An ultraintense laser injected a 10 J of power at $1.053\mu \mathrm{m}$ in 0.5 ps into a glass capillary of 1 cm long and $60\mu \mathrm{m}$ in diameter and accelerated plasma electrons to 100 MeV. One- and two-dimensional particle codes describe wakefields with $10\mathrm{GV}/\mathrm{m}$ gradient excited behind the laser pulse, which are guided by a plasma density channel far beyond the Rayleigh range. The blueshift of the laser spectrum supports that a plasma of ${10}^{16}{\mathrm{cm}}^{-3}$ is inside the capillary. A bump at the high energy tail suggests the electron trapping in the wakefield.

• Received 30 July 2003

DOI:https://doi.org/10.1103/PhysRevLett.92.205002