1. SRF DEVELOPMENT AT DARESBURY LABORATORY A. Wheelhouse ASTeC, STFC Daresbury Laboratory 2 nd PASI Workshop, RAL 3 rd – 5 th April 2013

2. Outline Mini PIPSS / IPS Programme –Aims & Objectives –Progress & Results SRF Cryomodule Development –Aims & Objectives –Progress Summary 4th April 2013PASI Workshop A Wheelhouse

3. Mini PIPSS & IPS Programme 4th April 2013PASI Workshop A Wheelhouse

4. Aims 4th April 2013PASI Workshop A Wheelhouse The fundamental remit of the Mini PIPSS & IPS, Industry Partnership Schemes is to develop the capability of UK industry in the manufacturing of superconducting RF cavities Mini PIPSS –Fabrication of a single cell niobium cavity (1-year) IPS –Fabrication of a bulk niobium 9-cell accelerating structure (3-year) Cell to cell alignment Tuning robustness and uniformity Tolerance management Cleaning/processing compliance RF surface integrity management Technology directly applicable to future large scale accelerator facilities.  Opportunity for Daresbury Laboratory and Shakespeare Engineering Ltd to develop unique capabilities in the UK  Enable Shakespeare Engineering Ltd to exploit the large SRF commercial opportunity

5. Objectives 4th April 2013PASI Workshop A Wheelhouse Mini PIPSS –Fabrication of a single cell TESLA SRF cavity –Acceleration gradient > 15 MV/m at a Q o better than 1 x 10 10 IPS –Fabrication of a 9-cell TESLA SRF cavity which will be qualified in 2 ways:- –Accelerating gradient > 20 MV/m at a Q o better than 1 x 10 10 after conventional Buffer Chemical Polishing (BCP) is performed –Accelerating gradient > 30 MV/m at a Q o better than 1 x 10 10 when Electro-Polishing (EP) chemical processing is performed  Aim to provide a clear indication of Shakespeare’s capability and assist in qualifying them as a potential supplier

6. Cell and Beampipe Forming Cavity half cells and beampipes fabricated by Shakespeare Engineering Half cells pressed on a 60 t hydraulic press –Pressing performed in 3 operations Beampipes were spun using a CNC spinning machine –Eliminates additional welded seam joint –Spinning of cones performed with intermediate heat-treatments –Beam tube finally formed on a mandrel  3 single cell cavities welded at JLab 4th April 2013PASI Workshop A Wheelhouse

7. PIPSS #01 (JLab) 4th April 2013PASI Workshop A Wheelhouse Multipactor Target Achieved 15.7 MV/m with a Q 0 of 1.15 x 10 10 CW and pulsed conditioning Gradient - 17.6 MV/m with a Q 0 of 2.17 x 10 9

8. PIPSS #01 (JLab) 4th April 2013PASI Workshop A Wheelhouse Additional BCP etch −Approximately 41µm removed

9. PIPSS #01 (JLab) 4th April 2013PASI Workshop A Wheelhouse Vac furnace run at 600ºC for 10 hours Plus an additional BCP etch −Approximately 28µm removed −Further high pressure rinses

10. PIPSS #01 (JLab) 4th April 2013PASI Workshop A Wheelhouse Further high pressure rinses

11. PIPSS #02 (Daresbury) 4th April 2013PASI Workshop A Wheelhouse Acid fume cupboard used to perform the BCP etch Thickness removed measured on a sample piece which doubled as a stirrer Acid temperature monitored  85µm removed in 2 etch runs –Cavity turned up the other way for the 2 nd run HPR performed for 1 hour Cavity sealed in a ISO4 class cleanroom

12. PIPSS #02 Evaluation 4th April 2013PASI Workshop A Wheelhouse VTF manually filled from a 1000lt dewar Reduced performance achieved on second cavity processed at DL  Ineffective temperature control on the BCP etch Improvements to BCP processing is underway –Further testing to be performed

13. PIPSS #03 (FNAL) EB weld good –Some inclusions EB weld inspection Electro-polishing monitoring 4th April 2013PASI Workshop A Wheelhouse Electro-polish - 150µmUltrasonic CleanHigh Pressure Rinse Vacuum Bake - 800ºC 2 hrs, <5x10 -07 mBar Electro-polish - 30µmUltrasonic Clean and Rinse High Pressure RinseVertical Test AssemblyHigh Pressure Rinse Slow evacuation and leak check Vacuum Bake - 120ºC 2 hrs, <5x10 -07 mBar Vertical Test FERMI Lab Standard Preparation

14. PIPSS #03 Tests FermiLab Tests Cavity tested at 2K Maximum accelerating gradient 25 MV/m with Q 0 =1.5x10 10 Gradient limited by a quench –First quench at 18 MV/m –Quenched twice at 21 MV/m –Finally quenched at 25 MV/m –Limited by repetitive quenches at 25 MV/m which showed no sign of conditioning after 20 mins No field emission above background was observed Some multipacting was noted at around 18 MV/m –Instabilities in P transmitted signal were observed –Common ILC-shape multipacting range –Multipacting processed Successfully met target 4th April 2013PASI Workshop A Wheelhouse

15. PIPSS #03 Tests 4th April 2013PASI Workshop A Wheelhouse Target

16. PIPSS #03 - Further Qualification 4th April 2013PASI Workshop A Wheelhouse CBP Further processing performed Cavity has been CBP –Removing ~180µm Light 30µm electro-polish to remove a weld inclusion Vacuum bake at 800ºC Cavity to be tested 5/4/13 Typical before and after CBP

17. IPS Programme 3-year programme on-going Cavity drawings complete Tooling has been manufactured Pressing trials being completed with Copper –Assessing repeatability and reproducibility  Niobium half cells to be pressed soon Further beampipe spinning trials –Thicker sheets SRF infrastructure development –Automated BCP process –Automated HPR It is hoped that FNAL can continue to assist in qualifying Shakespeare with this structure. 9-cell cavity drawings BCP facilityHPR stand 4th April 2013PASI Workshop A Wheelhouse

18. ALICE SRF Cryomodule Development 4th April 2013PASI Workshop A Wheelhouse

19. Aims & Objectives To lead the design of a new, high current and world leading cryomodule. To educate and demonstrate effective: –Processing, –Handling, –Assembly, –Testing, –QA processes. To integrate the new cryomodule onto ALICE Commission cryomodule + cryogenics systems To validate cryomodule performance with beam 4th April 2013PASI Workshop A Wheelhouse

20. SRF Cryomodule Existing Cryomodule on ALICE ERL (New) Cryomodule International collaboration initiated in early 2006: –ASTeC (STFC) –Cornell University –DESY –FZD-Rossendorf –LBNL –Stanford University –TRIUMF (2009) Fabricate new cryomodule and validate with beam. Dimensioned to fit on ALICE: –Same CM footprint –Same cryo/RF interconnects –‘Plug Compatible’ 4th April 2013PASI Workshop A Wheelhouse

21. SRF Cryomodule Existing Cryomodule on ALICE ERL (New) Cryomodule 4th April 2013PASI Workshop A Wheelhouse ParameterALICETarget Frequency (GHz)1.3 Number of cavities22 Number of Cells per Cavity97 Cavity Length (m)1.0380.807 Cryomodule Length (m)3.6 R/Q (Ω)1036762 E acc (MV/m)12 - 15>20 CM Energy Gain (MeV)27>32 QoQo <5 x10 9 >1x10 10 Q ext 4 x 10 6 4x10 6 - 10 8 Max Cavity Fwd Power (kW)10 SW20 SW

22. Coupler Conditioning High power conditioning of the CPI input couplers: –Up to 30 kW (pulsed) –Up to 10 kW (CW) For these tests, couplers water/air cooled only No vacuum activity seen Pulsed Conditioning 4th April 2013PASI Workshop A Wheelhouse

23. Coupler Conditioning High power conditioning of the CPI input couplers: –Up to 30 kW (pulsed) –Up to 10 kW (CW) For these tests, couplers water/air cooled only No vacuum activity seen CW Conditioning 4th April 2013PASI Workshop A Wheelhouse

24. Cryomodule Assembly 4th April 2013PASI Workshop A Wheelhouse HOM assembly µ metal installation Cavity string Cavity wiring

25. Cold Tests (Off-line) Check the cryogenic performance Understand the processes and establish commissioning and operating procedures Validate instrumentation Cavity frequency verification Issue with tuner sticking had to be resolved Identify and resolve any unknown issues 80K tests successfully completed Attempted to cool-down to 4K however: Large temperature gradient between the two cavities Helium reservoirs did not fill completely Result of blockage between cavity bottom fill connection and excessive heat load at the input transfer line 4th April 2013PASI Workshop A Wheelhouse ParametersMeasuredSpecification Static Heat Load at 80K~ 7 W20W Static heat losses for the cavities at 80K ~ 3.5 W15 W at 4K Delta T across thermal shield at equilibrium < 5K<10K Delta T across the two cavities during cool-down < 5K Currently 50- 60K for ALICE

26. Cryomodule Evaluation Cryomodule installed and cooled to 2K Optimisation presently being performed on the cryogenic system Evaluation Programme:- Establish gradient and Q 0 Measure Lorentz force detuning at high gradient Performance measurements with piezo tuners Determine DLLRF control limitations wrt Q ext Evaluate the effect of beam loading with DLLRF, piezo control for various Q ext levels under pulsed and CW conditions Characterise cavities in CW mode at high gradient: –Evaluate thermal transients across cavity string and 2-phase line Synergies with PXIE operational requirements to be evaluated Cryomodule installed on ALICE 4th April 2013PASI Workshop A Wheelhouse

27. Summary  Verified the fabrication of a single cell SRF cavity  9-cell SRF cavity and infrastructure development progressing  UK SRF capability in a stronger position thanks to FNAL collaboration  Cavity string integrated into the cryomodule  Cryogenically commissioned cryomodule off-line  Cryomodule now installed in ALICE  Cryomodule characterisation about to commence 4th April 2013PASI Workshop A Wheelhouse