Implementing and constraining higher fidelity kinetics for DPAL models

TL;DR

This paper develops a detailed kinetic model for DPAL systems, capturing exotic processes and electron energy distributions, to improve understanding and prediction of laser performance and heat loading issues.

Contribution

It introduces an efficient kinetic modeling approach that resolves trace species, enforces conservation laws, and incorporates non-Maxwell-Boltzmann electron distributions in DPAL simulations.

Findings

Recombination processes are weaker than expected under relevant conditions.

Methane enhances performance more in experiments than in the model.

Electron energy distribution tracking is crucial for accurate DPAL modeling.

Abstract

Ionization, hydrocarbon breakdown, and other exotic processes can harm diode-pumped alkali laser (DPAL) performance and components. We develop a physical picture of these processes, including those that drive a non-Maxwell-Boltzmann distribution of electrons, and describe an efficient approach to solve these kinetics while resolving trace species, and enforcing conservation laws. Comparing the model to time-dependent experiments suggests that recombination and supporting processes are weaker than na\"{i}vely expected under relevant conditions, while methane seems to improve performance in the lab more than it does in the model. Overall, this work highlights the importance of tracking the true electron energy distribution, and how incisive experiments with time-dependent driving are. We also use the model to emphasize how ionization may pose more immediate heat loading problems in devices.