Insulator surface features resulting from cutting techniques

Surface features of similar plastic-metal laminate insulator geometries cut with a water jet and a machine tool are examined with a scanning electron microscope. Both secondary electron emission and backscattering electron emission are used to image and differentiate insulator surface structures. The insulator surface without and with gold coat were compared. Low level electron beam currents and accelerating surface voltages were applied in the former case preventing charge up and surface damage. General surface features appeared unaltered by the sample preparation. The surface features of the machine cut insulator and the water jet cut insulator were significantly and unexpectedly different. This may explain why the water jet cut piece tends to have a higher voltage hold-off as compared to the machine tooled piece.