Radial magnetosonic eigenmodes in a toroidal plasma with an ion-ion hybrid layer

The conditions for excitation of a standing magnetosonic wave structure in the region between the ion-ion hybrid cut-off layer and an antenna situated near the wall on the outside of a toroidal plasma have been derived. It is shown that low-order radial eigenmodes may be excited under usual conditions, but the order of the mode increases as the plasma density and its size increase. Such radial eigenmodes are shown to be more easily tracked than the usual magnetosonic toroidal eigenmodes.