A Study of Emission Lines from Electrical Trees

A study has been made of the gases appearing in the channels of bush and branch-like electrical trees propagating in low density polyethylene (LDPE) and cross-linked polyethylene (XLPE) subjected to a strong alternating electric field. The emission lines in the spectral range from 300 to 700 nm were observed with a monochromator and a vidicon tube followed by a multichannel analyzer. These lines, characteristic of the gaseous mixture created by the action of discharges on the channel walls, revealed then presence of CO, C02, and H2. The evolution of these lines was followed as a function of time.