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Optical properties of the output of a high-gain, self-amplified free-electron laser

Explore the optical properties of a self-amplified free-electron laser, including tunability, coherence, and spectral characteristics. Learn about experimental data, simulations, and analytical theory to better understand the temporal structure and coherence modes of the output radiation.

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Optical properties of the output of a high-gain, self-amplified free-electron laser

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  1. Optical properties of the output of a high-gain, self-amplified free-electron laser Yuelin Li Advanced Photon Source, Argonne National Laboratory 2004 CLEO/IQEC, San Francisco, May 15-21

  2. Self Amplified free electron laser • Continuously tunable • Produce reliable coherent X-ray radiation 2004 CLEO/IQEC, San Francisco, May 15-21

  3. The low-energy undulator test line FEL: future ALFF 6 Hz, 0.5 ps, 50 mJ @ 120-530 nm Milton et al., Science 292, 2037 (2001) 2004 CLEO/IQEC, San Francisco, May 15-21

  4. Single Photon Ionization or Resonant Ionization at Threshold FEL undulator hall The facility and application experiment Li et al., PRL 89 234801 (2002). 2004 CLEO/IQEC, San Francisco, May 15-21

  5. The FROG experiment at 530 nm 2004 CLEO/IQEC, San Francisco, May 15-21

  6. w0resonant frequency st coherence length sd/sz electron beam energy chirp The field of a SASE FEL (by solving Green’s function) is [S. Krinsky and Z. Huang, Phys. Rev. ST Accel. Beams 6, 050702 (2003).] Temporal structure: Analysis Goodman, Statistical Optics, (John Wiley & Sons, New York, 1985), p. 35. S. Krinsky, PRSTAB 6, 050701 (2003). Summing of random phasors: Chaotic light 2004 CLEO/IQEC, San Francisco, May 15-21

  7. Interest in temporal structure • Experimental data • Simulation • Analytical theory 2004 CLEO/IQEC, San Francisco, May 15-21

  8. Temporal structure: spike width and spacing Follow statistics for chaotic light exactly. Dt = 52 fs Li et al., PRL 91 243602 (2003). 2004 CLEO/IQEC, San Francisco, May 15-21

  9. Derivative of phase (frequency) Each intensity spike is a coherence mode. sw=0.0094 rad/fs Li et al., PRL 91 243602 (2003). 2004 CLEO/IQEC, San Francisco, May 15-21

  10. Spike number correlation between time and frequency domain Phase derivative Frequency domain statistics correlation with time domain • Each spike in freq domain is a coherence mode • The number of spikes in the two domains are statistically one to one. 2004 CLEO/IQEC, San Francisco, May 15-21

  11. <DwT>2.42  <Dw> 2/T mfreq sw/ Dw  (1/2st)/(2/T)  T/4st  mtime T=4mst T=2m/ sw Frequency domain statistics correlation with time domain Envelope Number of spikes in time and frequency domain 2004 CLEO/IQEC, San Francisco, May 15-21

  12. Conclusion SASE FEL output is chaotic: fully coherent transversely, but only partially coherent longitudinally Through measurement of the spectra, one can statisticall determine the temporal domain property, the most important one is the pulse duration for the future X-ray sources. Also the first time a chaotic light source is fully characterized. 2004 CLEO/IQEC, San Francisco, May 15-21

  13. SASE FELs are chaotic light sources…… Chaotic light Candles + incandescent lights Stars The sun but with longer coherence length and a single spatial mode. Each time spike represents a coherence region. 2004 CLEO/IQEC, San Francisco, May 15-21

  14. Seeding a SASE for better ……. FERMI@ELETTRA, scheme demonstrated at Brookhaven National Lab • Better longitudinal coherence/coherence control • Shorter pulse duration/Pulse shaping • Partly losing tunability…… 2004 CLEO/IQEC, San Francisco, May 15-21

  15. Acknowledgements J. Lewellen, V. Sajaev, K.-J. Kim, S. V. Milton, O. Makarov, R. Dejus (ANL) S. Krinsky (BNL) Z. Huang (SLAC) Work supported by the U. S. Department of Energy, Office of Basic Energy Sciences, Contract No. W-31-109-ENG-38. 2004 CLEO/IQEC, San Francisco, May 15-21

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