Horizontal Tests in a Vertical Cryostat Shrikant Pattalwar STFC Daresbury Laboratory UK Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Outline Introduction Test Configuration Seek Comments / Suggestion Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

ESS UK contribution €184m Total Construction cost €1.84B Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC STFC ESS Delivery In February 2015 STFC requested 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 ~6m ~1.2m Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Testing rate of ~1 cavity/week 

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Dressed Cavity Total of 84 dressed 704 MHz cavities: Plus 4 possible spares. Operating specification: 20 MV/m @ Qo > 5 x 109 Testing specification: 23.9 MV/m @ Qo > 5 x 109 Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Filename_20150922_ESS_VTF

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Conventional Method Immerse the Object (Cavity) in liquid helium bath (Vertical Cryostat) Pump on the Liquid helium bath with either cold compressor or Vacuum Pump to reduce the bath pressure to 30 mbar ( 2 K) Use 2K heat exchanger + JT valve to maintain liquid helium level Testing XFEL cavities at DESY 3 2 1 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 TTC 2015 Dec 1, 2015 SLAC

Vertical Cryostat for High-b 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 TTC 2015 Dec 1, 2015 SLAC

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) 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 TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Benefits 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 20 g/S 2 g/S 10,000 l 2,000 l Risks / Issues Additional assembly steps Additional leak checks during assembly Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Test configurations/Pros & Cons Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Typical Test Scenario (excluding cavity Assembly) Test can continue for few extra days if required Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Cryogenic Schematic KEEP CLEAR Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC Summary Proposal to conduct tests in horizontal configuration in a vertical cryostat Major benefits are due to substantial reduction in LHe consumption And also due to reduction in mass flow, leading to reduction in size the 2K system Mounting of Cavities on the Insert becomes more complicated but can be managed by introducing additional QC processes. So far we do not see any show stoppers or many issues We welcome any comments / suggestions/ identification of any potential issues Thank You Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC

Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC