Investigation of a Novel Atmospheric Pressure Microwave Cold Plasma Torch and Its Characteristics

This study proposes a coaxial structure atmospheric pressure microwave cold plasma device that utilizes argon as the main working gas. It achieves stable formation of atmospheric pressure cold plasma jet at low power (<50 W) with a jet length ranging from 1 mm to 32 mm. The paper analyzes the composition of the cold plasma using spectroscopy and investigates its composition changes at different positions along the jet. It also studies the appearance and reaction composition of the plasma filament under different shielding gases. Furthermore, it explores the effects of continuous and modulated microwave power on the length, appearance, and composition of the plasma filament. Finally, it examines the bactericidal effect of the plasma filament on Escherichia coli under various gas conditions, providing a foundation for further application research.