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WO2018112718A1 - Structure de source de rayons x réfléchissante d'une cathode à nanotubes de carbone à motifs - Google Patents

Structure de source de rayons x réfléchissante d'une cathode à nanotubes de carbone à motifs Download PDF

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Publication number
WO2018112718A1
WO2018112718A1 PCT/CN2016/110867 CN2016110867W WO2018112718A1 WO 2018112718 A1 WO2018112718 A1 WO 2018112718A1 CN 2016110867 W CN2016110867 W CN 2016110867W WO 2018112718 A1 WO2018112718 A1 WO 2018112718A1
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WO
WIPO (PCT)
Prior art keywords
carbon nanotube
ray source
conductive base
reflective
grid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2016/110867
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English (en)
Chinese (zh)
Inventor
冯鸿涛
张志诚
陈艳
谢耀钦
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Institute of Advanced Technology of CAS
Original Assignee
Shenzhen Institute of Advanced Technology of CAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Institute of Advanced Technology of CAS filed Critical Shenzhen Institute of Advanced Technology of CAS
Priority to PCT/CN2016/110867 priority Critical patent/WO2018112718A1/fr
Publication of WO2018112718A1 publication Critical patent/WO2018112718A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • 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

Definitions

  • the present invention relates to an X-ray source structure, and more particularly to a reflective X-ray source structure for a patterned carbon nanotube cathode.
  • Computed tomography is a powerful medical imaging diagnostic device that uses X-rays to scan a certain range of the human body layer by layer, acquires projection information, and then performs data processing and image reconstruction in a computer.
  • Traditional spiral CT imaging systems mainly include X-ray sources, high voltage generators, detectors, racks, slip rings and other components.
  • the X-ray source determines the imaging mode and imaging performance of the CT system to some extent.
  • the conventional X-ray source consists of a hot cathode and an anode. During operation, an electron beam is generated by thermally exciting free electrons. Then, under the action of the anode voltage, free electrons are accelerated to bombard the anode target to generate X-rays. Since the cathode filament (such as tungsten wire) needs to be heated to a certain extent, resulting in slow start-up of the X-ray source, short service life, and high power consumption, it is often necessary to replace the X-ray tube in time.
  • the technical problem to be solved by the present invention is to provide a reflective X-ray source structure of a patterned carbon nanotube cathode, which can solve the problem that the conventional X-ray source uses a hot cathode as an electron source, resulting in high operating temperature, high power consumption, and startup speed. Slow, short service life, is not conducive to the realization of the miniaturization of the radiation source, while achieving the regulation of field emission.
  • the present invention provides a reflective X-ray source structure of a patterned carbon nanotube cathode, which comprises a carbon nanotube, a conductive base, an insulating cover, an insulating spacer, a focusing barrel, a grid, and an anode target.
  • the carbon nanotube, the conductive base, the insulating cover, the insulating spacer, the focusing barrel and the grid are encapsulated inside the tube, and the bottom of the insulating cover is matched with the conductive base
  • the carbon nanotubes, the insulating spacers and the grid are sequentially mounted on the top of the conductive base from bottom to top, the focusing barrel is disposed at the top of the insulating cover, and the top of the tube is provided with a ball
  • the anode target is disposed in the X-ray generation channel.
  • the carbon nanotubes are micro-columns fabricated by micro-nano processing technology, and then a carbon tube is grown on the surface by a CVD process to accurately control the growth height of the carbon tubes, and Catalyst deposition on the surface of the microcolumn leads to the growth of 3D patterned carbon nanotubes.
  • the conductive base is provided with a first flange and a first step disposed on the first flange, and the bottom of the insulating cover is provided with the first step connected
  • the first stepped hole, the insulating cover is further provided with a second flange, and the second flange is connected to the first flange by screws.
  • the first step is provided with a second step
  • the insulating spacer is provided with a second stepped hole that is coupled with the second step, and the second stepped hole is connected Between the carbon nanotubes and the grid.
  • a central portion of the end surface of the secondary step is provided with a groove, and the size of the groove matches the size of the carbon nanotube.
  • a top step of the insulating cover is provided with a third stepped hole that is coupled to the focusing barrel.
  • the conductive base is connected with a supporting electrode, one end of the supporting electrode is connected to the conductive base, and the other end of the supporting electrode is connected to an external power source through a closed end of the tube.
  • the grid is provided with a first power line, one end of the first power line is connected to the grid, and the other end of the first power line passes through the tube
  • the closed end is connected to an external power source.
  • the focus barrel is provided with a second power line, one end of the second power line is connected to the focus barrel, and the other end of the second power line passes through the tube The closed end is connected to an external power source.
  • the second flange is provided with two through holes through which the first power line and the second power line pass, and at least two mounting holes through which the screws can pass.
  • the first flange is provided with a relief hole opposite to the through hole, and at least two threaded holes opposite to the mounting hole.
  • the carbon nanotubes are integrated as a field emission electron source of X-rays onto the conductive base.
  • a voltage is applied to the conductive base and the grid respectively to a threshold value, the current intensity generated by the carbon nanotubes is regulated by the grid, and the electrons are emitted from the carbon nanotubes.
  • the end face is pulled out, and the focus barrel is electronically focused to form a spot on the anode target, and X-rays are generated and transmitted toward the window to realize X-ray imaging.
  • This design is due to the large aspect ratio and extremely small radius of curvature of carbon nanotubes, which can emit large currents at relatively low electric field strength, and has low threshold voltage, high emission current density, and high stability.
  • Excellent field emission performance solving the problem that the traditional X-ray source uses the hot cathode as the electron source, resulting in high operating temperature, high power consumption, slow starting speed, short service life, and is not conducive to miniaturization of the radiation source;
  • the grid By using the grid as the gate and optimizing the insulating spacer to isolate the distance between the carbon nanotube and the grid to regulate the current intensity generated by the cold cathode of the carbon nanotube, and the grid can be instantly turned on or off, thereby realizing The regulation of field emission; the focus of the focusing barrel is also used to control the focused spot on the anode target, thereby improving the imaging quality.
  • the invention has the advantages of compact structure, stable performance, simple assembly, small size, convenient use, low cost and strong practicability.
  • FIG. 1 is an exploded view of a reflective X-ray source structure of a patterned carbon nanotube cathode of the present invention
  • FIG. 3 is an effect diagram of a 3D patterned carbon nanotube growth process.
  • a preferred embodiment of the present invention is a patterned carbon nanotube transmission X-ray source structure comprising carbon nanotubes 1 , a conductive base 2 , an insulating cover 3 , an insulating spacer 4 , a focusing barrel 5 , a grid 6, an anode target 7, a window 8 and a bulb 9, the carbon nanotube 1, the conductive base 2, the insulating cover 3, the insulating spacer 4, the focusing barrel 5 and the grid 6 are enclosed in the tube 9
  • the bottom of the insulating cover 3 is engaged with the conductive base 2, and the carbon nanotubes 1, the insulating spacers 4 and the grid 6 are sequentially mounted from the bottom to the top of the conductive base 2,
  • the focusing barrel 5 is disposed at the top of the insulating cover 3, and the top of the bulb 9 is provided with an X-ray generating passage 10 communicating with the inside of the bulb 9, the bottom of the tube 9 is closed, and the focusing barrel 5 is closed.
  • the top end is opposed to the incident end of
  • the conductive base 2 is preferably made of a metal conductive material, and has an embedded recess on the surface thereof to match the size of the carbon nanotubes 1 to realize the limiting action of the carbon nanotubes 1 and facilitate the carbon nanotubes 1 Applying a voltage;
  • the insulating cover 3 is preferably made of a ceramic material for fixing the grid 6 and receiving the focusing barrel 5;
  • the insulating spacer 4 is preferably made of a ceramic material for isolating the grid 6 and the carbon nanotubes 1;
  • 6 is preferably a 100 mesh tungsten mesh, and the tungsten mesh can be pulled out after applying a voltage;
  • the bulb 9 is preferably a glass bulb 9 for vacuum packaging the carbon nanotube 1, the conductive base 2, the insulating cover 3, and the insulating spacer 4 Focus bucket 5 and grid
  • the core structure composed of the net 6 provides a good migration environment for the electrons;
  • the anode target 7 preferably uses a large piece of copper as the anode, which is favorable for
  • the working principle of the reflective X-ray source structure of the patterned carbon nanotube cathode is to integrate the carbon nanotube 1 as a field emission electron source of X-rays onto the conductive base 2, when the conductive base 2 and the grid 6 are respectively After the voltage is applied to the threshold, the intensity of the current generated by the carbon nanotubes 1 is regulated by the grid 6.
  • the electrons are pulled out from the end faces of the carbon nanotubes 1 and subjected to electron focusing through the focusing barrel 5 to form a spot on the anode target 7 to generate X-rays. And it is transmitted in the direction of the window 8 to realize X-ray imaging.
  • Such a design is due to the fact that the carbon nanotubes 1 have a large aspect ratio and a small radius of curvature, can emit a large current at a relatively low electric field intensity, and have a low threshold voltage, a large emission current density, and stability. Strong and excellent field emission performance.
  • the X-ray source based on the carbon nanotube 1 when the surface electric field of the carbon nanotube 1 reaches a certain threshold, free electrons can be generated from the carbon nanotube 1, and it can be said that the generation of electrons is instantaneous. And no heat is generated in this process.
  • the X-ray source of the carbon nanotubes prepared by using these characteristics can solve the problem that the conventional X-ray source adopts the hot cathode as the electron source, resulting in high operating temperature, high power consumption, slow starting speed, short service life, and unfavorable realization of the radiation source.
  • the problem of miniaturization at the same time, by using the grid 6 as a gate and optimizing the insulating spacer 4 to isolate the distance between the carbon nanotube 1 and the grid 6 to regulate the current intensity generated by the cold cathode of the carbon nanotube, and the grid 6 can realize the instantaneous opening or closing, thereby realizing the regulation of the field emission; also controlling the focusing spot hitting the anode target 7 by the focusing action of the focusing barrel 5, thereby improving the imaging quality.
  • the carbon nanotubes 1 are micro-columns of a certain height (for example, 20 um) by using micro-nano processing technology, and then are grown on the surface by chemical vapor deposition (CVD). High carbon tube for precise control of carbon tube growth height, as well as micro-column end and side The catalyst deposition of the wall further grows the 3D patterned carbon nanotubes 1. It should be noted that, in the 3D patterned carbon nanotubes 1, the carbon tube is subjected to CVD growth on the surface of the heavily doped silicon wafer with a certain depth of micro-column, and the 3D patterned carbon tube is produced in one step, as shown in FIG. 2 . And Figure 3 shows.
  • the carbon tube and the side wall of the micro-column end surface are completely protruded, and the carbon tube extending to the periphery is formed into a 3D carbon tube structure, and the current generated between the carbon tube bundles is not affected.
  • the conductive base 2 is provided with a first flange 21 and a first step 22 disposed on the first flange 21,
  • the bottom of the insulating cover 3 is provided with a first stepped hole 31 which is coupled with the first step 22, and the insulating cover 3 is further provided with a second flange 32, the second flange 32 and the first method
  • the blue plate 21 is connected by screws.
  • the first step 22 is provided with a secondary step 23, and the insulating spacer 4 is provided with the second
  • the step 23 is matched with the connected second stepped hole 41, and the second stepped hole 41 is in communication with the carbon nanotube 1 and the grid 6.
  • the middle surface of the end surface of the second step 23 is provided with a groove, and the size of the groove matches the size of the carbon nanotube 1 to limit the carbon nanotubes 1 .
  • the second stepped hole 41 includes a large circular hole and a small circular hole reserved for a certain depth.
  • the large circular hole is used for alignment with the secondary step 23 of the conductive base 2, and the small circular hole is connected to the emission window of the carbon nanotube 1 Between the carbon nanotubes 1 and the grid 6, when assembled, the peripheral edges of the small circular holes can also press and fix the carbon nanotubes 1. It should also be noted that the depth of the small circular hole is controlled to be 0.2 mm, and the threshold voltage of the field emission can be satisfied by applying a small voltage to the grid 6.
  • the top of the insulating cover 3 is provided with a third stepped hole 33 which is coupled with the focusing barrel 5, and the third stepped hole 33 is used for fitting The focus barrel 5 is fixed.
  • the holes formed by the first stepped hole 31 and the third stepped hole 33 are The small circular through holes having the shape of the I-shaped shape, that is, the first stepped hole 31 and the third stepped hole 33 form an electron transporting passage at the center of the insulating cover 3.
  • the conductive base 2 is connected with a supporting electrode 11 , one end of the supporting electrode 11 is connected to the conductive base 2 , and the other end of the supporting electrode 11 is closed through the tube 9 .
  • the terminal is connected to an external power source.
  • the conductive base 2 is electrically connected to the carbon nanotubes 1 .
  • the support electrode 11 not only the voltage requirement of the carbon nanotubes 1 but also the core structure inside the bulb 9 (for example, the carbon nanotubes 1, the conductive base 2, the insulating cover 3, and the insulating spacers 4) are provided.
  • the support function of the combined structure of the barrel 5 and the grid 6 is focused.
  • the grid 6 is provided with a first power line, one end of the first power line is connected to the grid 6, and the other end of the first power line passes through the tube
  • the closed end of 9 is connected to an external power source to supply a voltage to the grid 6
  • the focus barrel 5 is provided with a second power line, one end of the second power line is connected to the focus barrel 5, the second power source
  • the other end of the wire is connected to the external power source through the closed end of the bulb 9 to supply a voltage to the focus barrel 5.
  • Reflective X-ray source structure of the patterned carbon nanotube cathode In addition, slits are reserved on the left and right sides of the insulating cover 3 to ensure that the two power supply lines are respectively connected to the focus barrel 5 and the grid 6 to apply corresponding voltages.
  • the second flange 32 is provided with two through holes through which the first power line and the second power line pass, and at least two mounting holes through which the screws can pass.
  • the first flange 21 is provided with a relief hole opposite to the through hole, and at least two threaded holes opposite to the mounting hole.
  • the reflective X-ray source structure of the patterned carbon nanotube cathode of the present invention can be used not only For the purpose of instant imaging of human organs and the detection of dangerous goods, X-ray radiation therapy for different diseases can also be realized.
  • the reflective X-ray source structure of the patterned carbon nanotube cathode of the present invention has compact structure, stable performance, simple assembly, small size, convenient use, clear imaging, low power, low cost and high controllability. And the advantages of practicality.

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  • X-Ray Techniques (AREA)
  • Cold Cathode And The Manufacture (AREA)

Abstract

L'invention concerne une structure de source de rayons X réfléchissante d'une cathode à nanotubes de carbone à motifs, comprenant un nanotube de carbone (1), une base électriquement conductrice (2), un capot isolant (3), une rondelle isolante (4), un cylindre de focalisation (5), une maille (6), une cible faisant anode (7), une fenêtre de béryllium (8) et un tube (9). La partie inférieure du capot isolant (3) s'adapte à la base électriquement conductrice (2), tandis que le nanotube de carbone (1), la rondelle isolante (4) et la maille (6) sont montés en séquence vers le haut sur la partie supérieure de la base électriquement conductrice (2). Le cylindre de focalisation (5) est disposé sur la partie supérieure du capot isolant (3). Lorsque la base électriquement conductrice (2) et la maille (6) appliquent respectivement des tensions qui atteignent un seuil, l'intensité d'un courant produit par le nanotube de carbone (1) est régulée par l'intermédiaire de la maille (6), des électrons sont extraits d'une surface d'extrémité du nanotube de carbone (1), un point lumineux formé par focalisation des électrons par l'intermédiaire du cylindre de focalisation (5) est projeté sur la cible faisant cathode (7), et un rayon X ainsi produit est émis vers l'extérieur en direction de la fenêtre de béryllium (8). L'utilisation de la structure de source de rayons X d'une part résout les inconvénients des sources de rayons X classiques qui utilisent une cathode chaude comme source d'électrons, ce qui conduit à des températures de travail élevées, une grande consommation d'énergie, une vitesse de démarrage lente, une durée de vie réduite et des difficultés à miniaturiser les sources de rayons, et d'autre part permet de mettre en œuvre la régulation des émissions de champs.
PCT/CN2016/110867 2016-12-19 2016-12-19 Structure de source de rayons x réfléchissante d'une cathode à nanotubes de carbone à motifs Ceased WO2018112718A1 (fr)

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Cited By (1)

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CN114005560A (zh) * 2021-10-22 2022-02-01 华能核能技术研究院有限公司 一种高温气冷堆吸收球落球限位装置及球床式高温气冷堆

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN114005560A (zh) * 2021-10-22 2022-02-01 华能核能技术研究院有限公司 一种高温气冷堆吸收球落球限位装置及球床式高温气冷堆
CN114005560B (zh) * 2021-10-22 2023-07-04 华能核能技术研究院有限公司 一种高温气冷堆吸收球落球限位装置及球床式高温气冷堆

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