Parametric study of an atmospheric pressure microwave-induced plasma of the mini MIP torch - I. Two-dimensional spatially resolved electron-number density measurements

The results of spatial distribution measurements of the electron-number density, N-e, in an atmospheric pressure microwave-induced plasma in argon are presented. Electron-number density is determined from the width of the hydrogen H-beta 486.13-nm line. The influence of the microwave input power in the range 80-150 W on the spatial distribution of N-e is first determined. For the selected input power of 100 W, the influence of molecular hydrogen in wet and desolvated nebulizer and support gas, and the corresponding changes in the electron density distributions are studied. The influence of potassium as a low ionization-potential element on the spatial distribution of N-e is also studied, with the result that a considerable lowering of the electron number density is detected. (C) 2000 Elsevier Science B.V. All rights reserved.