Femto second FEL Generation with Very Low Charge at LCLS

Transcription

1 Femto second FEL Generation with Very Low Charge at LCLS Yuantao Ding, For the LCLS commissioning team X ray Science at the Femtosecond to Attosecond Frontier workshop May 18 20, 2009, UCLA SLAC PUB 13525; PAC09, WE5RFP040 ( with C. Pellegrini ).

2 14 GeV, 20 pc : Elegant and Genesis simulations, Over compression 1 (L2 = 34.5 deg) UNDBEG(14 GeV) Longitudinal phase space Current profile head Average FEL power along undulator X ray FEL power 120 m 2 fs head 2.8e11 photons

3 Preliminary measurements at 1.5 Å, 20 pc Preliminary FEL measurements show an FEL gain over 5 orders, and the electron energy loss due to FEL is ~ 60 μj. Absolute bunch length and FEL power haven t measured yet, and more studies will be done.

4 Summary Measured low emittance and short bunch with 20 pc; Expected ultrashot x ray pulses with hundreds of GW; Such high power, ultrashort x ray pulses may open up new applications; The achieved beam may enable a more compact design of a future x ray FEL; Thanks to SLAC engineering, controls, operations,and RF support groups; thanks to R. Fiorito, C. Pellegrini, G. Stupakov and D. Xiang for many discussions. Thanks Paul Emma for providing many slides.

5 Low Charge and Single Spike Operation of the Swiss FEL in the Soft X ray Regime Sven Reiche Workshop X ray Science at the Femtosecond to Attosecond Frontier UCLA May 18 th 20 th, 2009

6 FEL Performance: 10 pc (short), 7 Ångstrom #!!& Saturation Length 25 m Pulse Energy 15 µj Peak Power 20 GW Bandwidth (rms) 0.25 % Divergence (rms) 6 µrad.*+/- #!!( #!!' #!!#! Energy of FEL pulse Saturation Size (rms) 24 µm #!!#$! " #! #" $! $" %! %" &! )*+,- )! $! (! FEL Beam Size #( Divergence Angle '! "! #' #& #$! / +,"-. &! %!! " *+#./0- #! ( $! #! ' & $!! " #! #" $! $" %! %" &! *+,-.!! " #! #" $! $" %! %" &! )*+,-

7 Peak Power Fluctuation Energy Fluctuation Peak Power vs Pulse Length #" Undulator Exit #! Parameter Fluctuation )%&*+( Energy 30% " Power 30% Length 8% Bandwidth 15% Size 10%!! " #! #" $%&'$( $' $% $! Divergence 11% Spectrum (central frequency) 70% Brilliance 40% 12!3+,4"5"0 * ) ' %!!"# $ $"$ $"% $"& $"' $"( $")!+,-./0

8 Conclusion Low charge option included in the design of the Swiss FEL project. Lowest charge is 10 pc but only to a later stage the compression is increased to yield sub fs pulses (Improved RF stability) Sub fs pulses at any wavelength of the Swiss FEL. At 1 nm and longer, they pulses have only a single spike at saturation with some degradation in the post saturation regime. Despite having a single mode the resulting statistic of the FEL parameters is more stable (less intrinsic fluctuation) pushing the fluctuation in peak power, energy and spectrum below 50%

9 Workshop on X ray Science... Attosecond Frontier, UCLA, May 18, 2009 Electron Beam Generation and Stability Issues for the Coherent Single Spike Mode Operation with Ultra Low Charges Yujong Kim PSI, CH 5232 Villigen PSI, Switzerland yujong.kim@psi.ch, PSI XFEL

10 PSI XFEL Optimized Layouts New Injector Layout with Laser Heater & ~ 450 MeV Optimization XI with New Injector for 10 pc Single Spike Mode single spike mode at 0.1 nm with 2 pc rms bunch length ~ GeV Optimization VIII single spike mode at 1 nm with 10 pc rms bunch lenght ~ GeV Optimization XI photon photon rms BW ~ 0.2% rms BW ~ 0.67% rms pulse length ~ nm See details from Sven's talk later rms pulse length ~ nm peak power ~ 19 GW peak power ~ 10 GW photons : 3.3e9 Low Emittance Gun based PSI XFEL Project Yujong Kim of Paul Scherrer Institut, Switzerland photons = 1.1e10 10

11 10 pc Summary of Tolerances parameters tolerance (rms) tolerance source gun laser arrival timing error 1 fs (rms) saturation length, arrival time single bunch charge error 1% (rms) saturation power injector S band RF phase error deg (rms) power, wavelength, arrival time injector S band RF voltage error 0.005% (rms) arrival time injector X band RF phase error deg (rms) power, saturation length injector X band RF voltage error 0.011% (rms) arrival time BC1 dipole power supply error 7.5 ppm (rms) arrival time LINAC1 S band RF phase error per klystron deg (rms) wavelength, power LINAC1 S band RF voltage error per klystron 0.010% (rms) wavelength, arrival time BC2 dipole power supply error 7.5 ppm (rms) arrival time LINAC2 S band RF phase error per klystron deg (rms) wavelength LINAC2 S band RF voltage error per klystron 0.011% (rms) wavelength Tolerance Criteria for Single Component Error ΔT arrival 1.7 fs (rms) ΔP sat /P sat 33% (rms) Δλ/λ 0.003% (rms) ΔL sat /L sat 5% (rms) These are tolerances for the single spike mode at 1 nm with 10 pc. Tolerances of the single spike mode at 0.1 nm with 2 pc are much tighter than these things! Low Emittance Gun based PSI XFEL Project Yujong Kim of Paul Scherrer Institut, Switzerland 11

12 Summary By performing the invariant envelope matching properly, slice and projected emittances at the end of injector are very promising. They are smaller than 0.1 µm for 10 pc and smaller than 0.4 µm for 200 pc. Operations with 10 pc and 200 pc are considered as the nominal modes, while the ultra short mode with 10 pc will be considered as an upgrade option. By the help of the excellent emittance, we can use the low charge operation to generate the coherent single spike at X ray region. We designed 13 different linac layouts with S band and C band RF linacs. Among them, C band based ones satisfy our design goal more easily (linac length < about 530 m, saturation of FEL power within a 50 m long undulator). To minimize the bandwidth of XFEL photon beams, compensation of energy chirping is a critical thing, which is normally difficult for us to compensate with a short S band linac. To realize the stable single spike mode operation at 0.1 nm with 2 pc, it seems that we need ultra tight RF jitter tolerances. However, in case the other single spike mode at 1 nm with 10 pc, its required tolerances are somewhat looser. Therefore, we selected the single spike mode at 1 nm with 10 pc as an upgrade mode. Low Emittance Gun based PSI XFEL Project Yujong Kim of Paul Scherrer Institut, Switzerland 12

13 Generation of intense attosecond x ray pulses using Echo Enabled Harmonic Generation (EEHG) FEL Dao Xiang, SLAC in collaboration with Z. Huang and G. Stupakov Presented at the Workshop on X ray science at the femtosecond to attosecond frontier, UCLA, May,18~20, 2009 dxiang@slac.stanford.edu

14 The principles of EEHG FEL EEHG FEL classic HGHG FEL Separated energy bands Key advantage Separated current bands

15 Generating attosecond x ray pulse using EEHG FEL Single pulse selection with an intense few cycle laser

16 Generating attosecond x ray pulse using EEHG FEL 1 2 Before dispersion After dispersion After dispersion 20 as Allows one to generate 1nm x ray from a UV seed laser Allows one to generate x ray pulse beyond the atomic unit of time (~24 as) X ray power profile

17 Summary EEHG is a new promising working scheme EEHG allows one to generate high power soft x ray with narrow bandwidth close to Fourier transform limit directly from a UV seed laser in a single stage Combining EEHG with BC allows one to extend harmonic numbers to a few hundred and make possible the generation of an isolated intense attosecond x ray pulse from a UV seed laser We thank A. Chao, Y. Ding, J. Wu, D. Ratner, P. Emma, W. Fawley, A. Zholents, S. Reiche, M. Borland for helpful discussions. Thanks!

18 Energy up grading of the SPARC photo injector, with a C band RF system R. Boni on behalf of the SPARC group Workshop on X ray Science at the Femtosecond to Attosecond Frontier UCLA, May 18 20, 2009 SPARC GROUP D. Alesini, M. Bellaveglia, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M.Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, B. Marchetti, A. Marinelli, A. Marcelli, M. Migliorati, A. Mostacci, E. Pace, L. Palumbo, L. Pellegrino, R. Ricci, U. Rotundo, C. Sanelli, F. Sgamma, B. Spataro, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario, INFN LNF, Frascati, RM, Italy. F. Ciocci, G. Dattoli, M. Del Franco, A. Dipace, A. Doria, G. P. Gallerano, L. Giannessi, E. Giovenale, G. L. Orlandi, S. Pagnutti, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia, I. Spassovsky, V. Surrenti, ENEA C.R. Frascati, RM, Italy. A. Bacci, I. Boscolo, F.Broggi, F. Castelli, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, V. Petrillo, A.R. Rossi, L. Serafini, INFN Mi, Milano, Italy. M. Mattioli, M. Petrarca, M. Serluca, INFN Roma I, Roma, Italy. L. Catani, A. Cianchi, INFN Roma II, RM, Italy. J. Rosenzweig, UCLA, Los Angeles, CA, USA. M. E. Couprie, SOLEIL, Gif sur Yvette, France M. Bougeard, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Salières, O. Tchebakoff, CEA Saclay, DSM/DRECAM, France.

19 SPARC energy up grading. C band Station 5712 MHz 50 MW/2.5µs C band ENERGY COMPRESSOR 90 MW/0.5µs S BAND Station 2856 MHz 45 MW Klystron N 1 40 MW 40 MW HIGH GRADIENT SECTION 120 MeV 9 MW E 240 MeV C band acc. structures 35 MV/m E 105 MeV ACC. STRUCTURE ACC. STRUCTURE 50 MW 50 MW GUN Up graded layout ΔE MeV 120 MW/0.8µs ENERGY COMPRESSOR Klystron N 2 S BAND Station 2856 MHz 45 MW X ray Science at the Femto to Attosecond Frontier UCLA, May 18 20, 2009

20 HV PULSED MODULATOR SCANDINOVA MODULATOR Full Solid State system 1400 mm NICHICON MODULATOR X ray Science at the Femto to Attosecond Frontier UCLA, May 18 20, 2009 Standard design with PFN & Thy.. but very compact because immersed in oil courtesy T. Shintake 1000 mm

21 Conclusions & Outlook % The SPARC energy up grading to > 200 MeV will be made with a C band system. % An R&D program to develop the C band sections at LNF is about to start. We aim to realize two GHz, TW, CI, 2p/3, 1.5 m. accel. Structures. % A call for tender will be issued after summer to purchase the power modulator % The klystron is supplied by a sole company. The order will be made in autumn X ray Science at the Femto to Attosecond Frontier UCLA, May 18 20, 2009