Analysis and Simulation of Anode Heating Due to Electron Field Emission

This paper considers the effect of anode heating from energetic electrons produced by field emission. Large electric fields accelerate emitted electrons as they traverse the vacuum gap toward the anode. Electron energy is transferred to the anode by collisions with the lattice. The nonequilibrium transfer of electron kinetic energy to anode thermal energy is examined quantitatively. Results demonstrate that the energy distribution of impinging electrons affects the transmission and dissipation of thermal energy. A Monte Carlo technique is used to resolve the thermalization of electrons and accounts for electron beam strength and spatial distribution. The results indicate that local heat fluxes of the order 10 kW cm occur at the anode surface and that heating is a strong function of field strength because of the exponential relationship between applied voltage and current. Under practical conditions, temperature increases of 10 C are predicted from a single point emission source.