Optical Measurement of the Velocity of Dielectric Surface Arcs

Surface flashover arc discharge velocities on electron-beam-charged polymer sheets have been measured directly by detecting the light emitted at two points along a straight arc and measuring the time interval between light pulses. For Mylar, the average velocity is 1.2 × 106 m/s, and for Teflon the average velocity is approximately 7.3 × 105 m/s independent of sheet thickness. These velocities are about two to four times higher than previous measurements. The techniques employed to produce single, straight surface arcs are described.