An imaging-based instrument for fundamental plasma studies

A description is given of an imaging-based instrument capable of mapping several fundamental properties of analytical plasmas, especially the inductively coupled plasma. The plasma fundamental parameters include electron temperature and number density, heavy-particle gas-kinetic temperature, analyte and argon atom and ion concentrations, and analyte emission intensities. These parameters can be measured on the same plasma running under identical operation conditions. The techniques to probe the basic plasma properties include Thomson scattering (for electron concentration and temperature), Rayleigh scattering (for heavy-particle temperature), computer-aided optical tomography (for three-dimensional emission maps), and laser-induced saturated fluorescence (for analyte and argon atom and ion number densities). A brief description of these techniques is presented. Also, a new approach to determining absolute number densities from fluorescence measurements is introduced. This novel method is based on normalizing a measured fluorescence intensity by the room-temperature Rayleigh-scattering signal. (C) 1997 Elsevier Science B.V.