Elliptical Polarization Undulator: EPU50
The ALS has four elliptically polarizing undulators, two in straight 4 and two in straight 11. All are arranged with chicanes so that two such devices can be installed to feed two independent beamlines. They can be used in a variety of polarization modes, including circular, elliptical, horizontal, and vertical. These modes can be chosen by appropriate phasing of the magnet rows. The brightness and flux curves below are shown for horizontal and circular polarization. Curves for elliptical and vertical polarization are similar to the horizontal polarization curve, but the minimum photon energy is higher.
