Scattering of ordinary-mode electromagnetic waves by density fluctuations in tokamaks

Discussion and applications are presented for two approaches for estimating the effects of scattering of electromagnetic waves by turbulent density fluctuations in tokamaks. Ordinary-mode waves propagating nearly perpendicular to the equilibrium magnetic field are considered. The multiple-scattering approach provides analytic results for the angular and spatial spreading of a microwave beam by the turbulence. The single-scattering approach yields numerical results and is derived by a compact technique involving Wigner functions. Both approaches are applied to idealized tokamaks to clarify relationships between the approaches and to test limits of applicability of the multiple-scattering approach.