Collective Thomson scattering in a relativistic magnetized plasma

The effects which the dielectric properties of a relativistic magnetized plasma have on the scattering of electromagnetic radiation, are investigated. The scattering is caused by fluctuations in the dielectric properties, which are assumed to derive from fluctuations in the electron density. The origin of the density fluctuations is not considered. Expressions for the scattering cross section and the scattered power accepted by the receiving antenna are derived for a plasma with spatial dispersion. The resulting expressions allow thermal motion to be included in the description of the plasma and remain valid for frequencies of the probing radiation in the region of ωpe and ωce, provided the absorption is small. Symmetry between variables relating to incident and scattered fields is found and can be shown to be in agreement with the reciprocity relation. Dielectric effects in a cold plasma have been investigated by a number of authors, most recently by Bretz and Hughes and Smith. The present work extends the theory of dielectric effects to hot and relativistic plasmas. Earlier results are confirmed in the cold plasma limit. Significant relativistic effects, of practical importance to the scattering of millimeter waves in large tokamaks, are predicted. (author) 11 refs., 5 figs