Propagation of electrostatic waves near the lower hybrid frequency in a toroidal plasma, NOVA-I

Resonance cones in a lower hybrid range of frequency are observed and confirmed under the combined influence of toroidicity and inhomogenity in a toroidal device NOVA-I. The resonance cone is investigated in two different plasma sources, i.e. (A) a steady plasma of low density (N sub(e) -- 5 x 109 cm-3), and (B) a pulsed tokamak plasma of high density (N sub(e) -- 2 x 1013 cm-3). In case (A), the experimental results agree well with the trajectories computed from a simple cold plasma dispersion relation. Even in the high density tokamak plasma of case (B), a wave penetration toward the plasma center is observed and its behavior also agrees qualitatively with the theory. (author)