N.E. Andreev1), B. Cros2), P. Mora3)

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LWFA using guided propagation of laser pulses in capillaries
N.E. Andreev1), B. Cros2), P. Mora3) 1)
Institute for High Energy Densities of Russian
Academy of Sciences, Moscow, Russia. 2) LPGP,
CNRS UMR 8578, Universite Paris XI, Orsay,
France. 3) Centre de Physique Theorique CNRS,
Ecole Polytechnique, France.
International Workshop on High Energy Electron
Acceleration Using Plasmas 2005 HEEAUP 2005  
8-10 June 2005 -Institut Henri Poincaré, Paris,
France
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Laser pulse channeling in a capillary waveguide
Laser pulse
ewgt1
for the Gaussian laser pulse E(r)
E0exp(-r2/r02) Energy coupling to the main
mode 98 at r0/a0.645
z
2a
Laser energy leakage IL(z) I0exp(- z / LD)
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Wakefield generation in gas filled capillary
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Wakefield generation in gas (H) filled capillary
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Wakefield generation in a capillary filled with He
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Radial structure of the wakefield at the plasma
edge
Numerical modelling is in a good agreement with
analytical theory
For the main mode in cylindrical capillary
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Long low-energy electron bunch will be trapped
and compressed in the wakefield
N.E Andreev., S.V. Kuznezov. Electron Bunch
Compression in Laser Wakefield Acceleration.//
http//icfa.lbl.gov/icfapanel.html/Newsletter/Spec
ial Issue Giens Workshop Proceedings, June 24 -
29, 2001.
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Energy spread decreases
substantially at the end of accelerating phase
in accordance with the theory for injected
electron bunches of small radius
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Spectroscopic Diagnostics of the Plasma Wakefield
Conclusion
Wakefield generated by short intense laser pulse
in gas-filled capillary can be measured
even in a nonlinear regime with OFI of gas
filling capillary
Hydrogen Na6.71017cm-3, Dcap77 mkm, r0
/ Rcap0.645, kpr03.8, PL9.6 TW,
PL/Pcr0.23 , qL 1018W/cm2, t 50 fs,
l 0.82 mkm
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Conclusions on the Laser Wakefield Generation in
Capillaries and Acceleration of e--bunches

• Regular resonant wakefield can be excited by the
  main mode laser field
• in a gas-filled capillary (of tens cm long) for
• the limited number of plasma wave periods.
• The length of a regular wakefield (for the same
  laser pulse intensity)
• increases for
• wider capillary,
• lighter gases,
• shorter pulses (higher plasma density).
• Radially profiled gas density or plasma channel
  in a capillary can provide
• decrease of laser energy losses (energy flux to
  the capillary walls),
• overcoming of the limitation on the wakefield
  length,
• wakefield structure suitable for the effective
  electron bunch compression (more than hundred
  times).