A new method for experimentally determining the electron density (ne) and the electron temperature (Te) in the negative glow of a nitrogen pulsed discharge is presented. It is based on optical emission spectroscopy (OES) and consists of a variation and refinement of relatively similar schemes previously reported for different working conditions by other authors. The bottom line is the measurement of the emission intensities of the (0,0) bands of the first negative system at 391.44 nm and of the (0,2) bands of the second positive system at 380.49 nm.The suggested procedure allows the establishment of the absolute values of ne and Te, as long as one calibration point is provided, such as the electron density at one specific discharge condition. If this calibration point is unavailable, the method nonetheless yields a qualitative dependence of Te and ne. Langmuir probe measurements confirm and validate the OES results for ne, thereby legitimizing the diagnostic technique developed. The interpretation of the results for Te is slightly more complex, and in some circumstances an accurate determination of Te may require further analysis.
In an Ar–N2 discharge, the high excitation transfer from Ar(3P2,0) to N2 produces an overpopulation of the high rotational levels of the bands of the second positive system (SPS), and so the spectra interpretation is not straightforward.
This paper presents a fit function for the SPS bands measured in Ar–N2, which allows us to study the excitation process contributions to the N2(C) level.
The procedure was tested in the negative glow of a pulsed Ar–N2 discharge at a pressure of 2.5 Torr, for different mixture concentrations. In this discharge, through the fitting, it was possible to calculate the variation of the N2(C) densities produced by different excitation processes as well as the variation of Ar metastable density.
In this work, results from two methods for the determination of the Ar(1s y ) densities are compared in an Ar-N 2 discharge. These methods involve measurements of optical emission spectroscopy (OES). The first method (band method) uses the bands belonging to the N 2 (C → B) second positive system, while the second method (branching fraction method) uses the line intensities corresponding to the Ar(2p x → 1s y ) transitions. These techniques were tested in the negative glow of dc discharge and the results show remarkable agreement.
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