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

Abstract

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 $n_e(0)=1.5\times 10^{17}{\mathrm{cm}}^{-3}$ and matched spot sizes in the range $20\hat{I}¼\mathrm{m}\lesssim W_M\lesssim 40\hat{I}¼\mathrm{m}$. 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 $4\times 10^{17}{\mathrm{W}\mathrm{cm}}^{-2}$, 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 quasi-linear regime.