A simple analytical model of the Coulomb cluster in a cylindrically symmetric parabolic trap

A cluster consisting of classical charged particles of the same sign in a cylindrically symmetric parabolic trap is considered in the approximation of a homogeneous distribution of particles over the cluster volume and with neglect of its discrete structure. Simple analytical expressions for the cluster size and potential energy in a trap of arbitrary anisotropy (the ratio of confining forces acting in the radial and axial directions) are obtained. The influence of possible inhomogeneity in the distribution of particles is estimated, and it is established that this factor weakly influences the potential energy of a cluster. The limiting case of a two-dimensional cluster is considered. The adopted approximation is valid for clusters with a sufficiently large numbers of particles. Application of the model to relatively small clusters is possible by introducing correction factors into the analytical expressions obtained. These factors are determined based on approximation of the results of numerical simulations.