Energy enhancement of laser-driven ions by radiation reaction and Breit-Wheeler pair production in the ultra-relativistic Breakout-Afterburner regime

The impact of radiation reaction and Breit-Wheeler pair production on acceleration of fully ionized Carbon ions driven by an intense linearly-polarised laser pulse has been investigated in the ultra-relativistic Breakout-Afterburner (BOA) transparency regime [1]. Against initial expectations radiation reaction at ultra-high laser intensities is found to enhance the energy gained by the ions. The electrons lose most of their transverse momentum and the additionally produced pair plasma of Breit-Wheeler electrons and positrons co-stream in the forward direction.This leads to changes in the phase velocity of the Buneman instability, that is known to aid ion acceleration in the BOA regime, by tapping the free energy in the relative electron and ion streams [2]. We show that this can further improve the highest Carbon ion energies [3].