AT-MEI-PE, RD, LIUWG 31-JUL-2008 1 R. Denz AT-MEI-PE LHC Luminosity Upgrade Protection of the Inner...
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Transcript of AT-MEI-PE, RD, LIUWG 31-JUL-2008 1 R. Denz AT-MEI-PE LHC Luminosity Upgrade Protection of the Inner...
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R. Denz AT-MEI-PE
LHC Luminosity UpgradeProtection of the Inner Triplet, D1, Correctors and
Superconducting Links/Leads
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Outline
Protection of IT corrector circuits
D1 protection
Inner triplet protection
Conclusions
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Protection IT corrector circuits today
Standard protection system for LHC corrector magnet circuits with dedicated QPS
– Midpoint voltage tap not available
– Requires additional current sensor and sophisticated digital detection electronics
– Dedicated protection system for HTS leads
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Protection IT corrector circuits after upgrade
Bridge based protection system using asymmetric midpoint tap
– Radiation tolerant version feasible using analog circuitry
– Enhanced noise immunity
Energy extraction system can be based on mechanical circuit breakers or on semiconductor devices
Dedicated protection system for HTS leads and/or links
– Voltage taps, thresholds etc. still to be defined
Space requirements for complete system:
– 0.5 x 19’’ rack per circuit
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Protection IT corrector circuits after upgrade
Bridge based protection system
– Already in use for D1 in point 2 and 8
Dedicated protection system for HTS leads and/or links
Space requirements for complete system:
– 0.5 x 19’’ rack per circuit
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IT protection today
Advantages
– It works !
– Limited space requirements (2 standard 19’’ racks only)
Drawbacks
– Relies on functionality of cold quench heater circuits
– Dumps stored energy into He bath
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IT protection after luminosity upgrade I
Different options for protection of the magnets and superconducting bus-bars
– Quench detection always based on bridge configuration
Dedicated protection system for HTS leads and/or links
Protection schemes can be easily adapted to other triplet layouts
Choice depends strongly on boundary conditions
– Radiation levels
– Available space
courtesy D. Nisbet, R. Ostojic
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IT protection after luminosity upgrade – options I
Quench heaters only
– Equivalent to insertion region magnet protection in LHC
• Works as well with one detector for both magnets
– Heaters of both magnets always fired energy dumped in He bath
– Robust, radiation tolerant, small (1 x 19’’ rack for two magnets)
– System can be build with existing designs – some components may be re-used
– As an option the development of a new quench power supply allowing long distance feeding and different heater pulse shaping is feasible
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IT protection after luminosity upgrade – options II
Quench heaters, warm by-pass and energy extraction
– Only heaters of quenching magnets are fired, warm by-pass (thyristor) and energy extraction system activated
• Other magnets will only quench due to propagation
– Cold by-pass (like for MB, MQ) is excluded due to high radiation load
– Semiconductor based energy extraction systems
• IGCT (Integrated Gate Commutated Thyristor) in parallel with a DC contactor
• DC contactor carries the current in closed state; IGCT ruptures the current in case of trigger
• Possible in radiation free area only – about 4 x 19’’ racks for two magnets (complete system)
– Mechanical circuit breakers
• Can be used in present areas as those systems are radiation tolerant
• Main constraints are space, procurement and maintenance
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IT protection after luminosity upgrade – options III
Quench heaters and energy extraction
– dI/dt created by energy extraction system will exceed quench-back limit
– Both magnets will be quenched but most of the energy will be transferred to dump resistor
• Less stress for magnet and cryogenics
• Faster cooling after quench possible
– Quench heaters will be fired as well but serve basically as a back-up
– Warm by-pass is not required
– Space requirements: about 4 x 19’’ racks for two magnets
• Valid for semiconductor based energy extraction system
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Conclusions
Protection of inner triplet correctors and D1 based on established designs and technologies
– In case correctors are powered with I > 600 A protection can be adapted
Protection of inner triplet
– Compatible with all powering layouts currently in discussion but the split powering solution is the preferred option
– Several options for protection possible – final choice will depend on boundary conditions
– Location of protection systems to be defined prior to any further development
– There won’t be sufficient manpower for extensive new developments
• Re-use of existing designs with necessary modifications applied
• Use of components available in industry (e.g. for energy extraction systems)