Electron density and temperature measurement by continuum radiation emitted from weakly ionized atmospheric pressure plasmas

Abstract

The electron-atom neutral bremsstrahlung continuum radiation emitted from weakly ionized plasmas is investigated for electron density and temperature diagnostics. The continuum spectrum in 450–1000 nm emitted from the argon atmospheric pressure plasma is found to be in excellent agreement with the neutral bremsstrahlung formula with the electron-atom momentum transfer cross-section given by Popović. In 280–450 nm, however, a large discrepancy between the measured and the neutral bremsstrahlung emissivities is observed. We find that without accounting for the radiative H2 dissociation continuum, the temperature, and density measurements would be largely wrong, so that it should be taken into account for accurate measurement.