Features of the plasma-channel formation during the voltage generator with the 1-MV/ns-voltage-rise-rate discharge to the vacuum axial line containing either closed via microconductor or open-ended gap

We experimentally established the role of electrodynamic processes in plasma channel formation during the high-voltage source with voltage rise rate of about ~1 MV/ns discharge to the coaxial line containing an inter-electrode gap, which is either open-circuited or enclosed with 5 mm long microconductor. Using the Faraday cup (both being unscreened and shielded with 10 mm thick organic glass plate) the transversal current I_t was measured. We established that during first 50 ns I_t is defined by voltage variations in time and plasma channel volume charge variations, and on times exceeding 500 ns - by particles and plasma flows. The comparison of I_t waveforms, acquired in air open-circuited gap experiments with the Faraday cup either staying unscreened or being shielded, shows that the current, observed at long times-scale, is defined by the particles flow from the expanding plasma, resulting from the electric explosion of either whole wire or just its surface-layer.