Fine structure of streamers

Abstract

Measurements have been carried out with a fast photomultiplier on a unique streamer in a point-plane gap in atmospheric air (positive direct tension applied to the point). Three different kinds of experiments have been done: streamer heads statistics as a function of applied voltage; streamer propagation in weak applied field; and streamer head characteristic dimension for which the value obtained is about 170 mu m.

Measurement of the electron density in Transient Spark discharge

“…After the Abel inversion, we found that the diameter of the streamer is ~155 μm. This agrees with the results of Gibert, et al [15] or Van Veldhuizen, et al [16] who also applied optical emission measurement. However, it is much larger than the streamer diameter 40 μm measured by Bastien, et al [17] who measured it from the broadening of H lines that is related to the current density, so it may be closer to real plasma "electrical" diameter.…”

Investigation of Discharge Dynamics and Chemical Kinetics in Microdischarges Generated in Nanosecond Multipin‐to‐Plane Pulsed N2/O2 Corona Systems

“…The optical microdischarge average diameter obtained from this picture is around 200 µm. Although this value is in the upper limit of the streamer diameter estimates generally published in the literature, it is in good agreement with values reported in refs 17, 37. The picture also indicates that the streamer bridges the electrode gap in less than 50 ns (the exposure time corresponding to this picture), a value that represents an upper limit of the streamer phase duration.…”

Reply to comment on `The role of photoionization in positive streamer dynamics'

“…Gibert and Bastien [19] reported the value 0.017 cm for the measured optical streamer diameter in air. As discussed above, l ρ defines the optical radius of the streamer.…”

“…In our notations the Penney and Hummert expression for S ph2 [15] is S ph2 = S i1 ψ air (pr θ )hp dθ (19) where ψ air (pr θ ) is the absorption function, tabulated in [15]. Equating (19) and (18) yields the relation between f and ψ air…”

“…The fit (22), however, overestimates the total rate of photoionization. Integrating (19) over the solid angle with ψ N2 = 1 and ph = 1 yields S ph2 = 4πS i . Physically this result is unrealistic: the rate of photoionization cannot exceed the rate of collisional ionization.…”