Microwave reflectometry for the study of density fluctuations in tokamak plasmas

The effect of small scale density fluctuations on the propagation of electromagnetic waves in an inhomogeneous magnetized plasma in the presence of a cut-off is investigated. It is shown that, provided the fluctuation scale length is greater than the free space wavelength of an incident plane wave, the scattered field is strongly enhanced from fluctuations near the turning point. Numerical results for wave propagation in a Tokamak plasma demonstrate the feasibility of reflectometry for the localized measurement of density fluctuations in the range k perpendicular to rho _i<<1.