Monte Carlo simulation of kinetic electron emission induced by MeV He+ and He++ ions incident on polycrystalline aluminium

A theoretical study of the characteristics of kinetic electron emission induced by He+ and He++ ions (in the MeV-range) incident on polycrystalline aluminium targets is presented in this paper. The models of interactions for the incident projectiles as well as for the excited electrons are described. Especially, the electron excitation induced by incident He+ is calculated by taking into account the structure of the composite projectile. Charge exchange processes by the projectiles are also considered. The subsequent electron transport and escape is calculated by means of a Monte Carlo simulation code. The calculated electron emission yield is compared to experimental results. The differences between He+ and He++ are discussed, the role of the electron lost by He+ being especially emphasised.