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Monte Carlo simulations of 1keV to 100keV electron trajectories from vacuum through solids into air and resulting current density and energy profiles
A. Hieke GEMIO Technologies, Inc., US
Keywords: Monte Carlo simulation, electron, matter, solid, gas, electron scattering, electron energy loss, electron beam irradiation, sterilization
Abstract: Increased awareness to use environmentally friendly methods for surface sterilization has rejuvenated interest in methods based on electron beam irradiation. Thus far, Monte Carlo electron beam simulations have been described either as typical electron optics simulations (i.e. collision free in vacuum), or exclusively in solids or gases with emphasis on the electron matter interaction. By combining different modeling approaches for the various domains a more complex simulation system can be created which permits to model the entire path of electrons from an emitting metal cathode, through high vacuum, through a solid object (typically a thin foil acting as wall), into air and onto a target. Very recently, highly accurate solutions for differential and total elastic scattering cross sections of electrons with E >=1keV on various neutral atoms have been published which are based on Dirac partialwave calculation using the ELSEPA code. These data are being incorporated in the presented simulation system. The mean free path between elastic scattering events for 100keV electrons in Titanium is about 50nm and the energy loss per distance traveled is on the order of 1.3eV/nm. The electron trajectory integration regimes are different for vacuum and medium. Electrons are continuously tracked and scattering events are considered individually, i.e. no averaging or “condensed history” or other simplifying approaches are employed in the simulation.
Nanotech 2008 Conference Program Abstract
