Possible Mechanisms of String Formation in Complex Plasmas at Elevated Pressures

Possible mechanisms of particle attraction providing formation the field aligned microparticle strings in complex plasmas at elevated gas pressures are theoretically investigated light Plasmakristall-4 (PK-4) experiment on board International Space Station. The interaction energy is addressed by two different approaches: (i) using dynamically screened wake potential for small Mach numbers derived Kompaneets et al., 2016, and (ii) introducing effect polarization trapped ion cloud discharge electric fields. Is found that both approaches yield which independent operational mode. In parameter space performed experiments, first approach can provide onset string only higher than 40–45 Pa, whilst mechanism based yields experimentally important pressure range 20–40 Pa may reconcile theory observations.