1. Accelerator/ Medium Beta Cavities Rocco Paparella on behalf of INFN Milano – LASA ESS Team www.europeanspallationsource.se April 21st, 2016

2. Talk: Overview Planning Medium Beta section – Requirements – INFN IK contribution Technology – INFN EM and mechanical design and analyses Verification strategy – “plug-compatible” strategy – QA/QC plan Organization Major procurements – Niobium – Cavities Top risks Plans for both prototypes and series cavities Summary 2ESS Annual Review - Lund - April 21st 2016

3. Medium Beta Cavities: Planning 3 Preliminary Design Review: 19 May 2016 Critical Design Review: Sep. 2016 ESS Annual Review - Lund - April 21st 2016

4. Medium beta cavities: Technical Performances MB cavity technical requirements Frequency (MHz)704.42 Number of cells6 Geometric beta0.67 Nominal Acc. Gradient (MV/m)16.7 Epeak (MV/m)< 45 RF peak power (kW)1100 Q external7.5 10 5 Q0 at nominal gradient> 5 10 9 Output energy to 570 MeV 36 SuperConducting 6-cells cavity at beta 0.67 9 cryomodules, 4 cavity each Independent RF power source for each resonators ESS Annual Review - Lund - April 21st 20164

5. Medium beta cavities: Technical Performances INFN In-Kind contribution: – Niobium procurement for the fabrication of 36 medium beta cavities. – Cavity fabrication of 36 medium beta cavities in the industry, including treatments, tuning, Helium tank integration, accomplishing the ESS requirements in terms of performances and functional interfaces. – Certification activities, documentation, ancillaries (flanges, vacuum valves, antennas, frames) – Cold test in a qualified infrastructure (DESY). – Transportation in special boxes and delivery at CEA cryomodule assembling facility. – Man power for the above activities. INFN Prototypes plan: – Built prototypes of both medium and high beta cavities. – INFN design, using Large and Fine Grain Nb, plug compatible with ESS cryomodule. – Full treatment (BCP, HPR, clean room) done in industry. – Final handling and test will be done in the qualified infrastructure at LASA. 5ESS Annual Review - Lund - April 21st 2016

6. Medium beta cavities: Selected Technology Optimum beta = 0.705 (peak of red line in TTF curve) 3D modeling with Siemens NX8 2D EM design tools with BuildCavity (interfacing to Superfish) 3D EM and mechanical design with Ansys tools Workbench and HFSS sharing the same 3D cavity model ESS Annual Review - Lund - April 21st 20166 First Natural Mode – Fixed Cavity = 86 Hz Water filled – von-Mises Stress (Mpa)

7. Medium beta cavities: Selected Technologies Baseline: +30% k & mode separation, with modest increase of peak fields (<10%) ESS Annual Review - Lund - April 21st 20167 ParametersINFN LASACEA Geometrical beta, β geom 0.67 Frequency (MHz)704.42 Optimum beta, β opt 0.705 Eacc at β opt (MV/m)16.7 Acc. Length L acc (m)0.855 Q ext @distance axis-Antenna Tip, D=61.26mm Cell to cell coupling, k1.55% ↗ (+30%)1.22% Pi and 5pi/6 mode sep. (MHz)0.70 ↗ (+30%)0.54 HOM-Most dangerous monopole frequency (MHz) 1742.4 G (Ohm)198.8196.6 At β opt =0.705 Transit time factor, T0.706 r/Q (Ohms)374394 E peak /E acc 2.55 ↗ (+7%)2.36 E peak (MV/m) @ Design42.640 B peak /E acc (mT/MV/m)4.95 ↗ (+3%)4.79 Mechanical parameter INFN Design Cavity wall thickness (mm)4.5 Stiffening ring radius (mm)70 Internal volume (l)69 Cavity internal surface (m 2 )1.81 Stiffness (kN/mm)1.69 Tuning sensitivity K T (kHz/mm)-171 Vacuum sensitivity K V for K ext ~ 20 KN/mm (Hz/mbar)30 LFD coefficient K L for K ext ~ 20 KN/mm (Hz/(MV/m) 2 )-2.5

8. Medium beta cavities: Integration and Verification Cavities will be fabricated using INFN design and will be plug compatible with CEA boundary conditions. – Shared acceptance criteria are under definition with ESS/CEA INFN design is relative to the cavity itself. Cavity interfaces, He tank geometry, flanges, tuner connections will be done on the basis of the CEA design. Detailed QA/QC has been set – 4 acceptance levels, 3 at factory and 1 after VT ESS Annual Review - Lund - April 21st 20168

9. Medium beta cavities: Organization at partner lab The activity relative to the Medium Beta Cavities will be covered, according to our proposal, within the estimated man power of 15 FTEs. Current organization: – P. Michelato, ESS responsible for INFN-Milano IK contribution – 8 researcher and 5 technicians ESS Annual Review - Lund - April 21st 20169

10. Medium beta cavities: Budget and cost-book ESS Annual Review - Lund - April 21st 201610 ActivityCost Niobium procurement for 36 cavities3.0 M€ Fabrication/treatments for 36 cavities4.4 M€ Certification, ancillaries, consumable, vertical tests, packaging, transports, etc. 1.6 M€ Manpower and mobility (15 FTE)1.5 M€ Total10.5 Million Euro Cost as from budget book Budget related to 36 cavities, no spares Extra cost per additional cavities 250 k€/each if it follows directly the series production Additional costs for cold tests and material under evaluation (about +1 Meuro)

11. Medium beta cavities : Major Procurements Niobium procurements – Specification under definition Review by experts as requested by TAC Feasibility of sheet scanning at DESY under investigation – Start call for tender by Spring/Summer 2016 – 4 delivery stages during production phase 11ESS Annual Review - Lund - April 21st 2016

12. Medium beta cavities: Major Procurements Cavity procurement – Technical specification under preparation – Cavity based on INFN design – All treatments at the company in order to have them ready for Vertical Test at qualified laboratory Agreement with DESY under definition 2 cavities each VT, insert under design – Start call for tender by Spring/Summer 2016 – First 4 cavities delivered to CEA by Dec. 2017 – Last cavity delivered in Sep. 2018 ESS Annual Review - Lund - April 21st 201612

13. Medium beta cavities: Top risks Availability of qualified companies at the time of the contract placement Modification of the boundary conditions for cavities during fabrication ESS Annual Review - Lund - April 21st 201613

14. Medium beta cavities: Next six months Prototypes – 1 st cavity ready by end of August, with complete treatments done at the company – VT for LG, FG cavities by September Series – Start CFT for Niobium and Cavities by Spring/Summer 2016 – Finalize contract with DESY for VTs ESS Annual Review - Lund - April 21st 201614

15. Medium beta cavities: Summary Prototypes activity well advanced – first cavity expected by end of August 2016 – RF test in September 2016 – Next one ready by mid-September 2016. Cold test for series under finalization with DESY – 2 cavities will be tested in one cooldown – Cold insert design in progress at DESY, taking benefits from LASA insert experience. INFN on the basis of its experience and what has been done so far is ready to start the procurement process for Niobium and Cavities. ESS Annual Review - Lund - April 21st 201615

16. Additional Material ESS Annual Review - Lund - April 21st 201616

17. Recap: one year ago … Status at April 2015: – INFN Milano – LASA activity on medium beta cavities started – First step: LG Medium beta and High beta cavities prototyping and testing – Medium beta series production (36 cavities) start by end 2016 – First 4 series cavities delivered by end 2017 Plan for subsequent months: – Design of medium beta cavities plug compatible with CEA boundary conditions – LG Nb ingot arrival at LASA – LG Nb ingot slicing (wire cutting) – Medium beta prototype ordering – Deep drawing of cells – Activities for the technological transfer of the cavity processing (BCP) to the industry – Vertical test adaptation for 700 MHz cavities 17ESS Annual Review - Lund - April 21st 2016

18. Prototypes: EM analyses Beam pipe cut-off frequencies – TE11 at 1291.5 MHz, TM01 at 1687.0 MHz. Below 2300 MHz, only one monopole HOM within 20 MHz of machine lines, its frequency is 1742.4 MHz. – High margin compared to 5 MHz required 18ESS Annual Review - Lund - April 21st 2016 Machine lines Harmonics Frequencies (MHz) 1352.21Beam 2704.42Acceleration 31056.63 41408.84 51761.051742.4 62113.26 Frequency =1742.4 MHz R/Q = 0.66 Ohm ∆f=0.70 MHz K=1.55%

19. Prototypes: status 2 medium beta prototypes cavities are under construction with the INFN design, fully plug compatible. – All treatments at the vendor Material: – Nb Large Grain: already in house, chemistry on disks done, heat treatment done – Nb FG: in house, now at Zanon. Deep drawing tools: two are ready, the third one in completion. – Deep drawing test on copper done!! – Deep drawing on Nb (LG and FG) this week ESS Annual Review - Lund - April 21st 201619

20. Prototypes: infrastructure Cavities delivery – first prototype by the end of August, – second one begin of September. Upgrade of E. Zanon infrastructure in progress – Cavity handling in the clean room – BCP and acid plant cooling power – UPW system – HPR mechanical and hydraulic – Cleaning and rinsing – Cavity Tuning Machine Cold test at LASA beginning of September – Cold insert at LASA: delivery foreseen in June. Main accessories already in house LHe probes and transfer lines Vacuum components – LASA Clean Room upgrade in progress ESS Annual Review - Lund - April 21st 201620

21. Series: QA/QC Three Acceptance Levels (Al1 – Al2 – Al3) at the producer One Acceptance Level (Al4) for RF cold test in qualified laboratory – If cold test is not OK: cavity will be sent back to the industries for recovery procedure (HPR) and prepared for a new cold RF test ESS Annual Review - Lund - April 21st 201621 LevelCavity status Needed documentsIf Level reached One “Naked” cavity after fabrication Mechanical Fabrication documentsProceed to Level Two Two Cavity after surface treatments Treatment documentsProceed to Level Three Three Cavity integration and last treatment Integration and last treatment documents Integrated cavity ready to be cold tested Four Cavity cold tested successfully Documents relative to cold test results Cavity can be sent to CEA for string assembly

22. Series: Data and cavity flow ESS Annual Review - Lund - April 21st 201622 Cavity production data Managing System Quality Control INFN Industry INFN Managing system Database (parameter analysis) INFN Experts Check Cold RF test Q 0 vs. Eacc CEA STRING ASSEMBLY CAVITY with TANK Documents for cold RF test acceptance Documents for full equipped cavity acceptance (for string assembly) MODULE ESS (approval) NCR