Estimation of poloidal and radial correlation lengths of Tokamak edge turbulence using reflectometer back scattered power and 1D modelling

Summary form only given. Analysis of the amplitude variations in the backscattered power of a 17-GHz fixed-frequency (edge plasma) O-mode reflectometer installed on the STOR-M Tokamak indicate variations which are consistent with a statistically random rough surface. The density cutoff layer is modeled as an infinite conducting rough surface with a Gaussian spread in surface height perturbations (radial variations in the isodensity contour) and surface correlation lengths in the poloidal and toroidal directions. The plasma reflected power has a mean value dominated by coherent/specular reflection, and fluctuations mostly due to incoherent/diffuse scattering. Plotting the mean reflected power as a function of horn to plasma distance d shows a standing wave superimposed on a 1/d/sup 2/ trend, implying a strong coherent backscatter component.