A scanning drift tube apparatus for spatio-temporal mapping of electron swarms

TL;DR

This paper introduces a novel scanning drift tube apparatus that maps the spatio-temporal evolution of electron swarms, enabling detailed analysis of their dynamics and deviations from hydrodynamic behavior.

Contribution

The paper presents the first implementation of a scanning drift tube system capable of detailed space-time mapping of electron swarms and compares experimental results with particle simulations.

Findings

Measured electron bulk drift velocity in argon gas.

First space-time maps of electron swarms demonstrated.

Observation of deviations from hydrodynamic transport.

Abstract

A "scanning" drift tube apparatus, capable of mapping of the spatio-temporal evolution of electron swarms, developing between two plane electrodes under the effect of a homogeneous electric field, is presented. The electron swarms are initiated by photoelectron pulses and the temporal distributions of the electron flux are recorded while the electrode gap length (at a fixed electric field strength) is varied. Operation of the system is tested and verified with argon gas, the measured data are used for the evaluation of the electron bulk drift velocity. The experimental results for the space-time maps of the electron swarms - presented here for the first time - also allow clear observation of deviations from hydrodynamic transport. The swarm maps are also reproduced by particle simulations.