SPOKE Cavities frequency preparation plan and RF control procedures Cecilia G. Maiano www.europeanspallationsource.se

Technical Commissioning of Systems After the handover from In-Kind Contributors and the testing at TS and tunnel installation the technical commissioning phase will start at ESS Planning has started at ESS, in order to define a proper structure in the Linac group/SRF section and set necessary procedures for this activities This presentation collects material for discussion, in order to properly match IK requirements and FREIA testing procedures to the information that will be needed during the technical commissioning activities 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Spoke Test/ Turn on Procedure Discussion - C.Maiano Operation readiness Before switching RF on, the ESS technical commissioning team will have to verify the ”operational readiness” of the modules, which is largely based on data collected by IK and TS activities E.g. are the cavities in the expected state? Are all subsystems functional? Are all connections properly routed? Are all interlock thresholds set to safe values? Operation Modes defined by ESS-34178 The technical commissioning team will need to handle the relevant interfaces with MPS and local technical interlock systems 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Reference data from IK and testing First discussions during the RF Cell Review (May 2017) and with MPS and interlock experts pointed out the need to have, during the technical commissioning, a fast access to the handover state of all systems Performance data of all tested cavities (in VT and at TS) E.g. Q vs Eacc curves, limitation mechanisms during tests, reference frequencies in various conditions (warm, cold before tuner action), probe calibration coefficients, nominal transmissions, cable calibrations, etc. Full understanding of the operation of all subsystems E.g. expected steps to tune, nominal tuner response per step, warm and cold coupler conditioning procedures and experience, etc. 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

1. Need for a local database At ESS we are settin up a system to handle the management of these data, in order to Verify operational readiness E.g. nothing unexpected has changed during storage and installation Make properly informed decisions by the SRF section of all operational limitations and correspondingly set the interlock protection levels E.g. Max field of a cavity before quench limitation or avoiding eccessive field emission regions, coupler conditioning signals, etc. 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Proposed path for the data All IK partners store production and test data during their activities, e.g. BW frequencies at warm/cold, transmissions, field flatness Antenna Qext and calibrations, cable calibration Power rise curves Position of harmful HOM modes We have to agree on a mechanism to transfer the data for consolidation at ESS, in a storage area accessible by the ICS, the commissioning/operation group and IKC. consolidation is ESS responsibility, IK partner submit data in any suitable “standardized” form that can be used to feed it 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Data documentation/transfer Example of an elliptical cavity (using our XFEL 3.9 GHz data) Passband measurement are retrieved from cavity producer and during the module assembly stage (any form used at IKC) Normalization to ESS ICS standard (HDF5, Nexus extension) => ESS Task Analysis logic built on the collected data (e.g. visualize, compare, etc.) => ESS Task We can implement it also for spokes 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

2. Need for a “user manual” Design criteria and test experience during the R&D and prototyping phase is documented by a large amount of reports, scientific and conference publications, by the IK contributors It is often a ”work in progress” snapshot, on the path to the technical maturity of the series components, one should be careful to extract values The ESS team/ SRF section needs to ”take ownership” of all design aspects and the valid design parameters Compile a summary report in consultation of IK partners and reach consensus for its finalization For “RF experts”, physics-oriented. Not just list of numbers, but design motivation 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Agreed path for the design information I am compiling a “summary” of all the current information concerning the cavity design (spokes and elliptical) and nominal system and subsystem parameters, starting from published material from the IK and involving the IK for the completion, its review and its finalization Focus is on the understanding of all design background in order to fulfill the goals of the technical commissioning phase at ESS Develop procedures at ESS for verification and measurement activities 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Example from the SPK document (+…) 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Spoke Test/ Turn on Procedure Discussion - C.Maiano SPK document (2) 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Spoke Test/ Turn on Procedure Discussion - C.Maiano SPK document (3) 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Example: Frequency preparation What are the expected cavity frequencies during all stages? Uncertainties? At least for the technical commissioning we will foresee measurements before proceeding to the further OM Goal frequency at 2 K (before CTS)? 352.132 +- 0.042 Assuming cavity sens tolerance 121-176 kHz/mm 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Typical questions (SPK example) Hard limit of tuner range to be enforced? N. Gandolfo email < 1.18 mm (~170 kHz) to limit stress < 400 Mpa Then goal frequency at cold need to be higher (including its estimated spread, which should then be quantified) Minimum value for the CTS action e.g. for piezo preload: 1.43-2.59 kN 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Spoke Test/ Turn on Procedure Discussion - C.Maiano MBL/HBL Example Requirements exists but are not readily usable for checks in OM1 (Ready for cooldown) or OM5 (Stand-By at 2 K). Commissioning team needs full strategy 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano

Spoke Test/ Turn on Procedure Discussion - C.Maiano Summary Requirements and Interface specifications are extremely important for the success of the project, but are not sufficient Technical commissioning of all systems will require the full understanding by the ESS team/SRF section of all design details These are not necessarily captured by requirement / interface specifications “Knowledge transfer” from the IKC to the project team! “Data transfer” to enable assessments and decisions by the project team from the IKC experience 2019-02-22 Spoke Test/ Turn on Procedure Discussion - C.Maiano