Characterization of a planar 8 mm atmospheric pressure wide radiofrequency plasma source by spectroscopy techniques

Atmospheric pressure planar radiofrequency (RF) 13.56 MHz discharge in Ar gas generated in a long gap is investigated. The discharge operation with and without a dielectric barrier on the electrodes is studied as a function of the applied power and gas flow. The source afterglow is characterized and is analyzed for possible large-scale biomedical applications where low gas temperature is required. The discharge is studied by relative and absolute emission spectroscopies. A gas temperature as low as 330 +/- 50 K is determined from the rotational-vibrational band of OH emission. The absolute value of the discharge continuum irradiation is used to determine the electron density and the electron temperature. The electron-atom and electron-ion contributions to the bremsstrahlung radiation are calculated and are compared with measured spectra. The electron density of 1.9 +/- 1 x 10(20) m(-3) and electron temperature of 1.75 +/- 0.25 eV are measured in the discharge without a dielectric barrier. It is found that presence of the dielectric has a negligible effect on electron temperature, whereas the electron number density is almost six times lower in the discharge with the dielectric barrier.