Plasma curvature effects on microwave reflectometry fluctuation measurements

Plasma poloidal curvature can significantly extend microwave reflectometry responses to high k ⊥ poloidal fluctuations. Reflectometry responses can be several orders of magnitude larger at high k ⊥ 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.