Atmospheric pressure plasma jet array in helium driven by microsecond pulses

In order to study the characteristics of a plasma jet array, the discharge was driven by a microsecond pulse generator with 1-μs rise time and 2-μs duration. With a needle-ring configuration, the discharge properties of the helium plasma jet array at different ground electrode positions and repetition pulse frequencies were studied by means of voltage and current measurement and light-emission pictures. The experimental results show that the discharge was initiated at the edges of the plasma jet array at first. With the increase of the applied voltage, the plasma jet occurred in the middle tube, and the plasma jet array was finally formed. When the gap between the ground electrode and the tube nozzle increased, the amplitude of discharge current increased at first, and then decreased (the maximum value was at the gap of 20 mm). With the increase of repetition pulse frequency, the discharge mode changed from filamentary discharge to homogeneous discharge, the discharge current decreased at first, and then remained unchanged.