Interaction of heavy ion beams with plasma electrons: role of many-electron ionization processes

Processes of multiple electron-impact ionization of ions in a plasma and a beam passing through the plasma have been considered. Using experimental data and theoretical calculations of the cross sections for $n$-electron ionization $\sigma_n$, the contribution from many-electron ionization rates $\langle v \sigma_n(v)\rangle$ to the total ionization rate has been determined as a function of the electron temperature of the plasma $T$. It has been shown that the total contribution of many-electron ionization rates to the total ionization rate in ion beams passing through the plasma is determined by the relation between the velocity of an ion beam $\langle v \sigma_n(v)\rangle$ and the thermal velocity of electrons in the plasma $v_{\text{th}}$. Many-electron ionization rates $\langle v\sigma_n(v)\rangle$ have been numerically calculated for $W^+$ ions for electron temperatures of the plasma from $1$ eV to $10$ keV and velocities of the ion beam $v_{\mathrm{p}} = 0$–$30$ a.u., where $1$ a.u. $\approx 2.2 \times 10^8$ cm/s is the atomic unit of velocity.