Direct observation of waves propagating near the lower-hybrid-resonance frequency

Electrostatically driven oscillations near the lower-hybrid-resonance frequency have have been studied in a linear plasma device. The index of refraction of these waves is measured directly and is seen to peak at a critical density as the wave propagates radially inward. A strong, nonlinear interaction is observed between the driven oscillations and the low-frequency drift-wave-like fluctuations which exist in this plasma.