Superconductive undulators with variable polarization direction

In the past planar superconductive undulators have been successfully developed and tested with beam. They produce linearly polarized light (X-rays) and allow to tune the emitted wavelength electrically. In this paper a novel type of superconductive undulators is introduced which allows to tune electrically in addition to the wavelength the polarization direction. A short prototype was built and tested in a LHe bath.