Linear modes in the presence of solitary ion holes

Linear perturbations of a plasma have been investigated which is structured by the presence of a kinetic ion hole equilibrium. A new dispersion relation, obtained by a two-dimensional stability analysis, exhibits two kinds of non-decaying modes. One is a transverse propagating ion acoustic type wave, which becomes dispersive in the long wave-length limit. The other branch represents aperiodic oscillations, which grow in time for k < k_cr, where k is the perpendicular wavenumber, and which destabilize the ion hole structure.