The Flashover Voltage of Polymethylmethacrylate in Vacuum under Direct, Alternating, and Surge Voltages of Various Front Durations

This paper presents results on flashover voltages across insulation surfaces and on the rate of surface deterioration in a vacuum of 10-5 torr under direct, alternating, and surge voltages of front duration in the range from 1-600 ¿s. The insulation material used was polymethylmethacrylate (PMMA) of cylindrical shape fitted between uniform field electrodes. The measurements were carried out on insulator specimens 25 mm in diameter and 5, 10, and 20 mm in length.