Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, SLIDE LIBRARY for instruction in VACUUM TECHNOLOGY AND APPLICATIONS Module 1: Vacuum Interlocks in Particle Accelerators First Edition Series Editor Dr. Badly WANTED Pierre M. Strubin

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, Basics on Interlocks 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. dont allow opening a valve) Interlocks must be –Designed into the system at an early stage –Reliable -> select appropriate sensors –Redundant when economically feasible

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, Vacuum System Prevent opening of leak detection valve if system isolation valve is not closed Turbo-molecular pump Roughing pump Close valve to system if speed of turbo-molecular <80% Example on a Simple Process ISOLATION VALVE OF ROUGHING PUMP VENTING VALVE OF ROUGHING PUMP VENTING VALVE OF TURBOMOLECULAR PUMP Active interlock: trigger an action Passive interlock: prevent an action

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, Protect the Vacuum System 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 close sector valves trigger beam abort wait for confirmation

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, 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

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, Protect Individual Components 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

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale Union für Vakuum-Forschung,-Technik und Anwendung Slide Library: Module 1Vacuum Interlocks in Particle Accelerators © IUVSTA, Interlocks should be considered as a global process As such, they should be modelised Pirani Gauges Sputter-ion Pumps Ion Gauges Cold-cathode Gauges Residual gas Analysers Sector valves RF system Injection system NEG activation Bake-out Beam Abort Hardware links Software links OR Proposed interlocks for the LHC beam vacuum system System-Wide Interlocks Example: LHC