Study of Driven Lower-Hybrid Waves in the Alcator Tokamak using CO2-Laser Scattering

The wavelengths, amplitudes, frequencies, and spatial distributions of driven lower-hybrid wave fluctuations are studied in the Alcator tokamak with use of C${\mathrm{O}}_2$-laser scattering. It is found that for incident microwave power densities from 0.4 to 4.5 kW/${\mathrm{cm}}^2$ the wave amplitudes are nearly independent of the relative phase of the electric fields at the exciting waveguides. The waves are not localized in resonant cones and they have frequency widths of from 0.5 to 6 MHz.