Development of Carbon Nanotube Field Emitters for X-Ray Source

2007 ◽  
Author(s):  
Xiomara Calderón-Colón ◽  
Otto Zhou
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
Imaging System ◽  
High Current Density ◽  
High Temporal Resolution ◽  
Stable Form ◽  
Cylindrical Shape ◽  
Flat Panel Display ◽  
Graphite Sheet ◽  
X Ray

Carbon Nanotubes (CNTs) have been shown excellent field emission emitters due to their unique properties. CNTs are a stable form of carbon; a graphite sheet rolls up forming a cylindrical shape with high aspect ratio, low turn-on field, high current density, high strength (1) and can generate quality x-ray radiation (2). These properties make carbon nanotubes very attractive for field emission applications. Field emission cathodes are the central part of field emission displays (FED) and carbon nanotubes field emission x-ray source. FED is a new flat panel display technology; this technology enables much thinner, lighter, and highest resolution displays than the cathode ray tubes (CRT). CNTs field emission x-ray source technology has applications in medical imaging and homeland security (2–7). The current thermionic cathodes have several disadvantages over CNT based field emission x-ray source such as slow response time, high power consumption, high operation temperature that reduces the lifetime of the x-ray tube (4) and large device size (3). Also CNT based field emission x-ray source offers improvement in high temporal resolution and capabilities for spatial and temporal modulation (7). CNT field emission x-ray source technology is available in single- and multi-beam imaging system. Multi-beam imaging system offers image of an object from multiple projection angles without mechanical motion (7).

Field-emission device with carbon nanotubes for a flat panel display

2001 ◽  
Vol 117 (1-3) ◽  
pp. 207-210 ◽  
Author(s):  
Yoshikazu Nakayama ◽  
Seiji Akita
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
Flat Panel Display ◽  
Flat Panel ◽  
Emission Device

Field emission properties of carbon nanotubes grown on a conical tungsten tip for the application of a microfocus x-ray tube

2007 ◽  
Vol 516 (2-4) ◽  
pp. 304-309 ◽  
Author(s):  
Chang-Kyun Park ◽  
Jong-Pil Kim ◽  
Sung-Jun Yun ◽  
Seoung-Hwan Lee ◽  
Jin-Seok Park
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
X Ray ◽  
Emission Properties ◽  
Field Emission Properties ◽  
Tungsten Tip

Mesh-Free Numerical Simulation for Carbon Nanotubes upon Bending

2010 ◽  
Vol 139-141 ◽  
pp. 17-21
Author(s):  
Bin Gao ◽  
Yu Zhou Sun ◽  
Jin Bao Wang
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strain ◽  
Vital Role ◽  
Higher Order ◽  
Least Square ◽  
Cylindrical Shape ◽  
Graphite Sheet ◽  
Current Configuration ◽  
Moving Least Square ◽  
Mesh Free

This paper presents a mesh-free numerical modeling approach for carbon nanotubes (CNTs) subjected to bending loads. The higher-order Cauchy-Born rule was employed to construct the higher-order continuum constitutive model. An initial equilibrium single-walled CNT (SWCNT) was viewed as been formed by rolling up a graphite sheet into a cylindrical shape. The deformation from an original SWCNT to the current configuration was approximated with the moving least-square (MLS) approximation, and the mesh-free computational framework was established in the theoretical scheme of higher-order gradient continuum. Mesh-free numerical simulations were carried out for SWCNTs, and the accuracy and convergence were discussed in comparison with the results of atomistic simulation. The buckling behavior was studied for various types of SWCNTs upon bending, and the buckling mechanism was investigated in virtue of the continuum variables, which showed that the maximum axial compressive strain played a vital role in the development of kinking.

Field-Emission Electron Source Using Carbon Nanotubes for X-ray Tubes

2008 ◽  
Vol 52 (4) ◽  
pp. 1057-1060 ◽  
Author(s):  
Hyun Suk Kim ◽  
Dao Quang Duy ◽  
Jae Hoon Kim ◽  
Hyung Joo Lee ◽  
Dang Mo Yoon ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
Electron Source ◽  
X Ray ◽  
Emission Electron

Field Emission Study of Carbon Nanotubes: High Current Density From Nanotube Bundle Arrays

2004 ◽  
Author(s):  
M. J. Bronikowski ◽  
H. M. Manohara ◽  
P. H. Siegel ◽  
B. D. Hunt
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
High Current Density ◽  
High Current ◽  
Multiwalled Carbon ◽  
Nanotube Bundles ◽  
Emission Behavior ◽  
Emission Study ◽  
Nanotube Bundle ◽  
Field Emission Performance

We have investigated the field emission behavior of lithographically patterned bundles of multiwalled carbon nanotubes arranged in a variety of array geometries. Such arrays of nanotube bundles are found to perform significantly better in field emission than arrays of isolated nanotubes or dense, continuous mats of nanotubes, with the field emission performance depending on the bundle diameter and inter-bundle spacing. Arrays of 2-μm diameter nanotube bundles spaced 5 μm apart (edge-to-edge spacing) produced the largest emission densities, routinely giving 1.5 to 1.8 A/cm2 at ∼ 4 V/μm electric field, and >6 A/cm2 at 20 V/μm.

Synthesis of Carbon Nanotubes and its Applications in Composites and Field Emission Light

2007 ◽  
Vol 539-543 ◽  
pp. 3491-3496
Author(s):  
Nyan Hwa Tai ◽  
Meng Kao Yeh ◽  
Chien Hsin Yang ◽  
Shis Hao Tseng ◽  
Chien Chao Chiu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Electron Microscope ◽  
Field Emission ◽  
Vapor Deposition ◽  
Rapid Heating ◽  
High Current Density ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Walled Carbon Nanotubes

Two processes, the floating catalyst chemical vapor deposition (CVD) process and the rapid heating and cooling (RHC) process, were adopted for synthesizing single walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). Batch production of SWNTs and MWNTs with the diameters of 0.8~1.5 nm and 15~40 nm, respectively, were prepared using the floating catalytic chemical vapor deposition (CCVD) process. The production rate is 70±20 mg every 10 minutes. The as-synthesized carbon nanotubes (CNTs) were used for fabricating carbon nanotubes reinforced composites and field emitter for lighting. On the study of nano-composites, around 70% enhancement of tensile strength was detected when 1.5 wt% MWNTs in the form of network structure were introduced to the phenolic matrix. Comparisons on the mechanical properties of the composites reinforced with the network MWNTs and SWNTs were made. Microstructures of the MWNTs and SWNTs were studied by Field Emission Scanning Electron Microscope (FESEM) and High Resolution Transmission Electron Microscope (HRTEM). In the RHC process for fabricating the device for lighting, the carbon nanotube array was grown on a silicon substrate which was pre-coated with a catalyst thin film. The synthesis process was performed in a thermal CVD chamber equipped with a rapid heating apparatus. The as-synthesized CNT array was then transferred onto the substrate which was coated with silver paste. After heat treatment, field emission properties of the CNT-based cathode were tested, high current density of 35 mA/cm2 and low turn-on voltage of 0.65 V/μm were achieved in this work.

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