A New Plasma Jet Array Source: Discharge Characteristics and Mechanism

A new plasma jet array source is reported, which has two plasma regions: a cylindrical bottle in which plasmas are generated to deposit charged species on the inner wall, and the outside atmosphere in which plasma jets are generated between the small holes in the underside of the bottle and the grounded sample underneath the bottle. Four temporal regions of discharge are found to exist during a voltage cycle, in which the first one has maximal amount of charge transfer but minimal discharge energy. The surface charges supply the seed charge to initiate and sustain the plasma jets, while restricting the intensity of each plasma jet because their amount is limited. Only the surface charges near the underside hole of the cylindrical bottle are possible to participate in the discharge. Therefore, the plasma jets have a good jet-to-jet homogeneity relatively independent of the number of jets and their relative positions, indicating that the plasma jets can be arbitrarily arranged to a large extent. This is an application advantage but with a limitation, i.e., two plasma jets cannot be closer than 2.5 mm, because the surface charge between them will be shunted, and therefore, the plasma jets will be weakened.