The formation of Coulomb clusters in a magnetic trap

Abstract

The possibility of confining the Coulomb clusters formed by charged diamagnetic particles in a nonuniform magnetic field in the state of levitation is confirmed theoretically and experimentally. On the basis of rather general assumptions about the symmetry properties of the magnetic field configuration, we have developed a theoretical approach to the calculation of the magnetic trap for diamagnetic particles. Equations determining the positions of a single particle and two-particle clusters in the magnetic trap, as well as the conditions of their steady state, are obtained. An experimental setup is described that is capable of creating such a trap with a magnetic field B≈1 T and |∇B|≈10 T cm−1. The formation and confinement of clusters of charge graphite particles of size 100–300 μm in the magnetic trap have been observed. Calculations of the trap and two-particle clusters in the trap have been performed. It is inferred that it will be possible to form stable three-dimensional dust structures such as Coulomb crystals and Coulomb liquids containing several thousands of particles under terrestrial conditions by using more intensive magnetic fields B>10 T. Less intensive magnetic fields (B≈0.1 T, |∇B|≈0.1 T cm−1) will be required for studying analogous structures under microgravity conditions aboard space vehicles.