Spectrum intensity of metal ion and transition boundary to gaseous phase in W break arc

The relationship of the spectral intensity for a W break are to the gaseous phase transition boundary is investigated. The average spectral intensity of tungsten metal ions is small at all are durations if the closed contact current is below the boundary closed contact current for phase transition, but increases rapidly when the latter current is exceeded, as does the aver age spectral intensity in the metallic phase. The instantaneous spectrum in tensity increases rapidly after the contact gap reaches the value correspon ding to the minimum point of the Paschen curve. At currents for which the t ransition ratio is 100%, the spectrum intensity has a peak just after are i nitiation and a minimum when the gap corresponds to the minimum of the Pasc hen curve; the intensity is also close to the maximum when the are transits to the gaseous phase. (C) 2000 Scripta Technica.