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SATURATION of THE NSLS DUV-FEL AT BNL

SATURATION of THE NSLS DUV-FEL AT BNL. A. Doyuran, L. DiMauro, W. Graves, R. Heese, E . D. Johnson, S. Krinsky, H. Loos, J.B. Murphy, G. Rakowsky, J. Rose, T. Shaftan, B. Sheehy, Y. Shen, J. Skaritka, X.J. Wang, Z. Wu, L.H. Yu National Synchrotron Light Source

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SATURATION of THE NSLS DUV-FEL AT BNL

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  1. SATURATION of THE NSLS DUV-FEL AT BNL A. Doyuran, L. DiMauro, W. Graves, R. Heese, E. D. Johnson, S. Krinsky, H. Loos, J.B. Murphy, G. Rakowsky, J. Rose, T. Shaftan, B. Sheehy, Y. Shen, J. Skaritka, X.J. Wang, Z. Wu, L.H. Yu National Synchrotron Light Source Brookhaven National Laboratory

  2. HGHG FEL HGHG OUTPUT * 266 nm, ~ 100 uJ, 1 ps (FWHM) * 88 nm, ~ 1 uJ SEED LASER 800 nm, ~ 30 MW MODULATOR RADIATOR d=3.89 cm, L=10 m, B=0.31 T d=8 cm L=80 cm B=0.22 T DISPERSIVE SECTION ELECTRON BEAM

  3. Deep UV Free Electron Laserat the Source Development Laboratory Dispersion Magnet: L = 30 cm dy/dg = 3 for 30 MW seed laser Modulator Wiggler : L = 0.8 m lw = 8 cm K = 1.67 Radiator (NISUS) Wiggler: L = 10 m, lw = 3.89 cm B = 0.31 T, K = 1.126

  4. Undulator & Electron Beam Parameters Measured electron beam parameters Undulator NISUS parameters

  5. HGHG FEL hardware NISUS th/tv12 th/tv11 QA QB QA Modulator DS YAG Triplet 3 19 18 17 16 15 9 Spectrometer

  6. Measurements of Electron Beam Properties 400 s = 400 fs rms 300 200 100 0 -1 -0.5 0 0.5 1 Time (ps) Longitudinal beam parameters Transverse beam parameters Measured by pop-in monitors along the NISUS Matching and alignment is done by automated MATLAB routines Q = 300 pC measured by zero-phasing method

  7. Beam based alignment of NISUS wiggler Initial (green) and corrected (blue) Beam trajectories (green) relative beam trajectories along the wiggler to the alignment laser (blue)

  8. NISUS Wiggler Diagnostics Alignment laser

  9. HGHG Gain Measurements Energy vs. distance along the wiggler For 30 MW seed power dy/dg = 3 HGHG saturates at 5th m in NISUS yielding ~100mJ energy For 1.8 MW seed power dy/dg = 8.7 HGHG saturates at the end of NISUS

  10. Shot to shot intensity fluctuations for SASE and HGHG SASE HGHG

  11. x x 0.23 nm FWHM Spectrum of HGHG and SASE at 266 nm HGHG and SASE measured spectra under same electron beam conditions HGHG spectral brightness is 2x105 timeslarger than SASE spectral brightness SASE spectrum is calculated with GENESIS by H. Loos after 20 m of the NISUS structure to have a fair comparison with HGHG SASE spectral brightness would still be lower than HGHG by an order of magnitude

  12. 0.35nm Estimation of SASE Pulse Length from Spectrum S. Krinsky and R.L. Gluckstern, Nucl. Instrum. Meth. A483, 57 (2002 Electron beam is ~1 ps FWHM

  13. HGHG Pulse Length Measurements Two-photon absorption pump probe autocorrelation trace • Pulse length is 0.63 ps • Seed laser 1.8 MW • Saturation at the end of wiggler

  14. K.E.R. CCD CH3++F- CH3F* CH3+-F- Camera 88 nm HGHG Imaging MCP Image Detector CH3F Super excited dynamics states VUV Skimmer Molecular Beam Source First User Experiment in DUV-FEL Ion Pair Imaging Spectroscopy F- IPIS Technique: Excitation of a molecule in the VUV/XUV accesses ion-pair states that dissociate. If one of the products is structureless (such as F-), then the kinetic energy release directly reflects the internal energy in the other product and the dynamics of the process. CH3+

  15. First User Experiment in DUV-FEL

  16. Summary & Conclusions • Gain of DUV-FEL at 266 nm has been studied for various seed laser powers. HGHG FEL saturates at the middle of the 10 m long NISUS wiggler • Spectrum of HGHG is measured to be narrow compare to SASE spectrum (2.3 Å) • Output energy is measured to be stable (7% RMS) which is mainly limited by the accelerator performance • Pulse length is measured to be 0.6 - 1 ps which proves that HGHG output is temporally nearly Fourier transform limited • The 3rd harmonic (88nm) of the HGHG is used in a chemistry experiment

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