Stopping highly charged ions in a laser-cooled one component plasma of [formula omitted] ions

Abstract

In-trap preparation of highly charged ions (HCIs) for precision mass measurements by cooling in a strongly coupled plasma of laser-cooled Mg 24 + ions is investigated by molecular dynamics simulations. For HCIs electrostatically decelerated below 1 eV the simulation suggests stopping times of a few 10 μ s for high charge states ( Q HCI = 40 , A HCI = 100 ). The deposited energy is found to be distributed almost over the entire crystalline plasma of N = 1 0 5 Mg 24 + ions due to collective target response. Almost all Mg 24 + ions stay within the acceptance range of the laser cooling force, thus allowing for the maintenance of the plasma conditions and efficient continuous cooling. Energy loss due to collective effects and hard binary collisions can be clearly distinguished, and can be of the same magnitude for the highest projectile charge states. While the former one can be described by the action of an effective stopping power, the latter is governed by large statistical fluctuations.