Infrared radiation from the insertion device in an electron storage ring

This work numerically investigates the infrared radiation from the insertion device addressing the spatial extent of the magnetic fringe field and the magnetic configurations. Near field effects are taken into account. The numerical results differ significantly from those obtained under the assumption of zero-edge-length fringe field. Such an assumption is frequently adopted in calculating the dipole edge radiation. Nevertheless, an insertion device features a periodic magnetic field. This periodicity allows radiated electric field from several magnetic poles of the insertion device to be accumulated. The infrared spectral intensity is determined by the residual of the spectral integration of the radiated electric field, contributed primarily from the extremities and residual full-strength magnetic pole of the insertion device. Meanwhile, the dipole edge radiation due to the acceleration contributed from a part of the bending magnet's fringe field along which the trajectory is deflected by an angle in the order of 1/γ with respect to the observation.