  This paper demonstrates and studies helium atmospheric pressure plasma jet
comprised of series of repetitive streamer breakdowns, which is driven by a
pure DC high voltage (auto-oscillations). Repetition frequency of the
breakdowns is governed by the geometry of discharge electrodes/surroundings and
gas flow rate. Each next streamer is initiated when the electric field on the
anode tip recovers after the previous breakdown and reaches the breakdown
threshold value of about 2.5 kV/cm. Repetition frequency of the streamer
breakdowns excited using this principle can be simply tuned by reconfiguring
the discharge electrode geometry. This custom-designed type of the helium
plasma jet, which operates on the DC high voltage and is comprised of the
series of the repetitive streamer breakdowns at frequency about 13 kHz, is
demonstrated.
