  An atmospheric plasma torch has been supplied with a gaseous mixture of
helium, water vapour and/or oxygen to study the production of reactive species
within its flowing post-discharge, in particular hydrogen peroxide. The
mechanisms responsible for the production of H2O2 have been investigated by
correlating measurements of mass spectrometry and absorption photospectrometry.
An absolute quantification of H2O2 has also been achieved and indicated that
for 5 mmol of water vapour injected in the He-H2O discharge, approximately 9.5
mol of H2O2 were produced in post-discharge.
