Excitation of magnetohydrodynamic surface waves at the plasma-metal boundary

The excitation of magnetohydrodynamic surface waves, propagating at the plasma-metal boundary along the external magnetic field by monoenergetic ion beams is considered. It is shown that the waves propagating along the beam are excited under conditions of the Cherenkov's resonance, while the oncoming waves - under conditions of the normal Doppler resonance. Stability conditions of these waves are found and the spatial amplification coefficients are derived in the low beam's density approximation