1. 16-17 March 2010 CERN Introduction by W. Weingarten Review of SPL RF power couplers 16/17 March 2010 Review of SPL RF power couplers 1

2. Cavity not operational or operation compromised due to fault originated from power coupler (PC), its operation, assembly, design, etc. Cavity contaminated Non dust-free assembly of PC /insufficient on-line monitoring of dust content in air Material peel off from PC outer conductor Break of RF window Vacuum leak Excessive reflected power Excessive cryogenic load Multipactor discharge in window Excessive mechanical stress (differential contraction) RF losses in joints Arcing or discharge in coaxial line Overheating of coupler tip Inadequate cooling of outer conductor Cooling fluid flow too high/low/non turbulent Cooling fluid flow too high/low/non- turbulent Joint located unfavourably in presence of standing wave (high E/H field) Faulty design of joint or wrong choice of material Inadequate cleaning of substrate Choice of thermally incompatible materials Too high secondary coefficient /wrong material Beam breakup due to periodic field perturbation by power coupler Wrong choice of cooling gas/liquid Wrong choice of cooling fluid (gas/liquid ) Multipactor discharge in coaxial line Wrong geometry favoring resonant condition Field flatness inadequate (faulty control of mechanical tolerances) Too high secondary coefficient /wrong material Wrong geometry favoring resonant condition Evaporation by RF power of particulate or gas deposits Excessive temperature (poor electrical conductivity) Multipactor discharge in coaxial line Too high secondary coefficient /wrong material Wrong geometry favoring resonant condition Error in coating parameters /thickness wrong OR gate AND gate Basic event Kind of Fault Tree Analysis Excessive mechanical stress (differential contraction) dissipation Poor cooling of ceramics Ceramics with high dielectric losses RF window located unfavourably in presence of standing wave (high E/H field)

3. RF window Excessive mechanical stress (differential contraction) RF window located unfavourably in presence of standing wave (high E/H field) Poor cooling of ceramics Ceramics with high dielectric losses Coaxial line and materials Error in coating parameters /thickness wrong Inadequate cleaning of substrate Discharges, arcing, multipactor Wrong geometry favoring resonant condition Too high secondary coefficient /wrong material Evaporation by RF power of particulate or gas deposits 16/17 March 2010 Review of SPL RF power couplers 3

4. Cryogenic issues Cooling fluid flow too high/low/non-turbulent Wrong choice of cooling fluid (gas/liquid) RF power issues and RF joints Faulty design of joint or wrong choice of material Joint located unfavourably in presence of standing wave (high E/H field) Clean assembly Non dust-free assembly of PC /insufficient on-line monitoring of dust content in air Excessive mechanical stresses Excessive temperature (poor electrical conductivity) Choice of thermally incompatible material s (differential contraction) Beam stability issues Beam breakup due to periodic field perturbation by power coupler 16/17 March 2010 Review of SPL RF power couplers 4