Research On Corbon Nanotubes Cold Cathode For Application In High Power Microwave Tube

Carbon nanotubes for its unique excellent field emission performance has been widely studied. Carbon nanotube cold cathode with high current density, low turn-on voltage, fast response, etc., and have a good field emission properties, high thermal conductivity properties, resistance to high temperature, and particle bombardment and other characteristics is high-power microwave tubes cold cathode field emission ideal material. With the high power microwave vacuum electronic devices to miniaturization,high efficiency and high frequency of development, the use of carbon nanotubes as a cathode material to meet the needs of the development of vacuum electronic devices.The main work of this thesis are as follows:1. simulation and calculation of carbon nanotubes cold cathode field emission properties. Due to carbon nanotubes have enhanced field emission effect and shielding effect. Through the simulation software of ion calculation obtained the optimal aspect ratio to improve the field emission enhancement effect. In order to reduce the influence of the shielding effect of the field emission, obtained by calculating the optimal contrast carbon nanotube array pitch, and calculate the carbon nanotube array emitting area, to meet the needs of field emission electron gun current.2. This paper studies the plasma chemical vapor deposition preparation processes and growth conditions of large area carbon nanotube cathode, the use of self-designed PECVD system on silicon and molybdenum sheet grown a large area of carbon nanotubes, by scanning electron microscopy and Raman spectroscopy, according to the growth and morphology of carbon nanotubes defective adjustment process and growth conditions. In order to obtain a larger field emission current study the wet spinning process for preparing carbon nanotube fibers as a field emission material, it has been a process and apparatus for preparing innovation wet spinning of carbon nanotube fibers.3. The carbon nanotube cold cathode field emission performance testing. Through independent research field emission testing system on the growth of the carbon nanotube cold cathode samples of field emission performance testing. We studied the effects of different growth conditions of temperature and time on the morphology and field emission properties of carbon nanotubes, to obtain the optimal growth temperature and growth time. Study the field emission properties of carbon nanotube fibers,compared to the field emission properties of carbon nanotubes obtained fiber is better than the prepared by PECVD carbon nanotube cathode material.4. carbon nanotubes cold cathode electron gun assembly simulation design and Preparation. According to the structure of TWT and theries of Pierce electron gun, in the CST software simulation of carbon nanotube field emission cathode assembly structural model, based on carbon nanotube field emission measured parameters obtained by fitting a carbon nanotube field emission FN equation. The simulation study on the electron gun cathode assembly the field emission electron beam convergence performance. Based on the electron gun assembly simulation model, obtained by processing the carbon nanotube cold cathode electron gun assembly sample; field emission performance test of electron gun assembly sample, pulsed field emission current and threshold electric field, the current density and other performance parameters; test results and simulation design roughly consistent.