On the Formation of Air Striated Discharge Plasma

In this work we present an air discharge stratification phenomenon in DC discharge tube in low pressure. We found that the addition of magnetic field can significantly produce discharge stratification. This discharge stratification was probably attributed to change in electronic dynamics processes, particularly variation in the electron energy distribution function due to the addition of a magnetic field. The number of striations is highly sensitive to the magnetic field configuration, discharge current, and gas pressure. This discharge stratification is considered as one of the manifestation of discharge instabilities [1–3]. These instabilities are usually considered undesirable because they disturb the homogeneity of the plasma column. For instance, for luminescent lamps, this means their failure [4]; for plasma etching in microelectronic industry, they destroy the homogeneity of plasma bulk region, and even affect the key process parameters such as electron energy distribution function and charged particle flux [5]; in particular, for high-power gas lasers, from an engineering point of view, they directly affect the optical pumping process, thus degrade or lose the efficiency of the laser [6]. Therefore, the investigation on the instabilities of gas discharge plasma is of great significance for these practical applications.