Verification of spark resistance formula for human ESD

Short-gap electrostatic discharge (ESD) events due to charged moving-objects provide a fatal electromagnetic failure to high-tech information equipment. For clarifying the mechanism, it is indispensable to elucidating the initial discharge process or spark process of ESDs. In the present study, with a 12-GHz digital oscilloscope, we measured the discharge current due to collision of a hand-held metal piece from a charged human body, and thereby derived the corresponding discharge voltage. Using two types of spark-resistance formulae proposed by Rompe-Weizel and Toepler, we verified their hypotheses assumed for spark conductivity with respect to charged voltages and collision speed. As a result, we found that both hypotheses are almost valid in the spark process, while they do not hold in the stage after the spark due to the occurrence of different types of discharges like glows and arcs.