SIMULATION OF KINETIC ELECTRON-EMISSION FROM BERYLLIUM BY KEV ION IMPACTS

A Monte Carlo simulation model of ion-induced kinetic secondary electr on emission from beryllium, a candidate material for plasma-facing com ponents in thermonuclear fusion devices, is developed. In the model, t he conduction electron excitation by a projectile ion and the cascade multiplication process of the excited electrons are involved in produc tion of secondary electrons in the solid. Due to increase in the excit ation probability, the secondary electron yield increases with increas ing impact energy and initial charge state of the projectile, and decr easing mass of the projectile. Nevertheless, the majority of secondary electrons are produced through the cascade process, so that the peak of the energy distribution of secondary electrons depends little on th e impact energy and the species of the projectile. Due to increase in the energy transferred from the projectile to the electrons, however, the distribution progressively broadens towards the high-energy side a s the impact energy is increased or as the mass of the projectile is r educed.