Destabilization of hydromagnetic drift-Alfvén waves in a finite pressure, collisional plasma

The hydromagnetic drift mode of the coupled drift-Alfvén wave is destabilized as a standing wave in a dense, current-free plasma in the presence of a density gradient. When an axial electron current is drawn, a localized Alfvén mode propagating against the current is destabilized, in addition to the unstable drift mode now propagating along the current. The measured wave properties, dispersion, and dependence on plasma parameters are found to agree with the theory derived for a finite β, collisional plasma.