  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.
