Preliminary Results of Corona Discharge Current Measurements in the Early Formation of Lightning on Tower

Lightning current as one of the most important parameters in the study of lightning physics and lightning protection have long been attended. Previously, due to the lack of suitable current measurement devices, the formation process of several milliampere corona discharges under thunderstorms and the development process of lightning channel up to hundreds of kiloamperes could only be measured separately, and the study of transition from corona discharge to leader process in lightning initiation stage has not been well-addressed. In this study, a 100 V shock tolerated preamplifier with a noise floor as low as 0.55 μV was designed and installed on Shenzhen Meteorological Gradient Tower (SZMGT) with a single 0.25 mΩ coaxial shunt for lightning current measurement. By using this device, we have successfully observed the corona discharges of several hundred milliamperes just before the formation of lightning leaders. The results showed that the preamplifier had achieved a noise level below 10 mA with a shock tolerance up to 220 kA.