1. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 1 Horizontal Tests in a Vertical Cryostat Shrikant Pattalwar STFC Daresbury Laboratory UK

2. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 2 Outline Introduction Alternative Approach to Conduct RF Tests Plans and Status

3. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 3 Introduction Evaluating RF performance of a SRF cavity is the first critical step towards building a Superconducting Accelerator. Once the R&D and proto-typing phase is complete the focus is on the through-put, particularly when 100s of cavities must be qualified in a short period of time to match the construction schedule. Such tests require large and expensive infrastructure.

4. CRYOGENICS OF EUROPEAN XFEL ACCELERATOR MODULE TEST FACILITY Bozhko Y., Petersen B., Schnautz T., Sellmann D., Wang X.L, Zhirnov A., Zolotov A., DESY Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 4 Conventional Method 1Immerse the Object (Cavity) in liquid helium bath (Vertical Cryostat) 2Pump on the Liquid helium bath with either cold compressor or Vacuum Pump to reduce the bath pressure to 30 mbar ( 2 K) 3Use 2K heat exchanger + JT valve to maintain liquid helium level Testing XFEL cavities at DESY 3 2 1 ~ 10 cavities / week

5. UK contribution €184m Total Construction cost €1.84B Challenges for ESS Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 5

6. Dressed Cavity Total of 84 dressed 704 MHz cavities: Plus 4 possible spares. Operating specification: 20 MV/m @ Q o > 5 x 10 9 Testing specification: 23.9 MV/m @ Q o > 5 x 10 9 Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 6

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8. Vertical Cryostat for High-  Cavities Requirements work out be: Usable LHe vessel diameter ~1.5 m (Diameter of a 704 MHz cavity ~ 0.5 m) Cryostat becomes sufficiently large to test cavities horizontally LHe bath volume ~3500 l LHe required per test ~7500 l Gas handling capacity ~20 g/S (2K Hex, 2K pump, distribution Pipes, Valves, safety devices, etc. ) Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 8

9. Alternative Approach: Horizontal Tests in a Vertical Cryostat Test 3 cavities simultaneously. Each cavity already has its own helium vessel: Necessary and sufficient condition is to cool the cavity to 2K Can be easily achieved by filling liquid helium in its own vessel (with a volume of ~ only 50 l each) Cryogenic Requirements: LHe per test reduces from: ~7500 l to ~< 1500 l (factor of 5!) Gas handling capacity reduces from: ~20 g/S to < 2 g/S (factor of 10!) Significantly simplified and lower cost ancillaries (2K Hex, 2K pump, distribution Pipes, Valves, safety devices, etc. ) Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 9

10. 10 Horizontal tests – Performance in near final configuration Automatic leak checks on helium vessel (Not possible in bath cryostat) More confidence in performance More than 75% saving on LHe Reduced test duration (quick cool- down/ warm up) Lower Operational Hazards (due to lower gas flow/less quantity of LHe) 75 % Saving on LHe and Gas Storage Risks / Issues Additional assembly steps Additional leak checks during assembly 20 g/S 2 g/S 10,000 l 2,000 l Benefits

11. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 11 Test configurations/Pros & Cons

12. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 12 KEEP CLEAR Cryogenic Schematic

13. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 13 Summary We plan to conduct tests in horizontal configuration in a vertical cryostat with about 75% saving on the use of liquid helium. This also lead to substantial reduction in infrastructure costs - reduced mass flow, smaller 2K system and Lhe/Ghe storage Mounting of Cavities on the Insert becomes more complicated but can be managed by introducing additional QC processes. Plans Many thanks ESS/ CEA/IPNO, DESY and Cryogenics group at CERN (Olivier Pirrote).

14. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 14 STFC-Rutherford Appleton Laboratory STFC – Astronomy Technology Centre WECOME to STFC - Daresbury Laboratory Oxford

15. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 15

16. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 16

17. STFC ESS Delivery ~1.2m ~6m In February 2015 STFC agreed to procure and test all high-β SRF elliptical cavities: Nb procurement Dressed cavity fabrication with industry Vertical tests Shipment to CEA Saclay for CM integration Testing rate of ~1 cavity/week  Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 17

18. Shrikant_Pattalwar ICEC 26, March 7-11, 2016, Delhi 18 Typical Test Scenario (excluding cavity Assembly) Test can continue for few extra days if required