NCSX NCSX Preliminary Design Review1 Conventional Coils and Structure Phil Heitzenroeder, Len Myatt, and Mike Viola for the NCSX Engineering Team

NCSX NCSX Preliminary Design Review2 Outline Overview of NCSX’s Conventional Coils –Toroidal Field (TF) –Poloidal Field (PF) –External Trim Coils Overview of the Structures for the Conventional Coils Stress Analysis Manufacturing Plans, Cost and Schedule Summary

NCSX NCSX Preliminary Design Review3 The Conventional Coils in NCSX Consist of the Trim Coils, Toroidal Field Coils, and Poloidal Field Coils “picture frame” cryoresistive external trim coils 18 Cryoresistive TF coils 6 Pairs of Cryoresistive PF Coils Leads shown are conceptual

NCSX NCSX Preliminary Design Review4 TF Design Wedged Configuration –Similar to PLT and TFTR TF coil design; machined nose wedge. B max at R=1.4 m.: +/- 0.5 T Max. current for 0.5 T: 16 kA (ref. current for reference scenario is 4.4 kA) LN2 cooled hollow copper conductor Glass-epoxy insulation 18 coils 12 turns/coil 604 kg/coil

NCSX NCSX Preliminary Design Review5 PF Coil Design The PF System provides inductive current drive, plasma position and shape control. The PF System consists of: A central solenoid made of 3 pairs of coils; 1 mid-coil pair (PF 4) Two outer coil pairs (PF 5 and 6) All coils are cooled by LN 2 temperatures Coil temp. increases less than 5°K All are of conventional construction (hollow copper conductor; glass / kapton / epoxy insulation) and are well characterized at LN 2 temperatures as evidenced by C-Mod.

NCSX NCSX Preliminary Design Review6 Coil Voltage Standoff Requirements & Coil Insulation PF1PF2PF3PF4PF5PF6TF Operating Voltage (KV) Maintenance Field Test Voltage (KV) Operating Voltage x Manufacturing Test Voltage (KV) Maintenance Test Voltage x Design Voltage Standoff (KV) Manufacturing Test Voltage x New Design Specification (KV) 34.2 Per Turn Thickness Dielectric Strength 1/2 Lap Layer Dry GlassGlass0.007Inches0.525KV Glass /2 Lap Layer of KaptonKapton/glass Adhesive Kapton/glass Adhesive /2 Lap Layer Dry GlassGlass Glass TOTAL Turn to Turn34.2KV Insulation Build Up All PF &TF Coils Insulation Build Up, Ground Wrap Glass insulation is 75 Volts per.001” Kapton is 5 KV for.001” and 7 KV for.002” 6 x (1/2 Lap Layers).010” GlassGlass0.12Inches9KV Graphite paint will be applied as the outer ground plane

NCSX NCSX Preliminary Design Review7 Central Solenoid Design The windings of all three coil pairs are identical; only the lead details differ. The solenoid assembly is clamped together by end castings (with 3 electrical breaks) and tie rods. The solenoid will be “hung” from the upper TF shelf and positioned in the center by the lower TF shelf.

NCSX NCSX Preliminary Design Review8 PF Ring Coil Details PF 4 PF 5 PF 6 A single copper size is used for all of the PF coils (including the solenoid) to simplify their manufacture and reduce costs.

NCSX NCSX Preliminary Design Review9 Trim Coils The External Trim Coils consist of an array of cryoresistive “picture frame” coils. 9 each, top and bottom 6 each located in the upper & lower outboard corners. Primary function is to reduce resonant errors (n/m= ½ and 2/3) that may result from manufacturing or assembly errors in the modular coil geometry. Will be installed at initial assembly, but power supplies will be installed later after requirements are determined based on initial operation. The outer Trim Coils were initially located at the mid-plane and the analysis showed excellent results. However, the mid-plane coils had to be split into upper & lower chamfer coils due to space constraints. The analysis will be redone for the new configuration.

NCSX NCSX Preliminary Design Review10 NCSX TF and PF Structural Support Concept End Castings are made in sectors with Elec. Breaks between them. CS Detail In-plane TF loads reacted primarily by wedging. Out of plane loads reacted primarily by upper & lower “shelves” which are connected through the thick modular coil shell (not shown) Self-supporting PF solenoid hung from upper structural “shelf”. Ring coils supported from shelf assemblies. Adjustable brackets provided for alignment.

NCSX NCSX Preliminary Design Review11 Straightforward Castings are Used (all are made of stainless steel similar to Type 316) Solenoid end castings Electrical breaks between each 120 degree segment Upper & Lower Shelves are Assemblies of Inner Crowns, Radial Beams, and Outer Crowns. Electrical breaks are provided at each interface.

NCSX NCSX Preliminary Design Review12 Coil EM Loads and Stresses Analyzed with ANSYS Analysis documented in project memo: L. Myatt, “Electromagnetic Stress Analysis of the NCSX TF and PF Coil Systems,” 09/24/03.

NCSX NCSX Preliminary Design Review13 Analysis focuses on (5) Important Load Cases T TF Only, t=0.0 s (Max TF coil current) T Ohmic Scenario, t=0.0 s (Max ~PF5 & PF6 coil currents) T High Beta Scenario, t=0.0 s (Max Modular coil currents) kA Ohmic Scenario, t=0.206 s (Max PF4 coil current) kA Ohmic Scenario, t=0.506 s (Max PF1 & 2 coil and Plasma currents)

NCSX NCSX Preliminary Design Review14 Maximum TF Coil Stresses Produced when B TF = 0.5 T This relatively coarse mesh results in a Smeared winding pack (WP) stress of 130 MPa. Results in a Safety Factor (SF, Allowable/Actual) of 230/130=1.8. Maximum stress occurs in the Wedge/De-Wedge transition region.

NCSX NCSX Preliminary Design Review15 Modeling Approximation in Wedged Region Suspect (Left) The design has the top and bottom of the wedged surfaces extending beyond the straight part of the inboard legs. (Right) The model has the wedged surfaces limited to the straight part of the inboard legs.

NCSX NCSX Preliminary Design Review16 TF Coil Displacements at B TF =0.5 T Outboard legs move 12.2 mm (1/2”) towards the machine axis. Abrupt stiffness transition in de- wedged region produces bending stresses shown previously. Plans in-place to refine the model and possibly to re-design this region to reduce this local bending stress.

NCSX NCSX Preliminary Design Review17 Stress in TF Shelf-Structure at B TF =0.5 T By design, the TF Coil Shelf-Structure carries no load when just the TF Coils are energized. This plot shows essentially zero-stress (23 Pa) for this load case, indicating that the coupled-field model is working correctly.

NCSX NCSX Preliminary Design Review18 Smeared Stress Summary for (5) Important Load Cases LC2 (1.7 T Ohmic, 0.0s) Produces Max Stress in CS, PF5, PF6 and Support Structure. LC4 (320 kA Ohmic, 0.206s) Produces Max Stress in PF4, and Max Vertical Tension in CS. Smeared WP and Structure stresses can be compared to P M +P B limits: –TF WP: 1.5x165/1.06 = 230 MPa –PF WP: 1.5x165/1.47 = 170 MPa –Structure: 1.5x435/1.00 = 520 MPa So…these coarse-mesh model results look OK.

NCSX NCSX Preliminary Design Review19 TF Stresses from 1.7 T Ohmic Scenario 3.5 kA TF current much less than 16.2 kA for B TF = 0.5 T. Max smeared stress of 42 MPa still occurs in Transition Region of Inboard Leg. Results in a SF of 230/42=5. Away from peak, stresses < 25 MPa. Solenoid at 1.7 T Ohmic scenario; t=0

NCSX NCSX Preliminary Design Review20 Stress in TF Shelf-Structure from 1.7 T Ohmic Scenario Max stress of 45 MPa occurs in PF5/6 Support Hardware. Results in a SF of 520/44.4=12. Feedback from budgetary estimates will lead to cost-reduction measures (i.e., a lighter structure with less machining).

NCSX NCSX Preliminary Design Review21 CS Stresses from 1.7 T Ohmic Scenario 25 kA in PF1/2 result in Max Stress 31.5 MPa Smeared, 46 MPa Unsmeared Results in a SF of 170/31.5=5 Note that this model does not include vertical compression from a Tie Rod structure.

NCSX NCSX Preliminary Design Review22 PF4 Stresses from 320kA Ohmic Scenario PF4/5/6 tied to TF Shelves in Vertical & Toroidal Directions (free in R). 14 kA PF4 current results in Max Stress 12 MPa Smeared, 18 MPa Unsmeared Results in a Safety Factor of 170/12=14

NCSX NCSX Preliminary Design Review23 PF6 Stresses from 1.7 T Ohmic Scenario 9 kA PF6 current results in Max Stress. 12 MPa Smeared, 18 MPa Unsmeared. Results in a Safety Factor of 170/12=14. Stresses in PF5 are lower by 20%.

NCSX NCSX Preliminary Design Review24 Effects of Radial Freedom on Ring Coil Displacements High Currents in PF5/6 during 1.7T Ohmic Scenario produce maximum deformations. Radial displacement contour plot on greatly exaggerated deformed shape shows how PF5/6 change shape. Max relative motion at supports is <0.6 mm for PF6.

NCSX NCSX Preliminary Design Review25 Max Vertical Tension in CS (No Preload Structure) At t=0.206 s of 320kA Ohmic Scenario, Polarity of PF3 opposes that of PF1/2. Un-Preloaded CS experiences vertical tensile stresses of 4 MPa. This load case will help determine the preload required to maintain vertical compression in CS. (Details TBD)

NCSX NCSX Preliminary Design Review26 TF/PF Coil Stress Analysis Summary Reference Scenarios produce TF Coil stresses well below stress limit (SF>5). TF Coils can produce 0.5 T, but SF drops to 1.8. Re-working the model and/or design in the Wedge/De-Wedge region should improve the SF for this 0.5 T operating condition. Reference Scenarios produce PF Coil stresses well below stress limit (SF>5 in CS not including Tie Rod Preload, SF>14 in PF4/5/6). Reference Scenarios produce Structure stresses well below limit (SF>12). Plan to “cost reduce” the structure by making it lighter and minimizing machining. CS Pre-Load structure is TBD, but critical load cases are identified. Relative motion in R at the Ring Coil supports is <0.6 mm (manageable). Winding pack models too crude to determine insulation stresses. (TBD)

NCSX NCSX Preliminary Design Review27 Development of Coil Costs and Schedules Process based costing spreadsheets were developed and used to produce the costs and schedules for the PDR coil designs. –Materials required and their costs are calculated based on geometry data inputted from the Pro-E coil drawings. –Labor is calculated based on the time required for the various manufacturing processes (conductor insulation, winding, vacuum-pressure epoxy impregnation, machining, testing). The cost factors are based on our previous experience in building and procuring coils. –Schedules are developed based on process times with some “rounding up” to account for “real world” production situations. –Engineering and design costs for Title II and III were estimated. –Up to date labor rates were used. –Trim coil costs were based on those developed earlier

NCSX NCSX Preliminary Design Review28 Coil Costs and Schedules -We Plan to Procure All Conventional Coils from Industry TF Coils are required for field period assembly Lower PF coils are required prior to machine assembly. Trim coils are required for field period assembly There are several commercial suppliers for the PF coils. They are small standard size and shape. The TF coils will be a bit harder to find a domestic supplier. The trim coils are small and not complicated to fabricate.

NCSX NCSX Preliminary Design Review29 Coil Costs and Schedules -We Plan to Procure All Conventional Coils from Industry TF Coil Winding TF Coil Leads Trim Coils TF Coil I&C Contingencies were assigned based on estimated risk factors.

NCSX NCSX Preliminary Design Review30 TF Coil Production Schedule The TF Coil procurement runs from 1 October 04 through 16 June 06

NCSX NCSX Preliminary Design Review31 PF Coil Production Schedule The PF Coil procurement runs from 3 October 05 through 28 July 06

NCSX NCSX Preliminary Design Review32 Development of Coil Support Structure Costs A “prototypical” specification was developed for the coil support structures. –This, along with drawings and Pro-E models, was made available on the NCSX Manufacturing Web on a new page made specifically for advanced information on forseen future procurements. –A request for budgetary Information was advertised in the Federal Opportunities Bulletin. In addition, we contacted companies who we thought would be interested. –Three budgetary estimates were received. The cost used in the project plan is based on an evaluation of these estimates (i.e., what we judged to be the likely cost if were going to award a contract today based on the present information). Good feedback on design details. We plan to significantly reduce machining and change machining details.

NCSX NCSX Preliminary Design Review33 Coil Support Structures Budget and Schedule CS is installed after the machine is assembled. Structures are required for field period assembly.

NCSX NCSX Preliminary Design Review34 Summary The “conventional coils” are conservatively designed and present low risk. –(18) Wedged TF coils cooled by LN 2. –Cryoresistive PF coils consisting of a central solenoid and 3 pairs of ring coils.. All use the same copper conductor for cost-savings. –Cryoresistive “picture frame” trim coils located above and below the machine and in the upper and lower corner regions on the outboard side of the TF coils. A simple support structure assembled from stainless steel castings is used for all the conventional coil supports. –Castings are straightforward in design and well within the state of the art. –Budgetary cost and schedule information obtained from industry. –Manufacturing input and stress analysis indicates that there is a good opportunity to further cost- reduce them. Cost and schedule estimates for the coils were made using “process-based” spreadsheets.