Spectroscopic investigation of wave driven microwave plasmas

Abstract

Large H atom line broadening was found throughout the volume of surface wave generated He- H2and H2 microwave plasmas at low pressures. The measured Doppler temperatures corresponding to the H Β, Hγ, Hδ, Hε, and H1 line profiles were found to be higher than the rotational temperature of the hydrogen molecular Fulcher- α band and the Doppler temperature of the 667.1 nm singlet He line. No excessive broadening has been found. The Lorentzian and Gaussian widths as determined by fitting the spectral lines with a Voigt profile increase with the principal quantum number of the upper level. In contrast, no such dependence for the Gaussian width has been observed in an Ar- H2 discharge. No population inversion has been observed from measurements of the relative intensities of transitions within the Balmer series. © 2009 American Institute of Physics.