Extreme ionization of heavy atoms in solid-density plasmas by relativistic second-harmonic laser pulses

Stripping heavy atoms in solid matter of most of their electrons requires the extreme conditions that exist in astrophysical plasmas, but are difficult to create in the laboratory1–3. Here we demonstrate solid-density gold plasmas with atoms stripped of up to 72 electrons (N-like Au72+) over large target depths. This record ionization is achieved by irradiating solid foils and near-solid-density nanowire arrays with highly relativistic (3 × 1021 W cm−2) second-harmonic femtosecond laser pulses of 8 µm) by energetic electrons generated near the nanowire tips. Larger laser spots could result in solid Au plasmas ionized up to He-like. Gold atoms were stripped of up to 72 electrons by irradiating gold foils and nanowire arrays with a relativistic 400 nm laser pulse. This work will open the door to the study of the atomic physics of highly charged atoms in very-high-density plasmas.