Coulomb structures of charged macroparticles in static magnetic traps at cryogenic temperatures

Electrically charged (up to $10^7e$) macroscopic superconducting particles with sizes in the micrometer range confined in a static magnetic trap in liquid nitrogen and in nitrogen vapor at temperatures of $77$–$91$ K are observed experimentally. The macroparticles with sizes up to $60\mu m$ levitate in a nonuniform static magnetic field $B\sim 2500$ G. The formation of strongly correlated structures comprising as many as $\sim 10^3$ particles is reported. The average particle distance in these structures amounts to $475 \mu m$. The coupling parameter and the Lindemann parameter of these structures are estimated to be $\sim 10^7$ and $\sim 0.03$, respectively, which is characteristic of strongly correlated crystalline or glasslike structures.