Review of SPL RF power couplers

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

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

3. Remaining Basic events 1/2 • 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 Review of SPL RF power couplers

4. Remaining Basic events 2/2 • 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 materials (differential contraction) • Beam stability issues • Beam breakup due to periodic field perturbation by power coupler Review of SPL RF power couplers