Testing of Twisted Racetrack Coil

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Testing of Twisted Racetrack Coil

• B. Nelson
• TRC FDR
• 15 Oct 2004

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Presentation Outline

• Primary objective
• Demonstrate that performance of finished coil
  matches predictions (and requirements)
• What is available in the facility?
• What do we want to test and how are we going to
  measure it?
• Test Plan / schedule
• Issues

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Test facility is in basement of TFTR Test Cell

• Facility will be used to test twisted racetrack
  coil and all production modular coils
• Facility features
• Test cell with safety features
• cryostat
• Utilities
• Power 2 kV and 48 kA
• Prototypical teflon insulated lead
• Pressurized LN2 system with subcooler
• Instrumentation
• 15 channels for strain gages
• 6 type E thermocouple channels
• Voltage and current from power supply
• DAS

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Test facility is in basement of TFTR Test Cell
Barn door (open)
Facility interior
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Test facility

• Facility features to be checked out on flat
  racetrack coil
• Operating procedures and safety systems work
• Cryostat N2 tight and cryostat cooldown system
  operational
• Power supply systems operational
• Leads work as advertised
• Pressurized LN2 system with subcooler operational
• Instrumentation and DAS operational
• Facility available for unanticipated and
  underanticipated RD
• Coil to VV insulation heat leak
• Cryostat boots
• Other

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Twisted Racetrack coil testing

• TRC is first coil with all prototypical features.
• We want to test performance in the following
  areas
• Geometric
• Electrical
• Hydraulic
• Thermal
• Structural
• Instrumentation and mag loops
• Power feeds
• Fatigue

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Geometric Performance
What Metric Criteria How
Gross winding pack shape relative to theoretical as-measured winding pack geometry within acceptable tolerance Winding center meets /- 0.02 inch tolerance budget Measure spherical seat and tapped hole spotfaces, cut coil into sections, preserving enough of these features to measure section
Winding form shape as-measured winding form shape is the same as pre-potted shape TBD Measure spherical seats, tapped hole spotfaces or other metrology feature locations before and after winding/testing
magnetic field measurement Field measurements consistent with geometric measurements Within 0.5 mm Romer arm / Hall probe technique


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Electrical Performance
What Metric Criteria How
Resistance Resistance at room temperature and LN2 temperature matches prediction Resistance within 1 of prediction Measure voltage drop as a function of temperature at leads
Time constant / Inductance Current waveform and voltage waveform match prediction Current waveform within 5 of prediction Measure transient voltage and current



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Hydraulic Performance
What Metric Criteria How
Flow rate Required flow rates can be achieved Flow rate within 10 of prediction Monitor dewar pressure, see how much LN2 comes out of coil
Pressure drop Pressure drop matches prediction for given flow rate Pressure drop within 10 of prediction Same test as above



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Thermal Performance
What Metric Criteria How
Cooldown from RT to LN2 temperature Winding form and winding cool down as expected Time to temperature within 20 of prediction Measure temperature of buried thermocouples and correlate with resistance measurements
Heating during current pulse Temperature rise of buried thermocouples matches prediction Temperature rise vs time within 10 of prediction for given current waveform Measure temperature of buried thermocouples
Cooldown between pulses Winding returns to pre-shot temperature within 15 minutes Temperature within 20 of prediction after 15 minutes Same test as above


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Structural Performance
What Metric Criteria How
Strain in winding form from cooldown to LN2 temperature Measured strain in winding form matches prediction for cooldown Measured strain within 20 of prediction Measure strain at 15 places on winding form
Strain in winding form from magnetic loads Measured strain in winding form matches prediction for magnetic loading Measured strain within 20 of prediction for given current Measure strain at 15 places on winding form
Gaps between winding packs and tee before, during and after magnetic loading Gap opening matches predictions TBD FM laser radar or other alternative TBD
Clamp behavior Clamps maintain preload throughout loading cycle Clamps have preload at beginning and end of testing Check gaps/belleville spring heights before and after testing
Global deflection from cooldown and magnetic loads Does overall coil deflection match Compare measured coil deflection to analysis FM laser radar or other alternative TBD
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FM laser radar

• FM modulated scanning laser used to determine 3-D
  topology of measured object
• System consists of laser head about 2 ft tall,
  connected by 10 foot cable to control system in
  2.5 x 2.5 x 4 ft box
• Depth of focus 8 inches at 10 ft. and lt 4 inches
  at 5 ft
• Magnetic field effects not quantified, but system
  works within 5 ft of CDX-U coils

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FM laser radar
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Fatigue Performance
What Metric Criteria How
Change in resistance vs strain in winding Resistance does not change over design life Final resistance within 1 of initial resistance Cannot measure on TRC, not enough time to perform cyclic tests
Change in deflection Measured deflection does not change over design life Final deflection within 10 of initial deflection Cannot measure on TRC, not enough time to perform cyclic tests
Degradation of cooling behavior Cooling behavior does not degrade over design life Final cooldown time between shots within 10 of initial cooldown time Cannot measure on TRC, not enough time to perform cyclic tests
Clamp behavior (Wear in pads, loose nuts, studs break, etc) Clamps maintain preload throughout design life Final clamp preload within 20 of initial preload Cannot measure on TRC, not enough time to perform cyclic tests
Degradation in crossovers, leads, connection blocks Crossovers, leads, and connection blocks have consistent performance over design life TBD Cannot measure on TRC, not enough time to perform cyclic tests
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Performance of Instrumentation
What Metric Criteria How
Temperature instrumentation is reliable and accurate T/C have consistent response and accuracy T/C measurement within 5 degrees of actual temperature Check T/C measurements at known conditions (e.g. after cooldown, all at LN2 temp)
Strain gages are reliable Strain signals do not drift Drift less than 10 Observe signals
Voltage taps work Voltage tap system can be used as reliable signal for coil protection system Voltage signals repeatable Observe signals


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Performance of Power Feed Cables
What Metric Criteria How
Power feeds can be routed as needed work at LN2 temperature Bend radius consistent with specs Min radius 12 inches Observe
Power feeds work at LN2 temperature No degradation, voltage drop matches prediction Voltage drop within 10 of prediction Observe T/C signal
Power feeds do not introduce heat leak into coils Lead temperature matches coolant temperature during idle Lead temperature same as coil temperature within 5 K Observe T/C signal
Power feeds do not kick or put undo strain on coil terminations No appreciable movement when energized TBD Observe
Error field within limits Error fields from power feeds negligable Field dies off like sextapole TBD
Frost at warm end of power feeds can be controlled Low power blower can eliminate frost at warm end No frost nor condensation on warm end of feed Observe
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Plan - 3 weeks needed, 2 weeks in baseline
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Potential issues what may change for type C
coil?
Component/system Issue Resolution
Cladding and chill plates Flat patterns and forming do not work properly tweak patterns so they form properly
Cladding and chill plates Application to winding form and winding difficult Revise method, add features as required
Metrology targets Metrology targets are robust and repeatable Modify targets as required
Winding Shims are too time consuming ??
Winding Shims are easy to apply Put shims between each layer
Electrical Not enough electrical insulation layer to layer Put shims between each layer
Lead blocks Winding does not lay or stay in lead blocks Revise, add features as needed
Lead openings Opening not large enough to fish through the cables with terminations Enlarge lead openings
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Potential issues what may change for type C
coil?
Component/system Issue Resolution
Tubing and fringe Difficult to apply Revise design as needed
Tubing Flow / cooling not adequate Revised design as needed

French toast Cracks during cooldown or operation pre-crack french toast after potting
Clamps Do not maintain preload Increase preload, TBD

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Unknown issues
Component/system Issue Resolution