Мicrochannel structure parameters in the initial phase of a spark discharge in a tip–plane gap in atmospheric-pressure air

The results of studying the initial phase of a spark discharge microstructure formation in a tip–plane gap 1.5 mm length in air are presented. Measurements show that, within 15 ns after breakdown, the channel is an aggregate of a large number of microchannels, the current in the channel rises almost linearly to a value of 1 kA, and the electron density reaches 2 $\times$ 10$^{19}$ cm$^{-3}$. Calculations of the kinetics of processes in a separate microchannel taking into account experimental data have been carried out. It has been found that the average electron temperature ranges from 4 to 8 eV, the electric field strength is $\sim$300 kV/cm, and electrical conductivity is $\sim$10 $\Omega^{-1}$ cm$^{-1}$. The results obtained show that it is the discharge microstructure that causes relatively high values of the average electron temperature along with a sufficiently high ionization degree.