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

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

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

4. 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 Dec 1, SLAC
Testing rate of ~1 cavity/week 

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

6. Filename_ _ESS_VTF

7. 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 Dec 1, SLAC

8. 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 Dec 1, SLAC

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)
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 Dec 1, SLAC

10. 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 Dec 1, SLAC

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

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

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

14. 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 Dec 1, SLAC

15. Shrikant_Pattalwar TTC 2015 Dec 1, 2015 SLAC