1 Testing of Twisted Racetrack Coil B. Nelson TRC FDR 15 Oct 2004

2 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

3 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

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

5 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” R&D –Coil to VV insulation heat leak –Cryostat boots –Other

6 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

7 Geometric “Performance” WhatMetricCriteriaHow Gross winding pack shape relative to theoretical as-measured winding pack geometry within acceptable tolerance Winding center meets +/ inch tolerance budget Measure spherical seat and tapped hole spotfaces, cut coil into sections, preserving enough of these features to measure section Winding form shapeas-measured winding form shape is the same as pre-potted shape TBDMeasure 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 mmRomer arm / Hall probe technique

8 Electrical Performance WhatMetricCriteriaHow ResistanceResistance 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

9 Hydraulic Performance WhatMetricCriteriaHow Flow rateRequired flow rates can be achieved Flow rate within 10% of prediction Monitor dewar pressure, see how much LN2 comes out of coil Pressure dropPressure drop matches prediction for given flow rate Pressure drop within 10% of prediction Same test as above

10 Thermal Performance WhatMetricCriteriaHow 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

11 Structural Performance WhatMetricCriteriaHow 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 TBDFM laser radar or other alternative TBD Clamp behaviorClamps 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

12 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 < 4 inches at 5 ft Magnetic field effects not quantified, but system works within 5 ft of CDX-U coils

13 FM laser radar < 4 inch focus at 5 feet Laser head Cryostat boundary

14 Fatigue Performance WhatMetricCriteriaHow 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 deflectionMeasured 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 TBDCannot measure on TRC, not enough time to perform cyclic tests

15 Performance of Instrumentation WhatMetricCriteriaHow 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 workVoltage tap system can be used as reliable signal for coil protection system Voltage signals repeatable Observe signals

16 Performance of Power Feed Cables WhatMetricCriteriaHow Power feeds can be routed as needed work at LN2 temperature Bend radius consistent with specs Min radius ~ 12 inchesObserve 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 TBDObserve 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

17 Plan - 3 weeks needed, 2 weeks in baseline

18 Potential issues – what may change for type C coil? Component/systemIssueResolution Cladding and chill platesFlat patterns and forming do not work properly “tweak” patterns so they form properly Cladding and chill platesApplication to winding form and winding difficult Revise method, add features as required Metrology targetsMetrology targets are robust and repeatable Modify targets as required WindingShims are too time consuming?? WindingShims are easy to applyPut shims between each layer ElectricalNot enough electrical insulation layer to layer Put shims between each layer Lead blocksWinding does not lay or stay in lead blocks Revise, add features as needed Lead openingsOpening not large enough to fish through the cables with terminations Enlarge lead openings

19 Potential issues – what may change for type C coil? Component/systemIssueResolution Tubing and fringeDifficult to applyRevise design as needed TubingFlow / cooling not adequateRevised design as needed French toastCracks during cooldown or operation “pre-crack” french toast after potting ClampsDo not maintain preloadIncrease preload, TBD

20 Unknown issues Component/systemIssueResolution