Results in Physics (Dec 2020)
Energy spectra of secondary electrons in dielectric materials by charging analysis
Abstract
Measurement of electron energy spectra of dielectrics is a challenge due to charging issues. This article presents experimental results of electron energy spectra of dielectric materials under electron irradiation obtained by transforming the charging process into a spectroscopic tool. The technique was verified on conductive materials in a previous paper. This method is based on capturing the charging transient of the secondary electron emission current. Dielectric materials are irradiated with a single train of pulses of monoenergetic electrons. The evolution of the number of emitted electrons as a function of time is measured. The rate of this evolution coupled to the arising potential on the surface of the material conveys the energy at which the secondary electrons are emitted. The total incident dose used in this method is about 10 pC/mm2, in contrast to the high doses required when other common methods are utilized. The use of low doses ensures a minimal distortion of the pristine state of the dielectric material by avoiding radiation damage, deep charging, defects, aging and other electron induced phenomena in the insulator. This method was applied to obtain the secondary electron energy spectra of the Kapton, Teflon, and Ultem polymers.
