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2D display of tungsten impurity in a free-burning arc using laser-induced fluorescence

We present laser-induced fluorescence (LIF) measurements, spatially and temporally resolved, of tungsten impurities eroded from the cathode of a free-burning argon arc. Saturation, but more drastically quenching processes limit a quantitative evaluation of the measurements. Applying a special measuring technique, we were able to determine relative densities and, via a Boltzmann plot, excitation temperatures. A 2D display of the metal impurity can be obtained with a planar LIF arrangement. It shows the distribution of that part of metal component being in a distinct mode of ionization and excitation. As known, the population distribution of the tungsten impurity is dominated by strong demixing effects.