High-resolution measurements of the electric field at the streamer arrival to the cathode: A unification of the streamer-initiated gas-breakdown mechanism

A time-correlated single-photon counting technique was used to verify the formation of a cathode-directed streamer inside the narrow cathode region following the interpulse phase of regular negative corona Trichel pulses in ambient air. A purely experimental approach was used to determine the spatiotemporal development of the electric field during the Trichel pulse rise with an extremely high resolution of 10 $\mu$m and tens of picoseconds. The results confirm the positive-streamer mechanism for Trichel pulse formation and provide supportive evidence for the hypothesis that the formation of a primary cathode-directed streamer occurs always in any streamer-initiated breakdown and prebreakdown phenomena associated with cathode spot formation.

Figure 1

Experimental setup for the $E/n$ determination in TP discharge. The embedded intensified CCD picture was taken with an exposure time of 1 ms. PMT stands for photomultiplier, and TS-SPC for time-correlated single-photon counting module.

Figure 2

Collision frequencies ${\nu }_m\left(U\right)$ and ${\nu }_e\left(U\right)$ for momentum and energy dissipation and the mean free path ${\lambda }_m\left(U\right)$ and the energy dissipation length ${\lambda }_e\left(U\right)$ in comparison with the highest frequency of the electric-field change ${\nu }_f\left(U\right)$ and the smallest length of the electric-field change ${\lambda }_f\left(U\right)$.

Figure 3

(a) SPS and (b) FNS signal distribution in TPs of negative corona in atmospheric-pressure air with a simultaneous current measurement (black line).

Figure 4

Electric-field strength distribution in repetitive TP in atmospheric-pressure air. The values corresponding to $E<3\times {10}^6$ V/m seen for $x<60$ $\mu$m and $t<16$ ns are at the noise level.

Figure 5

SPS signal recording preceding the TP.