1. 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 SATURATION of THE NSLS DUV-FEL AT BNL

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

3. Deep UV Free Electron Laser at the Source Development Laboratory Modulator Wiggler : L = 0.8 m w = 8 cm K = 1.67 Dispersion Magnet: L = 30 cm  = 3 for 30 MW seed laser Radiator (NISUS) Wiggler: L = 10 m, w = 3.89 cm B = 0.31 T, K = 1.126

4. Undulator & Electron Beam Parameters Energy177 MeV Charge300 pC Normalized emittance4 mm * mrad Compressed bunch length, RMS0.3-0.6 ps Energy spread, RMS0.05 % Period3.89 cm Number of periods (length)256 (10 m) Peak field0.31 T Betatron wavelength25 m Electron beam size, RMS (4 mm mrad)250 um Undulator NISUS parameters Measured electron beam parameters

5. HGHG FEL hardware 9 YAG Triplet 3 QA QB QA 1918 Modulator 17 DS 1516 th/tv12th/tv11 NISUS Spectrometer

6. Measurements of Electron Beam Properties Longitudinal beam parameters -0.500.51 0 100 200 300 400 Time (ps)  rms = 400 fs Transverse beam parameters Q = 300 pC measured by zero-phasing method Measured by pop-in monitors along the NISUS Matching and alignment is done by automated MATLAB routines

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

8. NISUS Wiggler Diagnostics Alignment laser

9. HGHG Gain Measurements For 30 MW seed power  = 3 HGHG saturates at 5 th m in NISUS yielding ~100  J energy For 1.8 MW seed power  = 8.7 HGHG saturates at the end of NISUS Energy vs. distance along the wiggler

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

11. HGHG and SASE measured spectra under same electron beam conditions HGHG spectral brightness is 2x10 5 times larger than SASE spectral brightness 0.23 nm FWHM x 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 x Spectrum of HGHG and SASE at 266 nm

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

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. First User Experiment in DUV-FEL Ion Pair Imaging Spectroscopy F-F- CH 3 + Molecular Beam Source Imaging MCP Detector CCD Camera Skimmer VUV 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. CH 3 F* CH 3 F 88 nm HGHG CH 3 + -F - K.E.R. CH 3 + +F - Image Super excited dynamics states

15. First User Experiment in DUV-FEL

16. Summary & Conclusions n 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 n Spectrum of HGHG is measured to be narrow compare to SASE spectrum (2.3 Å) n Output energy is measured to be stable (7% RMS) which is mainly limited by the accelerator performance n Pulse length is measured to be 0.6 - 1 ps which proves that HGHG output is temporally nearly Fourier transform limited n The 3 rd harmonic (88nm) of the HGHG is used in a chemistry experiment