Correlation Analysis Between Discharge Image Characteristics and Current of the Rod-Plate Gap Under Lightning Impulse

The discharge images with different types could express the discharge process at different angles, which plays an important role in discharge observation. Intensified charge-coupled device (ICCD) image is a key tool for observing and interpreting the fast dynamic discharge process because of the nanosecond scale exposure duration. There are still few analyses of the low-level features in ICCD images of meter-level gap discharge under lightning impulse and research on its correlation with current. Therefore, based on the electron multiplying ICCD (EMICCD), repetitive discharge experiments of the 1-m rod-plate air gap under standard lightning impulse were carried out. Synchronous discharge intensity images with nanosecond exposure time and time interval, discharge current, and voltage were collected. Combined with the analysis of image characteristics and discharge mechanism, the correlation between the longitudinal average light intensity along the rod-plate axis in images and the discharge current was proposed and verified, and the corresponding empirical formula of two parameters above was given and discussed. By analyzing the correlation between image characteristics and current, it is helpful for achieving a quantifiable description of discharge status and discharge characteristics and providing new research ideas for discharge space charge distribution and current monitoring methods.