Surface chemical changes of polymer cavities with currents above and below corona inception voltage

X-ray photoelectron spectroscopy, (XPS) has been used to follow the chemical changes that occur with applied voltage on the walls of cavities in polyethylene (PE). These cavities simulate voids found in commercial insulation. A wide range of current, time, and applied voltages above and below the corona inception voltage (CIV) have been explored. The XPS analysis area is much less than 1 mm² with the cavities in roughly the same size regime. During the XPS data collection, mass spectrometric analyses were made of evolved gases from the samples. Experimental techniques for the control of chemical purity, chemical analysis, and repeatability are discussed. Improvements on the CIV device design permit many measurements over a greater range of cavity size and emitting surfaces than were possible previously. The findings confirm the results on compositional changes on PE voids under discharge conditions that were found by A.M. Bruning et al. (1991)