Effect of external axial magnetic field on a helium atmospheric pressure plasma jet and plasma-treated water

Abstract

Potential in biomedical-related applications by atmospheric pressure plasma-treated water gradually increased recently. In order to enhance the generation of reactive species in atmospheric pressure plasma in regards to liquid treatment, this study aims to investigate the effect of external axial magnetic field on a helium atmospheric pressure plasma jet (APPJ) and plasma-irradiated water. Magnetic field strength up to 2.0 T was generated by an electromagnet in Helmholtz configuration. The dielectric barrier discharge (DBD)-based APPJ is driven by 4.4 slm helium and sinusoidal 30 kHz, 10 kV_pp signals. Plasma was mainly characterized by optical emission where vibrational and rotational temperature was estimated by nitrogen second positive system (2PS), and electron temperature and density by emission intensity line ratio method. Representative reactive species of nitrite, nitrate, and hydrogen peroxide concentration in the plasma-treated water were also quantified. Results of vibrational temperature and electron density showed a first drop then rise trend which partially corresponds to the reactive species in the plasma-treated water. No significant changes were found in rotational temperature, while electron temperature monotonically increased with the magnetic field.