1. Nb3Sn IR Quadrupole Program
GianLuca Sabbi
Second joint HiLumi LHC and LARP CM19 Meeting
Frascati, November 14-16, 2012

2. Topics/Goals for HiLumi-CM19
Development of 150 mm aperture IR Quadrupole – QXF models
Primary program focus, in preparation for construction project
Discuss how to address the most urgent technical issues
Refine model program: SQXF (1-2 m) and LQXF (3-4 m)
Identify and resolve key interfaces with other Work Packages
(Re)define and prioritize R&D plan in support of QXF
Conductor development, cable and coil fabrication, support structures and assembly, field quality, quench protection, radiation resistance, powering, cooling, alignment…
Expect 2-3 years before first QXF tests
Several platforms available, the most relevant are LQ, HQ, LHQ
Large investments to develop/optimize, ready to harvest results
Limited resources: only higher priority items can be preserved

3. QXF Progress since CM18
Aperture selection was main focus of CM18 – a clear direction emerged
Formal decision to adopt 150 mm was announced in early July
DOE guidance and program response following the aperture selection:
Formulate integrated plan US-CERN
Agreed on general approach and key program elements
Established CERN and US coordinators
Assigned deliverables and developed preliminary schedules
Reorganize LARP effort around the QXF development and coordinate with US core programs (GAD) for additional resources
Current focus on cable development, conceptual design
Significant redirection of LARP resources starting in 2013
Discussions are underway to define GAD contributions

4. QXF Focus Areas for HiLumi/CM19
Most critical issue: establish the cable design and fabrication process
Initial reference parameters were provided already at CM18
Procured strand (CDP & LARP) and fabricated many short sections
Complex optimization expected to require several more months
Conceptual design: identify critical issues (mechanics, protection etc.)
Interfaces with other WPs:
WP2 → WP3: requirements dynamic effects, persistent currents
Urgent – has direct impact on cable development
WP3 → WP2: provide/discuss estimates for field errors
WP3 ↔ WP6: powering and protection scheme
WP3 ↔ WP10: energy deposition and shielding requirements

5. QXF Focus Areas (2/2)
Organization of winding tests at different Labs to confirm cable choice
Also an opportunity to establish process for end part design
In parallel, perform design studies for various options, to be prepared to finalize the cross-section shortly after the cable (~March 2013)
Next on critical path will be the design of coil parts and tooling
Approach: identical parts, tooling, processes for all QXF models
Requires coordination of design and integrated procurements
For longer-term planning:
Refine schedule and links between short and long models
Role of SQXF/LQXF models vs. pre-series prototype (MQXF)
Construction plans for Q1/Q3 (US) vs. Q2a/b (CERN): compare assumptions for infrastructure, effort/schedule, cost

6. R&D Status/Plans – Conductor
Two main conductor designs have been used in LARP:
RRP 54/61 for SQ, LR, and 1st generation TQ/LQ/HQ/HQM models
RRP 108/127 for TQS03, LQS03, HQ/HQM, LHQ and QXF startup
Several new developments are underway, but time window is limited
A clear, realistic plan needs to be formulated and implemented
Better developed (high & well controlled Jc/RRR; long pieces
Larger filament size (magnetization effects, flux-jumps)
Smaller magnetization effects and flux-jumps
Less developed: control of properties, piece length
Increase and control Jc, RRR, piece length in RRP 108/127
Demonstrate potential alternatives (PIT, higher stack RRP)
Scale-up to larger billets for faster production an lower cost

7. R&D Status/Plans – LQ Platform
90 mm aperture, 4 m long, 200 T/m target gradient
Achieved in LQS01, surpassed by 10% in LQS01b
Reproduced best TQ (short) models built with the same conductor (RRP 54/61)
Latest LQ model (LQS03) uses RRP 108/127 with a target of 240 T/m (same as TQS03 with 108/127)
First test achieved 208 T/m with fast initial training
Overall good result, but several open questions:
Some results suggest a mechanical limitation
Unreliable SG data prevents direct confirmation
Low RRR may also be a contributing factor
A second assembly/test may help clarify these issues
Next in the plan: studies of quench protection limits

8. R&D Status – HQ Platform
120 mm aperture, 1.5 m long, 3x TQ/LQ forces, energy
HQ01 series of tests is close to completion:
184 T/m at 1.9K! Above 90 mm, 240 T/m scaling
Fine preload tuning together with full alignment
Encouraging data on stress & protection limits
Issues with coil design and fabrication process
Several HQM (mirror) tests of single coils:
Fast feedback on coil performance limits
Reaches SSL, but training is slow
HQ02 assembly expected in February
Incorporates cored cables, coil design and process improvements
However, new features are not uniformly implemented in all coils
Cable and parts are available for a third series of coils (HQ03) HQ
HQM

9. R&D Plans – HQ Platform
HQ01e-3: magnetic measurements and quench protection studies
HQ02: test second-generation HQ coils including
provisions for coil expansion during reaction
provisions for improved electrical integrity
cored cables for suppression of eddy current effects
HQM: test of special coils
Rad-hard epoxies (Matrimid and Cyanate ester)
New conductor designs (RRP 169, 217 and PIT wire)
HQM mechanical optimization in view of LHQ, QXF mirrors
HQ03 model with 4 identical coils of final design and process
Realistic field quality & performance reference for HL-LHC
Depending on program needs, HQ02-03 coils could also be used to validate new mechanical structures (BNL, longitudinal stacking)

10. R&D Status/Plans – LHQ Platform
After review, LHQ scope was reduced from quadrupole to mirror test
Goal: validate in long coils the design features optimized in HQ
Cored cables to control eddy current effects
1-pass cable for core compatibility and more efficient process
Braided insulation replacing fiberglass sleeve for long unit lengths
Decreased azimuthal compaction and increased longitudinal gaps to control conductor strain during reaction
Ti-doped conductor for increased strain tolerance
Aluminum oxide coatings for coil parts insulation
Optimized end parts to increase insulation, avoid sharp points
Increased inter-layer insulation layer thickness to 0.5 mm
Redesigned protection heaters, to avoid end spacer crossing
Evaluation/validation of Rad hard epoxies in long coils

11. R&D Planning at HiLumi/CM19
The R&D studies outlined in the previous slides are important for QXF and HL-LHC
Relatively small effort compared with the investment already made
These studies were part of the LARP plan, in fact the LHQ program is significantly reduced from the one presented at the last review
All results can be obtained in the next 2-3 years, before (in some cases, much before) they could be produced by the QXF platform
However, LARP will not be able to support this R&D while developing the 150 mm models according to the current schedule
Discussions are underway to use a combination of LARP and core programs to carry out these studies
Goal for HiLumi/CM19 is to discuss possible optimizations, define priorities and potential contributions to use as input for planning

12. Summary
A large knowledge base is available after 7 years of fully integrated effort involving three US Labs and CERN
Steady progress in understanding and addressing R&D issues that were perceived as potential show stoppers: conductor performance, mechanical support, degradation due to stress and cycling, length scale-up, coil/structure alignment, field quality, quench protection
Next few years will be critical and much work is still left to do:
Develop 150 mm aperture models and prototypes
Address remaining R&D challenges: control of dynamic effects, electrical integrity, process documentation, QA, rad- hard epoxies, develop and select production-class conductors
Need to integrate LARP effort with CERN, and core magnet development programs in US and EU Laboratories