Research On An Electron Gun Beam Based On Carbon Nanotube Array Cold Cathode

Carbon nanotubes(CNTs) have excellent performance in field emission. They can be used as cold cathode materials for the field emission devices. So in order to develop microwave source device with CNTs field emission cold cathode, the field emission characteristic of disordered CNTs cold cathode on a large plane area and array area has been researched. The following contents are studied in this paper:1. On the basis of experimental test results, fitting out the corresponding parameters of CNTs field emission, field emission simulation model of CNTs cold cathode is established. Based on the research of the procession of CNTs field emission cold cathode surface electric field distribution and influence of marginal effect of electric field, the distribution of the surface electric field becomes more uniform.2. Based on the actual magnetic field distribution, an electron gun with CNTs field emission cold cathode is designed. Through the simulation calculation of the electron gun,the results of the simulation calculation of the electron gun show that: the compression ratio of area was 22, the waist radius of the electron beam was 1.8 mm, the transparency of electron beam could be 60% and the output current density was 1.9A/cm~2.3. The carbon nanotube field emission cold cathode electron gun was manufactured.Test results show that the cathode emission current was 20 m A, anode current was 5m A.By analysing the results, we found that the cathode emission current was intercepted by the gate, and intercept currents, in turn, affected the area of carbon nanotubes which below the gate, and this destroyed carbon nanotubes and they could not launch electron.4. Two different structure of array carbon nanotube cold cathode electron gun are designed, the transparency of electron beam can reach to 100%.The simulation results show that the slot array carbon nanotube cold cathode electron gun can get the emission current and the current density is 2A/cm~2, the compression ratio of area is 20 and the current density of compressed is 11A/cm~2 The other kind of array carbon nanotube cold cathode electron gun with independent cathode emission cell has been simulated. The compression ratio of area is 12, carbon nanotube cold cathode emission current density is 1A/cm~2, and the current density of compressed is 1.5A/cm~2.