Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale

Union Internationale pour la Science,la Technique et les Applications du VideInternational Union for Vacuum Science, Technique and ApplicationsInternationale Union für Vakuum-Forschung,-Technik und Anwendung

Slide Library: Module 1 Vacuum Interlocks in Particle Accelerators

© IUVSTA, 2009 1.1

SLIDE LIBRARY for instruction in

VACUUM TECHNOLOGY AND APPLICATIONS

Module 1: Vacuum Interlocks in Particle Accelerators

First Edition

Series EditorDr. Badly WANTED

Pierre M. Strubin



© IUVSTA, 2009 1.2

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. 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



© IUVSTA, 2009 1.3

VacuumSystem

Prevent opening ofleak detection valve

if system isolation valveis not closed

Turbo-molecularpump

Roughingpump

Close valve to system if speedof turbo-molecular <80%

Example on a Simple Process

ISOLATION VALVEOF ROUGHING PUMP

VENTING VALVEOF ROUGHING PUMP

VENTING VALVE OFTURBOMOLECULAR PUMP

Active interlock: trigger an action

Passive interlock: prevent an action



© IUVSTA, 2009 1.4

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



© IUVSTA, 2009 1.5

Interlocking LHC Valves

Problem: very high pumping speed between sector valvesSolution: interlock each valve with local sensors,

then secure sectors by closing next and previous valves



© IUVSTA, 2009 1.6

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



© IUVSTA, 2009 1.7

Interlocks should be considered as a global processAs 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

OR

Proposed interlocks for the LHC beam vacuum system

System-Wide InterlocksExample: LHC

Documents

Union Internationale pour la Science,la Technique et les Applications du Vide International Union for Vacuum Science, Technique and Applications Internationale