Micro-PIXE analysis of impurity distributions in “trees” grown in high-voltage cables

Abstract

Abstract Water treeing and electrical treeing are degradation processes occurring in the polyethylene insulation of underground high-voltage cables that can lead to premature breakdown. In order to determine the nature and content of impurities present in the trees, which typically have dimensions of 50–200 μm, a PIXE (proton-induced X-ray emission) microbeam system with a beam-spot diameter of less than 20 μm has been installed on a 4.5 MV Dynamitron accelerator. The capabilities of this system are illustrated by multi-element radial scans that show the presence of a wide variety of contaminants in the trees.