Effect of O₂ additive on spatial uniformity of atmospheric-pressure helium plasma jet array driven by microsecond-duration pulses

Plasma jet array is a promising device for producing low-temperature plasma at atmospheric pressure. In our letter, the effect of O₂ additive on spatial uniformity of one-dimensional helium plasma jet array is described. The length of the plasma jet in the middle of the array before the injection of O₂ additive is less than that on the edges of the array. However, when a small amount of O₂ additive is injected into the plasma jet array, the length increases and becomes approximately the same as the length of the plasma jets on the edges of the array. The improvement of spatial uniformity of the plasma jet array is due to the enhancement of the Penning ionization in the plasma jets caused by O₂ additive. Too much quantity of O ₂ additive, however, may lead to discharge quenching in the plasma jet array.