Experimental Application of Lightning Currents to a Human Head Phantom

摘要

Lightning is a natural phenomenon in the field of high voltage discharges where high voltages and transient currents occur instantaneously. A lightning strike to the body especially to the head represents the most severe case where it is known that humans may still survive. However, mechanical and thermal damages are identified. In contrast, physiological effects are still not sufficiently investigated. We present a test-setup of a physical head phantom and obtained measurements of currents and voltages during applied discharges. The head phantom consisting scalp, skull and intracranial volume with dielectric parameters equivalent to human tissues. The experiments were carried out by 10/350 u.s impulse current generator using amplitudes of 18 kA and 42 kA (charging voltage of 5 kV and 10 kV). We recorded the following current distribution when initiating discharge: scalp 79-82%, intracranial volume 10-13%, skull about 7%. Within the first microseconds of impulse the current is rapidly increasing. Exceeding certain level and time, a flashover is evolved. The current distribution shifting to: scalp 4-10%, intracranial volume and skull less than 0.1%, flashover 89-96%. The head phantom was used to reproduce the electrical stress to human head assuming direct lightning strike. The high voltage is the result of high current flowing through the head phantom. With certain level of voltage across the head phantom a flashover is initiated leading to an ionized channel with even lower impedance. Current commutation takes place, so the current through the head phantom is reduced.