A THz Facility for the European XFEL M. Krasilnikov for PITZ (PITHz) team Workshop "Shaping the Future of the European XFEL: Options for the SASE4/5 Tunnels“, 6-7 December 2018, European XFEL P hoto I njector T est facility at DESY, Z euthen site (PITZ) <7 MeV <25 MeV + undulator?
PITZ “engine”: RF -Gun and Photocathode Laser Highlights of the facility Photocathode laser(s) (UV) Default laser system Institute of (Max-Born-Institute, Berlin) Applied Physics RF gun = for European XFEL! Gaussian: of the Russian • L-band (1.3 GHz) 1.6-cell copper cavity Academy of FWHM FWHM FWHM FWHM • Ecath>~60MV/m 7MeV/c e-beams Sciences ~ 2 ps ~ 2 ps ~7 ps ~7 ps • 650us x 10Hz up to 45 kW av. RF power New laser system • Cs 2 Te PC (QE~5-10%) up to 5nC/bunch • LLRF control for amp&phase stability FWHM FWHM FWHM FWHM ~ 11 ps ~ 11 ps ~ 17 ps ~ 17 ps • Solenoids for emittance compensation 3D ellipsoidal pulse shaper: Multicrystal birefringent pulse • Spatial Light Modulator shaper containing 13 crystals (SLM) based • Upgrade with Volume Pulse Train Time Structure : Bragg Grating (VBG) PITZ and EXFEL trains with up to 600 ( 2700 ) laser pulses Oscillator upgrade – 600 s Pharos-20W-1MHz t frontend Flattop Pulse length 0.25-10ps+ 100 ms Different lasers Cathode laser pulse: temporal profile OSS signal (UV) t FWHM t = 1 s various THz options = 25 ps edge 10-90 edge 10-90 (222ns) ~ 2 ps ~ 2.2 ps possibility of simultaneous usage birefringent shaper, 13 crystals | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 2
Accelerator based tunable IR/THz source for P&P at E-XFEL PITZ can be used as a prototype! Pump X-ray PITZ-like accelerator based XFEL (~3.4 km) & THz source (~20 m) Transverse profile probe THz correction E.A. Schneidmiller, M.V. Yurkov, (DESY, Hamburg), M. Krasilnikov, F. Stephan, (DESY, Zeuthen), “ Tunabale IR/THz source for pump probe experiments at the European XFEL, Contribution to FEL 2012, Nara, Japan, August 2012 • Accelerator based IR/THz source meets all requirements for pump-probe experiments (e.g., the same pulse train structure!) • Construction of a radiation shielded annex (reduced copy of PITZ facility) is possible close to user experiments at the European XFEL • Prototype of the accelerator already exists PITZ facility at DESY in Zeuthen PITZ XFEL (experimental hall) XFEL ( photon beamline tunnel) PITZ can be used for proof of principle and optimization! | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 3
IR/THz Options at PITZ: High-gain THz SASE FEL Case studies of generating THz radiation by PITZ electron beam Photocathode Booster (Linac) APPLEII Undulator RF Gun Deflecting Cavity Quadrupole magnet Proposal extension for SASE FEL Dipole magnet HEDA2 Screen 0 m PITZ beamline layout extension for simulation studies PITZ Highlights: ► SASE FEL for λ rad ≤ 100 µm (f ≥ 3 THz) • Pulse train structure • High charge feasibility (4 nC) • Advanced photocathode laser shaping • E-beam diagnostics Current PITZ “boundary conditions”: • 22-25 MeV/c max • Available tunnel annex • No bunch compressor • … • No undulator (yet…) • … | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 4
THz SASE FEL at PITZ Undulator and beam parameter space λ rad = 20 µm Conditions : λ rad = 100 µm APPLE- II Undulator* λ rad of 20 – 100 µm Max P z ~ 22 MeV/c Radiation wavelength gap g ≥ 10 mm 𝜇 𝑣 2 𝜇 𝑠𝑏𝑒 = 2𝛿 2 1 + 𝐿 𝑠𝑛𝑡 𝐿 𝑠𝑛𝑡 = 0.66 ∙ 𝐶 0 𝑈 ∙ 𝜇 𝑣 𝑑𝑛 Selections : 2 −4.46 𝜇 𝑣 +0.43 λ u of 40 mm 𝜇 𝑣 𝐶 0 = 1.54𝑓 22 MeV/c for 20 µm *Conceptual Design Report ST/F-TN-07/12, Fermi@Elettra, 2007 15 MeV/c for 100 µm THz SASE FEL Parameter Space with GENESIS ( λ = 100 µ m) SASE FEL simulations assuming: • Helical undulator with period length of 40 mm • Electron beam with 15 MeV/c momentum, 4 nC bunch charge, ~2 mm rms bunch length Preliminary conclusions: • Transverse normalized emittance ε n has almost no impact on saturation power • Beam peak current (charge) most impact | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 5
THz SASE FEL: Simulations for λ rad = 100 µm (3 THz) Setup: 4nC I peak ~200A, ~15MeV/c, FEL pulse energy FEL radiation pulse at z U =5m l u =40 mm, K=1.8, L u =5-7m (average and rms fluct.) temporal profiles spectral profiles Start-to-end: ASTRA GENESIS1.3 22ps 7% • Photocathode laser: 5mm, flattop 2/21.5\2ps FWHM FWHM • Gun and booster phases and main solenoid 2.3 mJ optimized for high I peak and small d E 6.2% 5 E-beam from experiment GENESIS1.3 7% 17ps FWHM • Photocathode laser: 3.7mm, Gaussian 11ps FHWM FWHM 2.0 mJ • Phase spaces from measurements 6.1% X- X’ Y- Y’ 5 30ps 11.05 mm mrad 7.13 mm mrad 22% FWHM 1.4 mJ FWHM t-P z 9.7% 5 | A THz Facility for the European XFEL | Mikhail Krasilnikov , Workshop "Shaping the Future of the European XFEL: Options for the SASE4/5 Tunnels“, 07.12.2018 Page 6
Studies on accelerator-based THz source at PITZ High pulse energy, tunable, pulse structure Laser based THz pulse PITZ-like high repetition energy is limited at high rate compact accelerator repetition rate, while most can produce ~mJ THz pulses ( l rad =20-100 m) IR/THz driven dynamics E-XFEL p-p laser needs pulse energy matching time structure ~mJ THz pulse @ MHz train above 1 μ J of XFEL X-ray pulses. (SASE simulation with PITZ beam, ~4 nC, I peak ~200A) Plot based on talk of M. Gensch “Follow up on THz Radiation” at ARD-ST3 Annual Workshop 19-21.07.2017,DESY, Zeuthen based on plot of M. Gensch and paper Green, B. et al. High-Field High- Repetition-Rate Sources for the Coherent THz Control of Matter. Sci. Rep. 6, 22256; doi: 10.1038/srep22256 (2016). But still SASE (starting from the shot noise) ... ?How to improve stability (CEP= carrier envelope phase)? | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 7
Options to improve THz radiation stability Pre-bunching “Seeding” • Photocathode laser pulse temporal modulation • Using IR laser, modulator and BC for E or d E modulations • Using CDR from short seeding bunch • Using corrugated structures • Using Dielectric Lined Waveguides - DLW (first experiments) E-beam current profile without (blue trace) with DLW (red trace), l =1.03 mm; The peaks are consistent with Measured Longitudinal Phase Space the wavelength of the structure 3.3 ps. In collaboration with CFEL (F. Lemery) F. Lemery et al., Experimental demonstration of ballistic bunching and APC FNAL (P. Piot) with dielectric-lined waveguides at PITZ, IPAC 2017, WEPAB122 | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 8
Single Cycle THz Pulse Generation from Undulator Participation in the LUSIA proposals Attosecond SIngle-cycle Undulator Light on the horizon Manipulated undulator radiation: The long-term vision of this LUSIA project proposal coherent emission from a chirped is to develop a new FEL-like technology to generate microbunched beam passing through isolated attosecond single-cycle pulses of light in the strongly tapered undulator X-ray region at a microJoule energy scale . experiment A targeted breakthrough towards the vision is a proof-of-principle demonstration of single-cycle 2 nd undulator radiation with a tailored electric waveform in the terahertz ( THz ) regime (fs pulses) at PITZ . 1 st experiment THz pulse Undulator radiation from microbunch seeded by short IR laser pulse calculated after the radiator undulator Seed 1 Simulations: Pécs University group (Hungary) T. Tanaka. "Proposal to Generate an Isolated Monocycle X-Ray Pulse by Counteracting the Energy (1 st method): 73.4 nJ Slippage Effect in Free-Electron Lasers." Phys. Rev. Energy (2 nd method): 113.4 nJ Lett.114.4 (2015): 044801 | THz activities at PITZ | Mikhail Krasilnikov, 23.05.2018 Page 9
Proof-of-principle experiment on THz SASE FEL at PITZ Using LCLS-I undulators (available on loan from SLAC) under study and negotiations Some Properties of the LCLS-I undulator Properties Details Type planar hybrid (NdFeB) K-value 3.49 (3.585) Support diameter / length 30 cm / 3.4 m Vacuum chamber size 11 mm x 5 mm Period length 30 mm Periods / a module 113 periods Reference: LCLS conceptual design report, SLAC-0593, 2002. l rad ~100 m <Pz>= 16.7MeV/c Preliminary conclusions on LCLS-I undulators at PITZ: ‣ Might be not such extremely high performance as for the APPLE-II, but is clearly proper for the proof-of-principle experiment! ‣ 4 nC electron beam transport through the vacuum chamber needs efforts, but seems to be feasible. | A THz Facility for the European XFEL | Mikhail Krasilnikov, Workshop "Shaping the Future of the European XFEL: Options for t he SASE4/5 Tunnels“, 07.12.2018 Page 10
Recommend
More recommend
