Effects of External Magnetic Field on Atmospheric Pressure Air Plasma Jet: An Experimental Study

Atmospheric pressure air is an alternative background gas that potentially can be used to replace the expensive noble gases in developing efficient plasma discharge. However, it is challenging to generate plasma discharge from the atmospheric pressure air due to the unconcentrated radical species produced, leading to the formation of random micro-discharge in the discharge region. In this study, the effect of an external magnetic field on the electrical characteristics of air plasma jets was examined experimentally. The experiments used a configuration of a plasma jet reactor driven by a 12kHz frequency with varied applied voltage from 8.5kV to 9.5kV. The background gas used was atmospheric pressure air. A ring magnet is used with 0.35T radial magnetic field strength and positioned under the ground ring. The results showed that the plasma discharge with a magnetic field has improved in terms of stability and efficiency and reduced the number of micro-discharges compared to the plasma discharge produced without the aid of an external magnetic field. Another noticeable observation is with the presence of an external magnetic field, plasma discharge is generated at 8.5kV compared to the plasma discharge without the aid of an external magnetic field which excited at a higher voltage applied (i.e., 9 kV). It has been discovered that the indirect coupled of magnetic fields to the plasma jet reactor is a convincing technique to enhance the stability and efficiency of plasma discharge, whilst reducing the formation of random micro-discharge of air atmospheric pressure plasma.