A Simple Model for an Ultracold Plasma

We consider an ultracold plasma composed of the same number of electrons and bosonic ions, at zero temperature. We calculate the ion and electron densities taking the long range interactions into account using a modified Thomas-Fermi approximation. We assume that ions are trapped by harmonic trap while electrons are only trapped by the ion cloud. For a cloud that contains 10⁴ electrons and 10⁴ ions confined with a trap frequency of 10 kHz, we find that stable radius is around 14 μm. (author)