Linear stability and mode structure of drift tearing modes

Ion viscosity and particle diffusivity effects on the linear stability and mode structure of drift-tearing modes are investigated. If only resistivity and diamagnetic effects are taken into account, the drift-tearing mode can exist only as a propagating wave packet, which is resolved numerically as an initial value problem. Ion viscosity, particle diffusivity, as well as finite electron compressibility, also considered in this paper, lead to radially localized modes. The mode growth rate is reduced by ion viscosity, but is increased by particle diffusivity. The instability threshold is not modified. The analysis is based on the analytic and numerical solutions of a reduced three-field fluid model.