The CompactLight Project (XLS) Gerardo D’Auria (Elettra-ST)

1. Funded by the European Union The CompactLight Project (XLS) Gerardo D’Auria (Elettra-ST) on behalf of the CompactLight Collaboration International Workshop on Breakdown Science and High Gradient Technology, HG2017Shanghai, 4 - 8 June 2018

2. Outline • Context • The CompactLight Project • The XLS Collaboration • Aims & Motivations • X-ray FELs • FEL Facilities • User’s demands and FEL requirements • XLS expected performance • Ongoing activities • Timeline, Milestones and Deliverables

3. The CompactLight Project (XLS) H2020 Design Studies (2018-2020) • http://compactlight.eu

4. List of Participants Italy 5 Neth. 3+1 UK 3 Spain 2 Australia 2 China 1 Greece 1+2 Sweden 1 Turkey 1 France 1 Germany 1 Switz. 1 Finland 1 Norway 0+1 Internat. 1

5. The XLS Collaboration

6. New generation Light Sources “The possibility of producing low charge (pC range), ultra-short (sub-micrometer), electron bunches with small emittance and high brightness, opens new possibilities to design and build compact, lower cost FELs, to produce high intensity, femtosecond long, coherent X-ray pulses in a wide wavelength range”. C. Pellegrini, “Cheaper, smaller, better” • With CompactLight we plan to design an Hard X-ray Facility using the very latest concepts for: • High brightness electron photoinjectors. • Very high gradient accelerating structures. • Novel short period undulators. • At a fixed wavelenght, the New Facility, compared with the Current Facilities, will benefit from: • A lower electron beam energy, due to the enhanced undulator performance. • Will be significantly more compact due to lower energy and high gradient structures. • Will have a much lower electrical power demand than current facilities. • Will have much lower construction and running costs.

7. XLS FEL Facilities Operational Facilities Under construction E.A. Seddon et al. 2017 Rep. Prog. Phys. 80 115901

8. Users requests 1. 10s-fs pulses 2. Peak brightness 3. Multi pulse (laser-FEL) 4. Transverse coherence 5. Pulse energy 6. Wavelenght tunability 7. Longitudinal coherence 8. High repetition rate 9. Multi pulses (FEL-FEL) 10. Variable polarization 11. Few-fs pulses 12. Sub-fs pulses Photon Science E.A. Seddon et al. 2017 Rep. Prog. Phys. 80 115901

9. XLS WPs WPs Relationship WP2 – FEL Science requirements and Facility Design WPs list Using SwissFEL as an example https://www.psi.ch/swissfel/ J. Clarke

10. WP2: FEL science requirements and facility design Lead Institute: STFC- Daresbury(J. Clarke) • Description of work: • Starting from the performance specification of the FEL, based on user-driven scientific requirements, the aim of WP2 is to identify and chose the most appropriate technical solutions for the FEL considering cost, technical risk and performance. • Deliverables: • A report summarising the requests from the users and defining the final performance specifications for the FEL (31/12/18). • A report summarising the FEL design, with the accelerator and undulator requirements to achieve the specification, i.e. electron energy, bunch charge, peak current, emittance, energy spread, undulator parameters, etc. (31/12/19). • The conceptual design report for a fully fledged Hard X-ray FEL facility, including cost estimates, with options for Soft X-ray FEL and Compton Source, (31/12/20).

11. XLS Performance XLS Preliminary Parameters and Layout

12. Hard X-ray User Facilities Comparison J. Clarke

13. 250 eV  to cover the carbon K edge. • 25 keV  requested by group studying extreme materials. • Pulse duration 50 fs not a definite requirement, “just a typical number”. • Pulse duration  100 as isolated pulses have definite science need identified (atomic and molecular physics), case for shorter pulses than 100 as to be determined. • Pulse energy  1mJ at 25 keV highly desired by extreme materials, higher welcome but to verify if feasible. • Repetition rate  100 Hz at 25 keV (high power lasers are combined in experiment and they only have low repetiton rate). • Repetition rate  500-1000 Hz or greater highly desirable for the soft X-ray, 250 eV to 2 keV. • Two colour output is required. • Two pulse output required with time separation of pulses set by the FEL between -20 fs and +40 fs. Larger time separations will be achieved within the beamline (split and delay). • Polarization variable, selectable below 2 keV. • Polarization  above 2 keV to be determined. Photon energies Pulse durations Pulse energy Pulse rep. rate Two colours exp. Polarization CompactLight Proposal Notes J. Clarke

14. Task 3.1–Gun design(RF, Solenoid, Cathode, Laser, Diagnostics) => D3.1 M18 => D3.3 M36 • S-Band Gun RF Design (CNRS + IASA+UAIAT-INFN+ALBA) • C-Band Gun RF Design (INFN +IASA+Sapienza) • X-Band Gun RF Design (CSIC-IFIC + UAIAT+ Sapienza) • DC Gun Design (TU/e) • Laser/Photocathode (IASA+CNRS+INFN) Task 3.2 –Compressor Design (Velocity Bunching, Magnetic Chicane) => D3.2 M18 => D3.3 M36 • S-Band Velocity Bunching(TU/e + IASA+ALBA) • C-Band Velocity Bunching (INFN +IASA+TU/e ) • X-Band Velocity Bunching(Sapienza+CERN+IASA+INFN) • Magnetic Compressor (ST + CERN+INFN+CNRS) Task 3.3 – X-Band Diagnostics (Transverse RF Deflector) => D3.3 M36 • Transverse RF Deflector (Sapienza + IASA) Task 3.4 – Linearizer Design (RF and passive linearizers) => D3.2 M18 => D3.3 M36 • X-Band RF Linearizer(Sapienza) • K-Band RF Linearizer (ULANC + Sapienza ) • Passive linearizers (CNRS) WP3: Gun and Injector Lead Institute: INFN-LNF (M. Ferrario)

15. Main Tasks: Review State of the art Gun / Injector (S, C, X-band) and pick the best for XLS Develop of novel high-repetition rate gun / injector (with K-band linearizer) Prototyping and test (if possible) Injector Gun Ultra-low emittance electron source, TU/e 400Hz S-band rf gun in CLARA LCLS S-band rf gun

16. Ankara’s full X-band hard X-ray FEL design study Based on SLAC X-band rf photoinjector[R. A. Marsh et al., Phys. Rev. ST Accel. Beams 15, 102001 (2012)] Preliminary design: 5.6 cell photo-cathode rf gun operating at 12 GHz, with 200 MV peak accelerating voltage, followed by 6 CLIC-like X-band accelerating structures, 70 MV/m gradient The rf gun and solenoid magnets have been designed using 2D Poisson/Superfish code. Beam dynamics studies have been performed using ASTRA Full X-band Gun (preliminary) • Bunch charge of 250 pC • The cathode is excited by a: • flat top laser • 3ps FWHM • rise/fall time of 0.3 ps • σz ≈ 200 μm • σx,y = 2 mm spot size Superfish + ASTRA simulation A. Aksoy

17. WP4: RF systems Lead Institute: CERN (W. Wuensch) Objective: define the RF system for the XLS linac design. • Description of work: • Define a standardized RF unit which can be used in all main and sub-design variants. Making a standardized design available can simplify the preparation of future construction projects, stimulate the industrialization process and cost savings by future facilities. Deliverables: • A parametrized performance and cost model of the RF unit to be used by WP2 for the facility optimization. The model will be established in computer code and described in a report, (30/06/19). • A design report of the optimized RF unit. Based on the parameters emerging from the facility optimization, the design of the RF unit will be established at the component level and described in a report, (31/12/20). • A report on the design and fabrication procedure, optimized for series industrial production, of the accelerating structure which is an important cost driver for the facility, (31/12/20).

18. Beyond the state-of-the-art Examples of Linac gradientsfor most recent X-ray FELs Preliminary parameters of the X-band RF unit, compared with the C-band SwissFELtechnology. Preliminary parameters of an optimized RF structure (X-band)

19. Ongoing design for the EuPRAXIA project Preliminary data for the 1 GeV linac of the EuPRAXIA@SPARC_LAB project INFN-LNF A. Gallo

20. WP5 - Undulators and Light Production WP5 Leader: ENEA Frascati (G. Dattoli - F. Nguyen) Deliverables Tasks Task 5.1 -Review the technology trends for undulatorsR&D worldwide, and compare the potential for innovation and performance. In particular: superconducting undulators enabling field amplitude adjustment along the undulator, enhanced-bandwidth FEL radiation or super-radiant light sourcesat short wavelengths. Task 5.2 - Select a few outstanding options to be considered for CompactLight. Task 5.3 - For the options selected in T5.2, perform asystematic optimization of the electron beam parameters at the linac-to-undulatorinterface to maximise the photon production, in close contact with WP2 and WP6. Task 5.4 - Report the conceptual design of the selected options as resulting from T5.3.

21. WP5 Ongoing Activities • Different undulator solutions subject to the following investigations • Shortest possible wavelength for a given beam energy. • Highest possible FEL performance (shortest gain length, highest saturation power) for a given target wavelength. • Highest possible undulator performance (shortest longitudinal space per undulator module, shortest undulator gap width) for a given focusing scheme. Task Leaders

22. X-Band Acc 12 GHz, No. Cell? G MV/m BC1Chicane X-Band Acc 12 GHz, No. Cell? G MV/m S-Band gun 3 GHz, 1.6? Cell 100 MV? S-Band Acc 3 GHz, No. Cell? 15 MV/m X-Band Lnz 12 GHz, No. cell? G MV/m BC2 Chicane Undulator lu ,K, No Section? 1 X-Band Acc 12 GHz, No. Cell G MV/m Undulator lu ,K, No Section? C-Band gun 6 GHz, 3.6? Cell 200 MV? S-Band Acc 3 GHz, No. Cell? 15 MV/m BC2 Chicane X-Band Acc 12 GHz, No. Cell? G MV/m BC1Chicane X-Band Lnz 12 GHz, No. cell? G MV/m 2 X-Band Acc 12 GHz, No. Cell? G MV/m Undulator lu ,K, No. Section? X-Band Acc 12 GHz No. Cell? G MV/m BC2 Chicane BC1Chicane X-Band Lnz 12 GHz, No. Cell? G MV/m? S-Band VB 3 GHz, No. Cell? G MV/m S-Band Acc 3 GHz, No. Cell? G MV/m S-Band gun 3 GHz, 1.6? Cell 100 MV? 3 X-Band Acc 12 GHz, No. Cell? G MV/m Undulator lu ,K, No. Section? X-Band gun 12 GHz, 5.6? Cell 300 MV? BC2 Chicane X-Band Acc 12 GHz, No. Cell? G MV/m X-Band Acc 12 GHz, No. Cell? G MV/m BC1 Dogleg 4 BC2 Chicane X-Band Acc 12 GHz, No. Cell? G MV/m Undulator lu ,K, No Section? X-Band gun 12 GHz, 5.6? Cell 300 MV? X-Band Acc 12 GHz, No Cell? G MV/m K-Band lnz 36 GHz, No. Cell? G MV/m X-Band Lnz 12 GHz, No. cell? G MV/m BC1Chicane 5 WP6: Beam dynamics and start to end modelling WP6 Leader UA-IAT (A. Aksoy) FEL performance studies, S2E simulations and Key parametersrs of the overall Facility

23. Linac layout • Injector & low energy section: • Up to 100-150 MeV energy shall be optimized according to requirements. • Thebeam dynamics shall be studied up to the first bunch compressor. • Optimization target parameters: • Charge  250 pC • Projected emittance < 0.5 mm.mrad • Sliced emittance < 0.4 mm.mrad • Charge profile as uniform as possible • Bunch length  may vary according to bunch compressors • .... High energy section: Simulations shall be performed together with bunch compressors and linearizers. Space Charge, Wakefield, CSR, static&dynamics imperfections will be taken into account. Optimization target parameters: • For longitudinal parameters: • high peak current 4kA; • stable beam phase; • stable peak current < 5%; • stable beam energy < Dl/l0; • small sliced energy spread < 0.05%; • uniform charge profile; • … • For transverse parameters: • small emittance growth < 10%; • small transverse jitter amplification < 1.2; • easy correctable lattice; • acceptance of large energy errors • …

24. M D Annual Meeting Midterm Proj. Rew. Kick-off Meeting Public WEB site Users Req. Time plan, Milestones and Deliverables 01-01-2018 31-12-2020

25. Coming event 1st Mid-Term Project Review Meeting, Hotel NH Trieste, June 19-20, 2018. Thanks for your attention!