Discharge characteristics of high voltage pulses inside rocks with increasing their applied number

By conducting experiments for granite and sandstone samples under different conditions, such as voltage amplitude and electrodes gap, the discharge characteristics of high voltage pulses inside the rocks with increasing their applied number have been investigated. In each of the experiments, a certain value for voltage amplitude and electrodes gap is set separately and then, pulses are applied on same surface of the rocks continuously. The time dependent voltage between the electrodes, the current in plasma and the transient states around the electrode tips are measured and recorded separately when each of the pulses is applied. By means of the wave forms of the voltage and the current, variation laws of the discharging time and the energy release into the plasma with increasing applied pulses number have been obtained. The relation between the number of applied pulses and the critical condition of discharge inside of the rocks has been found. Further, the relation between the number of applied pulses required to discharge and the voltage amplitude has been also analyzed. The reasons of why increasing applied pulses number has such effects on discharge characteristics of them inside the granite and sandstone samples have been found and demonstrated.