Determination of copper concentration in a SF/sub 6/ arc plasma in an electrical circuit breaker

Summary form only given, as follows. Measurements of particle temperatures and concentrations were performed for a transient and unstable plasma arc in an industrial circuit breaker operated in a 3 atm SF/sub 6/ gas. The large current intensity caused an important vaporization of the electrodes so that the plasma developed in a mixture of SF/sub 6/ and Cu. Time resolved photographs of the are obtained with interference filters showed a compact and homogeneous zone dominated by a S/sup +/-F plasma, and an inhomogeneous zone close to the electrodes dominated by Cu. Average electron densities and temperatures and also the total number of the different emitting atoms or ions were determined in the two zones by spectroscopy using simultaneous time resolved measurements at high and low spectral resolution. Particle concentrations were obtained after an estimate of the volumes of the different plasma zones by spectroscopical methods. Copper density was also inferred from absorption measurements on copper resonance lines by means of a bright flash produced by a Z-pinch discharge. This method allowed to overcome the problem of light beam random deviation by the strong turbulence in the plasma chamber.