A Simple Physical Model of Nonlinear Dependence of Helium Stopping Power on the Velocity of Low-Energy Hydrogen Ions

For the first time, the dependence of the probability of ionization of helium atoms on the velocity of a low-energy hydrogen ion beam is taken into account when the first ionization potential of target atoms exceeds the ionization potential of the charged particle beam atoms. Formulae describing the dependences of the helium stopping power on the beam energy of monoenergetic protons and deuterons are obtained. It is shown that their application makes it possible to calculate the helium stopping power adequately to the available experimental results.