Linear-field plasma jet arrays excited by high-voltage alternating current and nanosecond pulses

Abstract

Atmospheric pressure plasma jet arrays can expand the treatment dimension of a single jet to large scales effectively, and the arrays with a good downstream uniformity have a great potential for applications in the materials surface treatment and biomedicine. In this paper, a linear-field jet array with a ring-ring electrode structure in Ar is excited by alternating current (AC) and nanosecond (ns) pulse voltage, and the characteristics and downstream uniformity of the array and their dependence on the applied voltage and gas flow rate are investigated and compared through optical, electrical, and Schlieren diagnosis. The electrical and hydrodynamic interactions between the jets in the array are analyzed and discussed. The results show that the ns pulse excited jet arrays can generate relatively large-scale plasma with better uniformity, longer plumes, and higher intensity active species with a higher energy efficiency than the AC excited ones. No visible deviation of the plume and gas flow trajectories in the light emission and Schlieren images is observed for the ns pulse excited arrays. On the other hand, deviation of plume trajectories is shown to depend on the applied voltage and the gas flow rate for the AC excited arrays. The shorter duration of the interaction of the ns pulse excited jet arrays compared with that of the AC excited jet arrays results in the weaker effects of the Coulomb repellence force and the gas heating, which helps to maintain the uniformity of jet arrays. The reported results can help to design controllable and scalable plasma jet arrays in the economic Ar with good uniformity and higher energy efficiency for material surface and biomedical treatments.