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Extended interaction oscillator based on a modulation electron beam is studied in order to develop a compact, miniaturization, and low voltage millimeter wave vacuum devices. A modulation electron beam can be obtained by a field emission carbon nanotube cold cathode electron gun based on a microstrip structure. A disc-loaded waveguide structure EIO operating in 2π mode is simulated. Simulation results...
There are a lot of systems of carbon nanotubes synthesis. One of the most common is arc discharge system. The disadvantage of this method is its efficiency, repeatability, and control of the system. This work is a proposal of application of an electromagnetic field as an improvement of the arc discharge system. Among different solutions of the electromagnetic field generation, the coil placed on the...
We reported fabrication and field emission properties of carbon nanotube (CNT) field emitters which indicated the point-type CNT film emitter and line-type CNT film emitter. The CNT film field emitters were made by cutting CNT film using a razor. The CNT film emitters showed good emission properties such as the low turn-on field, the high emission current in a triode configuration. Especially, the...
The cold cathode x-ray source was fabricated by using the point-type CNT film emitter. The CNT x-ray source consists of the CNT point emitter, the metal mesh gate electrode and the tungsten target anode electrode. Those components were mounted in a small vacuum chamber. The fabricated CNT x-ray source shows a high resolution x-ray image at a low anode current and at a low anode voltage compared to...
Nanostructured thermionic energy converters may offer substantial advantages over traditional devices by reducing system complexity and requirements. However, they still face similar fundamental challenges, such as anode collection efficiency and the space charge effect, which have limited their performance to date. Here, we investigate a carbon nanotube-based thermionic converter, demonstrating that...
Field Emission Pattern Image of Carbon Nanotubes has been captured by using electron beam scanning analyzer. The measurement showed that the Faraday cup scanning method can provide a high resolution field emission sites distribution measurement (the best resolution is up to 0.01mm), which is higher than that using the transparent anode method.
In this paper, we report our first experimental findings that evidence the vacuum level in the test chamber can be responsible for variation in the field emission (Fowler-Nordheim) response of an electron source. This situation is exampled using a carbon nanotube sample measured in a parallel plate configuration.
We propose an advanced active current-control (ACC) unit composed of two cascade transistors for extremely stabilizing field emission currents. The upper transistor connected to the cathode modulates high voltages for field emission while the other one regulates emission current stably. Using the ACC unit developed, very stable emission currents were achieved from the fully vacuum-sealed x-ray tube...
A traveling wave tube (TWT) based on carbon nanotube (CNT) cold cathode is theoretically researched in this paper. A magnetic injection electron gun and helix slow-wave structure is adopted in the TWT. Simulation results show that the maximum output power of the CNT TWT can reach 54 W at 9.4 GHz with an input power of 50 mW, corresponding to the maximum gain of 30 dB, when the gyrating electron beam...
A gridded micro-focus X-ray electron gun based on carbon nanotube cathode has the advantages of small volume, clear imaging and high temporal resolution compared with the conventional X-ray source. An array of CNT bundle is simulated to reduce the electric field screening effects for achieving stable large current density. The gridded electron gun based on carbon nanotube cathode is simulated by three-dimensional...
We developed deep UV generation techniques with home-made wide bandgap anode and carbon nanotube (CNT) based cold cathode electron beam (C-beam). The wide bandgap anodes excited with high performance C-beam. The fabrication process for anodes were developed and optimized for high performance deep UV generation. Also, the performance of C-beams optimized. With the optimized C-beam and anode, we could...
Field emission of high current from carbon nanotube (CNT) emitters usually enforces them to be exposed to high electric fields (electrostatic forces) and Joule heating. In addition, vacuum packaging of field emitter devices are often carried out at high temperature. Under such circumstances, CNT emitters may be easily damaged, thus requiring highly crystalline and thermally stable CNTs. This study...
We tried to improve field emission properties of carbon nanotube (CNT) paste emitters by controlling the size distribution of aggregated SiC fillers. The SiC fillers used as an adhesion promoter strongly affects the dispersion of CNT paste, determining uniformity and reproducibility of the field emitter. We found, to date, that the optimum distribution is about 1 μm of D50, the value of the particle...
A new way to improve the current stability of an in-plane gated CNT emitters cathode with a closed loop control has been investigated. Ageing has been performed with a variation of external conditions by introducing hydrogen into the vacuum chamber and resulting in a low impact on the stability due to the feedbacked adjustment of the local electric field at the apex of CNTs given by the closed loop...
We propose a mathematical model for calculation of performance of field-emission cells. Demonstrated model allow calculating electrical potential distribution, trajectories of the emitted electrons and cell currents. Three different constructions of cell were examined. The main important features for cell performance were defined through the model. We assume that using this model will allow to simplify...
We fabricated the point-type CNT emitter for cold cathode x-ray source applications. The CNT point emitter was made by CNT film with a triangular tip shape, which was clamped using two stainless steel plates. Electrical properties of the point-type CNT emitter measured in triode structure showed the low turn-on and threshold electric fields, the high emission current and relatively high electron transmittance...
Local emission characteristics of the microscopic emission sites on a surface of large area field emitters is one of the most important factors which establish the macroscopic emission properties. This work is aimed to evaluate the local field emission characteristics using computerized field emission projector and technique of multi-channel recording of IVCs. The model sample is nanocomposite nanotubes...
VO2 (A) emitters with 10 nm gap between the cathode and anode were fabricated with the aid of focus ion beam etching. Excellent field emission properties were achieved under atmospheric conditions with turn-on voltage as low as 0.6 V and good emission stability over 30 minutes. This work provides a practical way to eliminate the vacuum needs of the field emission devices and has potential use in future...
Low-threshold field emission is the intrinsic property for nanocarbon materials. Emission characteristics of planar field cathodes with carbon nanotubes (CNT) deposited from solution to Si, Al, Pd substrates were studied. The field emission threshold value for horizontally aligned CNT was found as low as 4 V/μm. However, the field enhancement in these samples is negligible (<10). We propose to...
This report presents the results of calculation of electron-optical system consisting of a sheet CNT field emission cathode with a microgrid spaced from the surface of the emitter at 100 microns. On the basis of experimental data, it has been designed electron-optical system with a sheet CNT cathode with linear convergence of 6,25, and with the beam current density of 4,46 A/cm2. The thickness of...
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