1. What did we learn from TTF1 FEL? P. Castro (DESY)

2. Just to mention... Coupler effect in beam dynamics Energy oscillations in detuned cavities Long bunch train operation Gun trips/operation (covered by K. Flöttmann) Golden orbits in undulator …

3. Index: 1) Bunch compression 2) Diagnostics 3) Stability 4) Reproducibility

4. 1) Longitudinal bunch compression magnetic bunch compression

5. streak camera measurements of dipole radiation with a bandpass filter 515 ± 5 nm all single meas. average coherent transition radiation interferometry long. phase space tomography Long. bunch profile measurements at TTF1 3 mm = 10 ps

6. momentum time/longitudinal position (Simulation)Compression at TTF1 time/longitudinal position

7. momentum time/longitudinal position (Simulation)Compression at TTF1 time/longitudinal position

8. momentum time/longitudinal position (Simulation)Compression at TTF1

9. Coherent Synchrotron Radiation (CSR)  bend-plane emittance growth  s xx zz Power Wavelength coherent power incoherent power vacuum chamber cutoff N  6  10 9 e–e–e–e– R zzzz coherent radiation for  z  L0L0L0L0 effect

10. CSR effects in TTF1 screen energy

11. CSR effects in TTF1 screen energy

12. T. Limberg, P. Piot, et al. TraFiC 4 simulation CSR effects in TTF1 screen energy

13. compressor settings 1: short bunches compressor settings 2: long bunches τ len ~ 50 fs τ len ~ 100 fs long. modes: M  6 - 10 long. modes: M  2 - 3 Ability to tune the length of radiation pulse demonstrated at TTF1  z between 30 and 100 fs 10 and 30 μm

14. Bunch compression (summary) long. profile well understood: very short peak observed in agreement with photon beam measurements strong CSR effect on beam energy observed photon pulse length tuned between 30 and 100 fs (using two bunch compressors)

15. 2) Beam diagnostics long. profile monitors at resolution limit new techniques needed: EOS, deflecting cavity, … emittance meas. (quad. scan, wirescanner) initially failed BPMs in undulator and/or just upstream useful for reproducibility of SASE photon diagnostics were essential

16. First spectrum of SASE at TTF1 Photon diagnostics

17. Photon intensity monitor: large range: non-destructive position sensitive absolute calib. 50% signal decay in bunch train mostly used for SASE optimization

18. saturation at 98 nm (10 Sept. 2001)

19. fluctuations at 9 m

20. saturation at 98 nm (10 Sept. 2001) fluctuations at 9 m fluctuations at 14 m

21. saturation at 98 nm (10 Sept. 2001) fluctuations at 9 m fluctuations at 14 m statistical properties of SASE intensity extensively studied full characterization of the photon beam

22. Essential photon beam diagnostics: single bunch spectrum measurement: wavelength and intensity intensity meas. (non-destructive preferred) position monitor: photon beam not always on axis integrated into control system for optimization and for correlation studies!

23. E [  J]  [  s] Long term stabilityStability in bunch train 3) SASE stability at TTF1 SASE gain ~ 10 6 (a factor 10 below saturation) 4 hours SASE operation

24. E [  J]  [  s] Long term stabilityStability in bunch train SASE stability at TTF1 SASE gain ~ 10 6 (a factor 10 below saturation) 4 hours SASE operation

25. Time jitter of the electron beam Measured with streak camera by Ch.Gerth et al. (Proc. FEL Conf. 2002)

26. Beam stability (summary) good stability for SASE in TTF1 timing jitter measured: 0.6 ps RMS requirements for TTF2 1° ~ 0.6 mm = 2 ps minutes of timing meeting 30.4.03

27. 4) Reproducibility of SASE once SASE found/seen SASE found again after other experiments, shutdowns, etc. high sensitivity to magnet settings/cycling change to new energy/wavelength was a challenge all parameters have to be correct low energy / oversized magnets compression and optics changes

28. Wavelength tunability 1st lasing detuning cavities changing klystron 2 settings (modules ACC1 and ACC2)

29. later lasing was found with bunches of about 3 nC first lasing saturation was achieved with bunches of about 3 nC