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

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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

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HGHG FEL
HGHG OUTPUT 266 nm, 100 uJ, 1 ps (FWHM) 88
nm, 1 uJ
SEED LASER 800 nm, 30 MW
MODULATOR
RADIATOR
d3.89 cm, L10 m, B0.31 T
d8 cm L80 cm B0.22 T
DISPERSIVE SECTION
ELECTRON BEAM
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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
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Undulator Electron Beam Parameters
Measured electron beam parameters
Energy 177 MeV
Charge 300 pC
Normalized emittance 4 mmmrad
Compressed bunch length, RMS 0.3-0.6 ps
Energy spread, RMS 0.05
Undulator NISUS parameters
Period 3.89 cm
Number of periods (length) 256 (10 m)
Peak field 0.31 T
Betatron wavelength 25 m
Electron beam size, RMS (4 mm mrad) 250 um
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HGHG FEL hardware
NISUS
QA QB QA
th/tv12
th/tv11
Modulator
DS
YAG
Triplet 3
9
19
18
17
15
16
Spectrometer
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Measurements of Electron Beam Properties
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
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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)

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NISUS Wiggler Diagnostics
Alignment laser
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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
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Shot to shot intensity fluctuations for SASE and
HGHG
SASE
HGHG
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Spectrum of HGHG and SASE at 266 nm
HGHG and SASE measured spectra under same
electron beam conditions HGHG spectral brightness
is 2x105 times larger 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
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
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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

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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
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First User Experiment in DUV-FEL
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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