Formation of Wide Streamers during a Subnanosecond Discharge in Atmospheric-Pressure Air

Corona with Streamers in Atmospheric Pressure Air in a Highly Inhomogeneous Electric Field

“…However, their formation dynamics at such frame durations was untraceable. We think that it is similar to what is ob-served at voltage pulses of tens of nanoseconds [32] . With a frame duration of ∼10 ns and shorter, the emission intensity of negative streamer was insufficient for its identification, though the total emission intensity at the negative needle, compared to the positive one, was higher due to higher streamer formation rates (Figure 7).…”

“…1a at 2 kV is higher than 0.4 MV/ cm. This value is of the order of the electric field at pointed electrodes in nanosecond pulsed diffuse discharges formed by wide (ball) streamers [28,31,32] . Hence, similar mechanisms can be expected for discharges from sharp points at rates of voltage rise of <10 6 V/s and >10 12 V/ s. The rates >10 12 V/s correspond to diffuse discharges involving fast and runaway electrons at negative voltage polarity [33] and X rays at positive polarity [34] .…”

“…Such streamers propagated from needle electrodes with a tip radius of tens of microns at a slowly rising voltage [20,30] . Note that in some studies [31,32] , such streamers produced by nanosecond voltage pulses were termed broad or wide, and they were really wide, reaching 8 cm in diameter at high rates of rise of voltage (dU/dt > 10 14 kV/ns).…”

Electric streamers as a nonlinear instability: the model details

“…The dependence on field and correlation with velocity in our results presented in Figure 6a and 6b agree with the above-mentioned experimental trends [44]. Radii for negative streamers are obtained to be larger than those of positive streamers (compare Figures 7b and 6b), in agreement with experiment [46].…”

“…Very wide diameters, 1 cm were measured by Tarasenko et al [46], for both positive and negative streamers. The negative streamers have larger diameters for the same conditions (geometry and voltage), as seen from comparison of their Figures 4 and 5.…”