Arc root dynamics in the context of lightning strikes to aircraft

Abstract

During lightning strikes to aircraft, there is a displacement of the impacted area on the aircraft’s surface and the dynamic of the arc root is a key to understanding and predicting the damage produced on the aircraft skin. This work aims at studying experimentally this dynamic with a new method of producing sweeping arcs based on a stationary arc and an electromagnetic launcher propelling aeronautical test samples. The experiments are also achieved with a wind tunnel that blows the arc on the test sample for comparison. After a description of the previous experiments of arc root displacement and a distinction between the cathodic and anodic emission processes, this paper characterizes the arc root physical properties with direct visualization through high-speed cameras and electric measurements for different initial conditions. The results are separated by the arc root polarity and discussed to give an insight into the influence of the experimental conditions on the interaction between the electric arc root and the test sample during swept-stroke. It is shown that for a cathodic arc root, the nature of the displacement – continuous or jumping – highly depends on the current level and the speed of the relative motion between the electric arc and the test sample. For an anodic arc roots, the variations of these parameters provoke jumping modes of displacement with different characteristics.

Dynamics of the material ejection in a dipolar arc in continuous regime

“…The Handbook of vacuum arc science and technology [24] describes how some of the voltage signal peaks could be interpreted as brutal arc root displacement events, such as the ones consecutive to the death of a spot. This interpretation of electric arc signal is still relevant as described more recently by Andraud et al [26] where extinction and reattachment are correlated to voltage drops. Recently, a few authors have attempted to simulate electric fluctuations induced by an arc discharge, especially for metallurgical applications.…”