A collisional-radiative model applicable to argon discharge over a wide range of conditions. IV. Application to inductively coupled plasmas

Abstract

For pt.III see ibid., vol.23, p.526 (1990). The extensive collisional-radiative model is applied to plasmas generated by a RF coil in an atmospheric argon flow in order to investigate excitation mechanisms and departures from local thermodynamic equilibrium in several spatial positions in these discharges. Computations are carried out for various sets of input parameters, such as the electron kinetic temperature Te, the atom temperature Ta, the electron number density ne, the ground-state atom population n1, the plasma column radius R and the escape factors Lambda mn and Lambda m, characterizing the non-equilibrium plasmas under consideration. The numerical modelling presented yields reliable information on the populations in the excited levels and on the validity of the so-called 'close to LTE concept' and the occurrence of an ionizing or a recombining regime in the locations investigated. The effect of the changes in the discharge parameters Te, Ta, ne, R and Lambda 1n on the excitation mechanisms, together with the role played by the inelastic atom-atom collisions and by the recombination flow of electrons from a continuum, are also shown.