A Numerical Tool for Quantitative Analysis of Ionic-Liquid Ion Source Time-of-Flight Data

Abstract

This paper builds on prior work by presenting an updated numerical tool that allows for quantitative estimation of the species composition in the plume of an ionic-liquid ion source operating in the ion mode from time-of-flight data. Given an experimentally-measured time-of-flight curve, our tool estimates the current fraction of ions and ion clusters in the ionic-liquid ion source plume, enabling quantitative comparison of time-of-flight data collected at different operating conditions. A key update to the tool is the estimation of a finite-width energy distribution for primary species---particles that do not fragment in the source acceleration region---whereas the prior work assumed that the energy distribution of primary species was monoenergetic. The estimated finite-width energy distribution is able to better explain the sloped nature of time-of-flight curves at the arrival times of primary species relative to large detector response times, and agrees well with experimental measurements of the particle energy distribution. Finally, we demonstrate an application of the numerical tool for analyzing the angular and transient dependence of the species composition for an ionic-liquid ion source with a single porous carbon emitter.