Determination of failure mechanisms of RF cavity aperture windows

Failures of the SRS (Synchrotron Radiation Source) RF cavity windows seriously disrupted operations of the Daresbury SRS in 1983. The results and conclusions of a long-term study of the window environment and the mechanisms leading to failures are reported. This study involved both experimental investigations and computation of the electromagnetic fields in the window aperture together with computer simulations of the temperature and stress profiles leading to failure. The experimental field mapping was performed using a perturbation technique, and the MAFIA 3-D codes were used for the computer field modeling. The thermal and stress analyses were performed using the ANSYS finite element package. The modeling strategy is described, and the factors leading to failure are discussed. Conclusions are drawn with relevance to the SRS RF window failures and also to high-power window design in general