Diagnosis of atmospheric pressure low-temperature plasma parameters is of great significance to study the mechanism of plasma discharge and promote research in related application fields. For example, accurate and effective measurement of the molecular rotational and vibrational temperatures of gas discharge plasma can be used in many fields such as plasma spraying, plasma medical treatment, and aerospace combustion technology. The research content of this paper focuses on the diagnosis of plasma molecular temperature parameters in atmospheric pressure. Taking the needle-plate air discharge as an example, the plasma discharge emission spectrum data is obtained by a high-precision spectrometer, and the second positive system of nitrogen molecules (C³Π_u-B³Π_g) is calculated and analyzed by the optical emission spectroscopy, which aims to study and analyze the temperature parameter characteristics and internal mechanism of gas discharge plasma under different experimental conditions. In the experiment, the similarities and differences of plasma temperature parameters in different discharge states generated by positive and negative DC power supplies with different needle-plate distances are compared and analyzed. At the same time, in view of the low efficiency of manual fitting of emission spectra, we build a spectral data set using Python script and use the grid iteration method to achieve high-efficiency fitting of temperature parameters. The content of this paper is of great significance for promoting the research of plasma discharge mechanisms and the development of related application fields.

Plasma;temperature diagnostics;discharge mechanism;emission spectroscopy;needle-plate air discharge