1. 1 NCSX Modular coil winding pack To shim or not to shim? NCSX WBS 1 Engineering Meeting July 7, 2004 What is requirement? What is baseline winding pack design? What are alternate winding pack designs? How will we figure out what to do? What do we need to do now?

2. 2 What is winding requirement?  Winding current center must be within.06 inches of theoretical winding  If current center is more than 30 cm from plasma, some relaxation may be possible.

3. 3 Tolerance budget apportioned in thirds ElementTolerance budget Comment Winding form+/- 0.01 in.Baseline on drawing Copper claddingTBDCould be used to improve winding form tolerance if shims are allowed Insulated conductor size+/- 0.01 in.Based on NEEWC input VPI processTBDAssumed to be small Total for Coil Winding +/- 0.02 Assembly of coil in field period +/- 0.02 Adjusted to best fit, coil-to-coil with custom shims Assembly of field periods +/- 0.02 Adjusted to best fit with custom shims Total tolerance +/- 0.06 in. (+/- 1.5 mm) Minimum value, may be relaxed according to location around winding 1/3 for winding 1/3 for field period assembly 1/3 for final machine assembly

4. 4 Baseline design: accuracy achieved by shimming Each conductor layer can be custom shimmed 1.5 mm radius tolerance on winding center Custom shim layer to layer Custom shims adjust flanged joints between adjacent coil winding forms Custom lateral shim  Winding position continuously adjusted to AVOID TOLERANCE STACKUP  Form machined to high accuracy (Flanges to +/- 0.01 in, Contours to +/- 0.01 in)  Windings placed to high accuracy relative to each other and the form  Final position of coil form in assembly adjusted for optimum fit

5. 5 Baseline design: What are issues? Each conductor layer can be custom shimmed 1.5 mm radius tolerance on winding center Custom shim layer to layer Custom lateral shim  Measurement of each layer could be time consuming  What fraction of winding needs custom shimming?  What fraction can use standard shim?  Measurement tools may not work properly on insulation layer  Other issues

6. 6  Lumped shim concept  Estimate total keystoning at each position along winding pack  Shim between tee and ground wrap  Mid-course correction, if necessary  Variation: perform trial winding to quantify shim thickness  Pros  Less work measuring and shimming  Cons  Must be able to predict keystoning a priori  Hard to gage compressibility of winding pack and shims – are turns evenly distributed? What are alternate winding pack concepts? No keystoning, max shims Max keystoning, no shims

7. 7  No-shim – use winding form as is  Take what we get, no shims  Pros  Less work measuring and shimming  Cons  Art says this won’t work – islands too big What are alternate winding pack concepts? (2) current center shifts, but stellarator symmetry preserved Current center, desired Current center, actual

8. 8  No-shim – variable section winding form  Predict keystoning  machine winding form with variable section to put winding center in correct place without shims  Pros  Less work measuring and shimming  Cons  Must be able to predict keystoning a priori  Winding pack size varies, so clamps, cladding, chill plates must vary What are alternate winding pack concepts? (3) No shims, winding form maintains current center

9. 9  Other ideas  Pros  Cons What are alternate winding pack concepts? (4)

10. 10  Need experience winding prototypical coil to select shimming technique  Twisted racetrack will arrive this week  Conductor has been ordered and is in house  Ground wrap, insulation finalized  Cladding, chill plate ideas are firming up  Clamps are on order  Lead block design nearly complete  Try two shimming approaches:  Baseline on one side of coil  Alternate approach on other side of coil (lumped shim)  Trial winding first to determine lumped shim size How do we make decision?

11. 11  Order more conductor, if needed: Chrzanowski  Figure out correspondence between layers of glass and apparent thickness of shim: Chrzanowski et al  Get drawings of new lead block design to PPPL: Fogarty  Get drawings of new cladding to PPPL: Hargrove  Test Romer arm scanner on insulated conductor: Raftopolous  Order studs for stud welder: ?  Make fixture for locating studs: ?  Review TRT test objectives: Chrzanowski, Reiersen, Gettelfinger  Finish test plan: Nelson  What do we do next?

12. 12 Summary  We need to finalize winding pack shimming scheme  Trials on twisted racetrack will provide input  Recommend both the baseline concept and alternate concepts be included in winding / shimming trials on twisted racetrack