Low-Density Hydrodynamic Optical-Field-Ionized Plasma Channels Generated With An Axicon Lens

We demonstrate optical guiding of high-intensity laser pulses in long, low-density hydrodynamic optical-field-ionized (HOFI) plasma channels. An axicon lens is used to generate HOFI plasma channels with on-axis electron densities as low as n(e) (0) = 1.5 x 10(17) cm(-3) and matched spot sizes in the range 20 mu m less than or similar to< W-M less than or similar to 40 mu m. Control of these channel parameters via adjustment of the initial cell pressure and the delay after the arrival of the channel-forming pulse is demonstrated. For laser pulses with a peak axial intensity of 4 x 10(17) W cm(-2) , highly reproducible, high-quality guiding over more than 14 Rayleigh ranges is achieved at a pulse repetition rate of 5 Hz, limited by the available channel-forming laser and vacuum pumping system. Plasma channels of this type would seem to be well suited to multi-GeV laser wakefield accelerators operating in the quasilinear regime.