Plasma temperature determination based on the spectral lines intensity ratio: application in MDECR plasma

Plasma diagnostics is a crucial field for understanding and analyzing plasma properties, employing various techniques to determine the most important parameters such as electron temperature, density, and energy level distribution. Among these techniques, Optical Emission Spectroscopy (OES) is distinguished by its simplicity and cost-effectiveness. This study focuses on the OES line Ratio Method, which relies on measuring the ratio R, defined as the intensity ratio of two spectral lines that are directly linked to the electron temperature and energy distribution. The study identifies a critical constant C, which represents a critical value of the intensity ratio; its value indicates the degree of equilibrium. Furthermore, the method demonstrates its ability to identify population inversion, which is important in laser studies. Our study shows that the OES line ratio method is used to determine the electron temperature only in the case of R << C. The findings reveal that the temperature values obtained using this method align with those calculated through other approaches, such as the Boltzmann Plot Method, or those measured using Langmuir probes, confirming the method's reliability in diagnosing low-density, low-temperature plasma. We applied this method to the measurement of electron temperatures in the MDECR plasma, which were found in the range ( ) for argon. This result is comparable to those obtained by other methods, such as the Boltzmann diagram method ( ) or those obtained by other instruments, such as the Langmuir probe ( ).