Study of Controllable Polarization SASE FEL by a Crossed-planar Undulator.

Several methods to produce variable polarization have been under discussion for the European XFEL facility. One such method is to utilize a crossed-undulator scheme. In this paper, the polarization of X-ray radiation for longer wavelengths (0.4 nm and longer) of the XFEL is investigated. The degree of polarization and the Stokes parameters are calculated for different configurations. A first attempt at optimization of the configuration for XFEL parameters is presented.