1. 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 Institut Henri Poincaré, Paris, France

2. Laser pulse channeling in a capillary waveguide
ew>1
for the Gaussian laser pulse
E(r) =E0exp(-r2/r02)
Energy coupling to the main mode
98% at r0/a=0.645 z 2a
Laser energy leakage:
IL(z) = I0exp(- z / LD)

4. Wakefield generation in gas filled capillary

5. Wakefield generation in gas (H) filled capillary

6. Wakefield generation in a capillary filled with He

7. 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:

8. 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.//
Issue: Giens Workshop Proceedings, June , 2001.

9. Energy spread decreases substantially at the end of accelerating phase
ОИВТ РАН
Energy spread decreases substantially
at the end of accelerating phase
in accordance with the theory for injected electron bunches of small radius

10. 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: Na=6.7×1017cm-3, Dcap=77 mkm, r0 / Rcap=0.645, kpr0=3.8,
PL=9.6 TW, PL/Pcr=0.23 , qL= 1018W/cm2, t = 50 fs, l = 0.82 mkm

11. 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).