Research Design And Application Of High Circulation Carbon Nanotube Cold Cathode Electron Gun

As emission source of microwave vacuum electronics,Carbon nanotubes(CNTs)cold cathode electron gun has wide application prospects in the field of vacuum electronic devices for its instantaneous start,working at room temperature and high emission current density.However,the cathode emitter performance(emission current,stability.),grid capture,and electron injection quality of carbon nanotube cold cathode electron guns still need further improvement.In order to obtain more stable and reliable CNTs cold cathode electron guns for practical devices with better emission performance,systematic design and simulation of CNTs cold cathode electron gun are studied..A CNTs film is made on the surface of a cathode structure for practical devices by a print coating method to obtain a cold cathode.In the DC test conditions,the maximum emission current of the cathode is 22 mA,and the corresponding emission current density is 2.81 A/cm~2(the cathode area is 0.785 mm~2).In a continuous 30-hour stability test condition,the initial cathode emission current of 4.12mA decreased by a maximum of 9.5%.The practical CNTs cold cathode exhibited good emission characteristics and emission stability.The CNTs electron gun,which contains a planar cathode,a hole grid,a flat plate focusing electrode and an open hole anode,is designed by systematically simulating the main components of the electron gun.A uniform electron beam with a waist radius of 0.3 mm and a current density of 5.84 A/cm~2 was obtained by simulation.Further design the cycle of permanent magnetic focusing flow tube structure,and study the work performance of electron gun combined with practical devices.The simulation results show that the electron injection rate in the pipe body is 100%,with good laminar flow.We actually fabricated and tested the designed CNTs cold cathode electron gun.In the DC test conditions,high capture rate and temperature of the gird cause a small emission current.In an improved pulse test conditions,cathode emission peak current could reach to 28.8mA and anode peak current could reach to 13.54mA.In the docking test experiment of electron guns and flow tubes,the highest electronic flow rate of 85%was obtained.Practical CNTs cold cathode guns exhibit good emission performance,and the results can basically meet the application requirements of medium and low power microwave devices.