Meter-Scale, Conditioned Hydrodynamic Optical-Field-Ionized Plasma Channels

TL;DR

This paper presents a new method to generate meter-scale, low-loss plasma channels using a conditioning laser pulse to improve hydrodynamic optical-field-ionized channels, enabling longer guiding distances for high-intensity laser applications.

Contribution

The authors introduce conditioned HOFI (CHOFI) channels that significantly extend plasma channel length and reduce attenuation, demonstrated through experiments and simulations.

Findings

CHOFI channels achieve attenuation lengths over 21 meters.

Experimental electron density of about 1×10^{17} cm^{-3}.

Potential for meter-scale channels with only 1.2 J laser energy per meter.

Abstract

We demonstrate through experiments and numerical simulations that low-density, low-loss, meter-scale plasma channels can be generated by employing a conditioning laser pulse to ionize the neutral gas collar surrounding a hydrodynamic optical-field-ionized (HOFI) plasma channel. We use particle-in-cell simulations to show that the leading edge of the conditioning pulse ionizes the neutral gas collar to generate a deep, low-loss plasma channel which guides the bulk of the conditioning pulse itself as well as any subsequently injected pulses. In proof-of-principle experiments we generate conditioned HOFI (CHOFI) waveguides with axial electron densities of $n_\mathrm{e0} \approx 1 \times 10^{17} \; \mathrm{cm^{-3}}$, and a matched spot size of $26 \; \mathrm{\mu m}$. The power attenuation length of these CHOFI channels is $L_\mathrm{att} = (21 \pm 3) \; \mathrm{m}$, more than two orders of magnitude longer than achieved by HOFI channels. Hydrodynamic and particle-in-cell simulations demonstrate that meter-scale CHOFI waveguides with attenuation lengths exceeding 1 m could be generated with a total laser pulse energy of only $1.2$ J per meter of channel. The properties of CHOFI channels are ideally suited to many applications in high-intensity light-matter interactions, including multi-GeV plasma accelerator stages operating at high pulse repetition rates.