Destabilization of hydromagnetic drift-Alfven waves in a finite-$beta$, collisional plasma

We have observed experimentally the destabilization of both the Alfv\'en and the drift branches of the hydromagnetic, coupled drift-Alfv\'en wave in a steady-state, high-density (${n}_{0}\ensuremath{\approx}{10}^{13}\ensuremath{-}{10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) collisional plasma when an axial electron current is drawn along the magnetic field. The measured dispersion relation is in good agreement with solutions of our theoretical dispersion relation.