# Influence of plasma, surface, and angle on interlinked X-ray emission dynamics in femtosecond burst pulse ablation

## TL;DR

This paper studies how laser pulses affect X-ray emissions during material ablation, focusing on how surface changes and pulse types influence X-ray measurements.

## Contribution

The study reveals how surface topography and ablation plume interactions influence X-ray emission dynamics in femtosecond burst pulse ablation.

## Key findings

- Surface topography-induced shielding of X-ray emission occurs at fluences where characteristic surface structures form.
- MHz-burst pulses cause additional shielding from ablation plume interactions and shift X-ray photons to higher energy.
- GHz-burst pulses maintain a smooth surface, preventing X-ray shielding across all fluences.

## Abstract

The ablation of solid materials using ultrashort laser pulses at high intensities leads to the emission of X-rays. This effect is particularly pronounced when burst pulses are applied due to pulse-to-pulse interactions within a burst. Simultaneously, the resulting surface topography changes depending on whether single pulses or burst pulses are used. This study experimentally investigates the spectral X-ray emission during the ablation of 304L-steel with single and burst pulses, varying the detection angle and predefined laser parameters. The aim is to analyze how surface topography, which evolves during ablation, influences the measurements of X-ray emission during area irradiation. The results indicate that surface topography-induced shielding of X-ray emission occurs for single and MHz-burst pulses, but only at fluences where characteristic surface structures form. In the MHz-burst regime, additional shielding effects arise from interactions with the ablation plume, which also contribute to a shift toward higher-energy X-ray photons. In contrast, GHz-burst pulses preserve a smooth surface across all investigated fluences, preventing shielding of X-rays.