Development characteristics of plasma channel for rock breaking by pulsed discharge

As a “tool” for rock breaking by pulsed discharge, the development characteristics of plasma channel directly determine the crushing effect. In order to quantify the development characteristics of plasma channels in rocks, a rock breaking test platform of pulsed discharge was set up, and the breaking test of typical granite-tap water combined medium was carried out. The initiation and development process of plasma channels under the action of high voltage pulse were observed by a high-speed camera. Based on the energy balance equation of plasma channel and its development process, the impedance model of plasma channel in rock is established. The measured current and voltage data were used to invert the plasma channel length, channel radius and temperature curve. The calculated value of the channel length is 6.494 cm, and the relative error between the measured value and the measured value is less than $5 \%$. The maximum channel radius is 2.46 mm, and the maximum channel temperature is $3.03 \times 104 \mathrm{~K}$. It provides a theoretical basis for the study of rock breaking mechanism by pulse discharge.