Optical emission spectroscopy and collisional-radiative modeling for low temperature Ar plasmas

•Diagnostics of electron temperature and density for low temperature Ar plasma by an optical emission spectroscopy combined with a collisional-radiative (CR) model has been investigated and compared with a Langmuir probe diagnostics.•The CR model considers two-temperature electron energy distribution function and an escape factor for finite cylinder geometry in a capacitively-coupled plasma and an inductively-coupled plasma.•Two-temperature EEDF model works well with the non-Maxwellian plasmas and the finite-cylinder escape factor gives plasma emission spectra close to the measured spectra.