Study On Electron Source Technology Of Vacuumself-monitoring Carbon Nanotube Field Emission Cathode

Carbon nanotubes are regarded as a kind of high quality field emission electronic source material because of their superior electrical?mechanical and chemical properties.In the past more than 20 years,vacuum devices with carbon nanotubes as field emission electronic sources have been widely concerned and studied,among which the unique advantages are shown in vacuum microwave tubes?planar displays?X-ray tubes and other devices.This work mainly studies the vacuum self-monitoring performance based on carbon nanotube field emission electronic source devices.Firstly,the carbon nanotubes were grown directly on the metal substrate by thermal CVD method combined with the anodized technique,and the carbon nanotubes were characterized by scanning electron microscope?SEM?,and the results showed that the carbon nanotubes were uniform and crystalline,and the impurity content was very small,and the field emission performance was tested and studied.The current stability is excellent under long working conditions.The ionization gauge is designed by the combination of carbon nanotube cathode and focusing structure,and its simple structure is small in size,which can be integrated into other vacuum devices,which is beneficial to realize any time pressure monitoring and miniaturization of the device.This work mainly includes the following sections:?1?Using carbon nanotubes growing at the top of 1 mm stainless steel rod with diameter as electron emission source,two kinds of ionization gauge structures are designed,and their transmittance and vacuum test linearity in nitrogen atmosphere are studied.The results show that the electron transmittance can reach 80%,and the two structures show a good linear relationship between the normalized current and the pressure in the 10^-9-10^-66 Torr range.?2?The effects of vacuum gauge structure,electrode potential and environmental gas composition on sensitivity were investigated in detail.The experiment also analyzed the discharge components of carbon nanotubes at different currents at work,and showed that the gas discharge components of carbon nanotubes were mainly hydrogen,and there was also a small amount of nitrogen and carbon dioxide.?3?The cathode of two kinds of carbon nanotubes with different emission areas was grown on the base of alloy sheet,and the structure of field emission and ionization gauge was designed.The electron transmittance is studied,and the results show that the transmittance is related to the cathode emission area,and the corresponding transmittance of the cathode emission area is large.The vacuum measurement performance was studied in the nitrogen atmosphere,and there was a linear relationship between the normalized current and the pressure in the range of10^-9-10^-55 Torr.In addition,the sensitivity is related to the emission area of the cathode electron source,and the larger the cathode emission area,the greater the sensitivity.