Results from the Optical Replica Synthesizer at FLASH Shaukat Khan, University of Hamburg FEL 2008, Gyeongju, Korea G. V. Angelova, V. Ziemann ( UU/ISV, Uppsala, Sweden) M. Larsson, P. van der Meulen, P. Salén (FYSIKUM, Stockholm, Sweden) J. Bödewadt, S. Khan (University of Hamburg, Germany) F. Löhl, E. Saldin, H. Schlarb, E. Schneidmiller, A. Winter, M. Yurkov (DESY, Hamburg, Germany) A. Meseck (BESSY, Berlin, Germany) Aug 27th 2008
FLASH at DESY / Hamburg rf, laboratories, workshops 0 50 100 lab N PETRA experimental hall 150 200 250 *
FLASH at DESY / Hamburg rf, laboratories, workshops 0 50 100 lab N PETRA experimental hall 150 200 250 * eleration & bunch compression SASE bc1 bc2 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
How to measure the longitudinal bunch profile on the fs scale? 100 fs
1. Transversely deflecting rf structure ( LOLA ) R. Akre, L. Bentson, P. Emma, P. Krejick, Proc. EPAC 2002 Paris, p. 1882 M. Roehrs, C. Gerth, H. Schlarb, Proc. FEL 2006 Berlin, p. 300 M. Roehrs, PhD thesis Hamburg 2008 CCD camera OTR screen 2 0 x [mm] -2-4 1 0 0.5 1 1.5 2 t [ps] 200 150 100 50 0 horizontal kicker transversely dfl deflecting cavity 0.5 ρ/ρ max 0 0 0.5 1 1.5 2 t [ps] time resolution ~30 fs bc1 bc2 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
2. Electro-optical sampling (EOS) B. Steffen et al. Proc. FEL Novosibirsk 2007, p. 310 B. Steffen, PhD thesis Hamburg 2007 e.g. temporal decoding σ 0 TDS corrected signal fs fixed delay σ c optical stretcher P EO A BBO CCD nd 4 EOTD corrected signal -0.5 0 0.5 1 time [ps] time resolution ~55 fs achieved bc1 bc2 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
3. Coherent transition radiation (CTR) 2-stage single-shot spectrometer H. Delsim-Hashemi et al. Proc. FEL 2006 Berlin, p. 594 H. Delsim-Hashemi, PhD thesis Hamburg 2008 no intrinsic resolution limit, but result ambiguous bc1 bc2 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
4. Optical-replica synthesizer (ORS) E Saldin, E. Saldin E E. Schneidmiller Schneidmiller, M. M Yurkov, Yurkov Nucl. Nucl Inst. Inst Methods A 539 (2005), (2005) p p. 499 modulator electrons radiator chicane pulse replica energy electron distribution density coherent radiation bc2 bc1 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
4. Optical-replica synthesizer (ORS) E Saldin, E. Saldin E E. Schneidmiller Schneidmiller, M. M Yurkov, Yurkov Nucl. Nucl Inst. Inst Methods A 539 (2005), (2005) p p. 499 modulator electrons radiator chicane pulse replica energy electron distribution density coherent radiation bc2 bc1 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
4. Optical-replica synthesizer (ORS) E. Saldin, E. Schneidmiller, M. Yurkov, Nucl. Inst. Methods A 539 (2005), p. 499 electrons pulse modulator chicane radiator replica FROG = Frequency-Resolved Optical Gating (GRENOUILLE) electron distribution energy density coherent radiation time resolution given by wavelength (2.6 fs) plus slippage of electrons w.r.t. field bc1 bc2 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. hardware installation in 2007 first experiments in Oct 2007 N Laser Tunnel F L A S H t u n n e l optical station optical station I II telescope modulator radiator electron beam 0 5 10 m bc1 bc2 gun LOLA EOS ORS EOS SASE IR dump bypass 0 50 100 150 200 250 m
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. N F L A S H t u n n e l optical station optical station I II telescope modulator radiator electron beam 0 5 10 m
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. N F L A S H t u n n e l optical station optical station I II telescope modulator radiator electron beam 0 5 10 m
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. electrons modulator chicane radiator pulse replica electron distribution energy density coherent radiation 200 fs optical transtion radiation at 400 nm
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. electrons modulator chicane radiator pulse replica electron distribution energy density coherent radiation 200 fs
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. electrons modulator chicane radiator pulse replica electron distribution energy density coherent radiation 200 fs nematode
4. Optical-replica synthesizer (ORS) G. Angelova et al., Phys. Rev. ST Acc. Beams 11 (2008), 070702. Comparison: OTR from modulated bunches (black line) transversely deflecting cavity (blue dots) 400 signal [a.u.] 300 200 100 0 20 10 0 10 20 time [ps]
4. Optical-replica synthesizer (ORS) G. Angelova et al., EPAC 2008, Genova/Italy wavelength latest experiment: 200 fs pulse and moderately compressed (100 fs) electron bunch FROG = Frequency-Resolved Optical Gating (GRENOUILLE) time presently using a GRENOUILLE 8-500USB optimized for 500 fs pulses
Summary Commissioning - 200 fs pulse (800 nm) with uncompressed bunch, observing... coherent optical transition radiation at 400 nm... coherent synchrotron radiation from the radiator at 400 nm - 200 fs pulse with moderately compressed bunch, observing... first FROG traces with 500 fs resolution Next steps (Oct 08) - FROG traces with better resolution (replace GRENOUILLE) - look at fully compressed bunches Goals - measure longitudinal bunch profile with sub-10 fs resolution - prepare the ground for other -based applications (e.g. HHG seeding)
sflash: an experiment for seeding VUV radiation at FLASH (this conference TUPPH072) rf, laboratories, workshops 0 50 100 lab N PETRA experimental hall 150 200 250 * 0 5 10 m experiment HHG pump FEL probe FLASH tunnel electron beam ORS undulators sflash undulators LOLA TEO SASE undulators
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