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An optics-free method is proposed to generate X-ray radiation with spatially variant states of polarization via an afterburner extension to a Free Electron Laser (FEL). Control of the polarization in the transverse plane is obtained through the overlap of different coherent transverse light distributions radiated from a bunched electron beam in two consecutive orthogonally polarised undulators. Different transverse profiles are obtained by emitting at a higher harmonic in one or both of the undulators. This method enables the generation of beams structured in their intensity, phase, and polarization - so-called Poincar�� beams - at high powers with tunable wavelengths. Simulations are used to demonstrate the generation of two different classes of light with spatially inhomogeneous polarization - cylindrical vector beams and full Poincar�� beams., 10 pages, 3 figures

Powerpoint and pdf files of content presented and discussed at the Workshop: Designing Future X-ray FELs, Daresbury Laboratory, UK. The Free Electron Laser is a unique source of coherent radiation, able to operate into the hard X-ray and opening up new windows of scientific exploration. However, X-ray FELs are still in the first stages of their development with orders of magnitude improvements still achievable before theoretical limits are reached. Many new ideas to improve FELs towards these limits are being proposed. They can be difficult to model analytically and require significant numerical modelling, often requiring the use of many different codes and High Performance Computing. This workshop will bring together those proposing the new ideas and the numerical code developers to examine the state-of-the-art and find new ways forward.