On the use of the Hα spectral line to determine the electron density in a microwave (2.45 GHz) plasma torch at atmospheric pressure

The electron density of an argon microwave (2.45 GHz) plasma flame generated at atmospheric pressure has been determined by using the Stark broadening of the experimentally measured Hα line emitted by the discharge. The Hβ line was not observable under the experimental conditions of this discharge. Two methods have been employed to obtain the electron density from the Stark broadening of the Hα line. The first used the Gigosos–Cardeñoso computational model that considers the strong broadening of the Hα line by ionic dynamics. Alternatively, a second method based on a calibration of Stark broadenings of Hα and Hβ lines offered a simpler way to obtain the electron density.