Formation of Strongly Coupled Plasmas from MultiComponent Ions in a Penning Trap

This report reviews the production of strongly-coupled, multi-component, non-neutral, highly-charged ion plasmas in a cryogenic Penning trap. A unique ion source–Penning trap system has been developed and used an Electron Beam Ion Trap-Source (EBIT-S), able to produce ions up to U92+, has been combined with a cold-bore Penning ion trap. The developed experimental techniques such as the ion production, extraction, bunching, multi-ion species trapping and storage (ions up to Th80+), detection, cooling, and imaging are presented. The produced mixed plasmas, consisting of several ion species [e.g. Be+, Xeq+ (charge q = 34 ... 44)], are cooled to a temperature of about 1 degree Kelvin and below. These low temperatures were obtained by applying a sypathetic cooling scheme, using laser cooled Be+ ions. The determination of the temperature and the density from the laser resonance width and the fluorescence imaging of the Be+ clouds respectively, yield a Coulomb coupling parameter for the xenon ion plasma of over 1000, large enough for crystallization. Crystallization can be achieved at these relatively high temperatures since the Coulomb coupling parameter scales with q2.