Optimal laser pulse energy partitioning for air ionization

TL;DR

This paper explores how dividing a laser pulse into multiple sub-pulses affects air ionization, finding that at moderate energies, splitting reduces efficiency, but at higher energies, it can enhance plasma properties for better discharge triggering.

Contribution

It provides a numerical analysis of pulse partitioning effects on plasma channels, highlighting conditions where splitting improves ionization and discharge efficiency.

Findings

Splitting at moderate energies reduces ionization efficiency.

At higher energies, pulse splitting increases gas temperature.

Enhanced electron mean free path improves discharge triggering.

Abstract

We investigate the pulse partitioning of a 6.3 mJ, 450 fs pulse at 1030 nm to produce plasma channels. At such moderate energies, splitting the energy into several sub-pulses reduces the ionization efficiency and thus does not extend the plasma lifetime. We numerically show that when sufficient energy to produce multifilamentation is available, splitting the pulse temporally in a pulse train increases the gas temperature compared to a filament bundle of the same energy. This could improve the mean free path of the free electrons, therefore enhancing the efficiency of discharge triggering.