Simulation Study on the Self-Sustained Oscillations in DC Driven Glow Discharges at Atmospheric Pressure Under Different Gas Gaps

In this paper,a one-dimensional plasma fluid model is employed to study the selfsustained oscillations in DC-driven helium glow discharges at atmospheric pressure under different gas gaps.Our simulation results indicate that a harmonic current oscillation with tiny amplitude always occur at the onset of instability and transits into a relaxation one as the conductivity of the semiconductor is decreased.It is found that the dynamics of the oscillations are dependent on the gas gaps.The discharge can only exhibit a simple oscillation with unique amplitude and frequency at smaller gas gaps(2 mm) while it can exhibit a more complex oscillation with several different amplitudes and frequencies at larger gas gaps(2 mm).The discharge modes in these current oscillations have also been analyzed.