RF power coupler-Combined cavitation diagnostics

In order to identify safe operating regimes and to investigate the hydraulic behavior of the Input Power Coupler, which is a part of the radio frequency cavities used at the Synchrotron Light Source Facility at the Paul Scherrer Institute, a special research program was established. Since 2005, 10 leak events occurred which led to accelerator down-times up to several days. The aim of the research program was to perform conditional monitoring and to diagnose fault regimes, which may lead to water-to-air and water-to-vacuum leak accidents. Since fault detection and identification are tasks of high importance for safe operation, practical options for data collection, cavitation and possible structural rupture detection are discussed. The instrumentation, which was used for detection of cavitation and observation of structural behavior, consists of acoustic emission and structural acceleration sensors and a microphone. Noisy signals with captured cavitation (bubble growth and collapse) events have been analyzed by various advanced time-frequency methods.