1. Lecture 6. New FEL Schemes and Challenges X-Ray Free Electron Lasers Igor Zagorodnov Deutsches Elektronen Synchrotron TU Darmstadt, Fachbereich 18 22. June 2014

2. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 2 Contents  Motivation  Self-seeding scheme  Nonlinear harmonic generation  High-gain harmonic generation (HGHG)  Echo-enabled harmonic generation (EEHG)  Harmonic lasing  Purified SASE scheme (pSASE)  Energy spread cooling scheme  Table-top FEL  Outlook

3. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 3 electrons radiation Motivation Longitudinal profile with large statical fluctuations Transverse profile is coherent Coherence

4. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 4 Motivation Coherence Cooperation length: l c ~  π ρ (slippage length within one gain length) FEL spectrum c/  πl c c/l b FEL power πlc πlc lb lb seed

5. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 5 Self-seeding scheme J. Feldhaus et al, Opt.Comm. 140, p.341 (1997) G.Geloni et al, DESY 10-033 (2010)  SASE in the first undulator  monochromator filters the radiation  „seeded“ amplification in the second undulator  Grating monochromator  Gas cell monochromator SASE SASE-FEL electronen radiation amplifier monochromator

6. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 6 Non-linear harmonic generation Higher harmonics in undulator (spontaneous radiation) Spectral density in forward direction. The absolute bandwidth is the same

7. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 7 Non-linear harmonic generation Higher harmonics in FEL radiation Coupling factor in Lecture 3?

8. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 8 Non-linear harmonic generation A steady energy transfer? The electron energy changes as described by the equation

9. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 9 Nonlinear harmonic generation

10. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 10 Nonlinear harmonic generation A steady energy transfer?

11. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 11 Nonlinear harmonic generation Effective coupling factors

12. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 12 Nonlinear harmonic generation K = 1 K = 3 K = 10 Ratio of power gain length at the n-th harmonic to that at the fundamental:

13. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 13 Nonlinear harmonic generation Normalized high-gain FEL model

14. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 14 Nonlinear harmonic generation

15. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 15 Nonlinear harmonic generation

16. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 16 Nonlinear harmonic generation  Near saturation, roughly 1% of the power of fundamental is emitted in the third harmonic  Spectrum has the same width as that of the fundamental  The maximal power is decreasing function of harmonic number  Nonlinear harmonics have larger statistical power fluctuations from shot to shot

17. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 17 High-gain harmonic generation (HGHG)  energy modulation with frequency ω  conversion in density modulations  coherent radiation with frequency nω in radiator section

18. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 18 High-gain harmonic generation (HGHG)  in modulator energy changes  phase remains approx. the same

19. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 19 High-gain harmonic generation (HGHG)  in chicane higher energy particles are bent less than lower energy particles  energy of particles remains approx. the same

20. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 20 High-gain harmonic generation (HGHG)

21. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 21 High-gain harmonic generation (HGHG)

22. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 22 High-gain harmonic generation (HGHG) L.H.Yu et al, PRL 91, 074801 (2003) HGHG was demonstrated at the third harmonic of 800 nm temporally coherent radiation

23. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 23 Echo-enabled harmonic generation G. Stupakov, PRL 102, 074801 (2009)

24. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 24 Echo-enabled harmonic generation

25. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 25 Echo-enabled harmonic generation

26. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 26 Echo-enabled harmonic generation For HGHG For EEHG

27. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 27 Echo-enabled harmonic generation  the first laser produces energy modulation  the first chicane is strong, rotates phase space  the second laser produces again energy modulation  The second chicane converts the energy modulation in density modulation G. Stupakov, PRL 102, 074801 (2009)

28. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 28 Echo-enabled harmonic generation D.Xiang et al, PRL D.Xiang et al, PRL 108, 024802 (2012) experiment for EEHGonly the second laser ON both lasers ON

29. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 29 Harmonic lasing non-linear harmonic generation harmonic lasing

30. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 30 Harmonic lasing retuned to fundamental harmonic only

31. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 31 Harmonic lasing retuned to fundamental harmonic only

32. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 32 Harmonic lasing

33. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 33 Purified SASE scheme U1 U2 U3 … … U7 U8 U9 U10 U11 U12 U13 … U18 K = 2, λ 1 =0.6 nm 6 GeV K =6.3,λ 1 =4.2 nm λ 1 =0.6 nm

34. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 34 Purified SASE scheme U1 U2 U3 … … U7 U8 U9 U10 U11 U12 U13 … U18 K = 2, λ 1 =0.6 nm 6 GeV K =6.3,λ 1 =4.2 nm λ 1 =0.6 nm At the exit of U10 At the exit of U11 At the exit of U9  πl c ≈ 1 fs At the exit of U12  πl c ≈ 4~ 5 fs

35. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 35 Energy spread cooling scheme H.Deng, arXiv:1305.7041 (2013)

36. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 36 Energy spread cooling scheme

37. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 37 Energy spread cooling scheme Two electrons through modulator

38. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 38 Energy spread cooling scheme H.Deng, arXiv:1305.7041 (2013)

39. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 39 Energy spread cooling scheme H.Deng, arXiv:1305.7041 (2013)

40. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 40 Energy spread cooling scheme 1D simulations 3D simulations H.Deng, arXiv:1305.7041 (2013)

41. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 41 Table-top FEL External injection

42. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 42 Table-top FEL “Bubble” regime

43. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 43 Table-top FEL M.Fuchs et al, Nature Physics 5, 826(2009) H.-P. Schlenvoigt et al, Nature Physics 4, 130 (2008)  λ=740 nm  λ=17 nm spontaneous undulator radiation with laser-plasma accelerator

44. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 44 Table-top FEL M.Fuchs et al, Nature Physics 5, 826(2009) no FEL radiation so far

45. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 45 European XFEL 3rd SR generation 2nd SR generation 1st SRs Outlook Growth of brillance of X-ray and growth of computer power

46. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 46 Outlook Saturation? Wavelength of radiation λ= 0.25 A MaRIE (Los Alamos) concept Q. R. Marksteiner, FEL 2011, TUPA28, 2011 λ=0.5 A

47. PD Dr. Igor Zagorodnov| X-Ray Free Electron Lasers. Lecture 6 | 22. June 2014 | Seite 47 Outlook  shorter wave length  shorter radiation pulses  higher brilliance  longitudinal coherence  compact facilities „Meine Vision für DESY ist dass wir die deutsche Nobelpreisschmiede werden.“ Professor Helmut Dosch (Film „Licht der Zukunft“)