J.M. Gonzalez-Carmona1, J.C. Arroyo2, S. Martínez2, L. Cordova-Castillo1, A. Ruden2
1Centro de Ingeniería y Desarrollo Industrial, CIDESI-Querétaro, Querétaro, México
2Universidad Tecnológica de Pereira, Risaralda, Colombia
In the present work, the study and quantification of the parameters of argon plasma in a reactor during a plasma cleaning (PC) process was performed, using an AISI M2 steel cathode. Argon plasma assisted by AEGD was generated inside a reactor at a pressure of 1.0 *10-2 mbar and a temperature of 650 °C. The measurement of plasma parameters during PC was carried out using a HORIBA iHR320 OES spectrometer with a 1200 g/mm diffraction grating and implemented with a Langmuir probe with a surface area of 25.25 cm2, collecting data in real time from the plasma and its temporal evolution (15 minutes). During the CP, the mentioned parameters were kept constant. The quantification of the plasma parameters was based on the kinetic theory of gases, considering local thermodynamic equilibrium (LTE), using the Saha Boltzmann equations to determine the temperatures and electronic densities. During this quantification, an application was developed in Python programming language to process the spectra, performing web scraping to obtain the electronic transitions of Ar from the NIST database, identifying the different spectral lines coincident with the experimental spectra of Ar. Two methods were defined for the calculation of electron temperature (ET) and electron density (ED): the first, considers consecutive spectral lines and the second non-consecutive spectral lines. Similarly, an application was implemented to the analysis of current-voltage curves with a variable probe potential between -30 V and 30 V, processing and identifying the saturation regions for the calculation of the ET and ED. The plasma parameters obtained by OES and Langmuir differ, probably due to the plasma region analyzed, given that the probe is located at the opposite end of the reactor, considering that the optical fiber for OES points to a different place. On the other hand, the ED in the spectrometer area is lower than that of the probe, while its ET is higher than that detected by the spectrometer. Additionally, it is concluded that, despite the variations in ET in different areas of the plasma, there is a balance proven by the calculated values. The success of plasma in maintaining balanced ET changes is highlighted, evidenced by the positive results in the data analysis to verify if the plasma is in LTE. Finally, electronic temperatures of 1-2 eV and 2-4 eV and electronic densities between 0.5 and 2.0) * 10-21 cm-3 and between 0.5 and 1.0 * 10-14 cm-3 were obtained for the OES method and Langmuir probe respectively.