Plasma curvature effects on microwave reflectometry fluctuation measurements

Plasma poloidal curvature can significantly extend microwave reflectometry responses to high k(perpendicular to) poloidal fluctuations. Reflectometry responses can be several orders of magnitude larger at high k(perpendicular to) than that predicted by analysis based on two dimensional (2-D) slab geometry. As a result, the responses may approach the 1-D geometrical optics limit. This superresolution leads to a major modification of the spectral resolution of reflectometry. The phenomenon is analysed using a phase screen model for the general cases and the results are supported by detailed numerical 2-D realistic geometry full wave simulations for the specific case of the Alcator C-Mod tokamak.