Experimental study of the influence of the gas pressure and of the wave frequency on the spatial distributions of excited atoms in a surface wave produced plasma

Summary Form only given, as follows. The authors have reviewed the experimental study of the spatial distribution of excited atoms in plasmas, which reflects the kinetic processes of the discharge. In surface-wave-produced plasmas (SWP) the radial distributions of metastable and radiative atoms are related to those of both the electric field intensity and the electron density. Knowledge of SWPs has improved as a result of the extension of measurements of excited-atom distributions to a larger range of wave frequencies, gas pressures, and electric field azimuthal configurations. In addition, a tomographic method has made it possible to achieve an excellent radial and axial resolution for the study of the optically thin spectral lines and to extend measurements to experimental situations that could not be studied previously. Comparison of these results to predictions of a surface-wave-produced-plasma model that couples wave and plasma equations shows discrepancies that can be explained by two-step excitation rather than direct excitation from the ground level as assumed in the model.<>