JLAB Cryomodule Assembly Facilities Visit Report Tug Arkan, Yuriy Orlov March 26, 2012

Introduction Half day visit to JLAB Test Lab Facility (TLF) where the cavities are qualified and cryomodules are assembled. We also visited the new Test Lab Addition (TLA) which is currently under construction. 2

CEBAF 12 GEv upgrade project CEBAF 12 GEv upgrade project requires ten cryomodules (1497MHz CW) Each cryomodule has 8 cavities Each cavities has 7 cells Cavities are qualified (up to 27 MV/m administrative limit) in vertical test Dewar's Once assembled into cryomodule - average required cavity gradient = 19.2 MV/m 3

Cavity Qualification Workflow Procure bare cavities (bulk electropolished) from Research Instruments (RI) CMM Inspection RF Inspection Degrease Heat Treat 600 degree C EP Degrease RF Tuning CMM Straightness Helium Vessel Welding RF Measurements CMM Degrease HPR; First Assembly HPR; Final Assembly Leak Test 24 hour 120 C bake Vertical Test Disassemble beamline flanges and FPC (class 100 – cleanroom) – Field probe, and 2 HOM flanges stay assembled to the cavity post VT. – Cover the open flanges and put the cavity on the shelf in the cleanroom for storage until string assembly. Clean flange surfaces and wipe down cavity in clean room HPR Cavity String Assembly 4

Cavity String Assembly Workflow-I After 8 cavities are qualified and populated in the cleanroom, start the cavity string assembly: – Take the cavity from the storage shelf – HPR the cavity in the Class 100 cleanroom – Dry the cavity (vertical, attached to the Backtech cart) in the Class 10 area (6~10 hours) – While the cavity is still in the Class 10 area, vertical and attached to the Backtech cart: Assemble the waveguide coupler to the cavity Assemble gate valves to the first and last cavities as specified for the cavity string position Install cover plates to the cavity beampipe flanges 5

Cavity String Assembly Workflow-II 3 technicians working in the cleanroom. UHV cleaning of all the parts and hardware are done by the chemical group. Current throughput is to HPR and assemble 2 cavities per day (one HPR station in the cleanroom) Once all the 8 cavities are ready to be assembled in the string, the cavities are installed on the cavity support fixtures (aka lollipop at JLAB) 6

Cavity String Assembly Workflow-III 7 Assemble the cavities to the string (Class 100 cleanroom): Align the cavities Interconnect the cavities using aluminum hex seals. Beampipe flanges are female. Use JLAB design radial clamp, no bolts/nuts No interconnecting bellows Assemble all 8 cavities Slow pump down (~4 hours) the cavity string for leak check Leave the beamline under vacuum, actively pumped throughout the cold mass assembly with an ion pump Throughput: 12 days of assembly in the cleanroom to prepare, assemble and leak check 8 cavities

Some Highlights 8 No interconnecting beamline bellows. In order to keep the cavity to cavity spacing fix, 2 titanium rods are used JLAB design radial clamp for cavity interconnect flange assembly: -Stainless steel clamps -Anodized stainless steel conical spacers -Aluminum hex seal -Silver plated stainless bolts

Power Coupler 9 Cavity string is actively pumped during the cryomodule assembly. Before the warm end coupler assembly, the bellows squirm protection clamps are removed and the bellows of the couplers is collapsed in a controlled motion. Al55Mg serpentine gasket for the assembly of the coupler to the cavity. We were told that that this gasket is not very easy to assemble and often leaks.

Transport the cavity string out of the cleanroom 10 Open the cleanroom door; bring the assembled string transport fixture to the cleanroom doorway; transport the assembled string from the cleanroom fixture to the transport fixture; roll the transport fixture to the high bay area for cold mass assembly.

Cold Mass Assembly Workflow-I Due to the planned move of the current Test Lab Infrastructure to the new TLA facilities, 10 cavity strings were already assembled in the cleanroom. At the cold mass assembly area: – Transfer the cavity string from the transport to the cold mass assembly fixture – Weld the 2-phase header pipe to the cavities & interconnect them with bellows. Leak Check – Assemble instrumentation: Heaters, liquid level sensors, temp diodes and RF cables – Assemble the thermal intercepts – Assemble the cold portion of the tuners – Assemble 60 layers of MLI to the thermal shield – Assemble thermal shield into space frame (strong back) – Assemble the space frame to the cold mass – Align the cavities to < 0.5 mm – Complete the MLI assembly – Various electrical and RF checks – Assemble the space frame into the vacuum vessel – Final assembly Cryogenic end cans, warm-to-cold beampipes, warm tuner sections and air-side FPC components – Transport the assembled cryomodule to the test cave 11

Cold Mass Assembly Workflow-II 12 Cavity string on the transfer cart tooling in the High bay area assembled with the 2- phase header pipe Cold Mass in the cryomodule assembly area, assembled with thermal shield, MLI and space fame

Cold Mass Assembly Workflow-III 13 Space FrameThermal Shield Cold portion of cavity tuner Two-phase header

Cold Mass Assembly Workflow-IV There are 2 cryomodule assembly lines at Test Lab Facility 6 technicians per lines 12 weeks to assemble from cavity string to completed cryomodule ready to be tested in the test cave 3 sets of cavity string assembly tooling are available – One available for a cavity string in the cleanroom – Two available for cryomodule assembly Cavity string assembly is gated by available cryomodule assembly rails – Normally, cavity string assembly coordinated such that its completion coincides with the completion of a cryomodule (an assembly rail becoming available). 14

Throughput Notes-I 12 days for cavity string assembly in the cleanroom (3 techs): – HPR inside the cavity assembly cleanroom – Assembly of the cavity flanges at the vertical state – Radial Clamp for interconnecting cavities to a string at the horizontal state – Hardware cleaning optimized for assembly specific to this project: UHV clean all, but particulate free clean only few needed for the initial assembly of each flange 15

12 weeks for the cold mass assembly (6 technicians per assembly line, total 12 techs) – Comparable complexity to the 1.3GHz module cold mass assembly – Stainless steel 2-phase pipe, manual open air welding of the pipe and bellows – Cavity string kept under vacuum with active pumping by an ion pump throughout the complete cryomodule assembly process – Time consuming touch labor Instrumentation, MLI, mechanical connections Intermittent leak checks & RF checks 16 Throughput Notes-II

Test Lab Addition A new ~30,000 square foot building nearing the end of construction. Everything is under on roof, cavity fabrication, processing areas etc. New cleanroom for assembly and HPR New cold mass assembly area which can accommodate 100 feet long assembly lines (once joined with the old test lab area) 17

Radial Clamp beam pipe connection in SSR1 Slide by Yuriy 18

Stainless to Titanium transition Slide by Yuriy 19 Old style-Ti He vessel (SS now) Ti-SS transition join