GSI SIS 300 Wire, Cable, Magnet R&D Status

1. GSI SIS 300 Wire, Cable, Magnet R&D Status Juris Kaugerts GSI Darmstadt 19.12.2006

2. Wire Development • Low loss, small filament wire development at GSI has at present ceased since INFN is doing this • It is not clear that the present wire geometry that INFN is investigating (7 element restacking of Luvata OK3900 wire) is the best geometry for a low loss wire, both in terms of stacking pattern (to give low loss) and copper distribution • Time dependent magnetization measurements will be made at Twente on this wire and results compared to other such measurements (need test sample and wire parameters from INFN) to determine suitability of such a design • For above wire α (Cu+CuMn/NbTi )=3.67 ( without shaving 1st stage elements). For M. N. Wilson‘s proposed wire geometry, α=1.6 . For measured SSC outer layer wire, α=1.7 C.Mühle:Prinzipien der Magnetauslegung

3. Wire Development (cont.) EAS wire K201T4 RHIC wire Wire dia. = 0.67 mm Filament dia. = 4.3 μm Cu/NbTi = 2.21 RRR = 173 ρet =(0.58 + 0.89B)*10-10 Ωm Wire dia. = 0.64 mm Filament dia. = 5.71 μm Cu/NbTi = 2.24 RRR = 198 ρet =(1.24 + 0.9B)*10-10 Ωm C.Mühle:Prinzipien der Magnetauslegung

4. INFN ρet value • INFN measured 2.5*10-10 Ωm<ρet > 4*10-10 Ωm @ 0.5 T Was the sample annealed ? What was the RRR value ? C.Mühle:Prinzipien der Magnetauslegung

5. Wire Development (cont.) • Present INFN wire Jc = 2500 A/mm2 (4.2 K, 5 T) • Starting Luvata OK 39900 wire Jc = 3274 A/mm2 (4.2 K, 5 T) • SSC outer layer 0.651 mm wire Jc = 2511 A/mm2 (4.2k, 5 T) ( measured by A Ghosh, BNL from LBNL lot of 130 kg (50,000 m), with average piece of 1 km) Best value, during fabrication ~ 2760 A/mm2 (4.2K, 5 T) • SSC wire B944-2 with Cu-Mn interfilamentary matrix C.Mühle:Prinzipien der Magnetauslegung

6. Wire development (cont.) • For SSC wire B944-2 et = (4.15 + 1.9B)10-10 m (measured) et = 4.7 10-10 m (calculated) for RRR = 102. • However, et = 2.5 10-10 m (calculated) for RRR = 200 C.Mühle:Prinzipien der Magnetauslegung

7. Proposed Low Loss Wire Development • Start with a wire geometry that can lead to a final design which can be used for a low loss wire, rather than an “off the shelf wire“, which gives fast results but can not be adapted for the final design. • Suggestion: Start with design A of M.N. Wilson‘s GSI Report 29 and proceed to design C if A works, but lower losses are desired. C.Mühle:Prinzipien der Magnetauslegung

8. Wilson Design A C.Mühle:Prinzipien der Magnetauslegung

9. Wilson Design C C.Mühle:Prinzipien der Magnetauslegung

10. GSI Cable Development • Heat treatments and coil curing cycle simulations have been developed at BNL to give the desired goal value of strand adjacent resistance Ra = 200 μΩ for single layer and double layer coils • The variability of Ra across the cable and along the azimuthal direction in the coil can be significant (see SSC meaurements) • Present Ra measurements are made on rectangular stacks at constant pressure • Pressure across the cable inside an LHC magnet varies by a factor 3 and also depends on the magnet current • Ra variability can affect AC loss and field harmonics during magnet ramping C.Mühle:Prinzipien der Magnetauslegung

11. GSI Cable Development (cont.) • Need to see how high Ra can be made without significantly affecting magnet stability Minimum Quench Energy (MQE) measurements were made on cored LHC dipole outer layer cable for cables with Ra in range 0.5 μΩ to 9 mΩ (4 values– see my ASC 2006 paper) Need to interpret test results yet C.Mühle:Prinzipien der Magnetauslegung

12. Cable Development(cont.) • Plan to make a curved Ra measurement fixture and measure Ra as a function of location across the cable, as well as pressure on the cable stack • Measure pressure on the cable stack with capacitive pressure gauges ( developed by CERN ) • Work to be done at IHEP C.Mühle:Prinzipien der Magnetauslegung

13. 6 T SIS 300 Straight Model Dipole • IHEP has a contract to develop tooling for building a 1 m (coil length) long SIS 300 dipole • Tooling to be finished by Nov. 2007 • Build model magnet in 2008, using either cored Rutherford cable with EAS wire or (backup) LHC wire C.Mühle:Prinzipien der Magnetauslegung

14. 4.5 T Curved Dipole Temperature Margin • C. Carsten presented a 4.5 T dipole design with 23 mm thick coil collars on Oct. 6, 2006 at the GSI-INFN meeting • The temperature margin was given as 1.09 K • This ROXIE calculation used an inappropriate version of the NbTi critical surface formulation, developed by Bottura et al. Using the old version of the NbTi critical surface, I calculated a temperature margin of 1.142 K. With the more appropriate version, the value is 0.952 K, i.e. about a 0.2 K difference. C.Mühle:Prinzipien der Magnetauslegung

15. Conceptual Design Study Superconducting Bent Dipole Magnets Based on Double-Helix Coils C. Goodzeit & R. Meinke Advanced Magnet Lab, Inc. Presented at Kernforschungszentrum Jülich, Germany 12/4/2006

16. Double-Helix (DH) Coils Numerical calculations show pure dipole fields away from coil ends • Higher-order multipole fields are order 10-9 of dipole • Verified by measurements and analytical calculations C.Mühle:Prinzipien der Magnetauslegung

17. Advantages and Design Concept • Double-helix Coil • Better field uniformity than cos(q) coils • No magnet specific tooling • Large cost advantage for small production series • Fast low cost prototyping • Highly reliable due to unique insulation system • 4 Support Cylinders (G-11) • Defineprecise conductor path • Square or Round Conductor • Less expensive than Rutherford type cable • No significant cable degradation • Square cable emulates efficient conductor usage in cos(q) coils made from Rutherford type cable C.Mühle:Prinzipien der Magnetauslegung

18. Design Requirements Key Parameters: • Nominal Central Field: 4 Tesla • Nominal Temperature: 4.35 K (max. 4.5 K) • Beam Tube ID: 89 mm • Coil ID: 100 mm • Geometrical Length: 2727.1 mm • Bend Radius: 13,889 mm • Operational Current: O5,000 A • Operational Current Margin: 20% • Field Uniformity (all higher MPs): O 10-4 of Dipole • Reference Radius: 35 mm • Stray Magnetic Field (@ 250 mm): O 0.05 Tesla C.Mühle:Prinzipien der Magnetauslegung

19. Field Calculation Summary Comparison of straight, bent and straight with iron: Inom = 4,500 A Effect of bend on MP for given bend radius content negligible! C.Mühle:Prinzipien der Magnetauslegung

20. Coil Cross Section 3 5 4 2 1) Cold Beam Tube ( ID = 89 mm ) 2) 4-Layer DH Winding (illustration) 3) Composite Support Structure 4) Outer Insulation 5) Cooling Channel 1 C.Mühle:Prinzipien der Magnetauslegung

21. Coil with Iron Yoke 4 3 1) Yoke Alignment Key 2) Helium Bypass Hole 3) Utility Hole 4) ½ Yoke Lamination ID = 70mm OD = 175mm 5) Outer SS Shell 1 2 5 C.Mühle:Prinzipien der Magnetauslegung

22. Multipole Content of DH Coil along the Axis Dipole Field Purple:DH coil Blue:Conventional cos(q) coil without spacers (required for most applications) C.Mühle:Prinzipien der Magnetauslegung

23. Systematic & Random Errors in Straight Sections of DH Coils Potential Systematic Errors: • None Potential Random Errors: • Change in Coil ID • No significant effect on dipole field in DH • Twist of Coil • Insignificant due to inner SS support tube and precision of guide grooves • Twist Pitch Variation • Avoided by precision machining center C.Mühle:Prinzipien der Magnetauslegung

24. Summary Conceptual design of bent SC dipole magnet based on DH coils performed, which meets all specs. Advantages of Proposed Design: • Almost pure dipole field (except of saturation effects) • High reliable due to conductor placement in indiv. grooves • Easy manufacturing of bent magnet • Little magnet specific tooling (low cost) • Small series production without cost penalty • No initial expenses for spare magnets (manuf. As needed) • Use of square compacted cable emulates efficient conductor usage of Rutherford type cable C.Mühle:Prinzipien der Magnetauslegung