Insertion Device Radiation

Abstract

Synchrotron radiation from bending magnets is characterized by a wide spectrum from microwaves up to soft or hard x-rays as determined by the critical photon energy. To optimally meet the needs of basic research with synchrotron radiation, it is desirable to provide specific radiation characteristics that cannot be obtained from ring bending magnet but require special magnets. The field strength of bending magnets and the maximum particle beam energy in circular accelerators like a storage ring is fixed leaving no adjustments to optimize the synchrotron radiation spectrum for particular experiments. To generate specific synchrotron radiation characteristics, radiation is often produced from special insertion devices installed along the particle beam path. Such insertion devices introduce no net deflection of the beam and can therefore be incorporated in a beam line without changing its geometry. Motz [11.1] proposed first the use of undulators or wiggler magnets to optimize characteristics of synchrotron radiation. By now such magnets have become the most common insertion devices consisting of a series of alternating magnet poles and deflecting the beam periodically in opposite directions as shown in Fig. 11.1.