Modeling ion-induced electrons in the High Current Experiment

A primary concern for high current ion accelerators is contaminant electrons. These electrons can interfere with the beam ions, causing emittance growth and beam loss. Numerical simulation is a main tool for understanding the interaction of the ion beam with the contaminant electrons, but these simulations then require accurate models of electron generation. These models include ion-induced electron emission from ions hitting the beam pipe walls or diagnostics. However, major codes for modeling ion beam transport are written in different programming languages and used on different computing platforms. For electron generation models to be maximally useful, researchers should be able to use them easily from many languages and platforms. A model of ion-induced electrons including the electron energy distribution is presented here, including a discussion of how to use the Babel software tool to make these models available in multiple languages and how to use the GNU Autotools to make them available on multiple platforms. An application to simulation of the end region of the High Current Experiment is shown. These simulations show formation of a virtual cathode with a potential energy well of amplitude 12.0 eV , approximately six times the most probable energy of the ion-induced electrons. Oscillations of the virtual cathode could lead to possible longitudinal and transverse modulation of the density of the electrons moving out of the virtual cathode.