Characteristics of a kHz helium atmospheric pressure plasma jet interacting with two kinds of target

This study investigates the influence of two types of target, skin tissue and cell culture medium, with different permittivities on a kHz helium atmospheric pressure plasma jet (APPJ) during its application for wound healing. The basic optical–electrical characteristics, the initiation and propagation and the emission spectra of the He APPJ under different working conditions are explored. The experimental results show that, compared with a jet freely expanding in air, the diameter and intensity of the plasma plume outside the nozzle increase when it interacts with the pigskin and cell culture medium targets, and the mean velocity of the plasma bullet from the tube nozzle to a distance of 15 mm is also significantly increased. There are also multiple increases in the relative intensity of OH (A²Σ → X²Π) and O (3p⁵S–3s⁵S) at a position 15 mm away from nozzle when the He APPJ interacts with cell culture medium compared with the air and pigskin targets. Taking the surface charging of the low permittivity material capacitance and the strengthened electric field intensity into account, they make the various characteristics of He APPJ interacting with two different targets together.