WBS 1 Design decisions and issues WBS 11

WBS 1 Design decisions and issues • WBS 11 - PFCs • WBS 12 - Vacuum Vessel • WBS 13 - Conventional Coils • WBS 14 - Modular Coils • WBS 17 - Cryostat and Base • WBS 18 - Field Period Assembly NCSX WBS 1 Engineering Meeting August 13, 2003

Where are we with respect to CDR? · CDR seems like a long time ago · We have been addressing problems identified at CDR and dreaming up new problems · R&D effort has shown that some of our design concepts do not work, and others are ok. · It has not been a straight path · Where are we? 2 2

PFCs CDR design PDR design Relative Cost First wall surface > 2 cm from plasma, but issues regarding assembly clearance between VV and coils First wall surface still > 2 cm from plasma in tightest spot, but assembly clearance issue fixed No change Limiters at bolted field joints, v=1/2 Limiters at v=1/2, new attachment scheme Slight increase Upgrade-able to full coverage of panels, field assembly of panel supports to VV internal ribs VV ribs eliminated, field assembly to brackets attached with field welded studs Decrease for VV, slight increase for PFCs Internal trim coils deferred No change 3 3

Vacuum Vessel CDR design PDR design Relative Cost VV shape not optimized for assembly VV shape optimized for assembly (biggest vessel that mod coils can slide over with 1. 5 inches clearance) No change Vertical, bolted joints at v=1/2 Welded joints, canted at 25 degrees from vertical, still at v=1/2 Probably no change (more R&D) Port reinforcement in addition to port extensions Port stubs made from port extensions, leak checking issue addressed Possible decrease for VV Cooling lines clamped to outside of vessel Same design, models completed No change Solimide insulation on outside of vessel No change, may need local “scuff plates” for tight assembly regions No change Four hanging supports per field period and two lateral supports at NBI duct, issue with assembly Four top and four bottom hanging supports (re-located for assembly), two lateral supports at NBI duct No change 4 4

Conventional Coils CDR design PDR design Relative Cost 18 TF coils, bucked from solenoid structure 18 TF coils wedged, slight change in shape for larger mod coil shell No change 2 pairs solenoid coils 2 inner PF coil pairs, 1 mid PF pair and 1 outer PF pair PF 3 sized to same od as solenoid. Much better for assembly Probably no change, but tooling should be less Window-pane external trim coils No change 5 5

Modular Coils CDR design PDR design Relative Cost 18 coils wound from flexible cable in cast-and-machined winding form Same, but switched to M 50/E 04 winding geometry Same at this level Winding pack design – pancake winding, two pancakes, 18 turns/pack, no splices in winding pack, 24 k. A/turn Layer wound, 10 layers of 4 parallel turns, no splices, 44 k. A/turn Same compared to April est. Crossovers and leads – compensating leads, designed to minimize field errors Uncompensated feed to bore of coil, but field errors acceptable Slightly higher Clamp design – simple “U”-shape May be back to simple “U”, but need belleville springs at base of tee, pre-load feature parallel to tee Higher than original estimate Cooling design – cooled copper chill plates, details fuzzy Inner and outer chill plates thermally connected at clamp interfaces to cooled clamp or other design TBD Higher than original estimate 6 6

Modular Coils - continued CDR issues: PDR progress: - tolerances: can we make +/- 1. 5 mm? - keystoning problem addressed with smaller conductor and custom shimming the winding surface prior to placement of each turn - coil-coil assembly uses custom shims - field period to field period uses custom shims - final issue involves determination of actual location of winding pack after potting - wing nesting problem New shell geometry - Coil-to-coil spacing on inboard side Optimum twist - Thermal distortion/stress problem (what are the conductor properties? ) Still an issue, but property data suggests the problem occurs during cooldown, not operation 7 Remarks - 7

Cryostat and Base CDR design PDR design Relative Cost Frame and panel design with fieldapplied foam insulation and butyl rubber coating Frame and panel design with cut foam insulation and hard (fiberglass? ) outer surfaces Somewhat higher Port interfaces: single silicon rubber boot from outside of cryostat to port extension Double boot, from inside and outside of cryostat surfaces, interspace filled with insulation and dry nitrogen at positive pressure to cryostat and cell Somewhat higher Base consists of framed columns on sliding tracks same 8 8

Field period assembly CDR design PDR design Relative Cost Modular coils slide over vacuum vessel, TF coil assemblies slide over mod coil shell, port extensions welded in place Same, but decision firm to slide mod coils in groups of three Same operations, fixture costs may go up with more design resolution, April est. higher than CDR Assembly done in TFTR test cell Same? (still TBD) 9 9

Other issues CDR issue PDR progress Remark What are properties of composite copper / epoxy conductor? We have some data, including: DL/L to 77 K: . 32% (316 sst: . 28%) Mold shrinkage: . 04% Compression modulus: at RT: 20 e 6 psi? at 77 K: 5 e 6 psi? Thermal conductivity: 10 W/m. K? (pure copper ~400 W/m. K) Still need confirmation of key properties 10 10