Non-equilibrium constricted dc glow discharge in N2 flow at atmospheric pressure: stable and unstable regimes

The experimental results from the study of a constricted glow discharge in turbulent flow of nitrogen at atmospheric pressure are presented. The discharge was induced by a dc high voltage superimposed between pin-to-plane electrodes inserted inside a glass tube of 1 cm diameter. At a low current I < 20 mA it is established that the properties of the constricted glow discharge in gas flow are strongly different from those in gas at rest: the discharge in gas flow exhibits four different current regimes instead of only a single one in gas at rest. One of these regimes corresponds to a spiral twisting of gas flow by the constricted glow discharge. This effect can be used properly in plasma actuators designed for atmospheric pressure flow control. Gas blowing also enables the constricted N2 plasma to be in a strong non-equilibrium state with vibration and gas temperatures of about 6000 K and 600 K, respectively. So, a constricted discharge in N2 flow can serve as a compact and effective non-thermal plasma source useful in the remote treatment of different surfaces.