“…On the current-voltage characteristic, overheating instability develops on a segment with negative differential resistance under the condition −dU/dI > R b at point B (figure 3), where load characteristic U = U 0 − IR b tangents the currentvoltage characteristic, U 0 -voltage on high-voltage generator. This condition holds for both conductive water [13] and wet sand [18,19]. On the current-voltage characteristic, point A is the voltage onset on high-voltage electrode; linear ohmic segment A−B corresponds to current spreading and heating of near-electrode region, from 0 to 1.4 ms, the voltage slightly drops due to capacitor discharging; point B-overheating instability development; on segment B−C the plasma channel prop agates toward the cathode, from 1.4 to 3.4 ms.…”