Position location of a filamentary arc using a tristimulus chromatic technique

A technique is proposed for determining the location of an are-discharge fi lament in a circuit breaker or a plasma torch utilizing only three photo-de tectors, with the same spectral sensitivity, to observe the optical radiati on emitted from the are. The three detectors are placed at different azimut hal positions perpendicular to the central axis of the are filament and are arranged symmetrically with respect to the central axis of the are chamber and with their angular responses non-orthogonal. Outputs from the photo-de tectors are analytically processed to yield two chromatic parameters, r(n) (the nominal radial mode) and theta(d) (the dominant azimuthal mode), which define the are location in the laboratory frame (r*, theta). r(n) and thet a(d) are defined by algorithms used in chromatic processing. As an illustra tion, the technique has been applied to interpret some experimental results for determining the location of an SF6 are filament lying within the nozzl e of a gas-blast circuit breaker.