Comparison of active and passive spectroscopic methods to investigate atmospheric inductively coupled plasmas

A comparison of Thomson and Rayleigh scattering, diode laser absorption and line emission measurements is performed on a 100 MHz atmospheric argon-flowing inductively coupled plasma. The parameters, which are measured in two or more ways, are the electron density, the electron temperature and the heavy particle temperature. The optimized diagnostics show the same behavior for the electron density and temperature. Nevertheless, the Thomson scattering diagnostic is the best at retrieving the radial profile. The heavy particle temperature, as measured by using both Rayleigh scattering and diode laser absorption, is identical within the estimated errors. The technique of measuring the temperature during power interruption, with both Thomson scattering and emission spectroscopy, shows that the electron and heavy particle temperatures are not equal during the period of power interruption.