A Simple Method for Determining Shallow Charge Distributions in Dielectrics via Pulsed Electroacoustic Measurements

Abstract

The understanding of charge dynamics in dielectric materials is paramount in mitigating electrostatic discharge events for spacecraft. The most critical spacecraft charging events are found to result from incident electrons in the energy range of 10 keV to 50 keV. The charge embedded in dielectric materials in this energy range are deposited a distance into the material on the order of a few to tens of microns. One way to measure and understand the deposited charge is via pulsed electroacoustic measurements (PEA). However, the typical PEA spatial resolution of ~ 10 μm is not sufficient to resolve or discern charge deposited at the lower end of this incident electron energy range, where deposited charge distributions are obscured by the superposition of the signal originating from induced mirror charge on the electrode of the pulsed electroacoustic system. A simple method is proposed and demonstrated in which reference measurements from a pristine sample are used to separate the effect of the induced mirror charge from the measured embedded charge to obtain a more accurate determination of the deposited charge distribution.