1. C75 Cryomodule Planning E. Daly/T. Reilly 21 January 2016

2. Key Points The plan for a C75 cryomodule is to refurbish a C20 into a C75 –Same as previous (11) C50 cryomodules Adopt C75 cavity shape –Fabricate new 5-cell structures, use existing end groups –Affects CEBAF tuner and fundamental power coupler Continue to incorporate changes resulting from magnetic hygiene Build C75 on same cycle as C50 –Remove C20 late summer FY16, install C75 in summer of FY17 –Need to start cavity fabrication in Q3FY16 Continue to address critical spares C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

3. C75 Cryomodule Plan Refurbish existing C20 CM (similar to the (12) C50’s) –Resurface cavities and reuse all existing components (“the program”) –Change only what’s required to accommodate new cavity shape with higher gradient Adopt C75 cavity shape –Changes cell shape from OC to H C, reuse end groups –New cavity cells require processing; bulk removal thru VTA qual –New cavity shape drives changes to the tuner –Higher RF power (8kW) drives changes to fundamental power coupler Adds thermal straps to manage heat Similar to FEL02 (C50-12) thermal strapping => known solution –No other known impacts driven by C75 Continue to incorporate changes resulting from magnetic hygiene (C75DEV) –Most recently started with C50-11, applies to C50 and C75 –Change materials used for tuner components (springs, rods, bearings) to 316L where possible – Demagnetize other tuner components and helium vessel Critical Spares – HOM loads and fundamental power couplers C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

4. Plan for C75 Cavities Fabricate new 5-cell structures (pressing, machining, EBW) – Q3FY16 thru Q1FY17 Attached end groups from “pulled” C20 cavities to C75 5-cell structures – Q1FY17 Process fabricated C75 cavities – Q1FY17 thru Q2FY17 –RF/CMM Inspection, Bulk Chemistry (BCP), Heat Treatment 600C, Final Chemistry (HEP), RF Tune, CMM Straighten, HPR/Assem I/HPRAssem II, Pair Assembly, Vertical Test C75 Preliminary Design Review E. Daly/T. Reilly JAN2016 A. McEwen

5. Plan for C75 Cryomodule Components Execute “the program”, change only what is required SRF Engineering Group’s current thoughts on what’s required –Cavity Tuner Design new end clamps to match cavity geometry Asses capability of tuner function relative to C75 cavity stiffness Consider impact of microphonics due to new cavity shape –Fundamental Power Coupler (FPC) Add thermal straps to dissipate heat from higher power Similar to FEL02 Assess requirements to size and locate straps Engineering and design planned for Q2FY16 C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

6. CEBAF Cavity Tuner C75 Preliminary Design Review E. Daly/T. Reilly JAN2016 Swivel Yoke Assembly Cell Holder Assy Fixed* Cell Holder Clamp* Cell Holder Assy Swivel* (Inside Yoke Assembly) Cold assembly residing inside helium vessel Clamps on first and last cells apply tuning loads Tuning parameters are not significantly different from original CEBAF (OC) shape –Tuner resolution is capable of fine control (2 – 3 Hz) Wall of helium vessel

7. Cavity Tuner – Cell Holder Modification C75 Preliminary Design Review E. Daly/T. Reilly JAN2016 Revise holder for new cell shape Cell Holder Assy Fixed (Inside Yoke Assembly)

8. Cavity Tuner – Cell Holder Modification C75 Preliminary Design Review E. Daly/T. Reilly JAN2016 Revise holder for new cell shape Cell Holder Clamp May need to thicken clamp due for new cell shape

9. Cavity Tuner - Microphonics Loaded Q : Q L = 2.8 x 10^7  narrower bandwidth Tuner resolution is capable of fine control; Need to assess backlash New cell shape is less stiff so the plan is to add stiffening rings based on mechanical analysis –Can “tune” stiffness by location of stiffening rings on cell wall –Stiffening possible between end half-cells and end group if needed Analysis may indicate that HOM loads and elbows need support or damping –Compare C75 with C20/50 by analysis then develop plans for supports –IF C75 is less stable, propose G10 supports between elbows and tuner yoke structure to add damping Stiffening rings planned between cells but not decided on end half cells C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

10. Fundamental Power Coupler Copper plated stainless steel rectangular waveguide Thermal performance demonstrated in FEL module FL02 – capable of 8 kW forward power –Required additional thermal strapping for higher dynamic load as compared with CEBAF –Analysis required to confirm heat loads and thermal strap size New thermal straps may need to be fabricated C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

11. Fundamental Power Coupler C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

12. Critical Spares HOM Loads There are no spare HOM loads in inventory released for production Refurbishment assumes reuses of existing loads recovered from cavity pairs Ongoing R&D effort to develop and test new loads (C75DEV) –Wedges and parts are in hand, plan to assemble first set in FY16 –Plan to intercept C75 prototype pair with new loads Build inventory! Fundamental Power Couplers Very limited number of spare FPCs in inventory, none released for production Refurbishment assumes reuses of existing FPCs recovered from cavity pairs Forced to re-use FPCs that are of fair or poor quality Currently no suppliers available that can produce new copies of this assembly C75 does not plan to include supplier development Risk remains, supplier development effort is needed in near future! C75 Preliminary Design Review E. Daly/T. Reilly JAN2016 Raising Awareness

13. Summary The plan for a C75 cryomodule is very similar to refurbishing a C20 into a C50 cryomodule –Program is to reuse all components –Incorporate new C75 cavities – Bulk BCP –Build on same cycle as C50 refurbishment Remove a C20 in late summer of FY16, install C75-1 in late summer of FY17 Plan to start C75 cavity fabrication in Q3FY16 C75 cavity shape drives changes to the tuner and FPC –Tuner clamps need to be modified to match cell shape –Planned analyses are needed to understand tuner capabilities relative to cavity stiffness and changes to micorphonics –FPC will need thermal strapping (similar to FEL02) –Plan to complete thermal analysis and size heat straps –Plan to complete tuner and FPC analyses in Q2FY16 Continue to incorporate changes resulting from magnetic hygiene Continue to develop new HOM loads Begin supplier development for FPCs (not in C75) C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

14. Back Up Slides C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

15. Charge 1.Are the requirements and goals for the C75 cryomodule understood, well specified, and realistic? 2.Is the preliminary design conceptually complete, and likely to lead to an operating cryomodule with the desired characteristics? Will the design be flexible enough to take full advantage of ongoing R&D? 3.Is the C75 cryomodule planned adequately and “ready to go” for refurbishing activity to commence starting toward the end of 2016? If not, should refurbishments as C50 continue until outstanding issues are resolved, or should other paths (e.g., full C100 replacement) be pursued? C75 Preliminary Design Review E. Daly/T. Reilly JAN2016

16. Notes from 04SEP2015 C75 Cell Transplant Estimate Notes Need to remove cavities from C20/C50 and replace cells with higher performance low loss shape Impacts cells (obviously), tuner due to Qext change and FPC due to power handling of 8 kW Keep Dogleg assemblies Tuner (Ed) Needs new cell holders and magnetic hygiene pass (bearings, other magnetic parts, etc.) Analyze tuner and cavity stiffnesses Model studies Microphonics assessment FPC Waveguide (Ed – wild guess) Copy FEL waveguide for heat stationing Thermal analysis Need to develop suppliers for C20/C50/C75 CMs HOM Loads and Elbows (Scott, Ed) Consider rotating HOM end group by 45 degrees HOM loads are in short supply; assume we will use the OC HOM load design New design as back-up – locate and specify materials (Frank, Jiquan); was in C50 plan already Re-use HOM elbows All HOM loads submerged Impact on cavity pair assembly rails Cavity (Larry with help from Bill) In-house Ingot F material (RRR 120) for two as first articles Include cost for Ingot for one module’s worth ($30K from Gigi/Ganapati, lead time 4 to 6 weeks) Retain overall flange-to-flange length Need space to remove cells Keep FPC position fixed Include stiffening rings with LL Verify length and dimensions of candidate cavities on CMM to confirm intended OAL Deep draw tubes from disks for beam pipe extensions Assume saw cutting of 5-cells since we don’t need to save them? Coordination – Scott, Larry, Jody(?) Scientist support - % of Frank, Gigi, Bob Engineering analysis – Fred/Gary, Naeem (pressure testing and pull test) Nb mechanical properties verification with samples from commercial Ingot C75 Preliminary Design Review E. Daly/T. Reilly JAN2016