Magnet Systems Jim Kerby 20 Apr 2007 With

Magnet Systems Jim Kerby 20 Apr 2007 With thanks to my colleagues 1

Current Program Current focus: Demonstrate by the end of 2009 that Nb 3 Sn magnets are a viable choice for an LHC IR upgrade · Known major issues – Nb 3 Sn technology; Peak field on coil; Length; Consistency Three pronged approach: · Predictable and reproducible performance – TQ models (1 m, 90 mm bore, Gnom > 200 T/m, Bcoil > 12 T) · Long magnet fabrication – LQ models (4 m, 90 mm bore, Gnom > 200 T/m, Bcoil > 12 T) · Predictable and reproducible performance – HQ models (1 m, 90+mm bore, Gnom ~ 250 T/m, Bcoil > 15 T) But several new initiatives are under discussion—slim Q 0 options, for instance—we can not be completely locked in the box, and must be willing to contribute in the best way possible for LHC 2

Quadrupole Designs for the LHC IR From ASC 06 HQ Paper [1] LHC Design Report [2] R. Ostojic et al. , PAC-05 [3] S. Caspi et al, MT-15 [4] T. Sen et al, PAC-01 [8] R. Bossert et al. , ASC-06 [5] A. Zlobin et al. , EPAC 02 [9] S. Caspi et al. , ASC-06 [6] G. Sabbi et al. , ASC-02 [10] G. Ambrosio et al. , ASC-06 3

TQC and TQS Design Concepts Yoke Pad Key Shell Axial rod TQC • Stainless steel collars and skin • Control spacers to limit pre-load • End support plates, no pre-load Filler TQS • Aluminum shell over iron yoke • Assembly with bladders and keys • Aluminum rods for axial pre-load 4

TQC 01 and TQS 01 Quench Training TQC 01 TQS 01 SSL 4. 5 K SSL 3. 2 K • TQC 01: limited to 70% of short sample at 4. 5 K, but achieves 85% at 1. 9 K • TQS 01: start training at 80% of 4. 5 K short sample, limited to 87% in one coil • Maximum quench gradient was close to 200 T/m in TQC 01 and TQS 01 5

TQS 01 b & TQS 01 c Test Results • TQS 01 b: starts training at 75% of 4. 5 K short sample, plateau at ~82% (1 coil) • TQS 01 c: Trained at and 4. 5 K and 1. 9 K, ~80% plateau is conductor-limited 6

Field quality analysis: First TQ models show that the random coil block displacements are mostly within ± 50 microns which is factor of three larger than in production MQXB at the same fraction of coil aperture. This is an encouraging result given the differences between Nb. Ti and Nb 3 Sn technologies and the fact that MQXB field quality was polished on many preceding short models. The measurements reveal opposite ramp-rate dependences in TQC 01 and TQS 01 transfer functions that may be related to different interstrand contact resistances. 7

TQ Next Steps Starting from TQ 02, we are switching to RRP strand: • Higher current density, possibly different stress & stability characteristics TQS 02 • Coils use new Ti pole pieces to confirm adequacy • Assembly to be completed by the end of April • Test in May at FNAL (4. 5 K & 1. 9 K) • Discussion: cause of the 80%-87% plateau & planned corrections TQC 02 • Same coil design as TQC 01 (bronze pole with stress relief cut) • Significantly higher collaring pre-load (addressing TQC 01 problem) • Two coils possibly damaged during collaring (shim displacement) • Discussion: revise plan, minimize impact on schedule & milestones TQ 03 • Converged on coil design (Ti poles and no stress-relief cut) • Need to start parts procurement & coil winding (after TQ 02 spares) • Discussion: can we converge on a single structure for TQ 03? 8

LQ Status & Plans LQ “Design Study” is proceeding: • Finalized coil envelope and design (TQ); structure decision in June 2007 (? ) • Feb 07 Workshop focused on integration with other program components • TQ, LR, other supporting R&D and materials (conductor) LQ “Task” FY 07 plan: design & procure coil parts & tooling; start practice coils • Winding/curing tooling design approved by internal review on April 9 • End parts will be same as TQ Next steps: • Release drawings for winding & curing tooling • Confirm use of Ti pole pieces, determine length • Discuss reaction and impregnation tooling and procedures • Further clarify how/when feedback from rest of program will be integrated • Further clarify participation of LBNL and BNL 9

LQ Design study – G. Ambrosio Technological Quadrupoles Long Quad. Design Study Long Racetrack Long mirror Practice coils Long Quadrupole Goal: 4 m long, G 200 T/m, F = 90 mm 10

Long Racetrack · Support structure assembled at LBNL with dummy coils · Tested at BNL at 77 K · Ready to be used for LR 01 11

LR coils – LR 01 LRSC 01: · Coil impregnation – completed 4/ 16/ 07 · Prep for assembly - underway LRSC 02 · Coil reaction – heat cycle completed 4/ 19/ 07 · Coil prep for impregnation – through end of April · Coil impregnation – early/ mid May · Prep for assembly – mid May 1 st LONG RACETRACK · Coil assembly – mid/ late May · Hang, wire, cool down – end of May · Cold test –start early June 12

LQ Mech Design Development With collars With Al shell Analysis of TQC with Ti coils: OK! Hybrid concepts: SS shell + bladders 13

LQ: Next Steps · Conductor: – TQ 02 series results choice for LQ 01 54/61 or 60/61 · Coil Fabrication Technology: – TQ 02 series results Pole material (Ti or Bronze) · Mechanical Design: – Complete design of LQ with Al shell – Analysis of TQC 01 b, TQ 02 s and TQ 03 s – Generate mechanical design selection criteria · Quench Protection: – Design QP heaters for LQ, upgrade VMTF QP system 14

HQ Status & Plans HQ “Design Study”: goals, magnetic, mechanical, quench analysis reported at ASC Main focus is on fundamental technology issues – HQ is not a prototype 4 -layer coil w/TQ cable width – option of “standalone” test of outer double-layer • We need a “technology” HQ as part of the achieving the FY 09 goal • HQ can be designed to facilitate the transition towards a prototype Significant progress on mechanical design & analysis in recent months FY 07 HQ “task” plan is to get started on tooling design – requires radial envelope Recently, more emphasis on “standalone” outer double-layer test (130 mm aperture) Responding to CM 7 comments, considered increasing cable width in outer layers • No significant advantage in terms of stress • Quench protection issues not analyzed yet – high priority • Strand diameter TBD based on materials feedback We have confirmed the choice of a 10 mm cable – comments? 15

FY 07 progress: · Magnetic optimization of coil crosssection and ends · Mechanical design concepts with coil alignment · Detailed magnetic/mechanical analysis & comparisons Collar and pole locked with a key Collar and pad locked with a key 16

Summary of mechanical analysis Model 1 = coil#i pole#i glued 20 MPa tension between pole and coil HQ 1 HQ 2 HQ 3 HQ 1 out HQ 3 out 312 319 308 185 205 Iss (A) 10600 12450 11010 13500 17030 Peak field ss (T) 15. 74 16. 03 15. 49 14. 54 15. 37 300 300 185 205 Peak field (T) 15. 06 14. 99 15. 04 14. 37 13. 9 15. 37 Fx (MN/m) 3. 76 3. 38 4. 04 2. 73 3. 19 3. 9 Fy (MN/m) -4. 93 -4. 62 -4. 95 -3. 48 -4. 18 -5. 14 sq at 4. 2 K in high field (MPa) -165 -152 -136 -149 -153 -179 sq after excitation (MPa) -196 -177 -185 -194 -181 -219 Gradient SS (T/m) Gradient comparison (T/m) 17

Nb 3 Sn Strand Specification Rev-D 7/26/06 18

RRP-54/61 Production 490 kg 19

RRP Strand for LARP · For FY 08 LARP could use strands with the 127 -stack design – High Jc design has been achieved – Stability improves with decreasing sub-element diameter – Smaller low field magnetization – Option to increase strand diameter wider cable 20

Small Magnet R&D SQ 03: · Fabrication and test of 4 new coils – 108/127 strand • Possible candidate for LQ 02 – Conductor evaluation in operational conditions similar to the TQ/LQ magnets • Cabling degradation • Transverse stress degradation • Short sample current – Possibly use to address “bubbles” • Seen in TQs after 1. 9 K test 21

Radiation study – N. Mokhov · Based on detailed MARS 15 modeling and thorough analyses of coil apertures, distances to IP, low-Z spacers, stainless steel and high-Z liners, magnet splitting, and a set of TAS/TANtype absorbers through final focus region, it is shown that dipole-first, and shell-type & blocktype quad layouts are feasible for the LHC luminosity upgrade up to 1035 cm-2 s-1. · Work has started on design of radiation damage tests of materials for the superconducting magnets for the luminosity of 1035. · Q 3 -Q 4 FY 07 plans: further studies of block-type coil option; address a k. W-scale heat loads in the triplet; (possibly) perform calculations on a slim dipole; design Rad-Dam beam tests in an emulated LHC-like environment. · We have everything to respond to all energy deposition Oliver’s requests, but need someone! 22

Rad-Hard Insulation R&D Goal: Develop insulation/impregnation scheme that can withstand the expected dose at Max luminosity Plan A FY 07 Develop plans, schedule, cost FY 08 Q 1 -Q 2 Prepare samples and fixtures FY 08 Q 3 -Q 4 Irradiation & tests FY 09 Plan B Select alternative material Irradiation & tests SQ and/or TQ Rad-Hard Insulation Workshop Fermilab, April 20, 2007 (1: 30 – 6: 00 pm) 23

Improved insulation for Nb 3 Sn cables in superconducting magnets The result: robust insulation fabric with half the conventional thickness: The silane sizing is stable through Nb 3 Sn heat treatment. The tight weave (80 ct) is strong and flexible, no broken yarns, no Cu show through Conformation with cable is excellent, promotes easy coil winding. Silane survives heat treat, provides enhanced bonding with epoxy in final coil. New insulation has 20% higher shear strength! Good electrical properties We could coordinate materials and braiding process to make this new direct-braid insulation available to be applied to cable for LARP magnets. Question: are you (we) interested? 24

D 2 challenges: • D 2 apertures have the same polarity and negative coupling so most of the magnetic flux returns through the iron that needs to be relatively thick. • In spite of high current density, the quench field is ~10 T and the operating field may probably be 9 T instead of 14. 1 T quoted in the PAC 03 paper. It extends magnet length from 10. 0 m to 15. 7 m. • The next optimization steps will attempt to reduce the yoke OR, while keeping the field quality at a reasonable level. 25

New initiatives – P. Wanderer · LHC/LARP can benefit from BNL experience in developing – Slim magnets • “direct wind” CAD/CAM staff + machine produced Nb. Ti magnets for: – HERA IR upgrade (multielement) – BEPC IR upgrade (multielement) – ILC IR R&D (now underway) – Can we use this technology with Nb 3 Sn? – Magnetized TAS • Discussions with R. Gupta High Temperature Superconductor for quad coil in TAS – Basis: successful design, construction, operation of HTS superferric quadrupole for RIA R&D – Fast-cycling superconducting magnets for PS 2 and SPS upgrade • BNL modified RHIC dipole for GSI and fabricated and tested short model • Infrastructure for fast cycling magnet testing is available 26

Closeout New initiatives and participation…welcome! Magnet tests exploring the phase space…as upgrades become more real, we will be able to suggest real phase space to operate in. Proposal for new strand made…. options for larger diameter as required Continued R&D and studies on materials and cooling to make a real upgrade of LHC Thanks to all collaborators on an active and open meeting! 27