Integrated measurement system for high speed unsteady plasma flow and its application to electric arcs

An integrated measurement system for the study of high speed and high temperature unsteady plasma flows, such as those found in the vicinity of high current switching arcs, is presented. An optical high-speed imaging system is integrated with pressure sensing and spectroscopic measurement to gain insight into the complex unsteady flows in applications such as circuit breakers and internal combustion engines. The system permits direct and non-intrusive measurement to obtain new data on these transient events, which occur over a period of a few milliseconds. The imaging system captures at a rate of 1000000 images per second. Software techniques have been developed to control light sensitivity, to generate dynamic images of the high-speed flows; to measure trajectories, times, velocities, pressure change, and to analyse gaseous composition in the tested device simultaneously. The range of applications for this system is very wide. For demonstration purposes, a study of the electric arcing process within a low-voltage circuit breaker and an aeroplane engine ignition unit is presented. This is the first time that a system has been developed to provide detailed measurement of arc root immobility time and arc motion.