Propagation of Electrostatic Waves near the Lower Hybrid Frequency in a Toroidal Plasma, NOVA-I

Abstract

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 (Nₑ, ～5×10⁹ cm⁻³), and (B) a pulsed tokamak plasma of high density (Nₑ～2×10¹³ 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 thoery.