Superconducting Magnet Division Construction and test results of Construction and test results of kapton kapton insulated 2G HTS insulated 2G HTS cos cos θ θ coil coil θ θ θ θ θ θ L. S. Lakshmi � � , E. Willen � � � � � � � � � � � � , R. C. Gupta � � � � � � � � � � � Brookhaven � � � Brookhaven National National Laboratory, Upton Laboratory, Upton, New , New York York-11973 11973 � Particle Beam Lasers Inc., Northridge, California � � � Particle Beam Lasers Inc., Northridge, California -91324 91324 LT LTHF HFSW12 SW12 Slide No. 1 L.S. Lakshmi Napa, CA, November 6, 2012
Superconducting Presentation outline Presentation outline Magnet Division • Technical Objective G HTS conductor • Conductor details • Coil geometry, winding and testing Test results • • • Summary and Future plan Summary and Future plan Pole winding using 2G This work is part of HTS Dipole STTR with Particle Beam Lasers Inc. (PI: Eric Willen) Grant Award Number: DE-SC0007738 LTHF LT HFSW12 SW12 Slide No. 2 L.S. Lakshmi Napa, CA, November 6, 2012
Technical context Technical context Superconducting Magnet Division � To demonstrate a high field (>20 T) cosine theta magnet technology for the particle accelerator program � The proposed energy and luminosity upgrade of LHC at CERN will require high field dipole and quadrupole magnets Quadrupole Nb Quadrupole Nb 3 Sn Magnet Sn Magnet ( Courtesy: Bill Sampson, BNL) ( Courtesy: Bill Sampson, BNL) Dipole Dipole NbTi NbTi Magnet (BNL) Magnet (BNL) Cosine theta prototype magnets built in BNL using LTS materials � There is a compelling need to look for a conductor technology beyond the conventional LTS materials. � What are the alternate choices? How do we make them “fit for purpose” ? LTHF LT HFSW12 SW12 Slide No. 3 L.S. Lakshmi Napa, CA, November 6, 2012
Alternate conductors: HTS Alternate conductors: HTS Superconducting Magnet Division Key features of 2G (REBCO ) conductors � High current carrying capability at 4 K It decreases slowly with field � Robust mechanical properties Endures high mechanical stress (> 700 MPa) and high mechanical strain (>0.5%) � Withstands large heat loads � Friendly for “react and wind” technology Note: • Anisotropic electrical and mechanical properties • Reference: http://fs.magnet.fsu.edu/~lee/plot/plot.htm Critical bend radius is 6 mm • Material cost is significant complete replacement of conventional LTS might not be a cost-effective solution � High field magnets in a hybrid structure (LTS+HTS) � � � a practically viable new generation magnet technology for the LHC upgrade LT LTHF HFSW12 SW12 Slide No. 4 L.S. Lakshmi Napa, CA, November 6, 2012
Objective Objective Superconducting Magnet Division Feasibility study � Design and build prototype 2G HTS cos θ coils and a flat coil for a performance Mandrel comparison Inner pole Pole winding ( θ = 70 ⁰ ) and mid-plane Retainer piece for winding with complex end-geometry Mid-plane winding Optimize the winding parameters and Optimize the winding parameters and tooling for the complete coil Pole winding � Suitability of Kapton CI wrapping for turn- to-turn insulation and conductor protection- a Mid-plane winding unique and important design feature of this magnet. � Electrical test at 77 K : to understand the conductor / coil performance in the complex end geometry of a cos θ magnet LTHF LT HFSW12 SW12 Slide No. 5 L.S. Lakshmi Napa, CA, November 6, 2012
Conductor details Conductor details Superconducting Magnet Division Kapton CI wrapped 2G conductor (supplied by SuperPower Inc.) Bare conductor specification Width: 12.14 mm; Thickness: 0.12mm; Total length : 14 m Thickness of HTS layer: 1µm; Hastelloy : 50µm; Cu Stabilizer: 65µm Transport properties at 77 K, self field Transport properties at 77 K, self field Average Ic : 483 A; Minimum Ic : 477 A After kapton CI wrapping N= 28 Spirally wrapped with about 30% overlap between the adjacent Kapton layers Note : Transport current was tested at every 5 m at 77K; Ic is Thickness of the kapton CI tape : 25 µm defined under the voltage criterion of 1µV/cm Thickness of the wrapped conductor: 0.177-0.240 mm � The conductor Ic is very uniform along the entire length. � Kapton wrapping process did not cause any Ic degradation LTHF LT HFSW12 SW12 Slide No. 6 L.S. Lakshmi Napa, CA, November 6, 2012
Pole winding: fixtures Pole winding: fixtures Superconducting Magnet Division Pole Pole � � � � � Mandrel Mandrel 50 mm 50 mm Material: aluminium LTHF LT HFSW12 SW12 Slide No. 7 L.S. Lakshmi Napa, CA, November 6, 2012
Pole winding Pole winding Superconducting Magnet Division Conductor Conductor off off-spooling station spooling station Coil winding tension < 5 lb Coil winding tension < 5 lb Propeller winding station Propeller winding station LTHF LT HFSW12 SW12 Slide No. 8 L.S. Lakshmi Napa, CA, November 6, 2012
coil coil after the curing process after the curing process Superconducting Magnet Division Coil after activating the polyimide adhesive at 225 ⁰ ⁰ C ⁰ ⁰ ⁰ ⁰ ⁰ ⁰ Coil after activating the polyimide adhesive at 225 C Coil after uninstalling the inner pole Coil after uninstalling the inner pole LTHF LT HFSW12 SW12 Slide No. 9 L.S. Lakshmi Napa, CA, November 6, 2012
Voltage tap lay Voltage tap lay-out in the coil out in the coil Superconducting Magnet Division Voltage tap lay Voltage tap lay-out in the innermost and outermost coil turns out in the innermost and outermost coil turns Step 1: coil after installing the voltage taps Step 1: coil after installing the voltage taps 13 13 12 12 6 7 5 8 8 9 10 10 4 3 2 2 1 1 11 11 16 16 15 15 14 14 � voltage taps are installed in the smaller straight and critical bend sections � � � of the innermost coil turn LT LTHF HFSW12 SW12 Slide No. 10 L.S. Lakshmi Napa, CA, November 6, 2012
Electrical Test : Preparation Electrical Test : Preparation Superconducting Magnet Division Step 2: after reinstalling the winding on the mandrel and the restraining bars Step 2: after reinstalling the winding on the mandrel and the restraining bars Step 3: after Kevlar wrapping Step 3: after Kevlar wrapping LT LTHF HFSW12 SW12 Slide No. 11 L.S. Lakshmi Napa, CA, November 6, 2012
Test results Test results Superconducting Magnet Division Y axis represents the end-to end voltage in the coil block (V1-V16) Conductor length :14 m Dipole coil: I-V test at 77 K; self field Dipole coil: I V test at 77 K; self field Based on 1 µ µ V/cm criterion: Ic= 204 A µ µ 0.1 µ µ V/cm criterion: Ic= 187.8 A µ µ LT LTHF HFSW12 SW12 Slide No. 12 L.S. Lakshmi Napa, CA, November 6, 2012
Field components at 77 K; I = 200A Field components at 77 K; I = 200A Superconducting Magnet Division B || || - 0.23 T || || ( max.at the curved sections) B total - 0.23 T ( max. at the curved sections) B ⊥ ⊥ -0.16 T ⊥ ⊥ (max. at the top and bottom coil surface) Courtesy : Ramesh Gupta LT LTHF HFSW12 SW12 Slide No. 13 L.S. Lakshmi Napa, CA, November 6, 2012
Ic Ic (expected) :pole winding (expected) :pole winding Superconducting Magnet Division Production wire (M3-909-3) B || || - 0.23 T || || ( maximum at the curved sections) 0.448 Ic (average)= 483 A ( bare conductor) Ic (measured) = 204 A (pole winding, 77 K) Ic (calculated) in the coil=217 A (Lift factor* Ic(average)of the bare conductor) LT LTHF HFSW12 SW12 Slide No. 14 L.S. Lakshmi Napa, CA, November 6, 2012
How do the small coil sections behave? How do the small coil sections behave? Superconducting Magnet Division Inner to outer turn and Outer turn Inner most turn (straight sections) V9 V9 V6 V6 V10 V10 V5 V5 V5 V5 V11 V11 V4 V4 Innermost turn (straight sections) Outer most turn (straight sections) LTHF LT HFSW12 SW12 Slide No. 15 L.S. Lakshmi Napa, CA, November 6, 2012
current distribution in the coil current distribution in the coil Superconducting Magnet Division No local degradation in the complex curved sections of the coil Ic= 204 A; N=27 23 23 27 27 24 24 24 24 25 25 26 26 24 24 26 26 28 28 23 23 24 24 27 27 27 27 26 26 24 24 V12 V13-V12 V15 V16-V15 V10-V9 V9 V11-V10 V10 V12-V11 V11 V14-V13 V13 V15-V14 V14 V1 V2-V1 V2 V3-V2 V6-V5 V5 V4-V3 V3 V5-V4 V4 V7-V6 V6 V7 V8-V7 V8 V9-V8 V10 V13 V16 V2 V3 V6 V12 V14 V15 V4 V5 V7 V8 V9 V11 LTHF LT HFSW12 SW12 Slide No. 16 L.S. Lakshmi Napa, CA, November 6, 2012
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