Status of the Synchrotron Light Source DELTA & its Short-Pulse Facility. Shaukat Khan Center for Synchrotron Radiation TU Dortmund Germany

Transcription

1 Status of the Synchrotron Light Source DELTA & its Short-Pulse Facility 1 Shaukat Khan Center for Synchrotron Radiation TU Dortmund Germany

2 Light sources in Germany 2

3 DELTA, a university-based synchrotron light source 3 Configuration - thermionic gun - 80 MeV linac GeV synchrotron GeV storage ring Parameters circumference m beam energy 1.5 GeV beam current 130 ma beam lifetime 14 hrs at 100 ma hor. emittance 15 nm rad bunch length 100 ps energy spread user operation 2000 hrs/y (20 weeks) availability > 90% machine studies 1000 hrs/y (10 weeks) +200 hrs/y (20 x Fr)

4 DELTA, a university-based synchrotron light source 4 Configuration - thermionic gun - 80 MeV linac GeV synchrotron GeV storage ring U250: normal-conducting undulator, also used as storage-ring FEL U55: permanent-magnet soft-x-ray undulator SAW: superconducting asymmetric wiggler serving three beamlines

5 Superconducting asymmetric wiggler 5 Parameters (symmetric / asymmetric) number of periods 10 / 5 period length 144 / 288 mm max. B field 2.8 / 5.3 T opening angle 6.4 / 24 mrad critical energy 4.2 / 7.9 kev total length 2.50 m vacuum gap 10 mm N.A. Mezentsev, Proc. PAC 2005, Knoxville/USA, 256.

6 Study of the beam lifetime (R. Floegel, M. Jebramcik, H. Huck, S. Khan, D. Schirmer, G. Schmidt, A. Strasser, P. Towalski, T. Weis) 6 Steady improvement Study of contributing processes gas scattering limit Touschek limit M.Jebramcik et al., Proc. IPAC 2014, Dresden/Germany Results consistent picture, only if gas pressure ~ beam current (sync. rad. desorption) ~ bunch current (impedance effect?)

7 Improvement of the machine 7 New electron gun, pre-buncher and kicker pulsers (J. Friedl, G. Dahlmann, P. Hartmann et al.) - switching between multi-bunch and single-bunch and hybrid fill pattern possible Vertical alignment (T. Schulte-Eickhoff, G. Schmidt et al.) - improved orbit stability, beam lifetime, injection efficiency, and radiation background Fast orbit feedback (G. Schüneman, P. Towalski et al.) - against vibrations and 50-Hz noise (almost complete) Bunch-by-bunch feedback (M. Höner, A. Nowaczyk et al.) - longitiudinal, horizontal and vertical detection and feedback kicks at 500 MHz (every bunch) Many other small improvements (the DELTA team) - timing system, control system, power supplies etc.

8 Bunch-by-bunch feedback systems (M. Höner, A. Nowaczyk, and D. Teytelman, DIMTEL Inc.) 8 Three processors and power amplifiers - commercial components - digital system (diagnostics) Kickers (BESSY design) - longitudinal overdamped cavity - four transverse striplines Diagnostics examples - injection studies - beam loss monitor - multibunch mode damping rates harmonic number 192 M. Höner et al., Proc. IPAC 2014, Dresden/Germany

9 Education Two-semester course in accelerator physics 9 - lectures, exercises, computation, seminars, excursions Bachelor, master and PhD work - interdisciplinary: accelerators, lasers, synchrotron radiation research

10 Education Two-semester course in accelerator physics 10 - lectures, exercises, computation, seminars, excursions Bachelor, master and PhD work - interdisciplinary: accelerators, lasers, synchrotron radiation research Collaborations RF cavity design (Prof. T. Weis) - BERLinPro (ERL project in Berlin), BESSY-VSR (short pulses) FEL seeding - HGHG and EEHG at FLASH (DESY, Hamburg) Coherent THz radiation and bunch-by-bunch feedback - with ANKA at KIT/Karlsruhe + many other contacts

11 (F. Bahnsen, S. Cramm +, S. Döring ++, J. Greve, N. Hiller &, V. Judin &, M. Höner, H. Huck, M. Huck, S. Khan, R. Molo, L. Plucinski +, J. Raasch ++, A. Schick, C. Schneider +/++, M. Siegel &, P. Thoma &, P. Ungelenk; + FZ Jülich, ++ Univ. Duisburg-Essen, & KIT Karlsruhe) S. Bielawski, E. Rousse, C. Szwaj (Univ. Lille) 11 wavelength (nanometer) synchrotron radiation time resolution (picoseconds)

12 12 Based on coherent harmonic generation (CHG) - laser-induced energy modulation in an undulator - converted to density modulation in a chicane - coherent radiation of harmonics in a second undulator - coherent THz radiation in a downstream dipole 100 ps (33 mm) 45 fs (15 μm)

13 13 Based on coherent harmonic generation (CHG) - laser-induced energy modulation in an undulator - converted to density modulation in a chicane - coherent radiation of harmonics in a second undulator - coherent THz radiation in a downstream dipole - first implementation: ACO/France - recently: Elettra/Italy, UVSOR/Japan B. Girard et al., PRL 53 (1984), 2405 M. Labat et al., PRL 101 (2008), E. Allaria et al., PRL 100 (2008), ps (33 mm) 45 fs (15 μm)

14 14 Based on coherent harmonic generation (CHG) - laser-induced energy modulation in an undulator - converted to density modulation in a chicane - coherent radiation of harmonics in a second undulator - coherent THz radiation in a downstream dipole incoherent power coherent power P P n b n inc coh slice h = P = P bunch e e n n 3 10 bunch 2 slice 10 n b 2 h bunch 10 2 P inc 100 ps (33 mm) bunching factor b h : Fourier transform of longitudinal charge distribution 45 fs (15 μm)

15 15 Based on coherent harmonic generation (CHG) - laser-induced energy modulation in an undulator - converted to density modulation in a chicane - coherent radiation of harmonics in a second undulator - coherent THz radiation in a downstream dipole Echo-enabled harmonic generation (EEHG) - requires 3 undulators and 2 chicanes - more complex density modulation - higher harmonics, shorter wavelength

16 16 Based on coherent harmonic generation (CHG) - laser-induced energy modulation in an undulator - converted to density modulation in a chicane - coherent radiation of harmonics in a second undulator - coherent THz radiation in a downstream dipole Echo-enabled harmonic generation (EEHG) - requires 3 undulators and 2 chicanes - more complex density modulation - higher harmonics, shorter wavelength - first test: SLAC/USA - FEL saturation: SINAP/China G. Stupakov, PRL 102 (2009), D. Xiang et al., PRL 105 (2010), Z. Zhao et al, Nature Photonics 6 (2012), 360

17 17 Laser lab with titanium:sapphire laser system nm wavelength, SHG, THG, OPA - 8 mj at 1 khz repetition rate - 40 fs pulse duration - diagnostics: FROG and SPIDER

18 18 Telescope and beamline BL 3 - lenses for 800 nm, mirrors for 400 nm - integrated in the DELTA control system - in future evacuated

19 19 Undulator U periods of length 250 mm - new power supplies for K > 10 (800 nm at 1.5 GeV) - chicane rewired for R 56 = 130 μm

20 20 Diagnostics beamline BL 4 - water-cooled mirror - longitudinal overlap: streak camera - transverse overlap: cameras - Czerny-Turner spectrometer with APD - CCD spectrometers, powermeter etc. - gated UV iccd camera

21 21 VUV beamline BL 5 - plane-grating monochromator - photoelectron spectrometer - evacuated beamline for pump-probe - laser hutch

22 22 Terahertz beamline BL 5a - 6 toriodal mirrors -LHe-cooledInSbbolometer - FT-IR spectrometer with Si bolometer - ultrafast LN-cooled YBCO bolometer

23 23 Status seeding with 800 nm (7. harmonic: 114 nm seen) seeding with 400 nm (5. harmonic: 80 nm seen) - goal: seeding with 267 nm (5. harmonic: 53 nm) First results in CHG and THz proportional to current squared - first CHG spectra

24 24 CHG intensity (example) - 2nd harmonic of 400 nm: factor 600-3rd harmonic of 400 nm: factor 150 Boosted by rewiring the chicane magnets - R 56 value up to 130 μm

25 25 CHG intensity (example) - 2nd harmonic of 400 nm: factor 600-3rd harmonic of 400 nm: factor 150 Boosted by rewiring the chicane magnets - R 56 value up to 130 μm P coh 2 2 ( h B / ) J ( nab) 2 = P n 2exp 2 e e h 2 ΔE E 0 2π σ E 1 t A B R = 56 ΔE( t) ΔEmax exp 2 E0 σ E λ E0 4 σ t

26 26 CHG spectra - close to the Fourier limit - fringes for larger R 56 value - additional unexpected features - depending on laser chirp

27 27 Transverse coherence - double-slit experiments - speckle patterns Longitudinal coherence - double-slit experiments with delay - Michelson interferometer courtesy B. Schmidt, S. Wunderlich, DESY collaboration with Prof. Gutt, Univ. Siegen gated iccd camera f laser 1 khz 2.6 MHz f revol 400 nm 800 nm

28 28 Transverse coherence - double-slit experiments - speckle patterns Longitudinal coherence - double-slit experiments with delay - Michelson interferometer

29 29 Transverse coherence - double-slit experiments - speckle patterns Longitudinal coherence - double-slit experiments with delay - Michelson interferometer preliminary results M. Huck et al., Proc IPAC 2014, Dresden/Germany 32.4 fs 34.0 fs

30 30 RF phase modulation - eliminates multibunch instabilities - improves the beam lifetime Streak camera images of different modulation regimes: no modulation breathing two islands three islands time / synchrotron period time (ps) time (ps) time (ps) time (ps)

31 31 RF phase modulation - eliminates multibunch instabilities - improves the beam lifetime 1) Modulation frequency close to 32 x laser repetition rate - beating of THz and CHG intensity Streak camera images of different modulation regimes: no modulation breathing two islands three islands time / synchrotron period time (ps) time (ps) time (ps) time (ps)

32 32 RF phase modulation - eliminates multibunch instabilities - improves the beam lifetime 2) Synchronizing modulation to laser trigger - select phase with trigger delay Streak camera images of different modulation regimes: no modulation breathing two islands three islands time / synchrotron period time (ps) time (ps) time (ps) time (ps)

33 33 RF phase modulation - eliminates multibunch instabilities - improves the beam lifetime 2) Synchronizing modulation to laser trigger - select phase with trigger delay Streak camera images of different modulation regimes: no modulation breathing two islands three islands time / synchrotron period - CHG depends on electron density - THz depends on energy spread -CHG/THzstrongerwithmodulation time (ps) time (ps) time (ps) time (ps)

34 34 Coherent THz radiation - path length differences cause a gap - coherent emission in the THz regime - persists over sereval turns

35 35 Coherent THz radiation - path length differences cause a gap - coherent emission in the THz regime - persists over sereval turns G-L- Böttger, Bachelor Thesis TU Dortmund 2013

36 36 Equipment - InSb bolometer ~ 1 μs - NbN bolometer ~ 160 ps (KIT/Karlsruhe) - YBCO detector ~ 16 ps (KIT/Karlsruhe) - FT-IR spectrometer with Si bolometer ~ 1 ms A. D. Semenov et al., Proc. of IRMMW THz 2009, P. Probst et al., Appl. Phys. Lett. 98, (2011) G-L- Böttger, Bachelor Thesis TU Dortmund 2013

37 37 Narrow-band THz radiation - long intensity-modulated laser pulse - with Univ. Lille/France at UVSOR/Japan ( up to 500 GHz ) - experiments January/June 2014 at DELTA ( 1 to 5 THz ) C. Evain et al., Phys. Rev. ST Accel. Beams 13 (2010), P. Ungelenk et al., Proc. IPAC 2014 Dresden/Germany

38 Echo-enabled harmonic generation at DELTA 38 EEHG: Short pulses at shorter wavelength (~ 10 nm) - modulators: 2 short undulators (FLASH ORS design) - radiator: present U250 undulator - requires longer straight section - modified storage ring optics - additional undulator for "slicing" G. Stupakov, PRL 102 (2009),

39 Echo-enabled harmonic generation at DELTA 39 EEHG: Short pulses at shorter wavelength (~ 10 nm) - modulators: 2 short undulators (FLASH ORS design) - radiator: present U250 undulator - requires longer straight section - modified storage ring optics - additional undulator for "slicing" present layout: Diplom thesis, R. Molo: New layout, R. Molo:

40 Echo-enabled harmonic generation at DELTA 40 Femtoslicing - short and tunable wavelength -lowphotonrate A. A. Zholents, M. S. Zoloterev, PRL 76 (1996), 912 R. W. Schoenlein et al., Science 287 (2000), 2237 S. Khan et al., PRL 97 (2006), P. Beaud et al., PRL 99 (2007), electron bunch fs laser pulse fs x-ray pulse modulator dipole magnet radiator aperture New layout, R. Molo:

41 41 Summary DELTA is a university-based 1.5-GeV synchrotron light source short wavelength using a superconducting multipole wiggler improvents of the machine, education and collaborations intensified CHG short-pulse facility for VUV and THz radiation ready for users study of the laser-electron interaction and radiation properties EEHG and femtoslicing in preparation

42 42 Acknowledgements All colleagues at DELTA (machine, beamlines, workshops, administration) for their enthusiasm and excellent work Tax payer (DFG, BMBF, MIWF NRW) and FZ Jülich for project funding Colleagues at DESY, HZB, FZJ, GSI and many others for collaboration and valuable input EB"F4$o 2" BD4(:"T,>4,