Spectroscopic study of positive streamer in short air gap

The technique developed for experimental investigations of basic physical parameters has been executed by Amin´s metrological procedure modified for the spectroscopic time-resolved slit method. Relative and absolute luminosity intensities and shape parameters of waveforms of the second positive 2⁺(0, 0) and first negative 1^-(0, 0) nitrogen bands have been measured in a DC cone-to-hemisphere (point-to-plane) positive streamer corona in short air gap at a distance 4 mm from the anode, under gap voltage of 10 kV, gap length of 1 cm, at NTP, with spatiotemporal resolution in the range between 0.7 and 2.0 ns. The following basic physical parameters in streamer head zone of primary streamer wave have been found: the electric field peak amplitude-100 kV/cm, the electron number density-(1-3)·10¹³ cm^-3, the depth of on-axis electric field penetration into streamer body-0.2-0.25·mm, the length of an electric field damping along the outside boundary of the streamer head-1.0-1.5 mm, the radius-0.2-0.25 mm, and the front propagation velocity-2.5 10⁷ cm/s