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Questions by Ch. Adolphsen

Questions by Ch. Adolphsen. Timeline of when the gradient goal and processing recipe is frozen Plan for bringing industry on board (XFEL will be a big factor in this case)

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Questions by Ch. Adolphsen

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  1. Questions by Ch. Adolphsen • Timeline of when the gradient goal and processing recipe is frozen • Plan for bringing industry on board (XFEL will be a big factor in this case) • List of engineering support required (in FTEs) to finalize the dressed cavity designs and to interact with industry to build them • Plan for how the continuing R&D program will mesh with these activities D.Proch, GDE meeting Peking, Feb.07

  2. Q1:Timeline of when the gradient goal and processing recipe is frozen • Guess the gradient goal is 35 / 31.5 MV/m • Guess the way to this goal is S0/S1 • Tight loop effort, production type effort, basic R&D • Plus exchange of resonators in the three regions • The tight loop effort and lab exchange is a good method to overcome lab depended deficiencies and/or to detect uncovered male functions in the lab infrastructure • But the required effort in resources seem to be underestimated D.Proch, GDE meeting Peking, Feb.07

  3. My guess of resources needed for tight loop strategy • Present multi-cell cavity measurements result in unpredicted scatter (FE, sometimes low quench) • The preparation chain of chemistry, HP rinsing & assembly must be analyzed • Meaningful procedures after one good cold test: • Repeat assembly (3 x) • Repeat HP rinsing & assembly (3x) • Repeat chemistry & HP & assembly(3x) • Do this procedure for 6 cavities in order to pick 3 resonators for regional exchange • Each region: • Build 6 cavities • 18 cold tests with own cavities • Another 32 cold tests with exchange cavities • In total 50 cold test at each regional infrastructure D.Proch, GDE meeting Peking, Feb.07

  4. Example of required infrastructure:DESY H3 • Active man power (FTE): • 8 EP, BCP, HPW, assembly (Axel Matheisen) • 3 cryo operation • 2 cavity inspection, tuning, assembly • 2.5 cold measurement, T mapping • 2 cavity data bank, server, software • Total 17,5 FTE • Cavity throughput in 2006 • 74 cold tests with 49 TESLA 9-cell, 25 single cell + gun cavities D.Proch, GDE meeting Peking, Feb.07

  5. Conclusion at this point • This R&D effort must be duplicated for the production like effort • May be not by 100% • But with new companies additional measurement and diagnostic effort must be expected • R&D on single cells should be synchronised with multi-cell activities • This demanding S0/S1 plan requires more resources than are visible at this point in time • In this case de-scoping or extending the schedule should be done in order to present a trustable plan D.Proch, GDE meeting Peking, Feb.07

  6. Q2: Plan for bringing industry on board (XFEL will be a big factor in this case) • There are several EU companies with long time experience in cavity production • DESY has incorporated industry in planning for • Cost reduction in Cavity fabrication • Cost reduction in cavity preparation • XFEL is pushing for • Cavity production with performance guaranty rather than build to print • Transfer of EP to industry • It is more than natural to identify mutual benefit for both projects in a MoU and thus asure maximum synergetic benefit. D.Proch, GDE meeting Peking, Feb.07

  7. Q3: List of engineering support required (in FTEs) to finalize the dressed cavity designs and to interact with industry to build them • Here a (not complete) list of issues based on XFEL preparation, to be discussed: • Nb specification 0.2 MY • Cavity structural calculations, 0.4 MY stiffness • Completion of cavity drawing, 3D 0.3 MY • Detailed cavity fabrication spec. 0.5 MY • QA plan cavity fabrication, 0.4 MY tolerances • Establish EDM file for cavity fabr. 1.0 MY • Design (+built) T-mapping 0.8 MY • Design (+built) eddy current scanner 1.5 MY & tuning machine D.Proch, GDE meeting Peking, Feb.07

  8. Marc`s questions for discussion • What RD priorities are indicated by the RDR cost? Are these different from ongoing priorities and efforts? • Cavity production yield is too low ===> S0 • Are the cost interactions of ACD known well enough to allow this prioritization? • Large / Single crystal cavities could have high gain at lower cost; but statistics and quantitative cost numbers are missing • Is the RDR baseline cost estimate useful for this process or is more work needed simply to refine the RDR estimate in order to prioritize the RD? Much of the RDR technical is 'immature'. • The RDR is our best guess so far, but we have to wait for S0 results before refine RDR D.Proch, GDE meeting Peking, Feb.07

  9. Marc`s questions for discussion, cont. • How do the above interact with the design work now underway at DESY • Lower XFEL gradient might direct in different cavity preparation technology; but involvement of industry is THE guideline for ILC • When is down-selection information needed? What is the latest 'possible' moment at which decisions can be taken that minimizes the disruption to the most effort-intensive parts of EDR? For example CFS. I suspect the answer is now for some of the most important selections. • Marc: please give your vision • Each RD task can be categorized based on the answer to above. How is this best done? • We have to go through the list of RD tasks with our updated S0 knowledge, when available D.Proch, GDE meeting Peking, Feb.07

  10. Marc`s questions for discussion, cont. • Each RD task will be funding limited, many severely. Are there some which will then necessarily come too late to be part of the EDR? What does this mean for RD funding prioritization? What does it mean for the EDR schedule? • S0 is a honest and necessary attempt to understand the „mystery“ of performance scatter (Eacc, FE); without positive result any schedule pressure is meaningless. Unless we are willing to accept to reduce Eacc to XFEL performance??!! D.Proch, GDE meeting Peking, Feb.07

  11. Additional comment to Marc`s questions • How to react if a new and promising technology comes over the horizon? • Example of large grain / single crystal cavity • Obvious cost savings in Nb production • Less or no grain boundaries will reduce or eliminate negative grain boundary effects • EP could be substituted by BCP (single grain) D.Proch, GDE meeting Peking, Feb.07

  12. D.Proch, GDE meeting Peking, Feb.07

  13. D.Proch, GDE meeting Peking, Feb.07

  14. D.Proch, GDE meeting Peking, Feb.07

  15. D.Proch, GDE meeting Peking, Feb.07

  16. D.Proch, GDE meeting Peking, Feb.07

  17. D.Proch, GDE meeting Peking, Feb.07

  18. D.Proch, GDE meeting Peking, Feb.07

  19. D.Proch, GDE meeting Peking, Feb.07

  20. D.Proch, GDE meeting Peking, Feb.07

  21. D.Proch, GDE meeting Peking, Feb.07

  22. D.Proch, GDE meeting Peking, Feb.07

  23. Field emission scanning microscope (FESM) Several W-anodes & samples FUG power supply 5 kV, 50mA PID voltage regulation LabVIEW programs Picoamperemeter Keithley 6485 3D Piezotranslator 40nm/V XYZ-motors (100nm step) Motion controller Newport MM4006 • UHV system typically at 2·10-7 Pa • LabVIEW automated scans of U(x,y) for 2 nA • Scanning speed: (100×100) pixels in 1 hr • I/V curves and localization of stable emitters Piezo motion controller PI- 920126

  24. Profilometer with AFM and SEM with EDX Additional surface analysis of whole samples and relocalized areas of enhanced FE Optical profilometer with lateral resolution of 2 µm and height resolution of 3 nm combined with atomic force microscope AFM Scanning speed: (100×100) pixels in 1 min Scanning electron microscope SEM (XL-30) with energy dispersive X-ray analysis EDX

  25. Emitter distribution on single crystal Nb after BCP/HPR Alternative approach for mirror-like surfaces: large crystal Nb+BCP30µm/HPR PID-regulated voltage maps U(x,y) for 1 nA scanned area = 7.57.5 mm2 flat W-anode Øa = 100 µm anode voltage U = 4800 V electrode spacing Dz = 32 µm Dz = 24 µm no emission @ 120MV/m 2 emitters @ 150MV/m 5 emitters @ 200MV/m  best FE performance of all Nb samples yet

  26. r •  = h/r ~ w/r S ~ r2 w Protrusion HPR HPR+DIC Eon (MV/m) 48.5 103.3  166.7 17.4  147 31.2 S (m2) 1.6 × 10-20 9.6 × 10-12 S (m2) 7.2 × 10-20 3.3 × 10-16 Effect of DIC on particulate and protrusion emitters Eon(1nA) = 77 MV/m S particulate removed by DIC FE of protrusion much reduced by DIC

  27. emitter HPR HPR+DIC Eon (MV/m) 54.3 62.8  67.4 35.4  51.2 38.0 S (m2) 2 × 10-17 8.3 × 10-13 S (m2) 1.2 × 10-15 2.4 × 10-13 Effect of DIC on a flake-like emitter with exposed edge emitter of ~ 20 µm size destroyed by DIC remnants emitting at higher Eon! EDX: no foreign element detected (probably oxide of Nb)

  28. 2.5 µm 8 µm Evidence for correlation  fast FE quality control by emitter size Correlation between FE onset field and emitter size ? based on FE measurements and SEM analysis of 38 field emitters (ILC) 30 MV/m (XFEL)

  29. D.Proch, GDE meeting Peking, Feb.07

  30. Introduction • Fourth cavity production series:- 30 nine-cells fabricated by Zanon company (incl. 3 prototypes with irregularities during fabrication)- 15 cavities of Teledyne Wah Chang Nb; 14 cavities of Tokio Denkai Nb; 1 mixed cavity (Z111)- delivery from mid 2004 to end of 2005 • “Standard” cavity preparations:- first EP of 150µm, outside etching, 800C firing,i) final EP of (40 - 50) µm, test, 120C bake, testii) final BCP (“EP+”) of 10 µm, test,(120C bake, test) => 8 cavities D.Proch, GDE meeting Peking, Feb.07

  31. Data analysis • Comparison of maximum and usable gradient after various preparations • Usable gradient in vertical test:Lowest value of gradient for either - quench - x-rays exceed 10-2 mGy/min - or rf losses exceed 100 W in cw operation (comparable to app. 1 W pulsed)=> limitation of cryogenics !! • Analysis of- final EP- vs. BCP (“EP+”) - treatment- comparison before and after 120C bake • Not strictly following “first/last/best test” like in data base=> Choice of “reasonable” test (see add. transparencies) (e.g. ¾ of all cavities first test used before bake) D.Proch, GDE meeting Peking, Feb.07

  32. Usable gradientbefore andafter bake • Usable gradient before and after after 120C bake: D.Proch, GDE meeting Peking, Feb.07

  33. Summary of Results • Broad scatter of both, Eacc,max and usable gradient in vertical and Chechia tests !!! • Final EP:7 of 17 tested cavities are quench limited below 25 MV/m !!=> 3 cavities (Z83 (pre-series with fabrication problems), Z86 + Z93) with “real” quench=> 4 cavities have field emission => FE induced quench e.g. Z104 ??=> only 2 (Z83, Z104) of these cavities had T-mapping investigation !!! • Final BCP (“EP+”):7 of 8 tested cavities are limited between 26 MV/m and 30 MV/m=> very reproducable ??=> but Z111 only shows 16 MV/m limited by quench in equator region !! D.Proch, GDE meeting Peking, Feb.07

  34. Summary of Results II • 120C-bake often gives no improvement in Eacc due to quench limitation !!(but nevertheless some improvement in Qo (cryo losses!!)) • 3 cavities lost significant performance from vertical test to Chechia => assembly and cleaning procedure!! • Many cavities show significant field emission => preparation process not reproducable !! • re-processing with only HPR helps: Z103 little improvement Z87 LH welding + HPR, vertical test => some improvement Z94 big improvement!! D.Proch, GDE meeting Peking, Feb.07

  35. D.Proch, GDE meeting Peking, Feb.07

  36. Ep/Eacc=1.894 Bp/Eacc=4.308 mT/(MV/m) (R/Q)=104.6 Ohm G=277.43 Ohm D.Proch, GDE meeting Peking, Feb.07Jacek Sekutowicz, DESY October 18th, 2006

  37. Ep/Eacc=1.74 R=40.03mm Ep/Eacc=1.71 R=42mm Ep/Eacc=1.99 Bp/Eacc=4.23 mT/(MV/m) (R/Q)=1011.5 Ohm G=271.56 Ohm All data by p-p 2% FF D.Proch, GDE meeting Peking, Feb.07Jacek Sekutowicz, DESY October 18th, 2006

  38. D.Proch, GDE meeting Peking, Feb.07

  39. Comparison of DESY and KEK single results Included pilot run KEK recipe CBP+CP+Anneal+EP+HPR+Baking FE, Q-slope are removed N=32 Eacc=43.5+-4.8MV/m for ICHIRO Eacc=37.3+-4.1MV/m for TESLA DESY recipe EP+Anneal+EP+HPR+Baking Eacc=35.2+-3.6MV/m for TESLA BCP are removed EP technology is close between KEK and DESY. But still there is 6% margin for DESY, if they use KEK recipe. DESY can be push up the gradient about 6%, which guaranteed the BCD acceptance performance with high yield(>90%). N=12 D.Proch, GDE meeting Peking, Feb.07 Using DESY/ Detlef Reschke’s data.

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