Transcript Tests on production cryomodules Bob Kephart Sept 30, 2006 Introduction • The ILC cryomodule will evolve through several versions between now and the series production used.

Tests on production
cryomodules
Bob Kephart
Sept 30, 2006
Introduction
• The ILC cryomodule will evolve through
several versions between now and the series
production used to construct the machine
• The homework was:
– investigate what tests are needed on the final
production of industrial cryomodules
– and what special tests are needed when the
cryomodule design gets modified to make it
cheaper to manufacture.
– These tests may or may not be system tests our
task force is responsible for planning.
R. Kephart
LCFOA Oct 06
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Types of changes
• Assuming we are starting with “working”
prototype one can consider the types of
changes that might occur
• Types of changes
– Changes aimed at performance improvement
– Changes driven by cost reduction
• Reduce labor
• Reduce M&S costs
– Changes due to region of manufacture
• Availability of materials ( e.g. manufacturing standards)
• Regional vendors ( e.g. ceramic feed throughs)
R. Kephart
LCFOA Oct 06
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Performance Improvement
• Changes aimed at performance improvement
– Typically these occur until the project
management of an “approved” project “freezes”
the specification
– The number of objects tested is small
– The tests are extensive but focused on
performance validation
– Performance validation leads then to industrial
production and cost reduction
• This is ~ where XFEL is now
– TTF is the test bed
• ILC is not yet to this point…
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LCFOA Oct 06
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Performance Improvement
• ILC will be pushing performance for at least
several years
– Currently several cavity and cryomodule variants
– Seems unlikely that we could adopt an untested
design variant ( e.g. cavity shape, HOM change,
quad location, etc.) without both cryomodule test
stand AND beam tests
– At least one test facility needs beam, to validate
cryomodule performance improvements
– This will involve swapping modules in and out…
probably not consistent with use of TTF as a user
facility.
R. Kephart
LCFOA Oct 06
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Cost Reduction
• Changes driven by Cost Reduction
– Typically these occur until the project
management of an “approved” project “freezes”
the design for series production
– The number of objects tested is still small
– The tests are less extensive, more comparative vs
previous successful prototype
– Many improvements to cryostat, mounts, seals,
feedthrus, assembly procedures can be validated
on a CM test stand without beam
– Intertwined with industrial production which will
produce regional differences in the cryomodule
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LCFOA Oct 06
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Regional manufacture
• When CM design is “final” the project can call
for international tenders.
• This will lead to vendor selections and
“preseries” production
• It will be very difficult ( but not impossible) to
build identical cryomodules in all 3 regions
– Manufacturing capabilities of vendors ( e.g.
machine tools, weld technique, experience)
– Materials availability ( standard thickness mill runs
vs special order = cost, delay)
– Regional availability of “specialty items… eg. Feed
throughs, couplers, seals, sensors, etc.
R. Kephart
LCFOA Oct 06
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Regional manufacture
• Likely that we will end up with 3 different but
plug compatible cryomodules
• Each preseries unit will require extensive
testing to validate its performance and
reliability prior to and during mass
production of series units
• The number of units tested should be as
large as possible (determines MTBF region
that can be explored)
• Tests should be as realistic as possible
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LCFOA Oct 06
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Tests vs specific changes
Possible change
Cavity shape
Cavity Interconnect seals
cavity processing
HOM
instrumentation
cryogenic piping
cavity mount
slower tuner mechanics
fast tuner piezo
cold tuner moters
tuner electronics
main coupler
RF cermanic feed thru
inst. Feed thru
Alignment scheme
Quad location
Quad mount
radiation shield
super insulation
Vacuum Shell
Assembly technique
R. Kephart
vertical horizontal
test
test
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CM test
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MTBF
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String
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Beam
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How did other projects get burned ?
•
Tevatron
– Scrapped the first 10% of dipoles. ( constr. before complete design)
– Discovered two later failures
• lead flexing during ramped operation
• cold mass sag changing skew quad… during collider run
•
SSC
– costed and launched before they had a viable magnet design
– Original magnet aperture too small
– Quench protection OK for single magnet, not in string
– contributed to cost escalation & ultimate project cancellation
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LHC magnets
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LHC cost estimate based on early vendor estimates
Extensive test facility  performance seems not to be an issue
Vendor bids for series production were much larger than expected
CERN assumed part of work and much of the technical risk
Cost growth and delay (ie must validate cost for actual device built)
Transfer line… small untested vendor changes  big delays
SNS
– TJNL rushed delivery of modules to meet schedule
– vacuum leaks during cooldown
– unexpected HOM problems  rework
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LCFOA Oct 06
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LHC String test History
• LHC String test was designed in 1991, in
operation since 1994.
• It has tested several versions of the the
LHC magnets and operated for 12 years.
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LCFOA Oct 06
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Picture of LHC string test
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LCFOA Oct 06
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Conclusions
• A range of Test facilities are required to validate
likely changes aimed at performance
improvements, cost reduction, and due to regional
differences
• Tests should be as complete and extensive as
affordable with designs frozen as soon as adequate
performance is achieved
• These validations must take place before series
production or the project faces large risks
• In the case of LHC ( and XFEL) the test facility is a
long term investment that continues to operate well
into the series production of components.
• Seems likely that ILC will require test facilities of
similar scale.
R. Kephart
LCFOA Oct 06
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