Conceptual%20design%20of%20a%20laser%20wakefield%20experiment%20with%20external%20bunch%20injection%20in%20front%20of%20the%20laser%20pulse.

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Conceptual design of a laser wakefield experiment
with external bunch injection in front of the
laser pulse.
Arsen Khachatryan, Fred van Goor, Mark Luttikhof,
Arie Irman, Jeroen Verschuur, Bert Bastiaens, and
Klaus Boller. University of Twente, Enschede, The
Netherlands.
International Workshop onHigh Energy Electron
Acceleration Using Plasmas 2005 8-10 June 2005
-Institut Henri Poincaré, Paris, France
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Dutch Laser Wakefield Accelerators Program
University of Twente Laser Physics group
University of Eindhoven Physics and Applications
of Ion Beams and Accelerators group
FOM-Institute for Plasma Physics
Rijnhuizen Laser-Plasma XUV Source and XUV
optics group
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Support and Topics

• Foundation for Fundamental Research on Matter
  (FOM)
• Project duration 2002 - 2008
• External injection schemes (TUE, UT)
• Photo injector (TUE, UT)
• Ti-Sapphire laser (UT)
• Plasma channel (FOM-Rijnhuizen)

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LWFA
The Injection Problem
External Injection
Internal Injection (wavebreaking)
Injection in wakefield (behind laser)
Injection in front of laser
Self-modulated regime
All-Optical injection
Bubble regime
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Bunch dynamics
Laser a0 1.0 gg 30 Spot radius 30.5
mm Pulse duration 30 fs Plasma channel np
2x1018 cm-3 lp 24 mm Length 2.3 cm Injected
bunch FWHM duration 300 fs FWHM width 82
mm energy 1.6 MeV Accelerated bunch Emittance
8 p-mm-mrad Length (rms) 1 mm Radius (rms)
1.3 mm energy 453 MeV energy spread
2.8 Collection efficiency 44
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Longitudinal field
Normalized Ez
kpr
kp(z-ct)
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Transverse field
Focusing field
kpr
kp(z-ct)
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Average Bunch Energy
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rms Bunch Radius
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rms Bunch Length
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rms energy spread
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Normalized rms emittance
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Parameters for Proof-of-Principle Experiment
with ?1J, (30-50) fs Laser Pulse.
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The New Scheme

• Low-energy electron bunch
• Energy (g0) hundreds keVs to few MeVs
• Length (L0) up to a few hundreds microns
• Trapping distance Ltr 2 g02L0

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Experimental Set-Up
e-bunch
Parabolic mirror
Linac
Metal photo cathode
Plasma channel
3rd harmonic converter
Laser pulse
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Advantages of the LWFA scheme

• No ultra-short electron bunch is needed before
  the acceleration in the laser wakefield
• No femtosecond synchronization is required while
  injecting the bunch in the wakefield
• No transverse size of a few micron and precise
  transverse positioning are needed for the
  injecting e-bunch
• Effective longitudinal and transverse
  electron-bunch compression
• Good quality of the accelerated bunch
• Scaling to high energies (GeVs) is possible.

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End