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SLIDE LIBRARY for instruction in VACUUM TECHNOLOGY AND APPLICATIONS. First Edition. Pierre M. Strubin. Module 1: Vacuum Interlocks in Particle Accelerators. Series Editor Dr. Badly WANTED. Interlocks are implemented to Protect equipment (and sometimes personnel)
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SLIDE LIBRARY for instruction in VACUUM TECHNOLOGY AND APPLICATIONS First Edition Pierre M. Strubin Module 1: Vacuum Interlocks in Particle Accelerators Series Editor Dr. Badly WANTED
Interlocks are implemented to Protect equipment (and sometimes personnel) In general “active” methods (e.g. close a valve) Prevent inappropriate operations In general “passive” methods (e.g. don’t allow opening a valve) Interlocks must be Designed into the system at an early stage Reliable -> select appropriate sensors Redundant when economically feasible Basics on Interlocks
Example on a Simple Process VacuumSystem Passive interlock: prevent an action Close valve to system if speedof turbo-molecular <80% Turbo-molecularpump Active interlock: trigger an action Prevent opening ofleak detection valveif system isolation valveis not closed VENTING VALVE OFTURBOMOLECULAR PUMP ISOLATION VALVEOF ROUGHING PUMP VENTING VALVEOF ROUGHING PUMP Roughingpump
Divide the vacuum system into maintainable lengths Install sector valves Use robust sensors ion-pumps, cold-cathode gauges Implement redundancy Use voting scheme to close (e.g. 2 out of 3 sensors faulty) Require all sensors in good state to open sector valves Protect the valves against high energy beam impact In case of vacuum failure Protect the Vacuum System ➔ trigger beam abort ➔ wait for confirmation ➔ close sector valves
Interlocking LHC Valves Problem: very high pumping speed between sector valves Solution: interlock each valve with local sensors,then secure sectors by closing next and previous valves
Pressure sensors Not too difficult as long as the equipment is “on” Monitor the raw value proportional to pressure Sometime monitor auxiliary parameters e.g. emission for a hot-cathode gauge More tricky when equipment is off Avoid damaging filaments of hot cathode devices Need a chain of sensors At least one able to work at atmospheric pressure Interlocks to other systems e.g. RF cavities, electrostatic septa Protect Individual Components
OR OR System-Wide Interlocks Example: LHC Interlocks should be considered as a global processAs such, they should be “modelised” Pirani Gauges Sputter-ion Pumps Beam Abort Sector valves Hardware links RF system Ion Gauges Cold-cathode Gauges Injection system Software links Residual gas Analysers Bake-out NEG activation Proposed interlocks for the LHC beam vacuum system