Role of the laser chirp parameter in photoionisation

TL;DR

This paper investigates how the laser chirp parameter affects photoionisation in plasma generation, providing insights to optimize laser pulse parameters for more homogeneous plasma in particle accelerators.

Contribution

It offers a detailed quantum mechanical analysis of laser chirp effects on photoionisation, a novel focus in the context of plasma-based particle acceleration.

Findings

Laser chirp significantly influences photoionisation efficiency.

Optimized laser parameters improve plasma homogeneity.

Envelope shape also affects ionisation outcomes.

Abstract

Nowadays the development of novel particle accelerators is a hot topic for both experimental and theoretical sciences. In the CERN-AWAKE experiment electrons are accelerated in a cold rubidium plasma, generated by a short, intense laser pulse. We describe the corresponding photoionisation process with ab initio quantum mechanical calculations. In this paper we primarily investigate how the frequency chirping of the applied laser pulse influences the photoionisation. Secondarily we also study how the results of the numerical simulations depend on the shape of the envelope of the laser pulse. Based on our results, we give a recommendation to fine-tune the physical parameters of the applied laser pulse in order to improve the homogeneity of the rubidium plasma.