Resonant excitation of plasma waves in a plasma channel

TL;DR

This paper demonstrates the resonant excitation of plasma waves using a train of laser pulses in a plasma channel, achieving significant wave amplitudes and energy gains relevant for plasma accelerators.

Contribution

It provides experimental and numerical evidence of resonant plasma wave excitation with laser pulse trains in plasma channels, advancing plasma accelerator technology.

Findings

Guided laser pulse trains in plasma channels over 110 mm length.

Achieved plasma wave amplitudes of 3-10 GV/m.

Estimated energy gain of about 1 GeV in accelerator stage.

Abstract

We demonstrate resonant excitation of a plasma wave by a train of short laser pulses guided in a pre-formed plasma channel, for parameters relevant to a plasma-modulated plasma accelerator (P-MoPA). We show experimentally that a train of $N \approx 10$ short pulses, of total energy $\sim 1$ J, can be guided through $110$ mm long plasma channels with on-axis densities in the range $10^{17} - 10^{18}$ cm$^{-3}$. The spectrum of the transmitted train is found to be strongly red-shifted when the plasma period is tuned to the intra-train pulse spacing. Numerical simulations are found to be in excellent agreement with the measurements and indicate that the resonantly excited plasma waves have an amplitude in the range $3$ - $10$ GV m$^{-1}$, corresponding to an accelerator stage energy gain of order $1$ GeV.