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The ORS at FLASH and sFLASH

The ORS at FLASH and sFLASH. a new diagnostic tool for characterizing electron bunches. Peter van der Meulen Stockholm University Div. Molecular Physics. FLS2010, March 1-5, 2010, 48 th ICFA Advanced Beam Dynamics Workshop on Future Light Sources.

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The ORS at FLASH and sFLASH

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  1. The ORS at FLASH and sFLASH a new diagnostic tool for characterizing electron bunches Peter van der Meulen Stockholm University Div. Molecular Physics FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  2. electron bunch properties: longitudinal density profile slice emittance slice energy spread electron bunch: moving at v ≈ c ca. 20 mm long ca. 100 mm wide ORS: Optical Replica Synthesizer FLASH, XFEL, JFEL, LCLS: SASE SASE is very sensitive to the properties of the electron bunch need to control and measure these properties! hard to measure directly  measure an optical copy instead FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  3. ORS: Optical Replica Synthesizer FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  4. ORS: Optical Replica Synthesizer • Erbium fiber oscillator: • 1550 nm • ca. 54 MHz • amplified • frequency doubled, 1 mm PPLN • 1 – 5 mW • Clark-MXR CPA2001 • Ti:Sapph CPA system • 5 Hz (1 kHz) • ca. 700 mJ/pulse • 0.2 – 3.0 ps FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  5. ORS: temporal overlap delay FLASH 5 Hz trigger Er:fiber oscillator stretcher Ti:Sapph amplifier compressor to tunnel ca.54 MHz pulse train Fourier Transform 24th harmonic FLASH RF 1.3 GHz ca. 1.3 GHz ca.19 ns piezo + delay diff. freq. mixing vector modulator  …+ cos[(Dw.t + Da)/2] = 0 Matlab progam FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  6. ORS: Magnet structures • Undulators: • electromagnets • 1450 mm • 40 mm gap, 0.5 T max. • 14 poles (1/4,-3/4,1,-1…) • 4 power supplies • modulator vertical • radiator horizontal • Chicanes: • 4 dipole magnets • 1300 mm FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  7. ORS: spatial overlap calibration and OTR screens on 7Match and 3SUND1 Joern Boedewadt FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  8. ORS: temporal overlap Coherent OTR @ 385 nm PRSTAB 11, 070702, 2008 FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  9. GRENOUILLE* femtosecond optical pulse characterization based on SH FROG technique (autocorrelator + spectrometer) single shot measurement 2D phase retrieval algorithm => fully characterized pulse Electric field profile  electron bunch profile (I4) * Swamp Optics FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  10. ORS: FROG trace seed laser pulse: ca. 400 fs FWHM FROG trace: ca. 150 fs FWHM  FLASH’s electron bunch spike? Compatible with SASE!!! FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  11. ORS: FROG trace • ca. 1-5 mJ/pulse • ca. 150 fs FWHM • no direct comparison with TDC (LOLA)  FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  12. ORS at FLASH The ORS seems to work, but… • Some remaining issues: • cross check with TDC (LOLA) and/or EO measurement • laser power: 1 mJ/ pulse  30 mJ/pulse • better digital data collection: 8 bit  12/16 bit • what happens under further bunch compression? CSR? • what is the future of the ORS? FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  13. ORS: FROG trace A FROG trace obtained upon further compressing the electron bunch: FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  14. ORS at sFLASH temporary shutdown September 2009 rebuild ORS in new position FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  15. ORS at FLASH • Other applications of the ORS: • phase of optical replica pulse  energy chirp of electron bunch • slice energy spread • slice emittance • 3D spatial electron bunch characterization via coherent OTR • ‘echo’ test experiments (G. Stupakov, SLAC-PUB-13445, Oct. 2008) • ORFIR • general study laser – electron interactions FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  16. conclusions • first ORS results obtained in 2009!!! • the ORS seems a very useful addition to (s)FLASH, • as a diagnostic device. Some issues deserve further study. • more (parasitic) beam time is required to make the ORS • a standard and routine diagnostic technique. • ‘alternative’ applications of the ORS appear very promising. FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  17. Collaborators Stockholm University: Peter Salen Mathias Hamberg Mats Larsson Uppsala University: Volker Ziemann Gergana Angelova-Hamberg DESY: Holger Schlarb Florian Löhl Hamburg University: Joern Boedewadt Axel Winter Shaukat Khan BESSY: Atoosa Meseck DESY: E. Saldin, E. Schneidmiller & M. Yurkov DESY, 27 January 2009 FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  18. THANK YOU! FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  19. ORS: temporal overlap Holger Schlarb Florian Löhl FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  20. ORS @ sFLASH • What to do: • move undulators, dipoles and optical stations (+ cables) • re-build OS1 chicane in vertical plane; re-design OS2 chicane • change to HHG laser; 10% beamsplitter, ca. 4 mJ/pulse + compression • improve laser beam diagnostics • insert new OTR screens: • diffuse scattering screen • doped YAG screen for e-beam and laser? • better optical quality: surface and flatness FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  21. BOA pulse compressor Bother-free Optimized Arrangement fused silica transmission grating, ca. 1000 l/mm Swamp Optics • no angular dispersion • no pulse front tilt • no spatial chirp DESY, 27 January 2009 FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  22. I(r)  N  d2r’ dz (r’,z) Eone-electr(r-r’) 2 + N2 d2r’ dz exp(-ikz) (r’,z) Eone-electr(r-r’) 2 Icoh(r)  N2 d2(,k) (exp(ir))/( 2 + 2) 2  = k/ ORS contributions to sFLASH • imaging using coherent OTR/ODR: longitudinal bunch profile • high k – small wavelength compared to THz measurements • high intensity if (,k) = f() . g(k)  X but…. FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

  23. The ORS as a routine diagnostic? PRSTAB 11, 070702, 2008 what about the possibility to do an image reconstruction using algorithms similar to those applied in single-particle X-ray diffraction? multiple k’s and modulation using chirped seed pulses FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources

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