Development of Nb3Al Superconducting Magnets for LHC Luminosity Upgrade � - Technical Progress and Further Plan - � Akira YAMAMOTO � and � Tatsushi NAKAMOTO � KEK � CERN-KEK Committee, 3 rd meeting, 12 December, 2008 �
Advantage of Nb 3 Al over Nb 3 Sn � As of now, critical current density (Jc) of Nb3Sn is higher than Nb3Al. But, …. � Jc vs. Stress � Jc vs. B � Nb3Al � 4000 NbTi(4.2K) 3500 NbTi(1.9K) (NbTa)3Sn(PIT) 3000 Nb3Sn(RRP) Nb3Al(RHQT) 2500 Nb3Al(RHQT) Jc (A/mm2) 2000 1500 1000 Nb3Sn � 500 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 B(T) Presented at MT-20 By A. Kikuchi et al. Better mechanical performance of Nb3Al >> No degradation of Jc below 210 MPa. � For Nb3Sn (RRP), Jc is decreased to be around half at 150 MPa. � � @B=12T Jc~3000 A/mm 2 --> 1350 A/mm 2 � �
Objective For the LHC luminosity upgrade, we have been developing � -High fi eld superconductor and cable made with Nb 3 Al, � Complementary to Nb 3 Sn superconductor and magnet development at CERN and US-LARP. �
High Field Accelerator Magnet Development A Global Cooperation Network: Present � EU-CARE � France: CEA-Saclay � CERN � CERN-KEK � He Heat Transfer Study � Collaboration � CERN-US(DOE) � Japan � US-LARP � Magnet Technology Transfer � KEK � LBNL � NIMS � FNAL � Cabling, Subscale coil � BNL � SLAC � 4 �
High Field Accelerator Magnet Development A Global Cooperation Network: Proposal � EU-CARE � France: CEA-Saclay � CERN � CERN-KEK � He Heat Transfer Study � Collaboration � CERN-US(DOE) � Japan � US-LARP � US-Japan � Collaboration � KEK � LBNL � NIMS � FNAL � Magnet Technology Transfer � BNL � Cabling, Subscale coil � SLAC � 5 �
Participants / Collaborators � KEK: N. Kimura, T. Nakamoto, T. Ogitsu, K. Sasaki, � A. Terashima, K. Tsuchiya, Q. Xu, and A. Yamamoto, � NIMS: N. Banno, A. Kikuchi, and T. Takeuchi, � In cooperation of: � CERN: L. Rossi/G. de Rijk et al., (TBA) � Fermilab: M. Lamm et al., (TBA) � LBNL: G. Sabbi/S. Caspi et al., (TBA) � BNL/LARP: P. Wanderer et. al., (TBA) � CEA/Saclay: B. Bourdy et al (TBA) �
Technical Progress in 1st stage � JFY2006-2008 �
Development Items • � Strand development (KEK and NIMS) � � - Higher non-Cu Jc: Target 1500 A/mm2 at 15 T � � - Reduction of low- fi eld-magnetization � � � Ta-matrix (Non-superconductor at 4.2K) � � � � Ta sheath wire by KEK � Break at extrusion & drawing � � � � Nb sheath wire by NIMS � Effects to Jc? � � - Cu stabilization technique � � � Mechanical strength � ME493 � � � Electroplating on Ta-matrix wire � � � Long piece-length � Nb skin � • � Cable development (NIMS and Fermilab) � Nb � - trial fabrication � core � � � packing factor � � � twist pitch � � - race track coil � Ta inter fi lament matrix �
Nb3Al: Rapid Heating Quench Method � Mono- fi lament � Jerry-Roll: � Nb+Al sheets, Nb or Ta core � Multi- fi lament � Precursor (Nb/Al) � Rapid Heating Quenching (RHQ) � (Nb/Al)ss � Strand w/o Cu � Continuous Electroplating for Ta-matrix Wire � Cu stabilization � Area reduction � Rolling � 2 nd heating (800 �� 10h) � Nb 3 Al � A15 strand w/ Cu � 9 � ~1.5 m/h : thickness of ~170 μ m Cu �
Nb-Al billet fabrication experience (Hitach Cable) Extruder Billet size 1.35 � wire length # of fabrication ~2005 ~2008 100 ton 28 mm � ,< 150 mmL ~35 m many 400 ton 61 mm � ,< 300 mmL ~330 m ~30 + 9 4000 ton 141 mm � ,< 600 mmL ~4000 m 3 4000 ton billet �
Fabricated or fabricating strands � ������������������������� 2005 � ���� ���� ���� ���� ���� ���� 2003 � ������ ����� ����� ����� ����� ����� ����� ��� ��� ����������������� �� �� �� �� ��� �� �� �� �������������� ������ ������ ������ ������ ������ ������ ������ ������� Skin � � � � Nb � Ta � Nb Ta Nb �������������� ��� ���� ���� ��� ��� ��� ��� ��� �������������� ��� ��� ��� ��� ��� ��� ��� ��� ��������������� ����� � �� � ���� � ���� � ���� � �������������������������� � ����������� � � � ������� ���������������� ��� ���� ���� ���� ���� ���� ���� ���� ������������� μ �� �� ���� ���� �� ���� ���� �� �� ���������������� μ �� ��� ��� ��� � � � �� � ������������������� ��� ��� ��� ��� ��� ��� ��� ��� ������������������ �� �� � �� � � �� �� ����������� ���� ���� ��� ��� ��� ��� ��� ��� �������������� �� �� �� ���� �������������������� ���� ������������ ���� ����� ����� ������������������ ���� ���� ���� ���������������� μ �� ���� ��������� �� �� ���� ����������������� μ �� ��� ����������� ��� ��� ��� ���������������� �� �� �� ����������������� ��������������������� ���� �������������� ���� �������������� ��� ��� ��� ��������� ���� ���� ���� ���� ��������� ���� ���� ���� ���� ��������� ���� ��� ������������ ��� ��� ���
Mechanical Property of Nb3Al Wire (No Copper) � Nb-matrix (ME451) � Ta-matrix (ME476) � Vicker’s 700 600 hardness � 500 Vickers Hardness outer sheath Ta 400 central core Ta outer filaments 300 inner filaments 200 100 0 0 10 20 30 40 50 60 70 Area Reduction Ratio (%) 2000 20 ME476 0.2% Yield Stress Elongation ME451 0.2% Yield Stress Elongation 0.2 % Yield Stress (MPa) Fracture Elongation (%) 0.2% Yield Stress 1500 15 & Fracture Difference � Elongation � 1000 10 b/w Nb and Ta � is not so 500 5 signi fi cant. � 0 0 0 10 20 30 40 50 60 70 80 Area Reduction Ratio (%)
Continuous Electroplating for Ta-matrix Wire � KEK � 1) Strike plating of thin Ni on the surface � 2) Electroplating of thick copper � 3) Heat treatment for stabilize the bonding � � electroplating speed: ~1.5 m/h � � � (Cu thickness of ~0.17 mm) � NIMS � 1) Ion-plating of thin Cu � 2) High speed electroplating of thick copper � 3) Heat treatment for stabilizing the bonding � ion-plating speed: 120 m/h � electroplating speed: ~6 m/h �
Copper Stabilizer � Mechanical Bonding Strength � Rolling � RRR of electroplated copper Different EP solution � Bent wire to see the folds and � projections of Cu stabilizer �
Jc of Nb3Al Wire with Ta Matrix � Non-Cu Jc of ME476 (with Ta matrix) wire dia = 1.0 mm � ME476 w/ Ta 807 A/mm2 @15T � ME493 w/ Ta 718 A/mm2 @15T � Effect of the RHQ current on non-Cu Jc ( wire dia = 1.35 mm) (ME451 w/ Nb 946 A/mm2 @15T) � 1400 700 ME493 � 223 A 15 T 1200 224.5 A 600 16 T 226 A 18 T 1000 Non-Cu Jc (A/mm 2 ) 229 A Non-Cu Jc (A/mm 2 ) 500 230.5 A 800 400 600 300 400 200 200 100 0 0 10 12 14 16 18 222 224 226 228 230 232 B (T) RHQ Current (A) Note: Non-Cu Jc of the samples treated at � different RHQ current �
Low Field Magnetization � Ta-matrix (ME476, 493) � ME476-226-1.00 Non-Cu Jc = 807 A/mm2 @ 15T, 4.2 K 400 ME476-226A-1.00 4.4 K 2 K Magnetization M (kA/m) 200 Nb-matrix (ME451) � 0 ME451-226.6-1.03 Non-Cu Jc = 946 A/mm2 @ 15T, 4.2K -200 400 4.4 K ME451-226.5A-1.03 2 K -400 Magnetization M (kA/m) 200 -2 -1 0 1 2 Field (T) 0 -200 -400 -2 -1 0 1 2 Field (T) No fl ux jumps observed at 4.4 K �
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