The role of partial ionization on the instantaneous charge state of uranium projectiles in fully ionized plasmas from energy loss experiments

Abstract

In Morales et al. [Phys. Plasmas 24, 042703 (2017)], we analyzed the experimental energy loss of U ions with an initial charge state of 33+ and an energy of 1.4 MeV/u passing through a highly ionized hydrogen plasma from the measurements shown in Hoffmann et al. [Phys. Rev. A 42, 2313 (1990)]. However, in our previous work, we assumed a fully ionized hydrogen plasma and our theoretical predictions overestimated the data at the times of 30 and 35 μs. As the capture of bound electrons was missing in the previous version of the code, we explained those discrepancies due to the possible presence of a higher part of bound target electrons at these times. In such a case, the projectile charge-state should be lower, and therefore, the theoretical energy loss would be also smaller in consequence. The main novelty of this work is to include the partial ionization of the plasma target, which was neglected in our previous analysis, for the theoretical estimation of the ion beam charge-state. Here, we re-analyze the experiment with the new version of our charge-state computer code based on the Cross-Sectional Model (CSM) as described in R. Morales [Phys. Plasmas 29, 093112 (2022)]. We are showing that taking into account the small contribution of bound electrons present in the plasma target affects the projectile mean charge-state and a much better agreement with energy loss data is found with our new CSM code.