| A series of experiments, designed to help characterize the behavior of an analytical spark discharge in an external pulsed magnetic field, are described. Results include controlled formation and deformation of a spark's post-discharge torus utilizing different magnetic field configurations. One manifestation of this research was discovery of a new filamentary structure which extends from the spark conducting channel to the magnet pole face(s). These features were investigated via their refracted light (Schlieren) and spectroscopic (time/space/wavelength-resolved) properties. Time-resolved spectroscopic data indicate the spatial isolation of ionic species. Time-integrated, spatially-resolved data further demonstrate that the region of maximum emission intensity (for ionic species) is shifted 1100 ;We report the first application of time- and spatially-resolved "hook" spectroscopy to quantitatively determine the number density of species sampled by an atmospheric pressure analytical spark discharge. The new instrument consists of a tunable dye laser light source, a Mach-Zehnder interferometer, a stigmatic spectrograph, and a high fidelity image transfer system. The integrated number densities of ground state sodium atoms, ablated from a graphite electrode containing NaCl, are deduced from the corresponding hook spectrum. Data are obtained at various spatial windows with respect to the interelectrode axis and also at different times after the spark breakdown. Time dependent profiles of sodium species, generated by an atmospheric pressure analytical spark discharge, are calculated from hook separation near the Na D-lines. These lateral profiles are then transformed into the radial domain, using a derivative free Abel inversion process. Different approaches for optimization of the experimental parameters are shown. Advantages, limitations, and the practical ramification of the hook method are discussed. |
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