Undulator Operation

All components of installed undulators are under control of a generic computer code that is matched to the control system of the BESSY storage ring. This guarantees that at each of the eleven undulators, users have complete control over photon energy (gap) and polarization (shift) independent of users at other beamlines. This is made possible by the precision design and construction leading to a high quality magnetic field, by feed-forward corrections of the remaining and of the naturally occurring gap and shift dependent kicks and focusing, and a slow (6 sec) feed-back correction of the electron beam position. The focusing feed-forward mechanism reduces any variation of the electron beam cross section due to beta beat to an acceptable level.