Hybrid microwave-DC discharge in nitrogen at reduced pressures

The hybrid nonuniform microwave-DC discharge in nitrogen at pressure $1$–$15$ Torr is studied by the method optical emission spectroscopy with spatial resolution. Discharge is ignited between the microwave powered antenna and grounded disk electrode placed at the distance of $2.5$ cm from antenna. Antenna was positively biased relative to the grounded electrode. The ratio of the intensities of the nitrogen band at $337$ nm and the emission of the ion band at $391$ nm is used to determine the microwave field strength. Second positive system of nitrogen emission prevails over others in near antenna region. Emission of the first negative nitrogen ion system has the highest intensity near flat electrode. The vibrational distributions of nitrogen molecules and their dependence on direct current and position between antenna and grounded electrode are determined.