Molecular Dynamical Studies on Heat Transfer Characteristics in Electron Beam Processing

Abstract

As one type of particle beam processing, electron beam machining is quite popular for its high efficiency of energy conversion and its ease of beam production. In order to evaluate energy transfer by an electron beam qualitatively, the method of numerical simulation of high-energy electron behavior in substances is investigated. In this paper, a Monte Carlo simulation is presented in which high-energy electrons are decelerated in the course of atomic excitation involving Rutherford scattering by atomic nuclei. Beam energy here is transferred into the lattice system of a substance as a form of heat energy. Electron number density distribution in the substance as well as loss density disribution due to electron deceleration is calculated here. Although the shapes of these two distributions are similar, penetration depth of loss density proved to be about 30% smaller than that of electron number density, which was in fairly good agreement with the referenced data. Such a difference, which has never before been discussed in detail, is clarified numerically. In addition, beam reflection on the surface is of great interest, and numerical simulation, as shown in a previous experimental work, proved that power reflection is slightly less than mass reflection.