Characterization of a laser filament-induced plasma in air at 10 kHz using optical emission spectroscopy

TL;DR

This study uses optical emission spectroscopy to analyze the plasma parameters and chemical kinetics of high-repetition-rate laser filaments in air, providing insights into plasma dynamics at 10 kHz.

Contribution

It introduces a comprehensive spectroscopic diagnostic method to characterize plasma parameters and kinetics in high-repetition-rate laser filaments in air.

Findings

Measured gas and electron temperatures dynamics.

Determined species-specific decay times.

Analyzed nitrogen excitation mechanisms.

Abstract

The increasing availability of high-power Yb-based ultrafast laser-amplifier systems has opened the possibility of air filamentation at high repetition rates >1 kHz. In this new regime, accumulation effects cannot be ruled out, therefore, characterizing the plasma parameters and afterglow plasma-chemical kinetics becomes increasingly relevant. In this work, we use optical emission spectroscopy to measure nanosecond dynamics of gas temperature and electron temperature, species-specific decay times, and electron density of an atmospheric air laser filament produced by high average power femtosecond laser at a high repetition rate of 10 kHz. The molecular excitation mechanisms behind the nitrogen photoemissions are derived from vibrational distributions and temporal behavior of the studied emission bands. The presented diagnostic technique offers a complementary but more holistic measurement approach to optical probe schemes to characterize the laser-filament-induced plasma wake for high repetition rate filaments.