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.