1. Jim Clarke STFC Daresbury Laboratory and The Cockcroft Institute on behalf of the CLARA Project Team X-band FEL Face to Face Meeting, 29 th July 2015 CLARA: A new particle accelerator test facility for the UK

2. Free Electron Lasers FELs have made huge advances in the past few years –First X-ray FEL in 2009 (LCLS) then SACLA in 2011 –More X-ray facilities are under construction –Advanced soft X-ray facilities are also now operating routinely for users as well (FLASH & FERMI) The potential for improvements is enormous –Increased wavelength and intensity stability –Tighter synchronisation between FEL & external lasers –Ultra-short pulses of light (sub-fs) –Increased temporal coherence (monochromaticity) –Increased power –Two-colour or Multi-colour output (“Tailored Pulses”) –…–…

3. CLARA CLARA will be a purpose built dedicated flexible FEL Test Facility –Capable of testing the most promising new schemes We have strategically decided to focus on stability, synchronisation, and ultra short pulse generation –We are focussing on the longer term capabilities of FELs, not short term incremental improvements –Taking FELs into a new regime –By demonstrating these goals we will have to tackle all the challenges currently faced by state of the art FELs so we will be very well placed to meet the needs of the UK users when we design and build a national X-ray FEL

4. CLARA C ompact L inear A ccelerator for R esearch and A pplications An upgrade of the existing VELA Photoinjector Facility at Daresbury Laboratory to a 250MeV Free-Electron Laser Test Facility Proof-of-principle demonstrations of novel FEL concepts and development of future accelerator technologies Emphasis on Stability, Synchronisation and Ultra-short Pulse Generation Strathclyde INFN Frascati SwissFEL CERN INR Moscow DLS Oxford Liverpool Lancaster Imperial

5. Other Goals and Benefits of CLARA The opportunity for R&D on advanced technologies: –New photoinjector technologies –Novel undulators (short period, cryogenic, superconducting….) –New accelerating structures: X-Band etc... –Advanced diagnostics The enhancement of VELA beam power and repetition rate, enabling additional industrial applications. The possibility to use the electron beam for other scientific research applications: PLASMA ACCELERATOR RESEARCH ASTeC Strathclyde Manchester INFN Frascati ULTRAFAST ELECTRON DIFFRACTION ASTeC York Swansea UCL Manchester NOVEL ACCELERATION (DWA, DLA, THZ, …) ASTeC RHUL Liverpool Lancaster Manchester Oxford NOVEL PHOTON SOURCES (CDR, SMITH-PURCELL, …) ASTeC RHUL Oxford ASTeC CERN FERMI@Elettra RHUL INFN Frascati SwissFEL DLS Lancaster INR Moscow

6. FEL Layout Revised 25m Better optimised for mode locking and HB-SASE Radiator undulators reduced to 0.75m, spacing reduced to 0.5m Two modulators instead of one Total length the same 7 x 1.5m RADIATORS, 27mm PERIOD, ON-AXIS FIELD HORIZONTAL 1.1m GAPS, with QUAD, BPM, SCREEN + DELAY CHICANE Old layout New layout Radiator undulators

7. What will CLARA be able to do? Example: Reducing the spread of wavelengths Prove that a new idea called HB-SASE actually works –Would then build it in from the start of the UK FEL Will work at any wavelength and any repetition rate, no fancy optics required! NORMAL FEL

8. What will CLARA be able to do? Example: Generate few cycle pulses Prove that a new idea called Mode-locked afterburner actually works –Would then build it in from the start of the UK FEL –Able to probe ever faster processes (sub-attosecond)

9. CLARA Layout The existing VELA RF Photoinjector Facility ELECTRONS GENERATED HERE ELECTRONS ACCELERATED AND MANIPULATED INTERACTIONS WITH LASER BEAMS FEL OUTPUT GENERATED FEL OUTPUT STUDIED PLASMA TEST LINE Notes: 1. CLARA uses European RF frequencies 2. X-band cavity is used for phase space linearisation 3. Total length ~90m

10. CLARA Layout Linac 1 is 2m long, S-band on order from Research Instruments Linacs 2 to 4 are 4m long S-band devices previously installed on SwissFEL Injector Test Facility – now at Daresbury We would like to replace Linac 4 with X-band linac as test bed for CLIC technology

11. SwissFEL Equipment being transported to Daresbury

12. CLARA Accelerator Schematic S EU gun, S EU linac, X EU linearizing cavity Space reserved for laser heater Dedicated diagnostics sections Extraction to VELA at <50 MeV Extraction at full energy for other uses, eg Plasma Acceleration

13. Tracked Bunch - Entrance of FEL Optimised for 250 fs flat region to suppress effect of seed to bunch jitter All S-band simulation (230 MeV)

14. Tracked Bunch - Entrance of FEL Final linac replaced by 4m X-band linac No special optimisation, simple replacement in model (230 MeV)

15. Tracked Bunch - Entrance of FEL Final linac replaced by 4m X-band linac No special optimisation, simple replacement in model but now 65 MV/m (427 MeV)

16. High Repetition Rate Gun for CLARA 400Hz gun (ASTeC, Lancaster, INR Moscow) 1.5-cell gun to operate at fields of up to 120 MV/m with a 100 Hz repetition rate or 100 MV/m at up to 400 Hz repetition rate. Peak power of up to 10 MW and an average power of 10 kW. Max beam energy ~5 MeV Photocathode exchange system to accept cathode plugs of the INFN/DESY type An RF probe is included for active monitoring and feedback Symmetric H-shaped coupler for precise control of the phase of the incoming RF along both feeds. Gun cavity is being manufactured now

17. CLARA Status The Conceptual Design was published in July 2013 SwissFEL have provided the required 3 linacs, together with a number of quadrupoles and solenoids The project has now been split into Two Phases PHASE 1 – Front End, 50 MeV –This is happening now, with procurement progressing, and installation in 2015. First electrons April 2016. –Will enable access to bright, short, up to ~50 MeV electron bunches for UK accelerator science and technology community –Will enable new 400 Hz photoinjector to be characterised with beam whilst VELA/CLARA Phase 1 still operational (i.e. two guns) –Potential for early exploitation of 20 TW laser PHASE 2a – 150 MeV, up to bunch compression section –Funded, procurement started PHASE 2b – 250 MeV FEL Test Facility –Not Yet Funded – CLARA is a stated priority of STFC and additional funds are being requested from UK government JINST 9 (2014) T05001

18. VELA Notes: 1. VELA gun is from Strathclyde (ALPHA-X) 2. Max rep rate is 10 Hz but laser and RF capable of 400 Hz 3. 400 Hz gun being manufactured now

19. VELA Transverse Deflecting Cavity S-band Transverse Deflecting Cavity installed and operational Will enable much more detailed diagnosis of bunches (slice properties, bunch length with fs resolution)

20. VELA – TDC Commissioning First beam streaking – 5 th Dec ’14 TDC-off Amp10 Amp30 Amp40 A transverse kick of around 5 MV is required to achieve 10 fs resolution hence a 9-cell design has been chosen.

21. VELA + CLARA Phase 1 (2015) ~5 MeV ~50MeV

22. VELA + CLARA Phase 1 (2015) Phase 1 parameters: Max Energy~50 MeV Max Charge250 pC Norm. Emittance<1 mm mrad Min Bunch Length 50fs (rms), (10 MeV) Max Peak Current2kA Bunches/RF pulse1 Pulse Rep Rate10 Hz (400Hz later) ~5 MeV ~50 MeV ~5 MeV

23. The first footprints of CLARA…

24. Electron Hall

25. CLARA in the Electron Hall

26. The Electron Hall The biggest building on site (34m x 110m) –Big enough for CLARA (which is about 10m x 90m) But the Electron Hall is not fit for purpose –Since we want to build a very stable FEL, we need the temperature of the facility to also be very stable –Constant temperature to within 0.1 °C all year round (within the concrete bunker) –Currently the temperature within the building varies by at least 15 °C over the year

27. The Electron Hall Must be completely refurbished –Keep the same steel substructure –New walls and roof will provide much better insulation and so temperature stability will be much better –There will also be a new heating, cooling, and ventilation system STFC has approved this project and we are in the procurement phase now –Should be complete within ~18 months

28. How much is funded so far? FUNDED The Electron Hall refurbishment is also funded NOT FUNDED

29. Summary X-Ray FELs are a step change for light source users –Enabling experiments that were previously impossible –They are now the premier X-ray source –They can still be improved significantly CLARA will be an FEL Test Facility for the UK –Aiming to improve FEL performance with new untested operating modes –Emphasis on stability, synchronisation, and ultra short pulse generation –Developing our skills and technologies for a future UK X-ray FEL CLARA Phase 1 will start installation in 2015 –Phase 2 partly funded –Electron Hall refurbishment will start this year The introduction of X-band accelerating technology into CLARA appears to be straightforward and this is still our intention. If further linacs are replaced the beam energy could approach 1GeV in the future which might be interesting for exploitation of the FEL light. CLARA will be a unique facility for the UK Accelerator Community and is an essential stepping stone towards a UK FEL

30. Thanks to everyone who is contributing to the CLARA project