Shock-Tolerated Multi-Range Low-Noise Analog Front End for Lightning Current Measurements From Milliamperes to Hundreds of Kiloamperes

— Lightning current is a fundamental parameter in lightning research. Previously, Rogowski coils and low-resistance shunts were used to measure lightning current down to a few amperes. Higher value resistors were also used to measure corona discharge current at subampere level, but they were unable to record the increasing current of the lightning leader. As a result, the transition from a corona discharge to a lightning leader process has not been well-addressed. To address this issue, we designed a shock-tolerant multi-range low-noise analog front end (AFE) for recording lightning current in the range from milliamperes to hundreds of kiloamperes. Large geometry D-MOSFETs were used instead of current limiting resistors to achieve a noise contribution of less than 0.4 nV/√Hz with a protection voltage of up to 100 V, and a noise density of 1.0 nV/√Hz for the AFE was finally achieved. With the system on a tall tower via a 0.25-mΩ shunt, corona current pulses of around 50 mA were identified using digital signal processing, while it is also able to withstand current pulses of over 220 kA.