Experimental Evidence of MHD Surface Waves

MHD surface waves of $m=-1\mathrm{}$ (poloidal mode number of left-hand rotation) compressional Alfvén waves in cylindrical finite-$\beta$ plasma have been observed for the first time to propagate together with shear Alfvén waves. These modes also show a distinctive feature of the dispersion merging with that of shear Alfvén waves at the center of a plasma column when a limiting frequency below the ion cyclotron frequency is reached. The experimental results confirm a recent prediction concerning surface-wave properties of the first radial eigenmode of a nonaxisymmetric compressional wave in a plasma surrounded by an insulating boundary.