Variation of trapping/detrapping properties as a function of the insulator size

Abstract

Using the scanning electron microscope we have investigated the physical parameters determining the size effect of various dielectric samples submitted to a surface electric field. It is shown that the size effect is a function of the static permittivity and of the space charge distribution. The results are explained by the consideration of charge diffusion and polarization relaxation processes resulting from the space charge formation. A one-dimensional mathematical model has also been used to describe space charge distribution. The findings were consistent with the experimental observations.

Filled liquid silicone rubbers: possibilities and challenges

“…The films with high Y have compact polymer chains which can trap charges. [23] Trapped charges cannot flow easily and hence a higher electric field is needed to induce electron avalanches and thus the films possess high breakdown strength. [24] It is not possible to increase Y unlimitedly for a given composite since the formulations start to become inhomogeneous with the result that the opposite effect is encountered, i.e.…”

Effect of the insulator size on the breakdown strength

“…An experiment has been set for investigating if the various parameters that determine n are characteristic of the phenomena responsible of the breakdown occurrence (injection, charge distribution, energy storage, forces acting in a charged insulator). This research has been conducted by using the same method by different groups and the experimental results that will be reported in this work have been already published [5] [6]. Only the discussion is due to this paper authors.…”

“…In the charge steady state leakage regime the surface potential can be measured by using an X ray Energy Dispersive device [5]. The difference between the electron beam energy and the X ray spectrum cut off gives the surface potential.…”

“…Later on it has been related to charge trapping detrapping phenomena [5] [7]. More recently an interesting work has suggested that n could be related to the material structure and it has been shown that for polymers n depends on the monomer electron affinity [8].…”

“…For industrial application the user needs to know QBd, the DDT and the law relating E,, and S. In most of reported breakdown results EBd =S'" where n is about 0,5. However, this is not an universal value and may varies from zero [3] to more than 0,5 [ 5 ] . The point of interest is to know how n is linked with the presence of macroscopic defects or with the material microscopic structure.…”