OPTIMIZATION OF CIRCULARLY-POLARIZED RADIATION FROM AN ELLIPTIC WIGGLER, ASYMMETRIC WIGGLER, OR BENDING MAGNET

To collect circularly-polarized radiation from a bending magnet, elliptical wiggler, or asymmetric wiggler source, one must choose operating parameters to optimize their output according to user requirements. The trade-off between flux and degree of circular polarization is a basic feature of such dipole-type sources. In this paper, we discuss how to optimize the output based on two different criteria. The first is to maximize the intensity times the square of circular polarization degree (IP2), a widely used figure of merit in circular-dichroism experiments. The second is to maximize the intensity for a given degree of circular polarization, which is desirable in some cases. The results presented here provide guidelines for the design and operation of dipole-type sources to generate circularly-polarized radiation.