ACCELERATION OF CHARGED-PARTICLES AND PHOTONS IN THE WAKE OF A SHORT LASER-PULSE IN A THIN CHANNEL

We consider the formation of a charged plasma with a sharp front edge produced by a subpicosecond laser pulse propagating in a vacuum inside a thin channel. The channel eliminates pulse spreading due to diffraction. We estimate the density of the electrons driven into the channel due either to their acceleration in the plasma resonance region or to vacuum heating, the typical strength of the electric field that they produce, and the absorption of the laser radiation. This analysis is of interest for the acceleration of particles and photons with ultrashort laser pulses. We calculate the relevant acceleration length, the particle energy gain, and the value of the upshift of the photon frequency.