Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

• Autores: Prevosto, L.; Kelly, H.; Mancinelli, B.R.
• Año de publicación: 2012
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: J Appl Phys 2012;112(6)
• Materia: Current voltage curve; Direct current plasmas; Heavy particles; Ion saturation; Ion saturation current; Kinetic equilibrium; Langmuir probe diagnostics; Langmuir probe measurements; Large deviations; Nitrogen flow rates; Nominal power levels; Nonlocal thermal equilibrium; Radial profiles; Spectroscopic technique; Atmospheric pressure; Carrier concentration; Electron density measurement; Langmuir probes; Plasma jets; Probes; Electron temperature
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min -1. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 × 10 22 m -3, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K. © 2012 American Institute of Physics.
Fil:Kelly, H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.