Excitation of magnetohydrodynamic surface oscillations by charged-particle beams

A quasi-hydrodynamic approximation is employed to investigate the excitation of MHD surface oscillations in both a cold and a finite-beta plasma by monochromatic low-density charge-particle beams that are superposed and spatially distributed in the plasma space. Dispersion properties of the oscillations in the finite-beta plasma are obtained along with their excitation increments. It is shown that excitation of these oscillations by a low-density beam is less effective in the cold plasma than in the finite-beta plasma. It is noted that ion heating is possible due to the instability of the oscillations in the finite-beta plasma.