Mathematical Modeling of Pulsed Electron Beam Induced Heating and Sublimation in Graphite

A one-dimensional heat conduction model is presented to describe the heating and sublimation of a graphite target upon interaction with a polyenergetic electron beam. The beam delivers intense electron pulses of similar to 100 ns in width with energies up to 15 keV and an electric current of similar to 400 A. The electron beam efficiency and Knudsen layer just above the target surface during ablation are taken into account in the model. The effect of the distance between the electron beam tube output and target surface on ablation is assessed as well. The temperature distribution, surface receding velocity, ablation depth, and ablated mass per unit area are numerically simulated. For an efficiency factor of 0.6, the results indicate that the target surface can reach up to 7500 K at around two-thirds of the pulse duration. The onset of surface vaporization occurs within 30 ns from the pulse start. Under the same process conditions, the calculated ablated mass is about 3.8 mu g/mm(2). The estimated ablated mass per unit area is in good agreement with experimental data for an efficiency factor of 0.6. Available theoretical data on beam energy efficiency are in good accordance with the results of the current model corresponding to an efficiency of 0.6. (C) 2015 The Electrochemical Society. All rights reserved.