An analysis of highly synchronized and space-and-time resolved nitrogen FNS and SPS emission temporal waveforms produced by the repetitive DC streamer corona

Different experimental characterizations have been obtained when studying the primary streamer of the repetitive positive DC streamer corona in short air gap. The nitrogen first negative (FNS) and second positive (SPS) emission temporal waveforms have been recorded with high cross-correlated synchronization (not worse than 0.1 ns) and spatiotemporal resolution (around 0.01-0.1 mm and 0.2-0.8 ns). Absolute values and the ratio of the synchronized temporal waveforms of the SPS to FNS (0,0)-bands, the ratio of their altitudes and total emission power for both waveforms have been taken into account to determine peak values of the electric field and the electron number density within streamer head, which have been found to be 450-500 Td h (2-3) times 10¹⁴ cm^-3. For treatment of experimental results, the method has been applied that combines a spectroscopic technique and self-consistent parametric axially symmetric 2D model of the filamentary streamer head. The spectroscopic technique takes into account characterizations of all units of the measuring spectro-optical channel, including spatiotemporal resolution and resolution in wavelength. Chromatic aberration and astigmatism of the focusing lighting lens, errors in focusing the object onto input slit as well as correction of the slit apparatus function at non-uniformly illuminated input slit of the monochromator on width are accounted for as well.