Energy transfer in elastic collisions between electrons and trapped ions

TL;DR

This paper investigates how free electrons cause heating in trapped ion clouds, combining experimental observations, molecular dynamics simulations, and a theoretical model to understand and quantify the heating process.

Contribution

It introduces a model predicting ion cloud heating by electrons and experimentally verifies the model through simulations and measurements.

Findings

Electron-induced heating of ion clouds was observed and quantified.

Theoretical predictions matched experimental and simulation results.

Pushing effects by electrons were too weak to observe.

Abstract

Heating of trapped ion clouds by interactions with free electrons crossing the trapping potential was observed. A model describing such process was proposed and discussed. The presented approach predicts two effects: pushing and heating of the ions' ensemble by electrons. The former was found to be too weak for observation, however the latter was investigated experimentally. For comparison between experimental results and theoretical predictions, molecular dynamics simulations for various ion ensembles in various temperatures were performed to determine dependence between ion cloud geometry and its temperature. A heating rate coefficient was defined and determined together with temperatures of ion clouds bombarded with electrons. Good correlation between the two quantities was found, which agrees with the proposed model.