CN114678242A

CN114678242A - Cold cathode X-ray source and X-ray device based on carbon nano tube

Info

Publication number: CN114678242A
Application number: CN202210338152.7A
Authority: CN
Inventors: 余兆巽
Original assignee: Ningbo Nari Nord Medical Technology Co ltd
Current assignee: Ningbo Nari Nord Medical Technology Co ltd
Priority date: 2022-04-01
Filing date: 2022-04-01
Publication date: 2022-06-28

Abstract

The invention relates to a cold cathode X-ray source and an X-ray device based on carbon nanotubes. The cold cathode X-ray source based on the carbon nano tube comprises a shell, and an anode part and an emission cathode part which are positioned in the shell, wherein the emission cathode part is provided with a single-beam carbon nano tube or a carbon nano tube array, and the cold cathode X-ray source further comprises a gas suction part which is arranged in the shell and is used for adsorbing gas generated by the anode part and the emission cathode part when the X-ray is generated. The cold cathode X-ray source has the advantages of high vacuum degree, high stability, high power, small volume and the like, and the product quality of the cold cathode X-ray source adopting the carbon nano tube can be effectively improved, and the large-scale production, manufacturing and application of the cold cathode X-ray source are promoted.

Description

Cold cathode X-ray source and X-ray device based on carbon nano tube

Technical Field

The invention relates to the technical field of X-ray equipment, in particular to a cold cathode X-ray source and an X-ray device based on carbon nano tubes.

Background

X-rays, which are electromagnetic waves, have the characteristics of extremely high frequency, extremely short wavelength, high energy, high permeability, etc., and thus have wide applications in such aspects as medical diagnosis, disease treatment, material structure analysis, material nondestructive testing, spectroscopy or image analysis, etc.

Conventionally, an X-ray tube is used for generating X-rays, and the prior art has provided both a hot cathode ray tube and a cold cathode ray tube. However, most of the existing cold cathode X-ray tubes have the problems of lack of preparation process, poor emission stability, short service life and the like, for example, the existing preparation process of the carbon nanotube field emission electrode has poor compatibility with the traditional X-ray tube vacuum packaging process, and a satisfactory X-ray tube with independent vacuum packaging is difficult to obtain, so that the requirement of industrial use of an X-ray device cannot be met, so that the existing cold cathode X-ray tubes are far inferior to hot cathode X-ray tubes in the aspects of working performance, mass production, application range and the like, and the latter cannot be replaced at present.

Disclosure of Invention

In view of the above, the present invention provides a cold cathode X-ray source and an X-ray device based on carbon nanotubes, whereby one or more of the above mentioned problems and other problems of the prior art are solved or at least alleviated.

First, according to an aspect of the present invention, there is provided a carbon nanotube-based cold cathode X-ray source including a case, and an anode part and an emission cathode part within the case, the emission cathode part having a single bundle of carbon nanotubes or a carbon nanotube array, the cold cathode X-ray source further including a getter part disposed within the case for adsorbing gas generated by the anode part and the emission cathode part when generating X-rays.

In the carbon nanotube based cold cathode X-ray source according to the present invention, optionally, the getter part comprises:

a first getter material comprising a body portion having a first getter material and an attachment portion, the attachment portion being connected to the body portion and attached to an inner wall of the housing, the first getter material being activated when a temperature within the housing is not less than a preset temperature; and/or

A second getter portion including a heating portion connected to an external power source and a body portion having a second getter material that is heated after the heating portion is activated and activated when a predetermined temperature is reached.

In the carbon nanotube-based cold cathode X-ray source according to the present invention, optionally, the attachment portion and the body portion of the first gas absorption part are both configured in a ribbon shape, and the attachment portion is made of a magnetic material with a nickel-plated surface; and/or

The heating part comprises one or more heating coils at least partially arranged in the body part of the second suction part, the heating coils are connected with the external power supply through connecting wires, the connecting wires comprise molybdenum wires with the diameter of 0.5mm-0.8mm and/or nickel wires with the diameter of 1mm-1.5mm, and at least one part of the connecting wires are externally provided with ceramic insulating layers.

In the carbon nanotube based cold cathode X-ray source according to the present invention, optionally the gas comprises at least one of hydrogen, nitrogen, oxygen and carbon monoxide, and/or the first getter material comprises at least one of a zirconium-graphite getter material, a vanadium getter material and a titanium getter material, and/or the second getter material comprises at least one of a zirconium-graphite getter material, a vanadium getter material and a titanium getter material, and/or the preset temperature and/or the predetermined temperature is not less than 400 ℃, and/or the input current of the external power supply to the heating portion is not less than 1 ampere.

In the carbon nanotube-based cold cathode X-ray source according to the present invention, optionally, the housing has an inner layer, an outer layer, and an intermediate layer between the inner layer and the outer layer, the inner layer, the outer layer, and the intermediate layer are respectively made of an insulating ceramic material, a stainless steel material, and a Kovar alloy material by welding, and/or the housing is configured in a bulb shape, and/or a degree of vacuum in the housing is set to not less than 1X10^-9 TORR。

In the cold cathode X-ray source based on carbon nanotubes according to the invention, optionally the surface voltage stress of the inner layer is not higher than 10kV/mm and/or the surface voltage stress of the outer layer and/or the intermediate layer is not higher than 1 kV/mm.

In the carbon nanotube-based cold cathode X-ray source according to the present invention, optionally, the anode part is fixed within the case and includes an anode piece and a target piece that is fixed on the anode piece and generates X-rays upon receiving electron beams emitted from the emission cathode part; and/or the electron current range of the emission cathode part is 10mA to 200mA, and the extraction voltage range is-500V to-2500V.

In the carbon nanotube-based cold cathode X-ray source according to the present invention, optionally, the cold cathode X-ray source further includes a focusing part disposed between the emission cathode part and the anode part so that the electron beam emitted from the emission cathode part is incident to the target after being condensed; and/or the anode section further comprises a heat sink connected to the anode member and the inner layer of the housing.

In the carbon nanotube based cold cathode X-ray source according to the present invention, optionally, the housing is provided with an X-ray exit window, the X-ray exit window is made of an aluminum alloy material and a stainless steel material by welding, and the X-ray exit window is connected to the housing by the stainless steel material via welding.

Secondly, according to another aspect of the present invention, there is also provided an X-ray device comprising a carbon nanotube based cold cathode X-ray source as defined in any one of the above.

The principles, features, characteristics, advantages, etc. according to the technical solutions of the present invention will be clearly understood from the following detailed description taken in conjunction with the accompanying drawings. The cold cathode X-ray source has the advantages of high vacuum degree, high stability, high power, small volume and the like, and the product quality of the cold cathode X-ray source adopting the carbon nano tube can be effectively improved, and the large-scale production and application of the cold cathode X-ray source are promoted.

Drawings

The present invention will be described in further detail below with reference to the drawings and examples, but it should be understood that the drawings are designed solely for purposes of illustration and are not necessarily drawn to scale, but rather are intended to conceptually illustrate the structural configurations described herein.

Fig. 1 is a schematic structural composition diagram of an embodiment of a carbon nanotube-based cold cathode X-ray source according to the present invention.

Fig. 2 is a schematic front view of the first gas-absorbing part in the embodiment of the cold cathode X-ray source shown in fig. 1 in a deployed state.

Fig. 3 is a side view schematically showing the structure of the first air-intake portion shown in fig. 2.

Fig. 4 is a schematic front view of an example of a second getter device in the embodiment of the cold cathode X-ray source shown in fig. 1.

Fig. 5 is a partial sectional structural view of the second intake part example shown in fig. 4.

Fig. 6 is a schematic partly sectional structural view of an example of an X-ray exit window in an embodiment of the cold cathode X-ray source shown in fig. 1.

Detailed Description

First, it should be noted that the structures, compositions, features, advantages, etc. of the carbon nanotube-based cold cathode X-ray source and the X-ray device according to the present invention will be described below by way of example, but it should be understood that all the descriptions are given for illustrative purposes only and thus should not be construed as forming any limitation on the present invention. In this document, the technical term "connected" covers the direct and/or indirect connection of one part to another part, and the technical terms "front", "back", "inside", "outside", "above", "below" and derivatives thereof shall relate to the orientation in the drawing, and the invention may take a variety of alternative orientations unless explicitly stated.

Furthermore, to any single feature described or implicit in an embodiment or shown or implicit in the drawings, the invention still allows any combination or permutation to continue between the features (or their equivalents) without any technical impediment, thus achieving more other embodiments of the invention that may not be directly mentioned herein. In addition, general matters that have been known to those skilled in the art are not described in detail herein.

According to the design concept of the present invention, firstly, a cold cathode X-ray source based on carbon nanotubes is provided, for example, one or more such cold cathode X-ray sources can be configured in various devices requiring the use of X-rays to provide X-rays. Fig. 1 shows an embodiment of a cold cathode X-ray source based on carbon nanotubes, and components such as an emission cathode portion 20, an anode portion 30, and an air-intake portion 80 can be disposed inside a housing 10 of the cold cathode X-ray source 100, and the details of these components will be described below.

In the cold cathode X-ray source 100, the emission cathode portion 20 and the anode portion 30 are used in cooperation to generate X-rays. The emission cathode portion 20 may be in the form of a single bundle of carbon nanotubes or a carbon nanotube array, and may be optionally mounted on a base 60 or other suitable components in the casing 10, and the base 60 may be made of a suitable material such as stainless steel and may be mounted inside the casing 10 by a welding process, or may be integrally formed with the casing 10 by a process such as machining, casting, etc. In practical applications, it is considered that components such as the focusing unit 40, the grid 50, the second suction unit 82, and the like, which will be mentioned later, may be optionally mounted on the base 60, which is advantageous to form a compact structure. The emitter cathode portion 20 may be connected to an external power source through a high voltage wire 20a, which, when energized, emits an electron beam 90 and impinges on the anode portion 30. By way of illustration, in some embodiments, the electron current of the emission cathode portion 20 may be optionally set in a range of 10mA to 200mA, and the extraction voltage of the emission cathode portion 20 may be optionally set in a range of-500V to-2500V. It will of course be appreciated that the present invention allows flexibility in designing and configuring the respective performance parameters of the emitter cathode portion 20 according to the requirements of different applications, in order to better meet various practical requirements.

As for the anode portion 30, it may include an anode member 31 and a target member 32, the target member 32 may be generally made of tungsten material and may be fixed to the anode member 31 by a connection means such as laser welding, and after the cathode portion 20 is energized and emits electron beams 90, these electron beams 90 may pass through the grid 50 (which may be made of high temperature resistant alloy and connected to an external power source through high voltage wires 50 a), and then bombard the target member 32 and thereby generate X-rays, which may be emitted to the outside through an X-ray emission window 70 provided on the case 10 for use. Alternatively, the anode part 30 may be provided with a heat sink in some applications, such heat sink may be made of a material with good heat dissipation properties, such as copper, and may be configured in any suitable size and installed at a suitable position, for example, may be arranged between the anode part 31 and the housing 10 to achieve an enlarged heat dissipation area by means of the housing to achieve good heat dissipation, and to promote stable and reliable operation of the system, to increase the X-ray power, and the like.

In the embodiment of fig. 1, there is also shown a focusing portion 40 disposed between the emission cathode portion 20 and the anode portion 30 as an optional configuration, which is used to perform the function of focusing the electron beam 90, i.e. to make it possible to form a certain divergent electron beam 90 after being emitted from the emission cathode portion 20 and passing through the grid 50, and then to bombard the target 32 after being focused by the focusing portion 40, so as to achieve the effect of better generating X-rays by focusing energy.

Referring to fig. 1, a getter portion 80 is disposed inside a housing 10 of a cold cathode X-ray source 100 for adsorbing gas that may be generated during the X-ray generation process. Specifically, at the instant the electron beam 90 strikes the target 32 of the anode section 30 to generate X-rays, an instantaneous high temperature (e.g., as high as 2700 ℃ C.) will be created; as such, gases such as hydrogen, nitrogen, oxygen, and/or carbon monoxide will likely be generated during operation of the X-ray source 100. However, such gases are not desirable because they affect and reduce the high vacuum degree inside the X-ray source housing, which in turn leads to unstable operation of components such as carbon nanoarrays and performance degradation, and thus damages the product quality and application range of the X-ray source. In the cold cathode X-ray source 100, the gas can be reduced or removed by providing the getter portion 80, and the above disadvantage can be effectively solved.

By way of illustration, fig. 1 shows two different embodiments of the suction device 80, namely a first suction device 81, which can be operated in a passive suction mode, and a second suction device 82, which can be operated in an active suction mode. It should be understood that both the first suction part 81 and the second suction part 82 can be used individually or in combination in the solution of the invention, and they each allow flexibility in terms of, for example, the structural configuration, the arrangement position, the number of configurations, the materials used, etc., depending on the requirements of the actual application.

First, as for the first air suction part 81, please refer to fig. 1, fig. 2 and fig. 3 in combination, it can be configured to have a body portion 811 and an attachment portion 812, the body portion 811 can be made of a suitable getter material (such as one or more of a zirconium-graphite getter material, a vanadium getter material and a titanium getter material), and the attachment portion 812 can be made of any suitable material (such as a magnetic material with a nickel-plated surface) according to actual requirements, for example, they can be formed by a cold press molding process. For example, the attachment portion 812 and the body portion 811 may optionally both be configured in a band shape, which is exemplarily illustrated in fig. 2 and 3. Both the attachment portion 812 and the body portion 811 may be connected together and the attachment portion 812 may be attached to the inner wall of the housing 10 by welding or the like so that the body portion 811 may contact and absorb undesired gases that may be generated during operation of the cold cathode X-ray source 100.

The getter material of the body portion 811 can be selected and arranged to be activated when the temperature inside the casing 10 is not lower than a preset temperature (for example, 400 ℃ or other temperature values, which can be considered according to actual demand), that is, the first gas-absorbing part 81 starts to operate only after the ambient temperature inside the casing 10 is higher than or equal to the preset temperature, so that the application flexibility and pertinence of the gas-absorbing part can be improved, and the operation in a relatively low temperature environment where adverse gas may not be formed can be avoided.

As for the second suction portion 82, please refer to fig. 1, 4 and 5 in combination, it may be configured as a body portion 821 and a heating portion 822. Body portion 821 may be formed of a suitable getter material (e.g., one or more of a zirconium-graphite getter material, a vanadium getter material, and a titanium getter material, which may be the same or different than the getter material of first getter portion 81), and the getter material selected will be heated after heating portion 822 is activated and activated to start operating when a predetermined temperature (e.g., 400 ℃ or other temperature value, which may be set according to actual needs and may be the same or different than the predetermined temperature) is reached, so that the application flexibility and pertinence of the getter portion may be improved, and operation in a relatively low temperature environment where adverse gases may not be formed may be avoided.

As a further example, heating portion 822 may conveniently be electrically heated to promote a faster temperature rise of body portion 821. For example, as shown in fig. 5, heating portion 822 may be optionally configured in the form of one or more heating coils, and the heating coils may be disposed wholly or partially inside body portion 821 made of a getter material, so that heat energy is generated by the heating coils to cause body portion 821 to be heated and heated up after an input current of, for example, not less than 1 ampere or the like is supplied from an external power source, and when body portion 821 reaches its predetermined temperature relatively more quickly due to the heat energy generated by the heating coils and the temperature rise of the internal environment of casing 10, operation is started to purge the gas inside casing 10 to maintain a high vacuum degree, and it is ensured that the elements inside the cold cathode X-ray source casing are in a better operating environment, and thus, operation can be stably and reliably performed for a long period of time.

The basic construction of an embodiment of the second air intake is generally illustrated in fig. 4 and 5 in a schematic manner. The body portion 821 in the second suction part may be configured in any suitable shape such as a cylinder, a sphere, a rectangular parallelepiped, etc. as required, and the heating part 822 may be disposed inside the body portion 821 for a heating process, and the heating part 822 may be connected to an external power source through a connection wire 82 a. The connecting leads 82a may be made of molybdenum leads 823, nickel leads 824 or other suitable materials, alone or in combination, and may be provided with a structure such as a ceramic insulating layer 825 at the outer portion of a part or all of the connecting leads and connected to an external power source at an end portion 826 of the connecting leads extending out of the housing 10, so as to be safe, reliable, durable, and the like. By way of example, a molybdenum wire with a diameter of 0.5mm to 0.8mm may be used, and a nickel wire with a diameter of 1mm to 1.5mm may be connected to an end of the molybdenum wire, and a ceramic insulating layer may be provided on the outside of a part or all of the nickel wire, as exemplarily shown in fig. 4 and appropriately simplified in fig. 5.

In the cold cathode X-ray source 100, the housing 10 provides a space for accommodating other components, and can be configured in any suitable shape according to different application requirements, such as a bulb shape, a rectangular parallelepiped shape, and the like. The housing 10 may have an outer layer 11, an inner layer 13 and an intermediate layer 12 therebetween, which is shown schematically in fig. 1. For the inner layer 13, the outer layer 11 and the intermediate layer 12, they may be made of corresponding suitable materials, for example, insulating ceramic materials, stainless steel materials and Kovar alloy materials may be used, respectively, and these materials may then be joined together by a process such as laser welding to form a complete housing.

As described above, in the cold cathode X-ray source 100, by disposing the Kovar alloy material between the outer layer of the case of the stainless steel material and the inner layer of the case of the insulating ceramic material, it is possible to take full advantage of the performance characteristics of the Kovar alloy material itself to advantageously facilitate the case to achieve high sealing performance. This is because, when X-ray exposure is generally generated in the cold cathode X-ray source 100, high temperatures are instantaneously generated in the housing 10, and continued exposure causes high temperature accumulation to be formed in the housing 10; in contrast, since the Kovar alloy material has a controllable low coefficient of thermal expansion, the intermediate layer 12 using this characteristic material can maintain high sealability well under high vacuum conditions between the outer layer 11 and the inner layer 13 of the case and between the inner layer 13 and the anode part 30, thereby preventing the deterioration of the battery performanceWhile allowing the vacuum to be maintained at a high level (e.g., no less than 1x 10)^-9TORR), which can effectively avoid the decrease of the working performance caused by the sharp instability of the carbon nano array under the condition of lower or worse vacuum degree level. Therefore, by adopting the different material combinations, the welding process and the like, the aim of maintaining the high vacuum degree in the shell can be fulfilled, so that the technical problem of maintaining the high vacuum degree in the stainless steel tube body which exists in the industry for a long time but cannot be effectively overcome is solved, and the working performance and the quality of an X-ray source product can be greatly improved. Therefore, the cold cathode X-ray source is completely suitable for low-cost and large-batch production and manufacture, and has a very wide application range.

It should be noted that, as an alternative, the housing 10 may be designed such that the surface voltage stress of the inner layer 13 thereof is not higher than 10 kV/mm; also, as an alternative, the housing 10 may be designed such that the surface voltage stress of the outer layer 11 and/or the intermediate layer 12 thereof is not higher than 1 kV/mm. In this way, by adopting the above designs alone or in combination, electrical safety requirements can be better met in some applications, for example, the inner layer 13, the intermediate layer 12 and/or the outer layer 11 of the housing can be promoted to have a correspondingly longer creepage distance function, and undesired damage caused by residual voltage stress applied to the inner layer 13, the intermediate layer 12 or the outer layer 11 after escaping the insulation protection can be avoided.

With continued reference to fig. 1, an X-ray exit window 70 arranged on the housing 10 is also shown in this embodiment. The X-ray exit window 70 may optionally use an aluminum alloy material 71 and a stainless steel material 72, and these materials are joined together and fixed to the housing 10 by, for example, a laser welding process, etc., for example, the stainless steel material used for the outer layer 11 of the housing 10 may be identical or similar to the stainless steel material 72 in the X-ray exit window 70, and for example, when both the aluminum alloy material 71 and the stainless steel material 72 are joined by welding, a suitable welding material 73 such as a titanium-copper alloy material may be used therebetween, thereby promoting better welding sealing effect, welding joint quality, high temperature resistance, etc.

During the operation of the cold cathode X-ray source 100, the electron beam 90 emitted from the emission cathode portion 20 bombards the palladium member 32 of the anode portion 30 to generate X-rays, which are then emitted through the X-ray emission window 70 to the outside for use. By using various material selection combinations and laser welding processes, such as those described above, it is possible to satisfy the requirements of shielding and filtering the emitted X-rays, promote the maintenance of high vacuum between the X-ray emission window 70 and the housing 10, and facilitate the long-term high-temperature working environment (e.g., over 450 ℃ and the like).

Furthermore, according to an aspect of the present invention, there is further provided an X-ray device in which one or more carbon nanotube-based cold cathode X-ray sources according to the present invention, such as those exemplified above, may be arranged. It is to be understood that the X-ray devices provided by the present invention may include, but are not limited to, various types of devices used in many fields such as medical diagnosis, disease treatment, material structure analysis, nondestructive testing of materials, spectral analysis, image analysis, and the like.

The carbon nanotube-based cold cathode X-ray source and X-ray device according to the present invention have been illustrated in detail above by way of example only, and these examples are provided only for illustrating the principles of the present invention and the embodiments thereof, and not for limiting the present invention, and various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, all equivalents are intended to be included within the scope of this invention and defined in the claims which follow.

Claims

1. The cold cathode X-ray source is characterized by further comprising an air suction part which is arranged in the shell and used for adsorbing gas generated by the anode part and the emission cathode part when X-rays are generated.

2. The carbon nanotube-based cold cathode X-ray source of claim 1, wherein the getter portion comprises:

3. The carbon nanotube-based cold cathode X-ray source of claim 2, wherein the attachment portion and the body portion of the first getter part are each configured in a ribbon shape, and the attachment portion is made of a magnetic material plated with nickel on a surface; and/or

4. Carbon nanotube based cold cathode X-ray source according to claim 2, wherein said gas comprises at least one of hydrogen, nitrogen, oxygen and carbon monoxide, and/or said first getter material comprises at least one of a zirconium-graphite getter material, a vanadium getter material and a titanium getter material, and/or said second getter material comprises at least one of a zirconium-graphite getter material, a vanadium getter material and a titanium getter material, and/or said preset temperature and/or said predetermined temperature is not less than 400 ℃, and/or the input current of said external power supply to said heating portion is not less than 1 ampere.

5. The carbon nanotube-based cold cathode X-ray source of claim 1, wherein said housing has an inner layer, an outer layer and an intermediate layer between said inner layer and said outer layer, said inner layer, said outer layer and said intermediate layer are made of insulating ceramic material, stainless steel material and Kovar alloy material, respectively, by welding, and/or said housing is configured in a bulb shape, and/or a degree of vacuum in said housing is set to not less than 1X10^-9 TORR。

6. Carbon nanotube based cold cathode X-ray source according to claim 5, wherein the surface voltage stress of the inner layer is not higher than 10kV/mm and/or the surface voltage stress of the outer layer and/or the intermediate layer is not higher than 1 kV/mm.

7. The carbon nanotube-based cold cathode X-ray source of claim 1, wherein the anode portion is secured within the housing and comprises an anode member and a target member secured to the anode member and generating X-rays upon receiving electron beams emitted from the emitting cathode portion; and/or the electron current range of the emission cathode part is 10mA to 200mA, and the extraction voltage range is-500V to-2500V.

8. The carbon nanotube-based cold cathode X-ray source of claim 7, further comprising a focusing portion disposed between the emission cathode portion and the anode portion such that the electron beam emitted from the emission cathode portion is incident on the target after being condensed; and/or the anode section further comprises a heat sink connected to the anode member and the inner layer of the housing.

9. Carbon nanotube based cold cathode X-ray source according to any of claims 1-8, wherein the housing is provided with an X-ray exit window, the X-ray exit window being made by welding in an aluminium alloy material and a stainless steel material, and the X-ray exit window being connected to the housing by the stainless steel material via welding.

10. An X-ray apparatus, characterized in that it comprises one or more carbon nanotube based cold cathode X-ray sources according to any one of claims 1-9.