Laser guiding for high energy plasma accelerators

The excitation of plasma waves by the laser wakefield mechanism in the resonant, linear regime allows to achieve controllable accelerating electric fields in the 10 GV/m range. Injected electrons will acquire an energy gain in the GeV range provided that the laser pulse is guided over the dephasing length. The structure of the wakefield in a plasma column, created by a monomode laser pulse propagating in a capillary tube, filled with gas is studied numerically. The simulations show that in the central bulk part of a plasma column where the laser intensity exceeds the ionization threshold, the wakefield structure is similar to that of an infinite homogeneous plasma. Monomode guiding over 50 Rayleigh lengths (12 cm) of high intensity ultra-short laser pulses (10 ¹⁷ W/cm², 350 fs) has been experimentally demonstrated in dielectric capillary tubes, in a range of parameters relevant to wakefield excitation.