Time of Flight Mass Spectrometry with Direct Extraction of a Uranium Plasma

TL;DR

This paper presents a modified Time of Flight mass spectrometer that directly extracts ions from laser-induced plasma, enabling immediate analysis of plasma composition and energy distribution without additional ionization steps, with applications in nuclear forensics.

Contribution

The study introduces a novel TOF mass spectrometry method for direct plasma ion extraction, eliminating the need for collisional cooling or ionization, and demonstrates its application to uranium for nuclear forensic analysis.

Findings

Direct measurement of plasma ion composition achieved.

Energy distribution of plasma ions obtained directly.

Application demonstrated on uranium for nuclear forensic relevance.

Abstract

We demonstrate a Wiley-McClaren Time of Flight Mass Spectrometer modified to allow direct extraction of ions from a laser-induced plasma. Unlike many other methods that utilize mass spectrometry to investigate laser-induced plasmas, no collisional cooling or further ionization of the plasma is required prior to acceleration, allowing measurements of the plasma ion composition to be obtained directly. Furthermore, we show using the laser ablation of gadolinium as an example that we are able to obtain the translational energy distribution of the plasma directly and infer information about the relative composition of ions within different regions of the plasma plume. The approach is then applied to laser ablation of a uranium sample as a step toward probing the chemistry under conditions relevant to a nuclear fireball for nuclear forensics applications.