ARES Linac: Research & Development on High Brightness Electron Bunches

1. SINBAD-ARES - A Photo-Injector for external Injection Experiments in novel Accelerators at DESY Accelerator Research Experiment at Sinbad Barbara Marchetti, Ralph Assmann, Ulrich Dorda, Florian Burkart, Eva Panofski, Paul Andreas Walker, Francois Lemery, Daniel Marx, Frank Mayet, Max Kellermeier, Sumera Yamin, Sonja Jaster-Merz, Willi Kuropka, Farzad Jafarinia, Klaus Floettmann, Reinhard Brinkmann, Wolfgang Hillert Please see also Acknowledgments at the end of the presentation.

2. Outline Introduction: The SINBAD Facility and the ARES linac Overview of the SINBAD/ARES layout and example of working points (simulations) Status of the installations, conditioning and commissioning High Energy Diagnostics Beamline Conclusion | ARES Linac | Barbara Marchetti, EAAC 2019

3. Outline Introduction: The SINBAD Facility and the ARES linac Overview of the SINBAD/ARES layout and example of working points (simulations) Status of the installations, conditioning and commissioning High Energy Diagnostics Beamline Conclusion | ARES Linac | Barbara Marchetti, EAAC 2019

4. SINB AD is a new Facility at DESY-Hamburg Itfocuses on Research and Development on ultra-fast Science and high gradientAccelerators Short INnnovative Bunches and Accelerators at Desy | ARES Linac | Barbara Marchetti, EAAC 2019

5. ARES isoneofthe Experiments located at SINBAD Itis a conventional RF Photo-InjectorfortheProductionof high BrightnessfselectronBunches withEnergy > 100MeV ARES Linac at SINBAD | ARES Linac | Barbara Marchetti, EAAC 2019

6. Thereis a strong Connection between ultra-shortBunches andnovelAccelerators Why do we build a “conventional” Photo-Injector for SINBAD? Conventional S-band RF technology allows to produce stable and reproducible electron bunches. R&D on producing high brightnesse-buncheswith bunch length at fs/sub-fs and excellent arrival time stability: important research in its own right, enables understanding ultimate limitations in photo injectors. Characterization of ultra-short (~fs), low charge (~pC to sub-pC) bunches is technically challenging  R&D on novel diagnostics devices and fs-level synchronization. Short bunches fit into very compact (novel) accelerators with short accelerating field wavelength. They constitute excellent probes to measure energy gain and the quality of the acceleration. The chosen electron bunch energy (100-230MeV) helps with damping the space charge effect and velocity dispersion in beam transport, thus allowing reaching high brightness and >1kA local peak current; | ARES Linac | Barbara Marchetti, EAAC 2019

7. Outline Introduction: The SINBAD Facility and the ARES linac Overview of the SINBAD/ARES layout and example of working points (simulations) Status of the installations, conditioning and commissioning High Energy Diagnostics Beamline Conclusion | ARES Linac | Barbara Marchetti, EAAC 2019

8. Conceptual Layout of the Accelerator (including ATHENAe) Photo-injector parameters: 2.998 GHz normal conducting linac 10-50 Hz rep. rate, single bunch mode Energy: 100 MeV (compressed beam), on crest before energy upgrade: 155MeV, on crest after energy upgrade: 230MeV Typical final bunch charge : 0.5-30 pC Typical final bunch length : sub-fs to few fs Arrival time jitter < 10fs RMS After the commissioning of the linac will be moved at the exit of the experimental area Dogleg to second experimental area Photo-Injector RF cavity for Energy Upgrade Matching Beamline PolariX TDS & diagnostics Beamline Linac Magnetic compressor z[m] 2.5 0 ~12.2 ~17.7 ~31 ~39 • At themomentonlythelinacandmatchingsectionhavebeeninstalled. • Sequentsections will beinstalled in stages. • Two Experimental Areas: EA1, EA2 | ARES Linac | Barbara Marchetti, EAAC 2019

9. Conceptual Layout of the Accelerator (including ATHENAe) After the commissioning of the linac will be moved at the exit of the experimental area Dogleg to second experimental area Photo-Injector Matching Beamline PolariX TDS & diagnostics Beamline Linac Magnetic compressor z[m] 2.5 0 ~12.2 ~17.7 ~31 ~39 Experimental Area 1 (EA1) Temporaryinstalledhere in 2019 Experimental Area 1 (EA1) Will latermove after thedogleg | ARES Linac | Barbara Marchetti, EAAC 2019

10. Experimental Area 1 (EA1) • EA1 isplannedtobeinstalled at theARES LINAC by 2019; • Will movetotheDogleg in 2021; • Open for transnational access (ARIES); • Possibleusers: ACHIP, Beam Diagnostics, DielectricStructures, medicalimaging. | ARES Linac | Barbara Marchetti, EAAC 2019

11. The Technical Design of the temporary Experimental Area is completed, the components are ready Vertical Steerer Vertical Steerer XFEL Phase Shifter (Permanent Magnetic Chicane) Conceptual Design by: Florian Burkart Frank Mayet Francois Lemery Willi Kuropka Sonja Jaster-Merz (stripedetectorcollaboration) Ulrich Dorda Laser-to-Electron Overlap Diagnostic Chamber …to Matching Region and Spectrometer… …to Matching Region and Spectrometer… Horizontal Steerer Horizontal Steerer ACHIP@ARES Undulator ARES Screen Station (10µm res) ARES Screen Station (10µm res) Laser Coupling Chamber Horizontal Steerer Horizontal Steerer Experimental Chamber SmarPod 6D Positioning Beam Profile Measurement (~µm res) DLA Interaction Point Microbunching Diagnostic (CTR) Experimental Chamber SmarPod 6D Positioning Beam Profile Measurement (~µm res) DLA Interaction Point Vertical Steerer Vertical Steerer See poster: F. Mayet, “Status report on the dielectric laser acceleration experiments at the SINBAD/ARES linac” 18/09/2019, 19:00 50-100 MeV e- from ARES 50-100 MeV e- from ARES Quadrupole Triplet Quadrupole Triplet Damped Laser Table Damped Laser Table | ARES Linac | Barbara Marchetti, EAAC 2019

12. Beam Production, Compression and Transport to Experimental Station 2 (EA2) Matching Beamline to second experimental area and laser in-coupling (LWFA experiment) Dogleg to second experimental area Matching Beamline to BC Photo-Injector Magnetic compressor RF cavity for Energy Upgrade Diagnostics beamline EA2 Linac z[m] 2.5 0 ~12.2 ~17.7 ~31 ~39 • See posters: • E. Panofski, Electron Beam matching Strategies for External Injection in LWFA for SINBAD-ARES • 18/09/2019, 19:00 • S. Yamin, Design Studies for Permanent Magnetic Quadrupole Triplet for Matching into Laser Driven Wake Field Acceleration Experiment with External Injection at SINBAD • Yesterday’s poster session. Responsibleperson: F. Lemery | ARES Linac | Barbara Marchetti, EAAC 2019

13. SIMULATIONS donewith ASTRA and IMPACT-T Example of working point to EA2 Case E =200 MeV Beam at plasma entrance: tRMS = 0.31 fs ΔE/E E = 0.16% nex = 0.11e-06 m*rad ney = 0.12e-06 m*rad Peak current = 0.74 kA Brightness = 5.65 *1016 A*m-2 Beam at the bunch compressor exit: Charge = 0.81 pC tRMS = 0.20 fs E = 200.2 MeV ΔE/E = 0.12% nex = 0.11e-06 m*rad ney = 0.10e-06 m*rad Peak current = 1.13 kA Brightness = 10.74 *1016 A*m-2 Preliminary – being optimized in iteration with plasma accelerator simulations Simulations by F. Lemery and S. Yamin | ARES Linac | Barbara Marchetti, EAAC 2019

14. Externalinjection at ARES/ATHENAe • RF photo-injector provides a well-know, well-characterized and well tunable electron • External injection of short electron bunches promises excellent beam quality (1 GeV, 0.2% energy spread, < 0.2 mm emittance). • Unique possibilities for beam manipulation and synchronization • Stepping stone to a stagedmulti-GeV high performance plasma accelerator. Experimental Area 2 Experimental Area 1 (I) TWS3 (II) Dogleg 5.6 m Available Laser Parameters withinthe KALDERA frame: 100 TW, 3 J, 30 fs Acceleratingstructure Solenoid Bunchcompressor ExternalInjection Simulationsandlayoutstudiesongoingbeing iterated with performance simulations. Dipole / Quadrupole / Matching Gun TWS1 TWS2 Undulators Dump [m] Laser plasma Electrons 0 2.5 12 23.5 31 34.3 37.2 39.7 ~46 ~50 Slide by F. Burkart Photons | ARES Linac | Barbara Marchetti, EAAC 2019

15. Outline Introduction: The SINBAD Facility and the ARES linac Overview of the SINBAD/ARES layout and example of working points (simulations) Status of the installations, conditioning and commissioning High Energy Diagnostics Beamline Conclusion | ARES Linac | Barbara Marchetti, EAAC 2019

16. The Design ofthe ARES Photo-InjectorallowsbroadTuning ofthe longitudinal Phase-Space ofthe Beam at theCathode (1/2) REGAE-like Gun Cavity- 1.5 Cells Standing Wave – exchangeable Cathode-Plugs • Why use different cathode-types ? • Semiconductors, (e.g. Cs2Te) : • High QE ( e.g. 4%-11%) • Slow response time ~ ps • Metals (e.g. Cu): • Lower QE ( e.g. 0.014%) • Faster response time < ps Peak gradient: 117 MV/m for 6MW input power RF flat-top pulse length: 4.5µs | ARES Linac | Barbara Marchetti, EAAC 2019

17. The Design ofthe ARES Photo-Injectorallowsbroad Tuning ofthe longitudinal Phase-Space oftheBeam at theCathode (2/2) Slice_Emittanceand Slice-EnergySpreadminimized • Ybdopedlaser(PHAROS from Light Conversion) • Pulse energy ≥1mJ • Central wavelength: 1030 nm (4th harmonic 257 nm) • Pulse lengthrangetunable: 180fs-10ps FWHM Linear Longitudinal Phase-Space • DESY-developed transverse flat-top shaping system • Range for flat-top shaping: 20µm-0.2mm RMS Design by Lutz Winkelmann & Sebastian Pumpe – group I. Hartl | ARES Linac | Barbara Marchetti, EAAC 2019

18. The Photo-Cathode Transverse Shaping System hasbeensuccesfullycommissioned in January 2019 Scintillator Laser on cathode Measured data (Lutz Winkelmann, Christoph Mahnke): Aligned and characterized two flat-top laser sizes at the scintillator cathode: - 320µm diameter (FWHM) - 54 µm diameter (FWHM) | ARES Linac | Barbara Marchetti, EAAC 2019

19. The Photo-InjectorhasbeeninstalledandtheConditioningofthe RF-Gunisongoing • First RF-gun cavity and related diagnostics installed • Ongoing procurement of second RF-gun cavity with modified cooling channels allowing integration of second solenoid. • Conditioning of first gun cavity achieved in May 2019 RF-pulse length 4.5us, rep. rate 10Hz, 4MW power in the gun  then problems with waveguide network Solenoid Example of Focused Dark Current In-vacuum cathode exchange system RF-gun Example of LLRF signals from the RF-gun | ARES Linac | Barbara Marchetti, EAAC 2019

20. The Photo-InjectorhasbeeninstalledandtheConditioningofthe RF-Gunisongoing • After investigations on the waveguide network the source of problems has been identified and exchanged.  the new waveguides have been conditioned up to the nominal parameters 50 Hz,6.7 MW with 4.5 µs RF pulse length the new system is being reconnected to the RF gun in this weeks’s shutdown. Solenoid In-vacuum cathode exchange system RF-gun Picture of one of the damaged bends in the waveguide network, which currently has been replaced. | ARES Linac | Barbara Marchetti, EAAC 2019

21. The LinacCavitieshavebeenprocuredandinstalled Matching Region Diagnostics Temporary Energy Spectrometer • RF cavities embedded in solenoids • 20 MV/m for 45MW input power •  About 75MeV energy gain per cavity expected with our RF station Linac cavities The two accelerating cavity are currently undergoing conditioning Future Exp. Area ACHIP and Reserved space for 3rdlinac cavity | ARES Linac | Barbara Marchetti, EAAC 2019

22. Outline Introduction: The SINBAD Facility and the ARES linac Overview of the SINBAD/ARES layout and example of working points (simulations) Status of the installations, conditioning and commissioning High Energy Diagnostics Beamline Conclusion | ARES Linac | Barbara Marchetti, EAAC 2019

23. The PolariX TDS Project is an Example of Development of Advanced Diagnostics for fs Bunches that we pursue Collaboration between: • Novel design of TDS with tunable direction of the streaking field invented at CERN (Alexey Grudiev) • Cavity design matches specifications of 4 experiments: FLASHForward, FLASH2, SINBAD/ARESat DESY and ATHOS beamline at PSI. • It will allow sub-fs longitudinal diagnostics at SINBAD-ARES • The design gives full control of the streaking direction, which can be tuned continuously in order to characterize the projections of the beam distribution on different transverse axes. Coordinatedby: Grudiev (CERN), P. Craievich (PSI), B. Marchetti (DESY)

24. The PolariX TDS Project is an Example of Development of Advanced Diagnostics for fs Bunches that we pursue • Novel design of TDS with tunable direction of the streaking field invented at CERN • First prototype cavity has been produced and characterized at PSI  tuning free assembly procedure • Performed high power conditioning at CERN Collaboration between:

25. The PolariX TDS Project is an Example of Development of Advanced Diagnostics for fs Bunches that we pursue • In September 2019 first demonstration of the prototype performances with beam has been performed at DESY (FLASHForward beamline) • PolariXTDS cavities for SINBAD-ARES will be available in 2020. Collaboration between: More details in talks: - R. D’ Arcy in WG1, 17/09/2019, 19:00 - P. Gonzalez Caminal in WG5, 19/09/2019, 17:00

26. We have performed detailed Simulation-Studies for the Design of the PolariX-TDS Beamline at SINBAD-ARES Simulations performed with Astra and elegant Reconstruction of 3D charge density distribution Longitudinal Phase Space Original phase space + reconstruction Original Longitudinal Resolution = 3.4 fs D. Marx et al., Nucl. Inst. and Methods in Physics Res., A 909 (2018) 374–378 Reconstructed Longitudinal Charge Profile Longitudinal Resolution = 2 fs • D. Marx et al., J. Phys.: Conf. Ser., vol. 874, (2017)012077 • New paper submitted recently Longitudinal Resolution = 0.18 fs | ARES Linac | Barbara Marchetti, EAAC 2019

27. Outline Introduction: The SINBAD Facility and the ARES linac Overview of the SINBAD/ARES layout and example of working points (simulations) Status of the installations, conditioning and commissioning High Energy Diagnostics Beamline Conclusion | ARES Linac | Barbara Marchetti, EAAC 2019

28. Conclusions and Outlook The SINBAD-ARES accelerator at DESY is a normal conducting S-band accelerator for the production of ultra-short bunches to be injected into novel accelerators. The accelerator will foresee two experimental areas for performing experiments in the different frameworks such as ACHIP collaboration, ARIES program and ATHENA project. The RF-gun and first cavity of the linac section are in the conditioning-phase. The photo-cathode laser has been commissioned. First electron beam is expected soon. The installation of the bunch compressor and high energy diagnostics beamline is planned for 2020. The design of the high energy diagnostics beamline including the novel PolariX TDS aims at the complete characterization of the phase-space of the beam with temporal resolution down to 0.2fs. | ARES Linac | Barbara Marchetti, EAAC 2019

29. Acknowledgments The setup of a new accelerator requires an enormous technical effort. I would like to thank all the DESY technical group for having supported us with this project. In particular I would like to thank: Markus Huening, Ingo Peperkorn, Joerg Herrmann, J. Rothenburg, Holger Schlarb, Sven Pfeiffer, Frank Ludwig, Matthias Hoffmann, M. Titberidze, Sven Lederer, Jakob Hauser, LutyLilje, Stefan Baark, Ingmar Hartl, Lutz Winkelmann, Christoph Mahnke, Kay Wittenburg, Maike Pelzer, GeroKube, SilkeVilcins, Matthias Werner, Manon Foese, Gerd Tews, Rolf Jonas, Olaf Krebs, Joachim Mueller, Bernward Krause, Matthias Thede, Christian Helwich, Jan Kuhlmann, Benno List, Marco Scheer, OezkanBiskin, Marcel Rosan, Jan Thiele, Christian Wiebers, Maximilian Holz, B. Belusic, H. Heller, Olaf Henler, Tim Wilksen, R. Bacher I would kike to thank also the colleagues of the Hamburg Alliance and in particular Hossein Delsim-Hashemi and Benno Zeitler for the support on technical problems and diagnostics. Finally I would like to thank our collaborators from CERN ( in particular A. Grudiev, W Lee Millar, N. Catalan-Lasheras, G. McMonagle and W. Wuensch) and PSI (in particular P. Craievich, M. Bopp, H.-H. Braun, F. Marcellini and M. Pedrozzi) and the internal collaborators for the PolariX TDS project (in particular R. D’Arcy, S. Wesch, Pau Gonzalez Carminal, Mathias Vogt, Siggi Schreiber, KatjaHonkavaara, F. Christie, J. Osterhoff). Thankyouforyourattention! | ARES Linac | Barbara Marchetti, EAAC 2019

30. Barbara Marchetti MPY1 barbara.marchetti@desy.de +49-40-8998-3840