Laser for SPARC

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Laser for SPARC

• Carlo Vicario
• Ilario Boscolo
• Simone Cialdi
• Andrea Ghigo
• Franco Tazzioli

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SPARC Step 1
photo injector
5.0 m
RF sections
Undulator
1.5 m
D
20º
6.0 m
14.5 m
1.5m
10.0 m
6 m
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Plan of SPARC Bunker
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SPARC Bunker
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Laser cleaning Room
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Laser Requirements
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Laser layout
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Zoom on Oscillator
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Zoom on Amplifier
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Emittance simulation with Parmela code with
different risetime of square pulse

• Input Parameters
• Pulse duration 11.66 FWHM
• 0.3 mm mrad eth
• Epeak120 MV/m, B.27 T

94 of bunch for no rise time, 81 of bunch for 1
ps rise time achieve sase saturation with
undulator lengthlt10m
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Emittance simulation with Homdyn code for
elliptic spot on cathode
enx,eny
Ellipticity
Circular spot can be obtain with conventional
optics (cylindrical lens)
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Emittance simulation with Homdyn code for energy
and time jitter
Working point nominal charge Q1nC, RF phase
27.5
DQ 5 Den 4.45 DQ - 5
Den 7.51
Other Simulation for time jitter shows that Dt
1ps (1RF) Den 4
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Transport to the RF-gun

• Spatial flattener pinhole position-dependent
  attenuator
• Frequency tripler
• Transport Optics in evacuated pipe
• 72 Incidence compensation gratingcylindrical
  lens

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Transport to the RF-gun
Energy Losses Flattener
62 Transport optics 38 3th
harmonic generation 90
20 mJ in IR needed to obtain 500 mJ on cathode _at_
266 nm for Q.E.10 -5 to extract 1 nC
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Time pulse shaper
TiSa large bandwidth allows the square pulse
shaping via frequency manipulation. With
amplitude and phase control an arbitrary shape
can be produced. The pulse shaper must be
inserted before the amplifier to avoid damage.
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Time pulse shaper
Phase-only modulation preserves optical band to
perform pulse stretching! Specified flat top
can be obtained by phase-only modulation. No
control on phase of shaped pulse but no problem
for photoemission!
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Liquid crystal spatial light phase modulator in
Fourier plane
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Collinear Acousto-Optic modulator (AOM)
F. Verluise and al, Opt. Lett.25,8 (2000)
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Comparison between optical modulators
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Conclusion 1
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Conclusion 2

• To be studied
• Time Pulse Shaping.
• Effects of the uniform time distribution on
  amplification and next pulse handling.
• Optical transfer line to preserve transverse and
  longitudinal distribution.

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Conclusion 3

• Stability of high energy amplified pulses is an
  issue.
• Improvements in cathodes quantum efficiency
  simplifies the problem.

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Acknowledgments
S. De Silvestri, M. Nisoli, S. Stagira.
M. Ferrario, M. Boscolo, V. Fusco, F. Sgamma.
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