Polarity-induced asymmetric effects of nanosecond pulsed plasma jets

Low energy, nanosecond pulsed, bullet-like plasma plumes are generated with a concentric, tubular electrode-based device energized by unipolar +/-6 kV, 140 ns pulses. The plasma plumes consist of ionization fronts propagating away from both electrodes at speeds of the order of 107 cm s-1, indicating photoionization may dominate the plasma formation and propagation process. The polarization of the transient electric field near the device nozzle exit affects the dynamics of the plasma plumes, resulting in differences in the plume length and propagation velocity. Although closely analogous to typical streamers, the plasma 'bullets' maintain unique characteristics in plasma initiation and formation.