Polarization of Undulator Radiation

The polarization characteristics of undulator radiation were investigated. Calculation shows that the radiation is linearly polarized for each harmonic and that the plane of polarization is dependent on the azimuth of the observing direction as well as the angle of deviation θ from the beam axis. When the observation is made at small θ values compared to the reciprocal of the relativistic beam energy γ, the radiation is polarized nearly in the orbital plane, while at larger θ values the plane of polarization rotates with the aximuth.