Design Review for EP at the ANL/FNAL Superconducting Cavity Surface Processing Facility (SCSPF)

1. Design Review for EP at the ANL/FNAL Superconducting Cavity Surface Processing Facility (SCSPF) February 12, 2007 ANL Group: Mike Kelly, Scott Gerbick, Bill Boettinger (NE) FNAL Collaborators: Cristian Boffo, Kerry Ewald Speaker: Mike Kelly

2. Charge to the Committee • Evaluate the technical soundness of the design to meet the ANL/GDE EP goals for FY07-FY09. Does the design meet the criteria in the specification document generated jointly by ANL/FNAL which was reviewed at the TTC-KEK meeting? • Will the system be ready for commissioning in July 2007 using a single-cell niobium cavity? • Assess the suitability of the design for performing up to 11 EP procedures in FY07. • Assess the suitability of the design for performing up to 50 EP procedures per year in FY08-09.

3. Design Review at KEK, October 2006 • Conceptual Design Review for EP at the joint ANL/FNAL SCSPF • Attendees: Hasan Padamsee, Kenji Saito, Tsuyoshi Tajima, Kwang-je Kim, Lutz Lilje, Axel Matheisen, Marc Ross, Helen Edwards, John Mammosser, Cristian Boffo • Location/Time: KEK/September 26, 6-7:30 pm • Description: Mike Kelly presented on the approach for EP for the chemistry room 1 of the SCSPF. More detailed discussions of two hardware items, a cavity holding fixture and a rotating seal assembly, took place. Committee chair (H. Padamsee) General Remarks • This was a presentation of the concept of the EP system to be built at ANL, and the status of the preliminary design of a few of the key components. The important next steps are to incorporate the suggestions below, and continue with a full engineering design, with assembly drawings and prints for fabrication. The design should also address the system for valve operation, quantities to be measured, and the arrangements for preliminary HPR of single cells after EP. • The preparations for the next stage should take until the end of the year. • It was recommended that the full engineering design be reviewed at the advanced stage before procurement and fabrication should proceed (This Review).

4. Design Review at KEK, October 2006 Comments/Advice: • Holding fixture: Move rods out radially to so that the fixture/cavity may be set stably on a table or other flat surface. • Holding fixture: Consider extending the long support rods or having extensions to protect the cavity flanging. • Rotating Seal: Use support pins/cables to eliminate the possibility of excessive torque on the bellows • Rotating Seal: Minimize dead space/trapped volumes in the assembly when the cavity is rotated vertically. A small trapped volume at the top the cavity/seal assembly was pointed out for the proposed design. • Rotating Seal: Use the main flange at the back (body) of the seal assembly to retain the Teflon seal rather than the separate retaining ring. • Rotating Seal: Consider carefully the height of the cathode and “dam” relative to the cavity beam axis. The EP assembly must be suitably leveled so that the space for hydrogen removal is not blocked and that the cathode is never exposed to air during EP. The dam/acid plumbing should accommodate variable flow rates. • General Approach: Consider increasing the volume of acid (from 200 liters) in the circulation loop during EP. • General Approach: The aluminum heat exchanger for acid chilling may in practice have an unacceptably high corrosion rate. Have a plan to replace with a Teflon device if needed.

5. Outline • (Brief) Historical Overview • Performance goals for the ILC EP system at the SCSPF • The ANL/FNAL joint Superconducting Cavity Surface Processing Facility (SCSPF) • Technical Approach and Details • Cost & Schedule

6. I. Historical Overview: Four Decades of Electropolishing Niobium Cavities for SCRF (Helical Nb resonator developed at ANL for a heavy-ion linac: Surface Processing was EP in collaboration Karlsruhe) EP is still the most reliable method to achieve high performance in Nb SCRF cavities

7. I. Historical Overview: ANL Recipe for EP • Based on the Siemens' process from the early 1970’s • Niobium cavity is the anode of a voltaic cell • High purity aluminum cathode • Electrolyte (acid): 85:10 mixture of Sulfuric, Hydrofluoric Acid Examples of EP at ANL Double spoke Quarter-wave Triple spoke Co-axial half-wave

8. II. Performance goals: A specification document for EP at the SCSPF (Completed in ’06) …specifications are based upon the parameters discussed at the TTC meeting December 5-7, 2005 at Frascati (see summary spreadsheet prepared by J. Mammosser.) • https://ilcsupport.desy.de/cdsagenda/askArchive.php?base=agenda&categ=a0561&id=a0561s8/moreinfo/DESY_041205.pdf The system will be designed as a pre-production system with primary consideration for: • Flexibility of operating conditions to permit a study of the EP parameter space • The use of components with proven reliability, commercial availability and suitability for industrial or large-scale production. • Transferability of systems and techniques to other laboratories or industrial facilities. This specification and the engineering design to follow will be presented to an international group of technical experts who have agreed to provide guidance (This Review).

9. II. Performance goals: GDE Planning for US Cavity Processing Throughput (Target 2 - $50M SRF in ’08-’09)

10. III. SCSPF: Superconducting Cavity Surface Processing FacilityLocation: Argonne Building 208 • Facility Cost with manpower $2M • Safety Review Completed in 2006; 700 man-hours and $100K • EP Operations started in 2006 20 m

11. III. SCSPF: ANL Portion

12. III. SCSPF: Class 1000 Anteroom

13. III. SCSPF: ANL/FNAL (New) Shared Infrastructure 38 l/m 2-stage RO 3000 cfm NOx, HF scrubber 10 kW Chiller 1200 gallon storage 750 A @ 20 V Air Scrubber DI Water System Chiller/EP Supply

14. III. SCSPF: Control Console/Procedure Monitoring Re-Entry into ANL chemistry room after EP – Jan 2007

15. IV. Technical Approach: Technical goals for EP at the SCSPF • Tailor the system to the dimensions of the 1.3 GHz geometry • Design for ease of assembly and disassembly • Ensure tanks, pumps, acid lines are accessible and cleanable – no sulfur buildup • Empty the cavity of acid and fill with water rapidly at the end of the procedure (keep the cavity wet before HPR) • Use a pure aluminum heat exchanger for much improved heat transfer to the acid • Include a provision for separating the acid flow rate from the need to maintain constant temperature • Provide timely direct hands-on experience for FNAL/ANL personnel

16. IV. Technical Approach: Major Components • Flow scheme/plumbing • Controls/data logging • Mechanical/structural

17. IV. Technical Approach: Horizontal Orientation during EP

18. IV. Technical Approach: Flow schematic

19. IV. Technical Approach: Pumps Astipure PFD2

20. IV. Technical Approach: Two-way valves WB-2W8P

21. IV. Technical Approach: Three-way diaphragm valve Furon UPM3

22. IV. Technical Approach: Control System • Ventilation (8 – valves) • Pumps (4 – Teflon bellows) • Acid Handling (11 two- and/or three-way valves)

23. IV. Technical Approach: Example Ventilation Checklist

24. IV. Technical Approach: Example EP checklist for ANL cavity acid handling portion of the full EP procedure

25. IV. Technical Approach: Data Logging • Windows PC running LabView (8 ADC’s, 64 Control bits, 2 DAC’s, GBIP interface) • We will monitor/log temperature from three locations (2 locations inside cathode, inside cavity, external acid holding tank) using Teflon encapsulated thermocouples • We will monitor/log total current, voltage • We will measure flow rate using paddle wheel flow meter (on the return to the holding tank) • Initially we will perform periodic monitoring/calculation of: • Hydrofluoric acid concentration within the electrolyte • Niobium salt concentration of the electrolyte • Cavity rotational speed • Rinse water pH and resistivity • Nitrogen/Air flow • Heat exchanger coolant flow

26. IV. Technical Approach: A Cavity Holding Fixture 2.5 cm stainless (titanium) tube Spider Assembly Pin with expanding diameter “quick” pin clamps here using aluminum “seat” clamp

27. IV. Technical Approach: A Rotating Acid Seal O-ring Guide Bushings Teflon Bellows Rotating Shaft Main Body Lip Seal Dam Back Plate

28. IV. Technical Approach: End Group Attachment to Cavity Adapter Flange Rotating Seal Assembly Chain clamp

29. IV. Technical Approach: Cavity lowered into assembly using manual hydraulic lift Bosch Slides Bosch Slides

30. IV. Technical Approach: Half Section of End Group Assembly; elements of the electrical circuit indicated Bronze ring (rotor) • P.S. cables to bronze drum • 8-pair carbon brushes on drum OD, joined with a bronze rotor ring • 8 bronze feedthroughs through rotating bearing • 8 bolted lugs for cable connections to the cavity (hose clamp + copper braid) Bronze drum (stator) Cable connection to cavity (8) Bronze feedthrough, (8) Carbon brushes (8 pairs)

31. IV. Technical Approach: Half Section of End Group Assembly; Electrical circuit showing isolation washers • P.S. cables to bronze drum • 8-pair carbon brushes on drum OD, joined with a bronze rotor ring • 8 bronze feedthroughs through rotating bearing • 8 bolted lugs for cable connections to the cavity (hose clamp + copper braid) Bronze feedthrough, (8) Bronze drum (stator) Isolation washers, (8) Bronze ring (rotor) Cable connection to cavity (8) Carbon brush (8 pairs)

32. IV. Technical Approach: Cathode Loading, Acid Draining, Water Rinsing

33. Design Review at KEK, October 2006 Comments/Advice: • Holding fixture: Move rods out radially to so that the fixture/cavity may be set stably on a table or other flat surface. • Holding fixture: Consider extending the long support rods or having extensions to protect the cavity flanging. • Rotating Seal: Use support pins/cables to eliminate the possibility of excessive torque on the bellows • Rotating Seal: Minimize dead space/trapped volumes in the assembly when the cavity is rotated vertically. A small trapped volume at the top the cavity/seal assembly was pointed out for the proposed design. • Rotating Seal: Use the main flange at the back (body) of the seal assembly to retain the Teflon seal rather than the separate retaining ring. • Rotating Seal: Consider carefully the height of the cathode and “dam” relative to the cavity beam axis. The EP assembly must be suitably leveled so that the space for hydrogen removal is not blocked and that the cathode is never exposed to air during EP. The dam/acid plumbing should accommodate variable flow rates. • General Approach: Consider increasing the volume of acid (from 200 liters) in the circulation loop during EP. • General Approach: The aluminum heat exchanger for acid chilling may in practice have an unacceptably high corrosion rate. Have a plan to replace with a Teflon device if needed.

34. IV. Technical Approach: Design Available on FNAL ILC Document Server

35. Tour of the SCSPF

36. V. Cost & Schedule: Work Packages ANL interest is to develop the complete capability for building, processing, testing, operating 1.3 GHz cavities

37. V. Cost & Schedule: Proposed ANL SCRF to GDE/Gerry Dugan as presented May 2006 Proposed FY06 included: • Agreement by the ANL-FNAL-GDE collaboration on an EP specification • Performing engineering design of the physical EP apparatus to be located initially in the ANL portion of the chemistry facility • Performing engineering design review with technical experts from the U.S. and abroad • Initiating the procurement and construction of hardware for the EP apparatus Proposed FY07 activities are: • Assemble and commission an EP system by the middle of FY07 (0.75 FTE, $65 K M&S) • Electropolish ILC cavities in the second half of FY07 (0.75 FTE, $110 K for eighteen EP procedures) • Design and construction of an HPR system at the joint facility for rinsing after EP (1 FTE, $200 K M&S) • Interface with U.S. EP vendors/develop and optimize hardware suitable for large-scale EP (1 FTE) Cost summary (07): Labor (K$ M&S (K$) Indirect cost (K$) Total cost (K$) 612.5 375 307 1294.5

38. V. Cost & Schedule 60

39. V. Cost & Schedule Manpower as of Feb. 1 Kelly/Gerbick: 8 man-months total since Aug. 2006 Boettinger: 620 hours Additional required manpower to commission with single-cell Kelly/Gerbick: 8 man-months Boettinger: 200 hours Purchased Hardware Costs Additional Required Hardware Total Cost to commission: $502 K

40. V. Cost & Schedule: Planning with FNAL for testing/operations • A clear cavity is being fabricated at FNAL with simplified ends • Model cavity end-groups are being fabricated; may be attached to the clear cavity to mockup a full test of assembly procedures • DESY is providing a 1-cell cavity to FNAL/ANL to be used for initial testing • HPR following EP either elsewhere or in G150 facility

41. EP Project Status • EP Design Specification 100% complete • EP Engineering Design 80% complete • EP Design Review 60% complete • EP System/component procurement 60% complete • EP system assembly 10% complete • EP Interface with industry 10% complete (this activity limited by funding in FY07) • HPR following EP performed elsewhere or with existing facility (this activity limited by funding in FY07) • Based on the proposed schedule and progress to date the EP design and engineering group believes this project is on track to perform electropolishing of a single-cell cavity by July 2007

42. Additional Material: HPR in G150 facility • Supplied with 18 MW-cm deionized water at 20 l/m, up to 3000 PSI • Rinsed and dried in a curtained clean area

43. Additional Material: Test of End Group Fri. Feb 9, 2007 • Filled with water, rotated shaft on lip seal at 20 rpm, pressurized to 2 PSI • First test looks good; long term operation to be tested

44. Additional Material • Fluoride specific electrode; untested; requires dilution by ~50X