Simulation of experimental data from the proposed C-Mod reflectometer

A six-channel, narrowband reflectometer is expected to go into operation on Alcator C-Mod during its first year of operation. Several programs have been developed to model the effects of both refraction and diffraction on the received signal. Results indicate that careful design and alignment will be necessary to avoid large variations in signal phase and amplitude caused by small variations in plasma position. Simulations of the effects of coherent fluctuations and driftwave turbulence on the echo indicate that both can in some cases degrade the localization of the reflection layer.