A novel method to determine the electron temperature and density from the absolute intensity of line and continuum emission: application to atmospheric microwave induced Ar plasmas

An absolute intensity measurement (AIM) technique is presented that combines the absolute measurements of the line and the continuum emitted by strongly ionizing argon plasmas. AIM is an iterative combination of the absolute line intensity-collisional radiative model (ALI-CRM) and the absolute continuum intensity (ACI) method. The basis of ALI-CRM is that the excitation temperature T-13 determined by the method of ALI is transformed into the electron temperature T-e using a CRM. This gives T-e as a weak function of electron density n(e). The ACI method is based on the absolute value of the continuum radiation and determines the electron density in a way that depends on T-e. The iterative combination gives n(e) and T-e. As a case study the AIM method is applied to plasmas created by torche a injection axiale (TIA) at atmospheric pressure and fixed frequency at 2.45 GHz. The standard operating settings are a gas flow of 1 slm and a power of 800W; the measurements have been performed at a position of 1 mm above the nozzle. With AIM we found an electron temperature of 1.2 eV and electron density values around 10(21) m(-3). There is not much dependence of these values on the plasma control parameters (power and gas flow). From the error analysis we can conclude that the determination of T-e is within 7% and thus rather accurate but comparison with other studies shows strong deviations. The n(e) determination comes with an error of 40% but is in reasonable agreement with other experimental results.