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Long Quadrupole Giorgio Ambrosio

BNL - FNAL - LBNL - SLAC. Long Quadrupole Giorgio Ambrosio. DOE review of LARP program Jun. 19-20, 2008 LBNL. OUTLINE: The road to the LQ LQ main features and plans FY08 development and issues Schedule and budget. Long Quadrupole. Main Features: Aperture: 90 mm

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Long Quadrupole Giorgio Ambrosio

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  1. BNL - FNAL - LBNL - SLAC Long Quadrupole Giorgio Ambrosio DOE review of LARP program Jun. 19-20, 2008 LBNL • OUTLINE: • The road to the LQ • LQ main features and plans • FY08 development and issues • Schedule and budget Long Quadrupole – G. Ambrosio

  2. Long Quadrupole Main Features: • Aperture: 90 mm • magnet length: 3.6 m Goal: • Gradient: 200+ T/m Timeframe: • Performance and reproducibility by the end of 2009 • Testing 3 LQs Long Quadrupole – G. Ambrosio

  3. The road to the LQ Long Quadrupole – G. Ambrosio

  4. 2006 2007 2008 2009 LARP Long Racetracks LARP LQ Design Study LARP Long Quadrupoles Plan for Length Scale-Up LENGTH SCALE-UP CHALLENGE: No Nb3Sn accelerator magnet longer than 1m has ever been built LARP plans to have a successful 4m long quadrupole by end of 09 FNAL Long Mirrors LARP TQs Long Quadrupole – G. Ambrosio

  5. Long Coils R&D - Results • 2nd Long Racetrack (4m coils): 96% of SSL So we can successfully make long Nb3Sn coils! But the LR had flat coils without ceramic binder, and coils were not heat treated in a closed cavity under pressure • 1st Long Mirror (2m coil): ~ SSL • ~ Accelerator quality coil using PIT conductor • Cos-theta coil w wedges, end spacers 98% SSL taking into account simulated temperature increase • 2nd Long Mirror (4m coil): 87% SSL • ~ Accel. quality coil using RRP 114/128 • Performance improved by heating the outer layer  instability Front view of mirror magnet Long Quadrupole – G. Ambrosio

  6. LR result: segmented shell Long Quadrupole – G. Ambrosio

  7. “Original” & Present plans We had delays, some parts were skipped, but we want to keep the 2009 LQ goal  “it can be done, but not without pain!” 2N+ 1R No 3rd generation In FY08 In FY07-08, No ceramic binder Long Quadrupole – G. Ambrosio

  8. Mitigation factors • Significant effort for fabrication and inspection of practice coils • Started before definition of latest details (holes for coil lifting, pockets for trace wiring) • Saved time with some extra costs • LQ coil reaction and impregnation at two labs (BNL, FNAL) • This is going to save time during LQ coils production • Providing risk mitigation (equipment failure) • Cost of fixtures and tooling at two labs • Continuous coil fabrication until successful inspection • Travelers continuously updated to be able to start production right away Long Quadrupole – G. Ambrosio

  9. LQ main features* *LQ Design Report available on LARP web site at: https://plone4.fnal.gov/P1/USLARP/MagnetRD/longquad/designreport/ Long Quadrupole – G. Ambrosio

  10. Conductor • Cable: • LQ cable design = TQ cable design • 27 strands, 0.7 mm diameter, • 10 mm wide cable, 1° keystone angle • Strand: • OST-RRP 54/61 for LQ01 • Strand used in TQS02 and TQC02 coils and LR • Good performance at 4.5 K • Performance at 1.9 K under investigation • Higher number of subelements (108/127) may be used in following LQs • See schedule for options Long Quadrupole – G. Ambrosio

  11. Magnetic Design • Coil layout = TQs • 2 layers (NO splice) • iron closer to coils in shell structure • Peak field in ends with collar structure Long Quadrupole – G. Ambrosio

  12. Mechanical Design - I • LQ Magnet Structure Review • Nov 28-29, 2007 at BNL • LQC = Long TQC - LQS based on TQS Long Quadrupole – G. Ambrosio

  13. Scale up issues: TQC models didn’t exceed 200 T/m Collaring long coils TQS structure needs modifications for long magnets Segmented shell Improvements introduced based on TQS test results Plan: Procure in FY08 both shell and collar long structures Provides options & back up 1st LQ with shell-based structure Best performance, shorter assembly, easier to replace coils 2nd LQ with collar-based structure Reusing LQ01 coils (done w TQs) 3rd LQ with structure depending on previous results LQMS Review plan TQS LQS Long Quadrupole – G. Ambrosio

  14. Advantages of Proposed Plan • Larger probability of success within FY09 by developing both structures • Providing back-up (LQC01 back-up for LQS01) and options (several options after LQS01 tests) • We are building a large and unique set of expertise and experimental data for the design of the structure for the LHC phase-II upgrade • All 3 labs are strongly involved with this plan  the best intellectual contribution from all experts  very high level of internal scrutiny Long Quadrupole – G. Ambrosio

  15. LQMS Review close-out Long Quadrupole – G. Ambrosio

  16. LQMS Review close-out • “However, from our perspective”: • Concerns about schedule, changes from TQS to LQS, stresses, coil alignment, end-load, TQ performances • Addressed: • Shear stress addressed in dedicated technical note • Available at: https://dms.uslarp.org/MagnetRD/longquad/shear_note_V4.doc • Schedule concerns addressed by 2 lab for R&I, LQ priority, contingency • LQS with iron pads at TQS; test of 1m LQS structure at LN, and of whole LQS structure at 300 K with dummy coils • TQS02 tested (2 times) replacing limiting coils • Replies/responses to all recommendations are in the back-up slides Long Quadrupole – G. Ambrosio

  17. Quench Protection • Goal: • MIITs < 7.5  Temp ~ 380 K (adiabatic approx) • Quench protection param. (4.5 K) – conservative hypothesis • Dump resistance: 60 mW(extract ~1/3 of the energy; Vleads ~ 800 V) • 100% heater coverage ( heaters also on the inner layer) • Detection time: ~5 ms based on TQs with I > 80% ssl • Heater delay time: 12 ms based on TQs with I > 80% ssl Long Quadrupole – G. Ambrosio

  18. LQ plans and work in progress Long Quadrupole – G. Ambrosio

  19. Fabrication and test plans • Coils are being fabricated at FNAL and BNL • 2 practice coils at FNAL, 1 at BNL • 4 coils by the end of FY08 • 3 at FNAL, 1 at BNL • Start spare coils in Q4 • 6 coils in FY09 (more using contingency) • 2 at FNAL, 4 at BNL • Shell structure: design, procurement & test at LBNL • Ready by the end of FY08 • Test of 1m model at LN & whole structure at 300K with dummy coils • LQS01 mechanical assembly and pre-load at LBNL • LQS01 electrical assembly and prep for test at FNAL • Collar structure: procurement at FNAL • Some parts held in contingency until Q4. • All LQ models to be tested at FNAL • LQ01 test in Feb 2009 Long Quadrupole – G. Ambrosio

  20. LQS design • 20 mm shell • 4-split iron yoke • Iron masters with 2 bladders and 2 interference keys • Iron pads with holes for coil end support and tie rods • Stainless steel sheet between coil and pad laminations • Shell: 4 segments, 0.8 m long • Yoke: 50 mm laminations with 3.3 m long tie rods • Pads: 50 mm laminations with 3.3 m long tie rods • Masters: 2 segments, 1.6 m long • Stainless steel axial rods w 24.5 mm diameter Long Quadrupole – G. Ambrosio

  21. Coil-pad sub-assembly Pads bolted around the coil Bolts “disappear” under compression Yoke-shell sub-assembly Gap keys keep yoke stacks apart and pre-tension the shell Assembly - I Long Quadrupole – G. Ambrosio

  22. Assembly of 4 single shell-yoke sub-assemblies Connection of shell-yoke sub-assemblies with tie rods Insertion of coil-pad sub-assembly Assembly - II Long Quadrupole – G. Ambrosio

  23. All parts in house Instrumentation of 0.8m section in progress 0.8m section will be fully assembled with dummy coil and tested at LN LQS status Coils: FNAL, BNL Structure: LBNL Test: FNAL Long Quadrupole – G. Ambrosio

  24. OK OK ? OK OK Long Nb3Sn coil challenges • Conductor: • Need km-size strand piece length, and long cabling runs (250 m for 4m long quad coils) • Insulation: • Need technique for long coils • Reaction: • Need long oven • The displacements due to differential expansions scale with length • Total friction force scales with length • Impregnation: • Impregnation time increases with length • Handling: • LARP set criteria for Max strain: -0.15%< e <0.05% LQ coil Long Quadrupole – G. Ambrosio

  25. LQ Coil Fabrication • Coil design: • LQ coils = TQ coils w minor modifications • React&Impr fixture change: • From 2-in-1 used for TQ coils to single coil fixtures for LQ • More symmetric coils (+) • New parts, new procedures (-) • Symmetric plates (as in LR) Long Quadrupole – G. Ambrosio

  26. Practice coil issues: Coil bowing after reaction (PC #2)  Pre-heat treatment of all fixture parts  Symmetric fixture (add top plate)  Reduce friction (mica) Damaged lead (PC#2) Due to coil bowing because of winding tension  Keep coil always under load  Introduce gaps only for HT? Damaged leads (PC #3) Due to shims overlapping  Continuous shims  Connect saddle to pole tip Inner pole shorter after HT (PC #3) Still under investigation  Introduce gaps only for HT? LQ coil fabrication issues solved ~solved good plan Long Quadrupole – G. Ambrosio

  27. Coil Instrumentation Will use Kapton “Traces” as in TQs • Voltage taps: 13 IL + 7 OL • Protection heaters:on both layers • Two traces (1.7 m each) per layer • Large ss strip with narrow heating areas • Successfully tested on Long Racetrack • “Bubbles” may reduce heater efficiency • Option: test at 4.5, 2.5 K and 1.9K (at the end) • Strain gauges: 4 IL + 1 OL • Wires on trace for outer layer strain gauge • Gauges on the inner layer will be instrumented with wires Long Quadrupole – G. Ambrosio

  28. Magnet tests • Preparation for test • Adaptive QP threshold • Symmetric grounding • Handling and support of LQS at VMTF • Handling fixture ~modified for pivoting • Test all LQ magnets • Test at 4.5K and 2.5K (1.9K at the end) • Magnetic measurement, ramp rate dependence, RRR… • Magnetic measurement only ½ length • Thermal cycles to check “training memory” Pivoting LRS01 in prep. for test at BNL Long Quadrupole – G. Ambrosio

  29. QA Plan: QA for LQ coil production: • Travelers: • Each lab is responsible for its own travelers, • Travelers will be distribute to the 3 labs • Fabrication steps (HT cycle, impregnation, insulation) and measurement plan are the same • Discrepancy Reporting: • Assures efficient reporting and recording of all discrepancies • All LQ task leaders will receive all DRs • New feature for LARP • Documents on LARP web site (plone) • Easily available to the whole collaboration • Address: https://plone4.fnal.gov/P1/USLARP/MagnetRD/longquad/ Long Quadrupole – G. Ambrosio

  30. “Projectized” task • LARP is a collaboration with a program • LQ project-like features: • Plan: Task sheets with milestones, budget for each milestones, and commitment (technical, not financial) by task leaders and supporting labs to do the job • Budget: LQ had priority in the FY08 plans, and in the use of magnet contingency; • No core-programs support • QA: developed and implementing LQ QA plan Long Quadrupole – G. Ambrosio

  31. FY08 LQ budget (k$) after all contingency was allocated: Budget at FY08 start: $3.4M After mid-year contingency allocation: $4.0M After June contingency allocation: $4.2M including $413k for LRS02 FY08 Budget Long Quadrupole – G. Ambrosio

  32. Budget after contingency distrib. FY08 budget: Linear profile among milestones FY08 actual expenses FY08 budget: Spending just before milestones Budget and spending profile • LQ budget and expenses (w commitments) in $k We have similar plots for each task, For FNAL also with labor and M&S breakdown Long Quadrupole – G. Ambrosio

  33. Test cables extracted from coil 3 Schedule Options: - LQC01 with S01 coils, LQS02 with new coils (FY09 budget: $2.3M) - coils with new conductor for LQ03 (FY09 contingency) Long Quadrupole – G. Ambrosio

  34. Conclusions • The Long Racetrack has successfully opened the way for the use of coils and structures for long Nb3Sn accelerator magnets • The Long Quadrupole FY08 work is completing the development of coils and structures for this goal adding accelerator quality features • The Long Quadrupole FY09 plan aims at testing 3 LQs by the end of CY2009 exploring the use of shell and collar structures, providing: • larger probability of success • unique data and expertise for LHC-IR upgrades  and for any future use of Nb3Sn magnets for HEP appl. Long Quadrupole – G. Ambrosio

  35. BNL - FNAL - LBNL - SLAC Extra Long Quadrupole – G. Ambrosio

  36. LQMSR concerns I • The structure plan and decisions are perhaps a bit late for the stated goal of a demonstration in 2009- and you have to do better with respect to schedule that the program has done previously. Yes, there have been delays in the whole program. Therefore the LQ plan has features to reduce their impact, and the impact of other possible causes of delays: coils will be reacted and impregnated at two labs (BNL and FNAL), two long structures are under procurement, we are planning to reuse some LQ coils in different structures • The 4m shell design and process have numerous changes over what was demonstrated in the TQ program, raising the potential for unknown risks, and has challenging assembly operations. This should be carefully reconsidered. The changes should lead to performance improvement and help during the assembly of the long structure. Two tests of the LQS structure are planned with dummy coils: a test at LN of a 1m model, and a test at room temperature of the whole structure with Fuji films. Having both structures available provides further options and backup. Long Quadrupole – G. Ambrosio

  37. LQMSR concerns II • The impregnated coil development to date has eliminated the positive coil-collar registration, an essential feature of most successful collared accelerator magnet campaigns, and this appears to complicate the absolute alignment scale up to longer lengths, and potentially raise the conductor strain in ways that affect the ultimate gradient performance. Other parts of the program (such as the HQ) are looking at coil alignment. This is not among the first LQ goals, although it can be tested by introducing keys in the collar structure (possibly after successful test of the LQC without keys, and of a TQC with keys). Alignment features were removed from the collar structure in order to allow more uniform stress distribution among the coils. Long Quadrupole – G. Ambrosio

  38. LQMSR concerns III • The collared design performance results appear marginal both mechanically and in magnetic gradient. Have you really been careful enough with the coil strain state management conditions including low tech handling and tooling issues? See note by R. Bossert (TQC task leader). • The shell design places emphasis on axial restraint (all load), while the collared design does not (30% of axial load seen at the ends). The test results even qualitatively do not resolve this issue, raising doubt about its importance, and emphasis, and thus how this engineering issue really scales scales to 4 m, and why there are so many changes in LQ01. Because of the importance of selecting the better of the two azimuthal coil support options (collar/shell), we have not changed the axial support levels associated with the collar/shell designs.The LQ structures aim at reproducing the pre-loading conditions of the best TQ models for each structure. Most changes of the LQS structures aims at easy assembly (masters), same load (SS rods) and lower pre-stress in the outer layer. Long Quadrupole – G. Ambrosio

  39. LQMSR concerns IV • The anomalous results at 4.5K and 1.9K beg interpretation- at a minimum, this should include strand strain degradation studies coupled with analysis conductor sub-models that characterize peak strains in cable strands, and possibly retesting TQS02 with new coils to replace those suspected of being inferior. TQS02 has been tested with new coils showing some improvement at 4.5K, and no improvement at 1.9K. The understanding of these quench performance is among the main goals of the LARP magnet R&D (strand and cable tests, TQ models with new conductor, HQ). • We are concerned that all this may beat on the already narrow performance margins observed in the just completed 1m tests We agree. For this reason the results of upcoming conductor and magnet tests will be taken into account by the LQ R&D (possible use of different conductor, and modifications coil fabrication, magnet assembly and pre-loading procedures). Long Quadrupole – G. Ambrosio

  40. Impact of skipped/delayed parts • 3rd TQ generation – LQMS (LQ short models) • No test of LQS cross-section in TQ magnets • No test of TQC with alignment features • No test of 1m single-coil reaction fixture • Test of 127 sb conductor planned in FY09 • 2nd LR using coils reacted in closed cavity using ceramic binder • No test of reaction of long coils in a closed cavity using the ceramic binder ( accelerator quality coils) • The LM compensated only partially because used Al-bronze poles w gaps • LQ practice coils • No feedback about fixtures and procedures before 2008 Long Quadrupole – G. Ambrosio

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