The influence of voltage polarity on the regime of atmospheric-pressure glow discharge operation in flows of atomic and molecular gases

Electrical characteristics of atmospheric-pressure glow discharge at constant currents up to 40 mA in flows of atomic and molecular gases have been measured at volume flow rates varied within 0.5–5 L/min. It was found that the voltage drop on the discharge gap in molecular gases depends not only on the flow rate, but also on the polarity of applied voltage. As the gas flow rate increases, the discharge operation in oxygen and nitrogen becomes unstable and the voltage drop on discharge gap increases by several hundred volts. Both these effects are manifested much more strongly for a positive discharge voltage than for the negative voltage. In helium and argon flowing at a preset rate, the voltage polarity on electrodes does not influence the regime of discharge operation.