Measurements of Electric Field in Atmospheric Pressure Argon Plasma Jet Under Different Active Gas Types and Concentrations by the E-FISH

Low-temperature plasma is being studied in depth for its numerous applications in biomedicine, materials science, environmental science, and chemical engineering. Grasping the non-interventional electric field measurement and diagnostic techniques of plasma is of great significance for exploring plasma mechanisms in biology. This article reports the influence of working gas type (O
2
and N
2
) and concentration on the electric field of an argon plasma jet and presents measurements conducted using electric field-induced second harmonic (E-FISH) technique. The measurement results demonstrate that the electric field intensity of the argon plasma jet initially increases and then decreases with increasing O2/N2 concentration. The maximum electric field intensities of the argon plasma jet mixed with O2/N2 appear at concentrations of 0.1% and 0.7%, measuring 12.76 kV/cm and 13.28 kV/cm, respectively. Analysis of collisional ionization, adsorption ionization, and Penning ionization contributes to the understanding of this phenomenon.