Transcript liuwg_workshop_31-07-2008_rd

LHC Luminosity Upgrade
Protection of the Inner Triplet, D1, Correctors and
Superconducting Links/Leads
AT-MEI-PE, RD, LIUWG 31-JUL-2008
R. Denz AT-MEI-PE
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Outline
 Protection of IT corrector circuits
 D1 protection
 Inner triplet protection
AT-MEI-PE, RD, LIUWG 31-JUL-2008
 Conclusions
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AT-MEI-PE, RD, LIUWG 31-JUL-2008
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
AT-MEI-PE, RD, LIUWG 31-JUL-2008
 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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AT-MEI-PE, RD, LIUWG 31-JUL-2008
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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AT-MEI-PE, RD, LIUWG 31-JUL-2008
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
AT-MEI-PE, RD, LIUWG 31-JUL-2008
 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
courtesy D. Nisbet, R. Ostojic
– Radiation levels
– Available space
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IT protection after luminosity upgrade – options I
 Quench heaters only
– Equivalent to insertion region magnet protection in LHC
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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
AT-MEI-PE, RD, LIUWG 31-JUL-2008
– 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
AT-MEI-PE, RD, LIUWG 31-JUL-2008
– Semiconductor based energy extraction systems
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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
AT-MEI-PE, RD, LIUWG 31-JUL-2008
– Warm by-pass is not required
– Space requirements: about 4 x 19’’ racks for two magnets
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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
AT-MEI-PE, RD, LIUWG 31-JUL-2008
– 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)
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