1 are at the same low potential, the anode 2 is at a high potential, a positive electric field is formed between the anode 2 and the electron emission units 1, the electric field converges from the surface of each electron emission unit 1 to the axis of the anode 2, and the electron beam current E moves from the electron emission unit 1 to the axis of the anode 2 to bombard the anode 2, and finally, X-rays are generated.

In addition, the electron emission units 1 are arranged in a plurality of rows on the curved surface along the axial direction facing the axial line, and the electron emission units in the plurality of rows may be aligned in front and back rows or may be staggered in the recommended positions of the front and back rows, so that the positions of the electron beams generated by each electron emission unit bombarding the anode are not coincident.

The anode 2 has a hollow pipe-like structure, and a coolant can be flowed inside the anode. The structure of an anode and its support in the present invention is shown in fig. 21. The anode 2 is composed of an anode support 201A, an anode pipe 202A, and an anode target 203A. The anode support 201A is mounted on the anode pipe 202A and connected with the top end (small end) of the high-voltage power supply connection device 4 for supporting and fixing the anode 2. The anode line 202A is a main structure of the anode 2, and both ends thereof are connected to one ends of the two cooling connections 9A, respectively, and the inside thereof communicates with the cooling connections 9A, and serves as a passage through which a coolant flows in a circulating manner. The anode tube 202A is usually made of a high temperature resistant metal material, and has various structures, preferably a circular tube. In addition, the anode 2 may also be a cylindrical structure other than a hollow tube in some cases, such as when the anode thermal power is low. In addition, the anode target surface 203A is the position where the electron beam bombards the anode tube 202A, and there are various designs on the fine structure, for example, as shown in fig. 21 (1), the outer circle surface of the anode tube 202A is the position where the electron beam bombards, in this case, the anode tube 202A is entirely made of high temperature resistant heavy metal material, for example, tungsten or tungsten alloy, as shown in fig. 21 (2), the outer circle of the anode tube 202A is partially cut to form a small inclined plane, which becomes the position where the electron beam bombards, and the inclined direction of the inclined plane is the useful X-ray emitting direction, and this structure is designed to facilitate the useful X-ray emitting direction to be consistent, and preferably, as shown in fig. 21 (3), the anode target surface 203A is specially designed on the outer surface of the anode tube 202A, the anode target surface 203A is made of high temperature resistant heavy metal material, for example, tungsten or tungsten alloy, not less than 20 μm (micrometers) in thickness, and is fixed to the beveled facet formed at the outer edge of the anode tube 202A by plating, gluing, welding, or other means, in which case the anode tube 202A may be made of a common metal material, thereby enabling cost reduction.

In the present invention, the axis may be a straight line or an arc, and the whole may be a linear distributed X-ray device or an annular distributed X-ray device, so as to meet different application requirements. An effect diagram of a ring-shaped distribution of electron emission units and anode arrangement is shown in fig. 22. The anode 2 is arranged on the circumference of a plane, the electron emission units 1 are arranged below the anode 2, and two rows of the electron emission units 1 are arranged on the circumference of the anode 2 and are arranged on an arc surface with the center of the anode 2 as an axis, namely, the surface of each electron emission unit 1 points to the axis of the anode 2. The electron beam current E is emitted from the electron emission unit 1, is accelerated by a high-voltage electric field between the anode 2 and the electron emission unit 1, bombards the lower edge target surface of the anode 2, forms circularly arranged array X-ray target points on the anode 2, and the emitting direction of useful X-rays points to the circle center of the circumference where the anode 2 is located. The vacuum box 3 of the annular distributed X-ray device is also of an annular structure corresponding to the arrangement of the electron emission units 1 inside it and the shape of the anode 2. The annular distributed X-ray device can be a complete ring or a segment of ring, and can be applied to occasions needing circular arrangement of the ray sources.

Further, in the present invention, the array of the electron emission units may be two rows or a plurality of rows.

In addition, in the description of the electron emission units in the present invention, "independent" means that each electron emission unit has the capability of independently emitting an electron beam, and may be a discrete structure or a structure connected in some way in terms of specific structure.

In addition, in the description of the curved surface array distributed X-ray device of the present invention, the "curved surface" refers to various forms of curved surfaces including a cylindrical surface, a circular surface, an elliptical surface, or a curved surface formed by segmented straight lines, such as a regular polygonal cylindrical surface or a curved surface formed by segmented arcs, and the like, and the cylindrical surface and the circular surface as described above are recommended.

In addition, in the description of the anode arrangement position in the present invention, "axis" refers to the true axis or form axis of various forms of curved surfaces in which the electron emission unit is arranged, for example, the axis of a cylindrical surface refers to the central axis of a cylinder, the axis of a torus refers to the central axis of the inside of a torus, the axis of an elliptic curved surface refers to the paraxial axis near the segment of an ellipse, and the axis of a regular polygonal cylinder refers to the axis constituted by the centers of regular polygons.

In addition, in the present invention, the anode internal pipe section may be a circular hole, a square hole, a polygonal hole, an internal gear-shaped hole with a fin structure, or other shapes that can increase the heat radiation area.

Further, in the present invention, the curved array of the electron emission units is arranged in a curved line in one arrangement direction and in a straight line, a segmented straight line, an arc line, a segmented arc line, or a combination of straight and arc line segments in the other arrangement direction.

In addition, in the present invention, the curved array arrangement of the electron emission units may be uniform in interval between two directions, uniform in interval between each direction, inconsistent in interval between two directions, uniform in interval between one direction, non-uniform in interval between the other direction, or non-uniform in interval between two directions.

In addition, in the present invention, the overall shape of the vacuum box may be a rectangular parallelepiped, a cylindrical, a circular ring, or other structures that do not affect the relative arrangement relationship between the electron emission unit and the anode.

Examples

(System composition)

As shown in fig. 1 to 6, the external hot cathode distributed X-ray device of the present invention is composed of a plurality of electron emission units 1, an anode 2, a vacuum box 3, a high voltage power connection device 4, an emission control device connection device 5, a focusing device connection device 6, a vacuum device 8, and a power supply and control system 7. A plurality of electron emission units 1 are arranged in a linear array and are arranged on one side wall of a vacuum box 3, each electron emission unit 1 is independent, a strip-shaped anode 2 is arranged in the middle of the inside of the vacuum box 3, the anode 2 is parallel to the arrangement line of the electron emission units 1 in the linear arrangement direction, and a small included angle is formed between the anode 2 and the upper surface of the electron emission unit 1 in the vertical section of the linear arrangement. The electron emission unit 1 includes a heating filament 101, a cathode 102, a grid 107, an insulating support 103, a focusing electrode 104, a focusing segment 109, a connecting fixture 105, a filament lead 106, a grid lead 108, and a focusing device 110. The high-voltage power supply connecting device 4 is arranged on the side wall of the vacuum box 3, the inside of the high-voltage power supply connecting device is connected with the anode 2, and the outside of the high-voltage power supply connecting device is connected with a high-voltage cable in a pluggable mode. The emission control device connecting means 5 connects the filament lead 106 and the gate lead 108 of each electron emission unit 1 to each emission control unit of the emission control device 703. A vacuum device 8 is installed on a sidewall of the vacuum box 3, and the vacuum device 8 includes a vacuum pump 801 and a vacuum valve 802. The power supply and control system 7 includes a plurality of modules such as a control system 701, a high voltage power supply 702, an emission control device 703, a focusing power supply 704, a vacuum power supply 705, etc., and is connected to the heating filaments 101, the grid 107, the anode 2, the vacuum device 8, etc., of the plurality of electron emission units 1 of the system through power cables and control cables. The emission control device 703 is composed of a plurality of emission control units (the same as the number of the electron emission units 1), and each emission control unit is composed of a negative high voltage module 70301, a direct current module 70302, a high voltage isolation transformer 70303, a negative bias module 70304, a positive bias module 70305, and a selection switch 70306.

(working principle)

In the external hot cathode distributed X-ray device of the present invention, the power supply and control system 7 controls the focusing power supply 704, the emission control device 703, and the high voltage power supply 702. Each unit of the emission control device 703 starts to operate, the negative high voltage module 70301 generates negative high voltage and outputs the negative high voltage to the primary side of the high voltage isolation transformer 70303, so that a group of parallel terminals of the secondary side of the high voltage isolation transformer 70303 are suspended on the high voltage, that is, the dc module 70302, the negative bias module 70304, the positive bias module 70305, and the selection switch 70306 are all on the same negative high voltage, the dc module 70302 generates a dc current suspended on the negative high voltage and supplies the dc current to the heating filament 101, the heating filament 101 heats the cathode 102 to a high temperature (e.g., 500 to 2000 ℃) emission state, and the cathode 102 generates a large amount of electrons on its surface. The negative bias block 70304 and the positive bias block 70305 generate a negative voltage and a positive voltage, respectively, that are floating on the negative high voltage, and the select switch 70306 normally gates the negative voltage to the gate 107. In the electron emission unit 1, the filament 101, the cathode 102 and the grid electrode 107 are all at a negative high voltage, typically several kilovolts negative to several tens of kilovolts negative, and the focus electrode 104 is connected to the focus section 109 and to the sidewall of the vacuum chamber 3 through the connecting fixture 105, at ground potential, so that a small accelerating electric field is formed between the grid electrode 107 and the focus electrode 104. However, the gate 107 has a lower negative voltage than the cathode 102, so that electrons generated by the cathode 102 cannot pass through the gate 107 and are confined on the surface of the cathode 102 by the gate 107. The high voltage power supply 702 subjects the anode 2 to a very high positive high voltage, typically several tens to several hundreds of kilovolts positive, forming a positive large accelerating electric field between the electron emitting unit 1 (i.e., the side wall of the vacuum box 3, typically at ground potential) and the anode 2.

When it is necessary to generate X-rays, the power supply and control system 7 switches the output of the selection switch 70306 of any one of the emission control units of the emission control apparatus 703 from a negative voltage to a positive voltage in accordance with an instruction or a preset program, and changes the output signals of the selection switches 70306 of the emission control units connected to the electron emission units 1 in time series. For example, at time 1, the output of the selection switch 70306 of the first emission control unit of the emission control device 703 is switched from a negative voltage to a positive voltage, and in the corresponding electron emission unit 11, the electric field between the grid 107 and the cathode 102 becomes a positive electric field, and electrons move from the surface of the cathode 102 to the grid 107, and enter the acceleration electric field between the grid 107 and the focusing electrode 104 through the grid to obtain a first acceleration, and the nose cone shape of the focusing electrode 104 causes the electron beam to automatically focus during the first acceleration, so that the diameter of the electron beam is reduced, and after the electron beam enters the inside of the focusing segment 109, the diameter of the electron beam is further reduced by the action of the focusing magnetic field applied by the external focusing device 110. The electron beam with small diameter enters the inside of the vacuum box 3 through the hole at the center of the connecting fixing piece 105, is accelerated by the large accelerating electric field between the electron emission unit 11 and the anode 2, obtains energy, bombards the anode 2, generates a target point 21 on the anode 2, and generates the emission of X-ray at the position of the target point 21. At time 2, the output of the selection switch 70306 of the second emission control unit of the emission control device 703 is switched from the negative voltage to the positive voltage, the corresponding electron emission unit 12 emits electrons, a target point 22 is generated on the anode 2, and emission of X-rays is generated at the position of the target point 22. At time 3, the output of the selection switch 70306 of the third emission control unit of the emission control device 703 is switched from the negative voltage to the positive voltage, the corresponding electron emission unit 13 emits electrons, the target point 23 is generated on the anode 2, and the emission of X-rays is generated at the position of the target point 23, and so on, then the emission of X-rays is generated at the position of the target point 24, then the emission of X-rays is generated at the position of the target point 25 … …, and the cycle is repeated. Therefore, the power supply and control system 7 causes the electron emission units 1 to alternately operate at a predetermined timing by the emission control device 703 to emit electron beams, and alternately generates X-rays at different positions of the anode 2, thereby becoming a distributed X-ray source.

In addition, the gas released when the anode 2 is bombarded by the electron beam is pumped away by the vacuum pump 801 in real time, and high vacuum is maintained in the vacuum box 3, so that the long-time stable operation is facilitated. The power supply and control system 7 controls 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.

In addition, the external hot cathode distributed X-ray device is applied to the CT equipment, so that the CT equipment with good system stability and reliability and high inspection efficiency can be obtained.

(Effect)

The invention mainly provides an external hot cathode distributed X-ray device, which generates X-rays in a light source device, wherein the focal positions of the X-rays are periodically changed according to a preset sequence. The electron emission unit adopts the hot cathode, and has the advantages of large emission current and long service life compared with other designs; the electron emission units are independently fixed on the vacuum box, and a small two-pole or three-pole electron gun can be directly used, so that the technology is mature, the cost is low, and the application is flexible; 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 electron emission units can be linearly arranged and integrally form a linear type distributed X-ray device, and can also be annularly arranged and integrally form an annular type distributed X-ray device, so that the application is flexible; by the design of the focusing electrode, and the design of the external focusing means, the electron beam can achieve a very small focus. 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, convenience in control and low cost.

In addition, the external hot cathode 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.

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 combinations and various modifications of the above-described embodiments can be made within the scope of the gist of the present invention.

Claims (16)

1. An 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 electron emission units arranged on a sidewall of the vacuum chamber in a plurality of rows on a curved surface along an axial direction of the curved surface facing the axial line, and each electron emission unit being entirely outside the vacuum chamber; and

an anode composed of metal and disposed at an intermediate position inside the vacuum box in such a manner as to be arranged on the axis,

the anode is bombarded by the electron beam current from the electron emission unit, so that emission of X-rays is generated at the target position of the anode.

2. The X-ray apparatus according to claim 1,

further provided with: a power supply and control system having a high voltage power supply connected to the anode, an emission control device connected to each of the plurality of electron emission units, a control system for controlling the power supply,

the electron emission unit has: heating the filament; a cathode connected to the heating filament; filament leads led out from two ends of the heating filament; an insulating support surrounding the heating filament and the cathode; a focusing electrode disposed on the top end of the insulating support so as to be located above the cathode; a connecting fixing member arranged above the focusing electrode and hermetically connected with the box wall of the vacuum box,

the filament lead is connected with the emission control device through the insulating support,

the anode includes: an anode tube composed of metal and having a hollow tubular shape; an anode support disposed on the anode conduit; an anode target surface disposed on an outer surface of the anode tube and facing the electron emission unit.

3. The X-ray apparatus according to claim 2,

further comprising: the high-voltage power supply connecting device is used for connecting the anode with a cable of the high-voltage power supply and is arranged on the side wall of one end, close to the anode, of the vacuum box; the emission control device connecting device is used for connecting the heating filament and the emission control device; 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.

4. The X-ray apparatus according to claim 2,

the electron emission unit further has: a grid mounted between the cathode and the focus electrode and proximate to the cathode; and the grid lead is connected with the grid, penetrates through the insulating support and is connected with the emission control device.

5. The X-ray apparatus according to claim 2,

the electron emission unit further has: the focusing section is arranged between the focusing pole and the connecting and fixing piece; and a focusing device disposed so as to surround the focusing segment.

6. The X-ray apparatus according to claim 5,

further comprising: a focusing power supply included within the power supply and control system; and the focusing device connecting device is used for connecting the focusing device and the focusing power supply.

7. The X-ray apparatus according to claim 2,

the electron emission units are mounted on two opposite sidewalls of the vacuum box.

8. The X-ray apparatus according to claim 2,

the vacuum box is made of glass or ceramic.

9. The X-ray apparatus according to claim 2,

the vacuum box is made of a metal material.

10. The X-ray apparatus according to claim 2,

the anode target surface is an inclined plane formed by cutting off a part of the outer circle of the anode pipeline.

11. The X-ray apparatus according to claim 2,

the anode target surface is formed by forming heavy metal material tungsten or tungsten alloy on an inclined plane formed by cutting off a part of the excircle of the anode pipeline.

12. The X-ray apparatus according to claim 2,

the axis is a straight line or a piecewise straight line.

13. The X-ray apparatus according to claim 2,

the axis is a circular arc or a segmented circular arc.

14. The X-ray apparatus according to claim 2,

the arrangement intervals of the plurality of electron emission units are uniform.

15. The X-ray apparatus according to claim 2,

the arrangement intervals of the plurality of electron emission units are non-uniform.

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

the X-ray source used is the X-ray device of any one of claims 1 to 15.