New Procedure for Determination of Electron Temperatures and Electron Concentrations by Thomson Scattering and Analytical Plasmas

摘要

A new data-treatment procedure allows for more accurate determination of electron temperatures and electron concentrations in analytical plasmas. A Thomson scattering spectrum, useful for these determinations, is often not purely Gaussian in shape, even when the probed electrons possess a Maxwellian velocity distribution. Nonetheless, an unambiguous relationship exists between electron temperatures and concentrations that truly exist in a plasma and those calculated from a distorted Thompson scattering spectrum. Understanding this relationship permits a look-up table to be constructed, from which observed values can be corrected. Theory concerning this procedure is described and details for using it with both a ruby laser and frequency doubled Nd:YAG laser are discussed. Examples of electron temperature and electron concentration determined with this procedure in an ICP are given. The possibility of using the new procedure to study electron energy distributions is also assessed. Keywords: Thomson scattering; Inductively coupled plasma; Multielement analysis; Electron temperatures; Electron concentrations. (jhd)