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WO2018112718A1 - 一种图案化碳纳米管阴极的反射式x射线源结构 - Google Patents

一种图案化碳纳米管阴极的反射式x射线源结构 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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Prior art keywords
carbon nanotube
ray source
conductive base
reflective
grid
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PCT/CN2016/110867
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English (en)
French (fr)
Inventor
冯鸿涛
张志诚
陈艳
谢耀钦
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Shenzhen Institute of Advanced Technology of CAS
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Shenzhen Institute of Advanced Technology of CAS
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Priority to PCT/CN2016/110867 priority Critical patent/WO2018112718A1/zh
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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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Abstract

一种图案化碳纳米管阴极的反射式X射线源结构，其包括碳纳米管(1)、导电底座(2)、绝缘罩(3)、绝缘垫片(4)、聚焦桶(5)、栅网(6)、阳极靶(7)、铍窗(8)和球管(9)，绝缘罩(3)的底部与导电底座(2)配合并将碳纳米管(1)、绝缘垫片(4)和栅网(6)由下而上依次安装在导电底座(2)的顶部，聚焦桶(5)设置在绝缘罩(3)的顶部，当对导电底座(2)和栅网(6)分别施加电压到阈值后，通过栅网(6)调控碳纳米管(1)产生的电流强度，电子从碳纳米管(1)的端面拉出，经过聚焦桶(5)进行电子聚焦形成光斑打在阳极靶(7)上，产生X射线并朝铍窗(8)方向透射出去。采用该X射线源结构，能解决传统X射线源采用热阴极作为电子源而导致工作温度高、功耗大、启动速度慢，使用寿命短、不利于实现射线源的小型化的问题，同时实现对场致发射的调控。

Description

一种图案化碳纳米管阴极的反射式X射线源结构 技术领域
本发明涉及一种X射线源结构，尤其涉及一种图案化碳纳米管阴极的反射式X射线源结构。
背景技术
计算机断层成像设备(computed tomography，CT)是一种功能强大的医学摄影诊断设备，在利用X射线对人体某一范围进行逐层扫描，获取投影信息，然后在计算机中进行数据处理和图像重建。传统螺旋CT成像系统主要包括X射线源、高压发生器、探测器、机架、滑环等部件。
X射线源作为CT系统的关键核心部件之一，在一定程度上决定着CT系统的成像方式与成像性能。传统的X射线源由热阴极和阳极组成，工作时通过热激发游离电子的方式产生电子束，然后在阳极电压的作用下，游离的电子被加速，轰击阳极靶，产生X射线。由于阴极灯丝(如：钨丝)需要被加热到一定的程度，从而导致X射线源启动速度慢，使用寿命短，功耗大，常常需要及时更换X射线管。由此可见，传统的X射线源的这些缺陷导致其无法集成化和设备小型化，在一定程度上制约了CT系统的性能。此外，传统的X射线源通过金属阳极施加高电压从而将电子从碳纳米管尖端拉出，可控性能比较差。
发明内容
本发明所要解决的技术问题在于，提供一种图案化碳纳米管阴极的反射式X射线源结构，能解决传统X射线源采用热阴极作为电子源而导致工作温度高、功耗大、启动速度慢，使用寿命短、不利于实现射线源的小型化的问题，同时实现对场致发射的调控。
为了解决上述技术问题，本发明提供了一种图案化碳纳米管阴极的反射式X射线源结构，其包括碳纳米管、导电底座、绝缘罩、绝缘垫片、聚焦桶、栅网、阳极靶、铍窗和球管，所述碳纳米管、导电底座、绝缘罩、绝缘垫片、聚焦桶和栅网封装在所述球管的内部，所述绝缘罩的底部与所述导电底座配合并将所述碳纳米管、绝缘垫片和栅网由下而上依次安装在所述导电底座的顶部，所述聚焦桶设置在所述绝缘罩的顶部，所述球管的顶部设有与球管内部连通的X射线发生通道，所述球管的底部封闭，所述聚焦桶的顶端与所述X射线发生通道的入射端相对，所述铍窗设置在所述X射线发生通道的出射端，所述阳极靶设置在所述X射线发生通道内，当对导电底座和栅网分别施加电压到阈值后，通过栅网调控碳纳米管产生的电流强度，电子从碳纳米管的端面拉出，经过聚焦桶进行电子聚焦形成光斑打在阳极靶上，产生X射线并朝铍窗方向透射出去。
作为本发明优选的技术方案，所述碳纳米管是利用微纳加工技术制作出一定高度的微柱，然后利用CVD工艺在其表面生长一定高度的碳管，通过精确控制碳管生长高度，以及微柱表面的催化剂沉积，进而长出3D图案化的碳纳米管。
作为本发明优选的技术方案，所述导电底座设有第一法兰盘和设置于所述第一法兰盘上的一级台阶，所述绝缘罩的底部设有与所述一级台阶配合连接的 第一阶梯孔，所述绝缘罩还设有第二法兰盘，所述第二法兰盘与第一法兰盘通过螺钉连接。
作为本发明优选的技术方案，所述一级台阶上设有二级台阶，所述绝缘垫片上设有与所述二级台阶配合连接的第二阶梯孔，且所述第二阶梯孔连通于所述碳纳米管和栅网之间。
作为本发明优选的技术方案，所述二级台阶的端面中部设有凹槽，所述凹槽的尺寸与所述碳纳米管的尺寸匹配。
作为本发明优选的技术方案，所述绝缘罩的顶部设有与所述聚焦桶配合连接的第三阶梯孔。
作为本发明优选的技术方案，所述导电底座连接有支撑电极，所述支撑电极的一端与所述导电底座连接，所述支撑电极的另一端穿过所述球管的封闭端与外部电源连接。
作为本发明优选的技术方案，所述栅网设有第一电源线，所述第一电源线的一端与所述栅网连接，所述第一电源线的另一端穿过所述球管的封闭端与外部电源连接。
作为本发明优选的技术方案，所述聚焦桶设有第二电源线，所述第二电源线的一端与所述聚焦桶连接，所述第二电源线的另一端穿过所述球管的封闭端与外部电源连接。
作为本发明优选的技术方案，所述第二法兰盘设有两个可供所述第一电源线和第二电源线穿过的通孔，以及至少两个可供螺钉穿过的安装孔；所述第一法兰盘设有与所述通孔相对的避让孔，以及至少两个与所述安装孔相对的螺纹孔。
实施本发明的一种图案化碳纳米管阴极的反射式X射线源结构，与现有技术相比较，具有如下有益效果：
将碳纳米管作为X射线的场致发射电子源集成到导电底座上，当对导电底座和栅网分别施加电压到阈值后，通过栅网调控碳纳米管产生的电流强度，电子从碳纳米管的端面拉出，经过聚焦桶进行电子聚焦形成光斑打在阳极靶上，产生X射线并朝铍窗方向透射出去，从而实现X射线成像。这样的设计，是由于碳纳米管具有很大的纵横比和极小的曲率半径，在相对较低的电场强度下就能发射大电流，并具有阈值电压低、发射电流密度大、稳定性强等优异的场致发射性能，解决传统X射线源采用热阴极作为电子源而导致工作温度高、功耗大、启动速度慢，使用寿命短、不利于实现射线源的小型化的问题；同时，通过使用栅网作为栅极并优化绝缘垫片隔离碳纳米管和栅网之间的距离来调控碳纳米管冷阴极产生的电流强度，且栅网可以很好地实现瞬间开启或关闭，进而实现对场致发射的调控；还通过聚焦桶的聚焦作用来控制打在阳极靶的聚焦光斑，从而提高成像质量。此外，本发明还具有结构紧凑、性能稳定、组装简单、体积小巧、使用方便、成本低、实用性强等优点。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例的附图作简单地介绍。
图1是本发明的图案化碳纳米管阴极的反射式X射线源结构的爆炸图；
图2是3D图案化的碳纳米管生长工艺前的效果图；
图3是3D图案化的碳纳米管生长工艺后的效果图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
如图1所示，本发明的优选实施例，一种图案化碳纳米管透射X射线源结构，其包括碳纳米管1、导电底座2、绝缘罩3、绝缘垫片4、聚焦桶5、栅网6、阳极靶7、铍窗8和球管9，所述碳纳米管1、导电底座2、绝缘罩3、绝缘垫片4、聚焦桶5和栅网6封装在所述球管9的内部，所述绝缘罩3的底部与所述导电底座2配合并将所述碳纳米管1、绝缘垫片4和栅网6由下而上依次安装在所述导电底座2的顶部，所述聚焦桶5设置在所述绝缘罩3的顶部，所述球管9的顶部设有与球管9内部连通的X射线发生通道10，所述球管9的底部封闭，所述聚焦桶5的顶端与所述X射线发生通道10的入射端相对，所述铍窗8设置在所述X射线发生通道10的出射端，所述阳极靶7设置在所述X射线发生通道10内。
本实施例中，导电底座2优选采用金属导电材料制成，其上具有内嵌凹槽，匹配碳纳米管1的尺寸，从而实现碳纳米管1的限位作用，且方便对碳纳米管1施加电压；绝缘罩3优选采用陶瓷材料制成，用于固定栅网6和承接聚焦桶5；绝缘垫片4优选采用陶瓷材料制成，用于隔离栅网6和碳纳米管1；栅网6优选为100目钨网，钨网施加电压后可将电子拉出；球管9优选为玻璃球管9，用于真空封装碳纳米管1、导电底座2、绝缘罩3、绝缘垫片4、聚焦桶5和栅 网6组成的核心结构，为电子提供良好的迁移环境；阳极靶7优选采用大块铜作为阳极，有利于散热，且其电子轰击面具有一定的倾角，保证X射线的出光角度与铍窗8一致。
该图案化碳纳米管阴极的反射式X射线源结构的工作原理是，将碳纳米管1作为X射线的场致发射电子源集成到导电底座2上，当对导电底座2和栅网6分别施加电压到阈值后，通过栅网6调控碳纳米管1产生的电流强度，电子从碳纳米管1的端面拉出，经过聚焦桶5进行电子聚焦形成光斑打在阳极靶7上，产生X射线并朝铍窗8方向透射出去，从而实现X射线成像。这样的设计，是由于碳纳米管1具有很大的纵横比和极小的曲率半径，在相对较低的电场强度下就能发射大电流，并具有阈值电压低、发射电流密度大、稳定性强等优异的场致发射性能。基于碳纳米管1的X射线源在工作过程中，当碳纳米管1的表面电场达到一定的阈值后，就能从碳纳米管1中产生游离的电子，可以说电子的产生是瞬时的，而且这个过程中不产生热量。由此利用这些特性制成的碳纳米管X射线源，能解决传统X射线源采用热阴极作为电子源而导致工作温度高、功耗大、启动速度慢，使用寿命短、不利于实现射线源的小型化的问题；同时，通过使用栅网6作为栅极并优化绝缘垫片4隔离碳纳米管1和栅网6之间的距离来调控碳纳米管冷阴极产生的电流强度，且栅网6可以很好地实现瞬间开启或关闭，进而实现对场致发射的调控；还通过聚焦桶5的聚焦作用来控制打在阳极靶7的聚焦光斑，从而提高成像质量。
进一步，本实施例中，所述碳纳米管1是利用微纳加工技术制作出一定高度(如：20um)的微柱，然后利用化学气相沉积(英译简称：CVD)工艺在其表面生长一定高度的碳管，通过精确控制碳管生长高度，以及微柱端面和侧 壁的催化剂沉积，进而长出3D图案化的碳纳米管1。需要说明的是，所述3D图案化的碳纳米管1中，碳管在具有刻蚀一定深度微柱的重参杂硅片表面进行CVD生长，一步实现3D图案化碳管制作，如图2和图3所示。其中，微柱端面生长完全突出的碳管和侧壁生长向四周伸展的碳管，构造成3D碳管结构，并保证碳管束之间产生电流不相互影响。
为了更好地实现导电底座2和绝缘罩3之间的连接，所述导电底座2设有第一法兰盘21和设置于所述第一法兰盘21上的一级台阶22，所述绝缘罩3的底部设有与所述一级台阶22配合连接的第一阶梯孔31，所述绝缘罩3还设有第二法兰盘32，所述第二法兰盘32与第一法兰盘21通过螺钉连接。
为了更好地实现碳纳米管1、绝缘垫片4和栅网6之间的连接，所述一级台阶22上设有二级台阶23，所述绝缘垫片4上设有与所述二级台阶23配合连接的第二阶梯孔41，且所述第二阶梯孔41连通于所述碳纳米管1和栅网6之间。其中，所述二级台阶23的端面中部设有凹槽，所述凹槽的尺寸与所述碳纳米管1的尺寸匹配，对碳纳米管1起到限位作用。所述第二阶梯孔41包括预留一定深度的大圆孔和小圆孔，大圆孔用于与导电底座2的二级台阶23配合对准，小圆孔作为碳纳米管1的发射窗口连通于所述碳纳米管1和栅网6之间，装配时，小圆孔的四周边缘还可以压紧固定碳纳米管1。还需要说明的是，该小圆孔的深度控制在0.2mm，实现栅网6施加小电压即可满足场致发射的阈值。
为了更好地实现绝缘罩3和聚焦桶5之间的连接，所述绝缘罩3的顶部设有与所述聚焦桶5配合连接的第三阶梯孔33，该第三阶梯孔33用于配合聚焦桶5进行固定。还需要说明的是，第一阶梯孔31和第三阶梯孔33所组成的孔 的形状为工字形，也即第一阶梯孔31和第三阶梯孔33的小圆通孔在绝缘罩3的中心形成电子迁移通道。
进一步，本实施例中，所述导电底座2连接有支撑电极11，所述支撑电极11的一端与所述导电底座2连接，所述支撑电极11的另一端穿过所述球管9的封闭端与外部电源连接。其中，导电底座2与碳纳米管1相导通。由此，通过支撑电极11的设计，不仅提供碳纳米管1的电压要求，同时提供了球管9内部的核心结构(如：碳纳米管1、导电底座2、绝缘罩3、绝缘垫片4、聚焦桶5和栅网6的组合结构)的支撑作用。
进一步，本实施例中，所述栅网6设有第一电源线，所述第一电源线的一端与所述栅网6连接，所述第一电源线的另一端穿过所述球管9的封闭端与外部电源连接，从而为栅网6提供电压，所述聚焦桶5设有第二电源线，所述第二电源线的一端与所述聚焦桶5连接，所述第二电源线的另一端穿过所述球管9的封闭端与外部电源连接，从而为聚焦桶5提供电压。图案化碳纳米管阴极的反射式X射线源结构此外，绝缘罩3的左右两侧均预留有狭缝，保证两根电源线分别连接聚焦桶5和栅网6施加相应电压。
进一步，本实施例中，所述第二法兰盘32设有两个可供所述第一电源线和第二电源线穿过的通孔，以及至少两个可供螺钉穿过的安装孔；所述第一法兰盘21设有与所述通孔相对的避让孔，以及至少两个与所述安装孔相对的螺纹孔。这样的设计，一方面，通过安装孔和螺纹孔的设计，利用螺钉将绝缘罩3锁死在导电底座2上，实现绝缘罩3和导电底座2的固定，另一方面，通过通孔和避让孔的设计，保证了电源线绝缘，避免与其他电极发生短路。
此外，本发明的图案化碳纳米管阴极的反射式X射线源结构不仅可以用 于人体器官瞬间成像和危险品检测的目的，而且还能实现X射线对不同疾病的放射治疗。
综上所述，本发明的图案化碳纳米管阴极的反射式X射线源结构具有结构紧凑、性能稳定、组装简单、体积小巧、使用方便、成像清晰、功率低、成本低、可控性高和实用性强等优点。
以上所揭露的仅为本发明的较佳实施例而已，当然不能以此来限定本发明之权利范围，因此依本发明申请专利范围所作的等同变化，仍属本发明所涵盖的范围。

Claims (10)

  1. 一种图案化碳纳米管阴极的反射式X射线源结构，其特征在于，包括碳纳米管、导电底座、绝缘罩、绝缘垫片、聚焦桶、栅网、阳极靶、铍窗和球管，所述碳纳米管、导电底座、绝缘罩、绝缘垫片、聚焦桶和栅网封装在所述球管的内部，所述绝缘罩的底部与所述导电底座配合并将所述碳纳米管、绝缘垫片和栅网由下而上依次安装在所述导电底座的顶部，所述聚焦桶设置在所述绝缘罩的顶部，所述球管的顶部设有与球管内部连通的X射线发生通道，所述球管的底部封闭，所述聚焦桶的顶端与所述X射线发生通道的入射端相对，所述铍窗设置在所述X射线发生通道的出射端，所述阳极靶设置在所述X射线发生通道内，当对导电底座和栅网分别施加电压到阈值后，通过栅网调控碳纳米管产生的电流强度，电子从碳纳米管的端面拉出，经过聚焦桶进行电子聚焦形成光斑打在阳极靶上，产生X射线并朝铍窗方向透射出去。
  2. 如权利要求1所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述碳纳米管是利用微纳加工技术制作出一定高度的微柱，然后利用CVD工艺在其表面生长一定高度的碳管，通过精确控制碳管生长高度，以及微柱表面的催化剂沉积，进而长出3D图案化的碳纳米管。
  3. 如权利要求1所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述导电底座设有第一法兰盘和设置于所述第一法兰盘上的一级台阶，所述绝缘罩的底部设有与所述一级台阶配合连接的第一阶梯孔，所述绝缘 罩还设有第二法兰盘，所述第二法兰盘与第一法兰盘通过螺钉连接。
  4. 如权利要求3所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述一级台阶上设有二级台阶，所述绝缘垫片上设有与所述二级台阶配合连接的第二阶梯孔，且所述第二阶梯孔连通于所述碳纳米管和栅网之间。
  5. 如权利要求4所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述二级台阶的端面中部设有凹槽，所述凹槽的尺寸与所述碳纳米管的尺寸匹配。
  6. 如权利要求3所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述绝缘罩的顶部设有与所述聚焦桶配合连接的第三阶梯孔。
  7. 如权利要求1所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述导电底座连接有支撑电极，所述支撑电极的一端与所述导电底座连接，所述支撑电极的另一端穿过所述球管的封闭端与外部电源连接。
  8. 如权利要求1所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述栅网设有第一电源线，所述第一电源线的一端与所述栅网连接，所述第一电源线的另一端穿过所述球管的封闭端与外部电源连接。
  9. 如权利要求8所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述聚焦桶设有第二电源线，所述第二电源线的一端与所述聚焦桶连接，所述第二电源线的另一端穿过所述球管的封闭端与外部电源连接。
  10. 如权利要求9所述的图案化碳纳米管阴极的反射式X射线源结构，其特征在于，所述第二法兰盘设有两个可供所述第一电源线和第二电源线穿过的通孔，以及至少两个可供螺钉穿过的安装孔；所述第一法兰盘设有与所述通孔相对的避让孔，以及至少两个与所述安装孔相对的螺纹孔。
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