Evidence for Highly Charged Ion Coulomb Crystallization in Multicomponent Strongly Coupled Plasmas

Multicomponent non-neutral ion plasmas in a Penning trap consisting of ${\mathrm{Be}}^{+}$ and highly charged Xe ions, having different mass-to-charge ratios than ${\mathrm{Be}}^{+}$, are cooled to form strongly coupled plasmas by applying a laser-based collisional cooling scheme. The temperature of the plasma was determined from a Doppler broadened transition in ${\mathrm{Be}}^{+}$. For the Xe ions, which are centrifugally separated from the Be, the Coulomb coupling parameter was estimated to be $\approx 1000$. Molecular dynamics simulations of the ion mixture show ordered structures, indicating crystallization of the Xe.