Characterization of high-current pulsed arcs ranging from 100--250 kA peak
In this paper, we present the laboratory study on three experimental setups that produce a free arc channel subjected to the transient phase of a lightning current waveform. This work extends the high-current pulsed arc characterization performed in previous studies for peak levels up to 100 kA. Eleven high-current waveforms with peak value ranging from 100--250 kA with different growth rates and action integrals are studied, allowing the comparison of different test benches. These waveforms correspond to standard lightning ones used in aircraft certification processes. Hydrodynamic properties such as arc channel evolution and shock-wave propagation are determined by high-speed video imaging and the background-oriented Schlieren method. The arc diameter reaches around 90mm at 50 $\mu$s for a current of 250 kA peak. Space- and time-resolved measurements of temperature, electron density and pressure are assessed by optical emission spectroscopy associated with the radiative transfer equation. It is solved across the arc column and takes into account the assumption of non-optically thin plasma at local thermodynamic equilibrium. For a 250 kA waveform, temperatures up to 43000K are found, with pressures in the order of 50 bar. The influence of current waveform parameters on the arc properties are analyzed and discussed.