Evaluation of Lightning-Induced Transients in Aircraft Using High-Voltage Shock Excitation Techniques

The time history of a long-spark discharge to a simulated in-flight aircraft and the corresponding transient signals induced on an internal wire pair were measured in this study. Three separate induced coupling conditions related to the aircraft/lightning interaction process have been identified, and each condition has been studied. The three laboratory conditions are believed to be analogous, respectively, to (a) nearby lightning, (b) stepped-leader attachment and (c) return stroke discharge. A unique arrangement of high-voltage (long-spark) generators, electrically floating E-field sensors, fiber optic data links and transient digital recorders was used in this study. Using this equipment, high-voltage shock excitation tests have been developed for each condition and have been labeled E-dot, V-dot and I-dot, respectively, since in each case the induced coupling depends upon the time rate of change of the excitation source. This paper describes the test techniques and the experimental studies leading to the identification of the three test conditions.