Characterization of a hybrid flame/arc excitation source using monodisperse aerosol introduction

Abstract

A hybrid flame/arc excitation source together with a monodisperse droplet generator is used to inject solute particles into selected regions of the arc plasma. With astigmatic image transfer and a 0.5 [mu]s time constant detection system, individual solute vapor cloud emission profiles are detected in the arc tail flame. These emission profiles are always asymmetric with sharper leading edges. Emission profiles are presented for Ca at several positions in the arc tail flame. The (zinc) excitation temperature was measured at 6600 K in the region 1-2 mm above the arc conduction channel. A double aperture technique was used to estimate the arc convective velocity at about 50 m s-1. When the emission plume origin from a monodisperse droplet stream is positioned in the tail flame region, analytical line-to-background ratios typically are one-two orders of magnitude greater than when the plume origin is located below the conduction channel. Analytical curves from the tail flame region are linear over at least two-three orders of concentration, and detection limits are significantly lower than literature values for the region just under the conduction channel of an Ar-stabilized bent arc.