Magnet costs L. Bromberg J.H. Schultz ARIES Meeting & Review PPPL, October

Superconductor Options and Implications Nb 3 Sn wind and react (most conservative) –Conventional design (ITER-like), but with high temperature inorganic insulation –Presently being tested for VLHC design (3- D winding in cos-  magnets) Nb 3 Sn react and wind (less conservative) –Thin cross section (low strain during winding) –MIT magnet for LDX (floating coil) –Low conductor current, internal dump High Tc (most aggressive) –Epitaxially deposited on structure –YBCO 2-generation superconductor –Potential for low cost (comparable to NbTi) Ceramic insulation tape

Costing Magnet costing for the ARIES magnets substantially lower than that of present designs/machines –Cost savings due to Conductor improvements –Nb 3 Sn and HTS (YBCO 2 nd gen conductor) Structure improvements –How do we evaluate “complexity?” Costing of superconductor in stellarator by kA/m, rather than energy or weight (because of multipole field configuration)

Cost of 10 th of a kind vs 1 st of a kind Stellarators coils are more complex than tokamak coils –Design, tooling, winding, position assurance much more costly for first of a kind stellarator than for tokamaks Modern methods of design and manufacturing avoid many of the issues of fitting, with software that goes directly from design engineer to the floor (Pro- engineer in NCSX) Difficulty thus relative to winding/tooling

Winding Winding in stellarators is 3-D, vs ~2D winding for tokamaks Additional time for winding –DB Montgomery: ~ 5 (guess) –High energy physics ~ 3 (winding solenoids vs cos-  dipoles) –J. Schultz: ~ 1.5 (from 2D to 3D) Tokamaks already need 2-D winding –not winding in tension, which would result in cheaper winding operation –In ITER, winding to bring conductor into slots in radial plates

Tolerance Impact on Cost ?

Scaling Laws for Modeling Large Superconducting Solenoids, M. A. Green and A. D. McInturff, IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. I I, NO. I, 2292(2001)

$/kA-m of cable $/m of cable Cabling cost Costing Methods for SC cable $/kg of strand Raw materials data Conductor geometry & specs $/m of strand Strand diameter $/kA-m of strand Recent J c (H) performance data Cost analyses of superconductors for high-field magnets, Lance Cooley, LTSW 2003, Monterrey CA

PIT(Powder_in_Tube) * Reflects recent VAC/SMI bid and extruded tube quote ** Reflects recent presentation by Hasegawa at MT-18 *** * LHC-NbTi 27¢ $66 5T

Powder in tube

HTS Present cost of 1st gen wire ~ 100$ kA/m (BSSCO) Recent breakthrough in YBCO 2nd generation (344) –Multiple suppliers of tape Nominal current ~ 60 A, but have made 300 A, 100 m lengths (AMSC, SEI) Extrapolation to ~ 500 A reasonable, 900A aggressive extrapolation At 30 K, 12 T, expected current ~ 9 kA/tape At 50 K, 12 T, expected current ~ 2.7 kA/tape Present cost 2 nd gen ~ $/kA m

YBCO stuck at ~ 100 A-m for nearly a decade Oct 2005 – Nagoya Coated Conductor Center (NCCC) at ISTEC announces 50 kA- m wire (245 A x 212 m, PLD on IBAD-GZO), x 500 improvement ARIES-AT: Requires tape with ~ 5 MA-m, x 100 over NCCC Other commercial apps may only require x improvement

Dependence of J c on T and H ORNL/RABITS Performance, 0.3 micron, 2000 Wire Development Workshop Proceedings, St. Petersburg, Florida, February 10-11, 2000 Multi-Scale Characterization: Evaluation of Microstructuraland Superconducting Properties Across Multiple Length Scales in 2ndGeneration HTS Wire. Terry Holesingerand Leonardo Civale, Superconductivity Technology,,Alamos National Laboratory DOE PEER Review 2006

HTS costing At 64 K, 2 T: –20 $/kA m At 30K, large field –4 $/kA m, ~ independent of field –Still more expensive than Nb 3 Sn (~ 5 T, but not at 15 T!

Summary There is a potential for VERY large decrease in the cost of SC magnets Development of superconductor has until recently been funded by OFES, mainly through SBIR’s –However, recent interest from the HEP community in high field devices (including VHLC) –Decrease in cost is associated both with improved conductor as well as improved conductor/winding concepts.