  A study of the line shapes of hydrogen Balmer series lines in RF generated
low pressure H2/He plasmas produced results suggesting a catalytic process
between helium and hydrogen species results in the generation of 'hot' (ca. 28
eV) atomic hydrogen. Even far from the electrodes 'hot' atomic hydrogen was
predominant in H2/He plasmas. Line shapes, relative line areas of cold and hot
atomic hydrogen (hot/cold>2.5), were very similar for areas between the
electrodes and far from the electrodes for these plasmas. In contrast, in H2/Xe
only 'warm' (<5 eV) hydrogen (warm/cold<1.0) was found between the electrodes,
and only cold hydrogen away from the electrodes. Earlier postulates that
preferential hydrogen line broadening in plasmas results from the acceleration
of ionic hydrogen in the vicinity of electrodes, and the special charge
exchange characteristics of Ar/H2+ are clearly belied by the present results
that show atomic hydrogen line shape are similar for H2/He plasmas throughout
the relatively large cylindrical (14 cm ID x 36 cm length) cavity.
