Preliminary Review of LERF as Cryomodule Testing Facility for LCLS-II 03-04 August 2017 at Jefferson Lab. M. Ross, SLAC 03-AUG-2017

Introduction: Cryomodule testing for LCLS-II SRF production is on the project critical path. Recent discussion with Jefferson Lab indicates a path to develop a tool that promises substantial schedule advancement. The LCLS-II/JLab Cryogenic Systems group has prepared a proposal to adapt the existing Jefferson Lab Low Energy Recirculation Facility (LERF) for LCLS-II cryomodule testing. includes a suggested plan for testing 6 to 8 cryomodules during the period mid-FY18 through mid-FY19. LERF review, 03-AUG-2017

Any CM-repair/retest cycle will delay project end-date. LCLS-II CM testing: Cryomodule testing for LCLS-II SRF production is on the project critical path. Each CM to be tested in-turn using existing test-stands, one at Jlab and one at Fermilab. This ‘end-to-end’ scheme determines the project duration In contrast CM assembly is not tightly infrastructure-limited; both production lines have some redundant infrastructure However - Supply-chain, esp. qualified-cavities is an outstanding risk that may push project duration; i.e. beyond CM-test forecast. Any CM-repair/retest cycle will delay project end-date. CM test-facility downtime also is unrecoverable LERF review, 03-AUG-2017

LERF review, 03-AUG-2017

LERF review, 03-AUG-2017

Typical CM test cycle Prep  done outside test-enclosure; not included in cycle duration Install Cool-down Soak Check-out Max Gradient determination Full-unit operation Q0-estimation Warm-up Remove 4 weeks; cold testing itself less than 50% of that Recent testing has included LLRF system-qual and microphonics studies LERF review, 03-AUG-2017

7 test cycles are completed (or are now underway) since Oct 2016. CM rework – an update: 7 test cycles are completed (or are now underway) since Oct 2016. Six CM tested 37 to go, until early / mid CY2019. 4 CM have (or may require) retest (re-work, cross-test, severe repair) Both test-facilities have been subject to cryo retro-fit downtime Testing-duration has been extended (3 cycles) for technical studies: Microphonics, heat-stationing, fast cool-down Delay roughly 10 weeks wrt initial plan (~ 2 ½ test cycles) LERF review, 03-AUG-2017

Proposal (to be Reviewed): The LCLS-II Cryogenic Systems group has prepared a proposal to adapt the existing Jefferson Lab Low Energy Recirculation Facility (LERF) for LCLS-II cryomodule testing. includes a suggested plan for testing 6 to 8 cryomodules during the period mid-FY18 through mid-FY19. Initial estimates show this to be practical at a fully burdened cost of about 4M$.  The technical performance capability of LERF has been well established and should be well suited for this purpose. LERF review, 03-AUG-2017

CM Testing – Test Facility / Linac - Differences Neither (existing) TF can hold more than one CM LERF allows two (possibly three) LCLS-II CM SLAC linac has 12 CM-long monolithic segments; Interconnect can be tested at LERF Better test of linac cool-down process Neither TF provides nominal-temperature input 3-Bar He LERF uses CHL JT HX (similar to SLAC design) (Test Facility input He ~5K) LERF operational pressure  2.07 K, above nominal LCLS-II 2.0 K LERF review, 03-AUG-2017

The most severe risk is interference with ongoing CEBAF operations. Risks: The most severe risk is interference with ongoing CEBAF operations. CEBAF-cryo have procedures for connecting a warm CM into the operating sub-atmospheric system Operations – schedule planning strategy important LERF uses the main CEBAF south linac CHL refrigerator. Contamination and/or pressure transients in the 2.07K sub-atmospheric helium circuit are the primary concerns. LERF review, 03-AUG-2017

Please: Review the feasibility of LERF-SRF CM test facility proposal to advise the LCLS-II project: Is the overall plan reasonable, Is the scope of work practical, Is the schedule consistent with the available resources, Is the expected LERF cryogenic systems performance consistent with that needed for testing LCLS-II cryomodules, Is the plan for managing the work and the testing consistent with project requirements, and are the risks, especially the risk of interference to CEBAF operation, properly understood and mitigated? LERF review, 03-AUG-2017

Feasibility Review Charge Questions: LERF review, 03-AUG-2017