Thomson Scattering in the Solar Corona

The basis for the application of Thomson scattering to the analysis of coronagraph images has been laid decades ago.Even though the basic formulation is undebated, a discussion has grown in recent years about the spatial distribution of Thomson scatter sensitivity in the corona and the inner heliosphere. These notes are an attempt to clarify the understanding of this topic. We reformulate the classical scattering calculations in a more transparent way using modern SI-compatible quantities extended to field correlation matrices. The resulting concise formulation is easily extended to the case of relativistic electrons. For relativistic electrons we calculate the Stokes parameters of the scattered radiation and determine changes in degree and orientation of its polarisation, blue-shift and radiant intensities depending on the electron velocity magnitude and direction. We discuss the probability to see these relativistic effects in white-light coronagraph observations of the solar corona. Many mathematical and some basic physical ingredients are made explicit in several chapters of the appendix.