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 laboratory^1,2,3. 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 <10 J energy focused into a 1.6 µm spot. The short wavelength and high intensity enable the interaction to occur at a relativistic critical density^4,5 of 10²³ cm⁻³. Solid targets reach a higher average charge in 1- to 2-µm-thick layers, while the less dense nanowire plasmas are heated to much larger depths (>8 µm) by energetic electrons generated near the nanowire tips. Larger laser spots could result in solid Au plasmas ionized up to He-like.

剥离大多数电子的固体物质中的重原子需要天体等离子体中存在的极端条件，但很难在实验室^{1,2,3中产生}。在这里，我们展示了在大目标深度上具有被剥离多达72个电子（N型Au ⁷²⁺）的原子的固体密度金等离子体。通过用高度相对论（3×10 ²¹  W cm ^-2）的小于10 J能量的高次谐波飞秒激光脉冲辐射固体箔和接近固体密度的纳米线阵列，将其聚焦到1.6 µm光斑，从而实现了创纪录的电离。短波长和高强度使相互作用能够以相对论的临界密度^4,5 of 10 ²³  cm ^-3发生。固体靶在1至2 µm厚的层中达到较高的平均电荷，而密度较小的纳米线等离子体则通过在纳米线尖端附近产生的高能电子被加热到更大的深度（> 8 µm）。较大的激光斑可能导致固态的Au等离子体电离至He样。