Computer Simulations on Characteristics of Field Emission in a Vacuum Diode

To investigate the characteristics of field emission in a flat vacuum diode, a one-dimensional particle-in-cell (PIC) simulation of electron emission and transport in a flat vacuum diode is carried out in the paper. The influence and mechanism of the cathode material escape work and external electric field on the cathode surface electric field has been analyzed. To study the space charge effects of emitted electrons on the cathode surface electric field, Poisson's equation has been numerically solved for various cathode material escape work in different external electric fields. It has been indicated that the cathode surface electric field firstly oscillates and finally comes to a steady state, and it will take about 0.0003 nanoseconds to achieve the steady state for the diode gap distance of 0.1mm. The absolute strength of the steady cathode surface electric field decreases with the increase of cathode material escape work and the decrease of external electric field. The PIC simulation results of the steady cathode surface electric field coincide excellently with the theoretical analysis results.