Soft X-ray Self Seeding at LCLS FEL14. D. Ratner on behalf of SXRSS team Aug. 26, 2014

Transcription

1 Soft X-ray Self Seeding at LCLS FEL14 D. Ratner on behalf of SXRSS team Aug. 26, 2014

2 Self-Seeded FEL Concept SASE vs. Seeding Time Domain Frequency Domain Intensity (arb. units) SASE Intensity (arb. units) SASE Time (arb. units) Frequency (arb. units) 2

3 Self-Seeded FEL Concept SASE vs. Seeding Time Domain Frequency Domain Intensity (arb. units) Seeded SASE Intensity (arb. units) SASE Time (arb. units) Frequency (arb. units) 3

4 Self-Seeded FEL Concept SASE vs. Seeding Time Domain Frequency Domain Intensity (arb. units) Seeded SASE Intensity (arb. units) Seeded SASE Time (arb. units) Frequency (arb. units) 4

5 Self-Seeded FEL Concept SASE vs. Seeding Time Domain Frequency Domain Intensity (arb. units) Seeded SASE Intensity (arb. units) Seeded SASE Time (arb. units) Frequency (arb. units) 5

6 Self-Seeded FEL Concept SASE vs. Seeding Time Domain Frequency Domain Intensity (arb. units) Seeded SASE Intensity (arb. units) Seeded SASE Time (arb. units) Frequency (arb. units) 6

7 Self-Seeded FEL Concept SASE vs. Seeding SASE Seeded One problem: Time (arb. units) Intensity nsity ty (arb. units) Intensity (arb. units) Time Domain Frequency Domain Seeded 500 SASE 400 Where s the 1nm seed? Frequency (arb. units) 7

8 Self-Seeded FEL Concept SASE vs. Seeding SASE Seeded One problem: Time (arb. units) Intensity Inten nsitty (arb. units) Intensity (arb. units) Time Domain Frequency Domain Seeded 500 SASE 400 Where s the 1nm seed? Frequency (arb. units) 8

9 Self-Seeded FEL Concept Self-Seeding: The FEL seeds itself! J. Feldhaus et al., Optics Comm, 140,

10 Self-Seeded FEL Concept Self-Seeding: The FEL seeds itself! 70 Density (arb. units) Position (z/ ) FEL J. Feldhaus et al., Optics Comm, 140,

11 Self-Seeded FEL Concept Self-Seeding: The FEL seeds itself! Two components: a) Monochromator selects narrow-bandwidth seed 70 Density (arb. units) Position (z/ ) FEL J. Feldhaus et al., Optics Comm, 140,

12 Self-Seeded FEL Concept Self-Seeding: The FEL seeds itself! Two components: a) Monochromator selects narrow-bandwidth seed 70 Density (arb. units) FEL FEL Position (z/ ) J. Feldhaus et al., Optics Comm, 140,

13 Self-Seeded FEL Concept Self-Seeding: The FEL seeds itself! Two components: a) Monochromator selects narrow-bandwidth seed b) Chicane resets electron bunch to shot noise, matches delay of x- rays, and steers e- around optics electrons 70 Density (arb. units) FEL FEL Position (z/ ) J. Feldhaus et al., Optics Comm, 140,

14 Self-Seeded FEL Concept Self-Seeding: The FEL seeds itself! Two components: a) Monochromator selects narrow-bandwidth seed b) Chicane resets electron bunch to shot noise, matches delay of x- rays, and steers e- around optics Soft X-ray Self-Seeding Design chicane shot noise SASE bunching shot noise Seeded bunching 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ Y. Feng et al., FEL12, Nara, Japan, D. Cocco et al., Proc. SPIE, M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 14

15 Self-Seeded FEL Concept chicane shot noise SASE bunching shot noise Seeded bunching 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - wire BOD YAG Y. Feng et al., FEL12, Nara, Japan, D. Cocco et al., Proc. SPIE,

16 Self-Seeded FEL Concept chicane shot noise SASE bunching shot noise Seeded bunching 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - wire YAGSLIT Sapphire BOD YAG Y. Feng et al., FEL12, Nara, Japan, D. Cocco et al., Proc. SPIE,

17 Self-Seeded FEL Concept chicane shot noise SASE bunching shot noise Seeded bunching 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - wire YAGSLIT Sapphire BOD YAG Y. Feng et al., FEL12, Nara, Japan, D. Cocco et al., Proc. SPIE,

18 Physics requirements for SXRSS Physics and Location Constraints for Mono: 1) Provide resolving power greater than or equal to ) Energy range ev 3) Fit mono in 4m space (single undulator) 4) X-rays delayed less than 1 ps (to fit chicane) Und 9 Und 16 SXRSS HXRSS Y. Feng et al., FEL12, Nara, Japan, D. Cocco et al., Proc. SPIE,

19 Physics requirements for SXRSS Engineering Challenges 1. 3 optics chambers, 2 diagnostic chambers, 9 motors 2. Tight machine, alignment, and motion constraints 3. Challenging schedule Big thanks to N. Rodes, K. Chow, P. Montanez and the machine, tech, and alignment teams that made this possible 19

20 Optics design for SXRSS Optics designed by PSI, manufactured in Germany 20

21 Mechanical design for SXRSS Optics chambers designed by LBNL 21

22 Mechanical design for SXRSS Chicane and beam overlap designed at SLAC 22

23 Commissioning HXRSS 1 optical component SXRSS 5 optical components and 2 diagnostics chicane 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 23

24 Commissioning Commissioning Challenges 1. Setup SASE FEL in first section (not too much, not too little) 2. Track X-rays through the 5-component Monochromator 3. Measure positions of both electrons and X-rays 4. Overlap X-rays and electrons transversely 5. Overlap X-rays and electrons temporally chicane 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 24

25 Commissioning Commissioning Challenges Coherent radiation an obstacle for overlap diagnostics Coherent radiation X-rays electron wires 25

26 Commissioning Damage concerns Compromise between need to seed, and damage threshold To much pulse energy destroys grating 26

27 Commissioning Damage concerns Compromise between need to seed, and damage threshold To much pulse energy destroys grating 10 3 Single-shot (lower limit) Multi-shot damage Fluence (mj/cm 2 ) uJ, U8 IN 10 0 Minimum seed, 50fs pulse Photon energy (ev)

28 Commissioning Damage concerns Compromise between need to seed, and damage threshold To much pulse energy destroys grating 10 3 Single-shot (lower limit) Multi-shot damage Fluence (mj/cm 2 ) uJ, U8 IN 5uJ, U8 OUT 10 0 Minimum seed, 50fs pulse Photon energy (ev)

29 Commissioning Damage concerns Compromise between need to seed, and damage threshold To much pulse energy destroys grating 10 3 Single-shot (lower limit) Multi-shot damage Fluence (mj/cm 2 ) uJ, U8 IN 50x 5uJ, U8 OUT 10 0 Minimum seed, 50fs pulse Photon energy (ev)

30 y (mm) Commissioning Profile Monitor SXR:EXS:CVV:01 20Dec :46: ev Dec. 20, x (mm) Bandwidth (arb. units) First seeding! SXR spectrometer, 800 ev (resolution limited) 0.4 ev x shots average 5 3 Seeded Und x 105 Sase 20 consecutive shots average SASE Und

31 y (mm) Commissioning Profile Monitor SXR:EXS:CVV:01 20Dec :46: ev Dec. 20, x (mm) Bandwidth (arb. units) First seeding! SXR spectrometer, 800 ev (resolution limited) 0.4 ev x shots average Seeded Und x 105 Sase 20 consecutive shots average SASE Und ev E/E ev E/E

32 Commissioning Seeding with 2 nd order diffraction G beam direction chicane 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators 32 e -

33 Commissioning Seeding with 2 nd order diffraction G beam direction 2 nd order chicane 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators 33 e -

34 Commissioning Seeding with 2 nd order diffraction G beam direction 2 nd order chicane 1 st undulator 2 nd undulator e - grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators 34 e -

35 SXRSS Limitations Why isn t everything perfect? It s all the accelerator s fault: a) Fundamental SASE jitter b) Electron energy jitter c) Electron orbit jitter d) Nonlinear phase space of electron bunch e) Jitter of electron bunch phase space 35

36 SXRSS Limitations SASE Jitter Jitter Issues Electron Energy Jitter Frequency (arb. units) FEL Power Mustache plot Energy jitter 2.5 yr history Electron energy T. Maxwell 36

37 SXRSS Limitations Electron Phase Space LH:22.3 J Relative energy (MeV) R Longitudinal position (um) chicane e - 1 st undulator grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 37

38 SXRSS Limitations Electron Phase Space LH:22.3 J Relative energy (MeV) R56 Acts like chicane R56 = 2 N u Longitudinal position (um) chicane e - 1 st undulator grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 38

39 SXRSS Limitations Electron Phase Space LH:22.3 J Relative energy (MeV) R56 Acts like chicane R56 = 2 N u Longitudinal position (um) chicane e - 1 st undulator grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 39

40 SXRSS Limitations Electron Phase Space LH:22.3 J Relative energy (MeV) R56 Acts like chicane R56 = 2 N u Longitudinal position (um) chicane e - 1 st undulator grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 40

41 SXRSS Limitations Relative energy (MeV) Electron Phase Space LH:22.3 J Longitudinal position (um) chicane Normalized spectral brightness Slotted foil selects part of the beam slot10500 slot7000 slot5500 slot Photon energy (pixels) e - 1 st undulator grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 41

42 SXRSS Limitations Relative energy (MeV) Electron Phase Space LH:22.3 J Longitudinal position (um) chicane Normalized spectral brightness Slotted foil selects part of the beam Shoulders from nonlinear chirp? slot10500 slot7000 slot5500 slot Photon energy (pixels) e - 1 st undulator grating M3 SASE FEL 6-8 undulators X-rays 1uJ M1 slit M2 1nJ BOD10 BOD13 Seeded FEL 22 undulators e - 42

43 SXRSS Limitations Seeded wavelength stability Wavelength is stable to around 10-4 but still widens average bandwidth by ~15% raw single shots aligned single shots 43

44 SXRSS Limitations Seeded wavelength stability Wavelength is stable to around 10-4 but still widens average bandwidth by ~15% Chirp changes shot-to-shot 10 Relative energy (MeV) Longitudinal position (um) 44

45 SXRSS Limitations Seeded wavelength stability Wavelength is stable to around 10-4 but still widens average bandwidth by ~15% Chirp changes shot-to-shot 10 LH:22.3 J Relative energy (MeV) Longitudinal position (um) 45

46 SXRSS Limitations Seeded wavelength stability Wavelength is stable to around 10-4 but still widens average bandwidth by ~15% Chirp changes shot-to-shot Electron orbit changes shot-to-shot LH:22.3 J 10 Undulator Relative energy (MeV) e Longitudinal position (um) 46

47 SXRSS Limitations Seeded wavelength stability Wavelength is stable to around 10-4 but still widens average bandwidth by ~15% Chirp changes shot-to-shot Electron orbit changes shot-to-shot LH:22.3 J 10 Undulator Relative energy (MeV) e Longitudinal position (um) 47

48 SXRSS Limitations Need robust, available X-ray diagnostics: Transmissive SXR Spectrometer 48

49 July 29 th, 930 ev Latest Seeding Results (Undulators inserted for seeding) Seeding, 50fs (foil) SASE, 50fs (foil) 49

50 July 29 th, 930 ev Latest Seeding Results (Undulators inserted for seeding) 5x brighter Seeding, 50fs (foil) SASE, 50fs (foil) 50

51 July 29 th, 930 ev Latest Seeding Results (Undulators inserted for seeding) 5x brighter Seeding, 50fs (foil) SASE, 100fs SASE, 50fs (foil) 51

52 July 29 th, 930 ev Latest Seeding Results (Undulators inserted for seeding) 5x brighter 3x brighter Seeding, 50fs (foil) SASE, 100fs SASE, 50fs (foil) 52

53 July 29 th, 930 ev Latest Seeding Results Electron energy jitter limits seeding performance e- jitter > gain bandwidth Reducing jitter can double average brightness Gas detector intensity (mj) All shots e- energy cut e- energy histogram e- energy cut SASE e- energy cut, seed All shots, seed SASE Relative electron energy (E/E ) 0 53

54 July 29 th, 930 ev Avoiding Hutch Mono Undulators inserted Fraction of power in bandwidth Bandwidth (mev) Seeding, 50fs (foil) SASE, 50fs (foil) 54

55 July 29 th, 930 ev Avoiding Hutch Mono Undulators inserted Fraction of power in bandwidth % of power in 200 ev bandwidth Bandwidth (mev) Seeding, 50fs (foil) SASE, 50fs (foil) 55

56 July 29 th, 930 ev Avoiding Hutch Mono Hutch monochoromator loses factor of 10 or more in brightness Avoid mono and brightness increases factor of >50! Undulators inserted Fraction of power in bandwidth % of power in 200 ev bandwidth Bandwidth (mev) Seeding, 50fs (foil) SASE, 50fs (foil) 56

57 July 29 th, 930 ev Seeded gain length (930 ev) Gain length ~ 2m 57

58 July 29 th, 930 ev Seeded gain length (930 ev) Gain length ~ 2m During seeded d operation 58

59 Next Steps Accomplished Goals: 1. Achieved self-seeding at soft X-rays 2. Demonstrated seeding across ev range 3. Observe up to factor of ~5-50 increase in average brightness 4. Reach up to ~5000 resolving power 5. Wavelength stability of

60 Next Steps Accomplished Goals: 1. Achieved self-seeding at soft X-rays 2. Demonstrated seeding across ev range 3. Observe up to factor of ~5-50 increase in average brightness 4. Reach up to ~5000 resolving power 5. Wavelength stability of 10-4 Still to do: 1. Study optimal seeding conditions (vs. seed power, slit size, etc.) 2. Optimize taper to maximize seeding vs. SASE 3. Improve setup to reduce time, improve stability, and attract users 60

61 Next Steps Reducing setup time Target: Less than 30 minutes to switch from SASE to seed Low level GUIs to organize components High level programs to guide operators 61

62 Thanks! On behalf of SXRSS team: Thanks to the enormous group of people who made this project possible! 62