Stopping of multicharged ions in dense and fully ionized hydrogen

Abstract

Enhanced stopping and effective charges of energetic (${\mathrm{C}}^{4+}$, ${\mathrm{S}}^{7+}$, and ${\mathrm{Br}}^{6+}$) ions in dense plasmas are considered within the framework of the standard stopping model (SSM), the most economical extension to plasmas of the standard cold-matter formalism (Bohr-Bethe-Bloch). The main goal of this work is to check quantitatively the SSM predictions using the setup SPQRII (Stopping Plasma Quantitatively Reinforced) developed at Orsay. It consists of a dense hydrogen discharge inserted in an ion-beam line from a tandem Van de Graaff accelerator. Simultaneous ion spectrometry and plasma diagnostics yield quantitative energy-loss measurements, monitored by target free electrons. Specific aspects of the project such as, ion-beam--plasma interface, synchronization of plasma with beam time structure, and ion transmission in the target, are given due attention. Measured enhanced plasma stopping and projectile effective charge are then quantitatively matched with theoretical predictions, for ions with a kinetic energy between 1 and 2 MeV/amu. Relevance to heavy-ion-driven inertial compression is stressed.