Ion waves, drift waves and instability in a weakly ionized magnetoplasma

A unified treatment is given of low-frequency wave propagation in a weakly ionized magnetoplasma from the fluid equations in which ion inertia is retained. An analysis is made of the instabilities which arise due to the influence of drift of the electrons relative to the ions for three cases: (a) Parallel drift, EB, (b) Hall drift, EB, and (c) Diamagnetic drift, nB. In all cases an ion acoustic instability is found while additionally, for (c), there is a drift instability for strong magnetic fields. The instability boundaries in parameter space are delineated. Furthermore, for a transversely bounded plasma, the roots ω(k_z real) and k_z(ω real) of the dispersion relations are discussed and related to experimental observables. The results are applied to an interpretation of wave propagation and instability on a cylindrical positive column for which all three types of drift are simultaneously present. The relation of this work to the inertialess theories of the current-convective and crossed-field instabilities is also discussed.