Lichtenberg figures presenting electrostatic discharge patterns at different humidity

Electrostatic discharge (ESD) is a phenomenon that commonly exists on the insulation surface in electrical and electronic devices at different environmental conditions. In this letter, the surface charge pattern of PMMA subject to ESD at the different relative humidity (RH) is presented by Lichtenberg figures. The influence of RH on discharge processes is discussed. The results show that the voltage amplitude, polarity, and the shape of the electrode during ESD all have a significant influence on the surface discharge process. The surface discharge pattern at positive ESD is plum blossom-like while at negative ESD the surface discharge pattern presents a star-like pattern. The ESD process can be suppressed under the high RH condition. The study of this paper provides direct evidence on how ESD process is mitigated at different RH.