Charge-state dynamics of heavy-ion beams penetrating a hydrogen plasma

Abstract

The dynamics of charge-state fractions of Au- and U-ion beams, penetrating hydrogen plasmas, is investigated for 1.4 and 3.6 MeV/u ion energies and plasma electron temperatures Te = (0.6 − 3.0) eV and densities Ne =(1016 − 1020) cm−3. Calculations of the fractions as a function of the plasma thickness are performed by solving the balance rate equations with calculated ionization and recombination rates including those for dielectronic recombination (DR). The DR rates are calculated by the recently created computer code DRIMP using the fully relativistic multi-configuration approach and the so-called shifted Maxwellian velocity distribution function. Calculated by this method DR rates of Au- and U-ion beams passing through a hydrogen plasma are presented for the first time. Using the results obtained, the temperatures Te and densities Ne are found at which the equilibrium mean charges q̄ of Au- and U-ion beams are maximal for hydrogen-plasma length L≤ 100 cm. Dependencies of the plasma equilibrium thicknesses Xeq on the initial charge q0 of incident ions are investigated, and it is found that Xeq values are minimal at q0≈q̄.