Abstract

Magnetic field errors of undulator magnetic systems limit perfomance in both free-electron laser (FFL) and synchrotron radiation applications, either through loss of gain or brilliance, respectively. These errors are almost always present in undulators driven by permanent magnets, even with careful selection of magnets and stringent control of mechanical tolerances. The tolerable error levels and their nature differ significantly between FEL and synchroton applications, largely because the latter involves dynamics of a recirculating electron beam and harmonic emission is often employed. Specifically, the typical linac-driven FEL requires only that the dipole errors be carefully controlled for the purpose of obtaining a straight trajectory, while the synchrotron application may have both more stringent dipole specifications and may also include difficult quadrupole and sextupole requirements.

© 1991 Optical Society of America