CN107919257B - Carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube - Google Patents
Carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube Download PDFInfo
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- CN107919257B CN107919257B CN201711145890.5A CN201711145890A CN107919257B CN 107919257 B CN107919257 B CN 107919257B CN 201711145890 A CN201711145890 A CN 201711145890A CN 107919257 B CN107919257 B CN 107919257B
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- carbon nanotube
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J35/00—X-ray tubes
- H01J35/02—Details
- H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
- H01J35/06—Cathodes
- H01J35/065—Field emission, photo emission or secondary emission cathodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J35/00—X-ray tubes
- H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
Abstract
The present invention relates to a kind of carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tubes, belong to electromagnetic field field.The X-ray tube includes carbon nanotube microbeam array cathode, electron beam collimation focusing pole, anode, transmission target and ceramic and metal package.Carbon nanotube microbeam array cathode (3~50 μm), it is under negative high voltage (2000V) effect, effect launching electronics are caused by field, electron beam is through the Electron Beam Focusing pole of special construction collimation and after focusing, high velocity bombardment can be obtained the x-ray focal spot of micron order size to anode target surface.The present invention has abandoned the fields focus lens that volume is big, energy consumption is high and multipole beam forming cathode electron gun, therefore have it is small in size, low energy consumption, advantages of simple structure and simple, have a wide range of applications in the CT instrument or other x-ray imagings and analysis Instrument equipment of miniaturization.
Description
Technical field
The invention belongs to electromagnetic field fields, are related to carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube.
Background technique
The focal spot size of x-ray source is the critical technical parameter of the X-rays digital imaging apparatus such as CT, DR, is to determine X-ray
One of principal elements of key technical index such as clarity, the spatial resolution of imaging system.Microfocus X-ray x-ray source is made at present
Cathode is typically all tungsten hot cathode.But since the diameter of tungsten wire cannot be too thin, when the diameter of tungsten wire is less than 0.2mm,
Mechanical strength is not able to satisfy requirement, at the same it is heated after, be also easy to produce deformation or even blow.Therefore under prior art conditions, hot
E.g., the sectional area of cathode is difficult to further decrease that (patent of invention: CN 102884606 A [0021] metal tungsten wire is preferred
0.2mm).Therefore, conventional mode (103681181 B of such as 103189955 A of patent of invention CN, CN；CN 204885080
U the modes such as electron gun) are focused using fields focus lens and multipole, after being focused to electron beam, it is burnt to obtain small X-ray
Spot.But fields focus lens and multipole focusing electron gun volume are big, energy consumption is high, structure is complicated.It therefore, is at present micron meter
The x-ray source of very little focal spot, general volume is big, structure is complicated, expensive, may not apply to miniaturization, portable CT instrument
In equal radiation imaging apparatus, as shown in Figure 1.
Summary of the invention
In view of this, the purpose of the present invention is to provide a kind of carbon nanotube microbeam array field emission cathode Microfocus X-ray X to penetrate
Spool,
In order to achieve the above objectives, the invention provides the following technical scheme:
Carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube, including carbon nanotube microbeam array cathode, electronics
Beam collimation focusing pole, anode and transmission target；
The carbon nanotube microbeam array cathode, electron beam collimation focusing pole, anode and transmission target center be located at one
On straight line；Carbon nanotube microbeam array cathode launches the electron beam that beam diameter is 5~50 μm of Φ, and electron beam passes through electronics standard
After the collimation focusing of straight focusing electrode, electron beam further collimates and attenuates, and bombards after being accelerated by the high pressure of 30~100kV of anode
Onto transmission target, the x-ray focal spot of micron-scale is issued；
The effect of electron beam collimation focusing pole are as follows: by first grid to the emission current intensity of carbon nanotube cathod into
Row regulation, by aperture, the hole depth in setting first grid hole and second grid hole, the electric field strength being evenly distributed, thus
Realization is collimated and is focused to electron beam.
Further, which further includes ceramic and metal package, and the ceramic and metal package surrounds entire X-ray tube
Get up, using 95% aluminium oxide ceramics and ceramic metallization processing is carried out, for minimizing radiographic source in high pressure.
Further, the carbon nanotube microbeam array cathode is made of two annulus and the center of circle, 5~50 μ of outer annular diameter Φ
m。
Further, the carbon nanotube microbeam array cathode is made of two annulus and the center of circle, 5~50 μ of outer annular diameter Φ
M, and outer ring has the notch of " ten " font line, inner ring also has the notch of " ten " font line, but connects with " ten " font of outer ring
45 ° of notch of line are interleaved.
Further, the carbon nanotube microbeam array cathode is made of 7 regular hexagons, wherein 1 intermediate, periphery 6
A, periphery is to 5~50 μm of the diameter of a circle Φ being centrally formed.
Further, the carbon nanotube microbeam array cathode is spoke-like, including between two annulus, two annulus
" ten " font line and in enclose " ten " font line in the middle part of annulus, " ten " font line in the middle part of inner ring and two annulus it
Between 45 ° of " ten " font line it is interleaved, 5~50 μm of outer annular diameter Φ.
Further, the aperture Φ in the first grid hole1=100~200 μm, hole depth h1=50~100 μm, second grid
The aperture Φ in hole2=120~200 μm, hole depth h1=60~80 μm；
Cause the first, second grid gate hole internal electric field strong to prevent the first, second grid from generating deformation because of temperature raising
The variation of degree, to influence collimation and the focusing of electron beam, the material of the first, second grid is the small infusibility of thermal expansion coefficient
Metal, including tantalum and rhenium.
Further, the transmission target plates tungsten film, diamond chip is with a thickness of 0.25 using diamond chip as base material on surface
~0.5mm, tungsten film thickness are 1~10 μm.
The beneficial effects of the present invention are: with the progress of carbon nano tube growth technology in recent years and photoetching technique etc.,
Such as 104637758 A of patent of invention CN, lead to the method that carbon nanotube cold field emission cathode is directly grown in nickel metallic substrates,
The transmitting threshold value of the carbon nanotube field emission cathode of acquisition can be down to 1~2V/ μm, and the emission current of monopole carbon nanotube can reach
μ A magnitude.And the significantly strong adhesive force and conductive capability between carburetting nanotube and substrate of nickeliferous metallic substrates, therefore, greatly
Width extends the carbon nanotube cathod service life.Simultaneously as the progress of the technologies such as photoetching, can realize micron-scale in substrate
The growth of arbitrary shape carbon nano pipe array.Due to being processed by requirement of the invention for this carbon nanotube microbeam array cathode
Micron size order, the electron beam issued, by the structured electron beam collimation of spy proposed by the present invention and focusing electrode
After collimation or focusing, the focal spot size of micron order of magnitude can be easy to get.It can thus abandon that volume is big, energy consumption is high
Fields focus lens and multipole electron focusing lens.Thus, the micro- coke of carbon nanotube microbeam array cathode proposed by the present invention
Point X-ray tube has small in size, low power consumption and other advantages, in the CT instrument or other portable x-ray imaging instruments of miniaturization
It is with a wide range of applications in equipment.
Detailed description of the invention
In order to keep the purpose of the present invention, technical scheme and beneficial effects clearer, the present invention provides following attached drawing and carries out
Illustrate:
Fig. 1 is schematic structural view of the invention；
Fig. 2 is circular carbon nanotube microbeam array cathode schematic diagram；
Fig. 3 is discount vibram outlet shape carbon nanotube microbeam array cathode schematic diagram；
Fig. 4 is hexagonal carbon nanotube microbeam array cathode schematic diagram；
Fig. 5 is spoke-like carbon nanotube microbeam array cathode schematic diagram；
Fig. 6 is the equally distributed electric field obtained by electron beam collimation focusing pole；
Collimation and focusing schematic diagram when Fig. 7 is by electron beam collimation focusing pole.
Marked in the figure: 1- carbon nanotube microbeam array cathode；2- electronic collimation focusing electrode；3- electron beam；4- anode；5- is saturating
It shoots at the target；6- ceramic and metal package；7- high-tension cable；The first pole 8- grid；The second pole 9- grid；The first pole 10- gate hole；11- electricity
Line of force distribution；The second pole 12- gate hole.
Specific embodiment
Below in conjunction with attached drawing, a preferred embodiment of the present invention will be described in detail.
Carbon nanotube microbeam array cold field emission cathode Microfocus X-ray X-ray tube structure proposed by the present invention is as shown in Figure 1, packet
It includes: outside carbon nanotube microbeam array cathode, electronic collimation focusing electrode, anode target (reflecting target or transmission target) and cermet
Shell.
Carbon nanotube microbeam array cathode 1 launches the electron beam that beam diameter is 5~50 μm of Φ, and electron beam passes through electronics
After the collimation focusing of collimation focusing pole 2, the diameter of electron beam 3 further collimates and attenuates, by anode 4 (30~100kV) high pressure
After acceleration in bombardment to transmission target 5, the x-ray focal spot of micron-scale is issued.
(1) carbon nanotube microbeam array cathode: the present invention is on the basis for advanced optimizing carbon nanotube cathod growth technique
On, carbon nanotube microbeam array electronic beam field emission characteristic is studied and demonstrates, and combine microfocus X-ray radiographic source knot of the invention
Structure proposes several carbon nanotube microbeam array configurations for advantageously forming micro- focal spot and size: shape one: annular shape is (such as Fig. 2 institute
Show)；Shape two: discount vibram outlet shape (as shown in Figure 3)；Shape three: hexagon (as shown in Figure 4)；Shape four: spoke-like is (such as Fig. 5 institute
Show)；Wherein, shape one is most preferred shapes.
(2) electron beam collimation focusing pole: electron beam collimation focusing pole is the key core component for obtaining micron order focal spot.One
A effect is regulated and controled by emission current intensity of the first grid to carbon nanotube cathod, another important function is to lead to
The parameters such as the aperture for designing the first, second grid hole, hole depth are crossed, equally distributed electric field strength can be obtained, as shown in fig. 6,
To realize the function of being collimated and focused to electron beam, as shown in Figure 7.
First grid hole optimum-size: aperture 1=100~200 μm Φ, hole depth h1=50~100 μm；
Second grid hole optimum-size: aperture 2=120~200 μm Φ, hole depth h1=60~80 μm；
The first, second grid of electron bombardment will lead to the raising of its temperature, to prevent the first, second grid due to temperature increases
Generating deformation leads to the variation of the first, second grid gate hole electric field intensity inside high, to influence the collimation of electron beam and focus function
Energy.Therefore, the refractory metal that the material of the first, second grid should select thermal expansion coefficient small: such as tantalum, rhenium.
(3) transmission target: the transmission target that the present invention uses plates on surface using the high diamond chip of thermal conductivity as base material
Tungsten film.Diamond chip is prepared for chemical vapour deposition technique, and with a thickness of 0.25~0.5mm, the diamond chip of this thickness both had
There are enough mechanical strengths to resist vacuum pressure, also to X-ray self-absorption less than 10%.The thin tungsten film thickness is 1~10 μm,
It is prepared by the methods of magnetron sputtering method.
(4) metal ceramic tube outer housing: using 95% aluminium oxide ceramics and ceramic metallization processing is carried out.Relative to tradition
The glass envelope of radiographic source, 95% aluminium oxide ceramics has higher insulation performance, can be into the identical situation of maximal pressure
One step reduces the volume of ray tube, is conducive to the miniaturization of radiographic source.
Finally, it is stated that preferred embodiment above is only used to illustrate the technical scheme of the present invention and not to limit it, although logical
It crosses above preferred embodiment the present invention is described in detail, however, those skilled in the art should understand that, can be
Various changes are made to it in form and in details, without departing from claims of the present invention limited range.
Claims (5)
1. carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube, it is characterised in that: including carbon nanotube microbeam array
Cathode, electron beam collimation focusing pole, anode and transmission target；
The carbon nanotube microbeam array cathode, electron beam collimation focusing pole, anode and transmission target center be located at straight line
On；Carbon nanotube microbeam array cathode launches the electron beam that beam diameter is 5~50 μm of Φ, and electron beam is poly- by electronic collimation
After the collimation focusing of burnt pole, electron beam further collimates and attenuates, and bombardment is to thoroughly after being accelerated by the high pressure of 30~100kV of anode
On shooting at the target, the x-ray focal spot of micron-scale is issued；
Electron beam collimation focusing pole effect are as follows: adjusted by emission current intensity of the first grid to carbon nanotube cathod
Control, by setting aperture, the hole depth in first grid hole and second grid hole, the electric field strength being evenly distributed, to realize
Electron beam is collimated and is focused；
The carbon nanotube microbeam array cathode is made of two annulus and the center of circle, and 5~50 μm of outer annular diameter Φ, and outer ring has
The notch of " ten " font line, inner ring also have the notch of " ten " font line, but 45 ° of notch with " ten " font line of outer ring
It is interleaved.
2. carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube, it is characterised in that: including carbon nanotube microbeam array
Cathode, electron beam collimation focusing pole, anode and transmission target；
The carbon nanotube microbeam array cathode, electron beam collimation focusing pole, anode and transmission target center be located at straight line
On；Carbon nanotube microbeam array cathode launches the electron beam that beam diameter is 5~50 μm of Φ, and electron beam is poly- by electronic collimation
After the collimation focusing of burnt pole, electron beam further collimates and attenuates, and bombardment is to thoroughly after being accelerated by the high pressure of 30~100kV of anode
On shooting at the target, the x-ray focal spot of micron-scale is issued；
Electron beam collimation focusing pole effect are as follows: adjusted by emission current intensity of the first grid to carbon nanotube cathod
Control, by setting aperture, the hole depth in first grid hole and second grid hole, the electric field strength being evenly distributed, to realize
Electron beam is collimated and is focused；
The carbon nanotube microbeam array cathode is spoke-like, including " ten " font line between two annulus, two annulus
" ten " font line in the middle part of annulus is enclosed in and, " ten " font between " ten " font line and two annulus in the middle part of inner ring
45 ° of line are interleaved, and 5~50 μm of outer annular diameter Φ.
3. carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube according to claim 1 or 2, feature exist
In: the X-ray tube further includes ceramic and metal package, and entire X-ray tube is surrounded by the ceramic and metal package, using 95%
Aluminium oxide ceramics simultaneously carries out ceramic metallization processing, for minimizing radiographic source in high pressure.
4. carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube according to claim 1 or 2, feature exist
In: the aperture Φ in the first grid hole1=100~200 μm, hole depth h1=50~100 μm, the aperture Φ in second grid hole2=
120~200 μm, hole depth h1=60~80 μm；
Lead to the first, second grid gate hole electric field intensity inside high to prevent the first, second grid from generating deformation because of temperature raising
Variation, to influence collimation and the focusing of electron beam, the material of the first, second grid is the small infusibility gold of thermal expansion coefficient
Belong to, including tantalum and rhenium.
5. carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube according to claim 1 or 2, feature exist
In: the transmission target plates tungsten film, diamond chip is with a thickness of 0.25~0.5mm, tungsten film using diamond chip as base material on surface
With a thickness of 1~10 μm.
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| CN201711145890.5A CN107919257B (en) | 2017-11-17 | 2017-11-17 | Carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube |
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| CN201711145890.5A CN107919257B (en) | 2017-11-17 | 2017-11-17 | Carbon nanotube microbeam array field emission cathode Microfocus X-ray X-ray tube |
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| CN107919257B true CN107919257B (en) | 2019-04-26 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109087838A (en) * | 2018-06-19 | 2018-12-25 | 广州市昊志影像科技有限公司 | A kind of Microfocus X-ray X-ray tube based on carbon nano tube field-emission |
| CN109473329A (en) * | 2018-12-25 | 2019-03-15 | 深圳大学 | A kind of spatial coherence x-ray source of surface launching transmission-type array structure |
| CN109786193A (en) * | 2018-12-29 | 2019-05-21 | 同方威视技术股份有限公司 | A kind of x-ray source |
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| CN1909152A (en) * | 2006-08-02 | 2007-02-07 | 中原工学院 | Honeycomb type grid control cathode emitting structural panel display device and its production technique |
| CN101075529A (en) * | 2007-06-19 | 2007-11-21 | 中原工学院 | Planar display device with petal-shaped lower-grid controlled cathode structure and its production |
| CN203242592U (en) * | 2011-08-07 | 2013-10-16 | 张研 | Mesh-shaped high-performance carbon nanotube field emission array |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7826595B2 (en) * | 2000-10-06 | 2010-11-02 | The University Of North Carolina | Micro-focus field emission x-ray sources and related methods |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1909152A (en) * | 2006-08-02 | 2007-02-07 | 中原工学院 | Honeycomb type grid control cathode emitting structural panel display device and its production technique |
| CN101075529A (en) * | 2007-06-19 | 2007-11-21 | 中原工学院 | Planar display device with petal-shaped lower-grid controlled cathode structure and its production |
| CN203242592U (en) * | 2011-08-07 | 2013-10-16 | 张研 | Mesh-shaped high-performance carbon nanotube field emission array |
Non-Patent Citations (1)
| Title |
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| "Transmission-type microfocus x-ray tube using carbon nanotube field emitters";Sun Hwan Heo，et al.;《APPLIED PHYSICS LETTERS》;20070501;第90卷;第1-3页 |
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