Enhanced Control and Reproducibility of Non-Neutral Plasmas

The simultaneous control of the density and particle numberof non-neutral plasmasconfined in Penning-Malmberg traps is demonstrated. Control is achieved by setting the plasma's density by applying a rotating electric field while simultaneously fixing its axial potential via evaporative cooling. This novel method is particularly useful for stabilizing positronplasmas, as the procedures used to collect positronsfrom radioactive sourcestypically yield plasmas with variable densities and particle numbers; it also simplifies optimization studies that require plasma parameterscans. The reproducibility achieved by applying this technique to the positronand electron plasmas used by the ALPHA antihydrogenexperiment at CERN, combined with other developments, contributed to a 10-fold increase in the antiatom trapping rate.