Coherent control of plasma dynamics

TL;DR

This paper demonstrates the coherent control of plasma dynamics in laser wakefield acceleration using a genetic algorithm to optimize laser wavefront, significantly improving electron beam quality.

Contribution

It introduces a novel method of controlling plasma waves via phase manipulation with a genetic algorithm, enhancing electron acceleration performance.

Findings

Electron beam charge improved by an order of magnitude.

Electron beam angular distribution improved by an order of magnitude.

Optimal plasma wave steering is achieved through phase control, not just focal spot quality.

Abstract

Coherent control of a system involves steering an interaction to a final coherent state by controlling the phase of an applied field. Plasmas support coherent wave structures that can be generated by intense laser fields. Here, we demonstrate the coherent control of plasma dynamics in a laser wakefield electron acceleration experiment. A genetic algorithm is implemented using a deformable mirror with the electron beam signal as feedback, which allows a heuristic search for the optimal wavefront under laser-plasma conditions that is not known a priori. We are able to improve both the electron beam charge and angular distribution by an order of magnitude. These improvements do not simply correlate with having the `best' focal spot, since the highest quality vacuum focal spot produces a greatly inferior electron beam, but instead correspond to the particular laser phase that steers the plasma wave to a final state with optimal accelerating fields.