Beam Stability in Synchrotron Light Sources

Numerous third-generation light sources are now in a mature phase of operation, and several new sources are under construction. Submicron beam stability is being achieved routinely at many of these light sources in terms of both AC (rms 0.1- 200 Hz) and DC (one week drift) motion. This level of stability is a necessary condition for the success of x-ray free-electron lasers such as the Linac Coherent Light Source (LCLS) at Stanford or the European XFEL project. The different methods for addressing this problem at different laboratories— involving various combinations of passive noise identification and suppression, feedback, and feedforward — together with accomplishments to date will be discussed