The electrostatic surface discharge (ESD) between a charged thindielectric film on a conductive flat plate electrode and a sphereelectrode that is connected to the plate, and is either covered with anuncharged thin dielectric film or fare, was observed. Discharge currentwaveform, discharge gap length, current risetime, discharge photographs,current peak value, etc. were recorded. The initial charge generation byirradiation with beta-rays or ultraviolet light was not readilyapparent, so that the reproducibility of ESD experiments was not muchimproved. The charging polarity dependence of such a surface ESD betweentwo dielectric films becomes small with increasing film thickness. Thedischarge gap length of an ESD with an 12.5 μm uncharged film on theelectrode reduces to 50 or 70% of that between a charged film and asphere metal electrode. Peak current and transferred charge value ofsuch an ESD also decreases to roughly one-third of that between the filmand the electrode
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