On the Velocity-Current Relation of Positive Leader Discharges

Abstract

The velocity-current relation of positive leader discharges is of great importance in the research of lightning physics. However, the measured data in a wide range of current up to several hundred amperes are not available so far. To fill the gap, experiments on positive leader discharges in long air gaps under lightning impulses were carried out on the test site at an altitude of 2.1 km. The velocity and current of positive leaders were measured with the synchronized discharge current and high-speed video frames. An empirical formula for the velocity-current relation of positive leaders is given with the leader current up to 500 A. The measurements are also compared with the numerical simulations, and it is suggested that the initial tip radius of a propagating leader grows as the leader current increases.