High-speed photographic study of vaporclouds from wet droplets and the subsequent solid particles in an inductively coupled plasma†
Movies of an inductively coupled plasma (ICP) while nebulizing a concentrated sample of yttrium were recorded using a high-speed camera with short exposure time (10 μs) and fast framing rate (5000 frames per s). Clouds from large droplets can be seen in several successive frames as they travel downstream in the axial channel of the ICP. These droplet clouds are superimposed on the usual spatial structure of red YO, neutral Y atom and blue Y+ emission. As a particular large droplet moves downstream, its red emission cloud evolves into a faint white streak with a surrounding cloud of blue Y+ emission. The streak is attributed to a solid residue from the droplet. The velocity of the droplet and subsequent particle is measured to be 28 m s−1. The general characteristics of the droplet and particle clouds agree well with previous photographic measurements and those by other methods such as laser induced-fluorescence or scattering.