Level Predictions and Its Reduction Method of Electromagnetic Fields Due to Electrostatic Discharge Causing Electromagnetic Interference to Information Communication Equipment

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The transient electromagnetic fields due to electrostatic discharge (ESD) between charged metals have wide-band frequency spectra up to the microwave region, which cause serious malfunction to high-tech information devices. Such ESD fields are significantly affected by the presence of the metal, whereas the effect is not well understood. The head investigator of this research project previously developed a method for predicting the ESD fields using the finite-difference time-domain (FDTD) technique in conjunction with a spark current theoretically derived from the Rompe-Weizel spark resistance formula, which showed that the presence of the metal enhance the field level according to its dimension. The purpose of this research project is to develop computer simulation codes for the ESD fields based on the above findings, and is also to provide a technique for reducing the electromagnetic interference due to ESD fields. The outline of the results obtained in this research project was as f … More ollows. A spark model between two spherical metals being spaced at a gap was considered. The FDED method was used to compute the electromagnetic fields due to the spark between the metal spheres. Two types of spark gap excitation were investigated to differentiate the Maxwell equations concerning the ESD fields for the FDED computation algorithm. The excitation sources were a spark current and s spark voltage that were both obtained in closed forms from the Rompe-Weiziel formula for a spark resistance. As a result, we found that the current excitation is unable to compute the electric field waveform including the electrostatic field component before the ESD happens, while the voltage excitation modeling was confirmed by wide-band measurement of the magnetic field, good agreement was observed between the results that wave computed by the both excitations. The validity for the excitation modeling was confirmed by wide-band measurement of the magnetic field waveform due to a spark between metal balls. At present, we are constructing a new FDTD algorithm which enables us to predict the ESD fields caused by the spark between charged metals having arbitrary shapes, and also examine the effects of ferrite core attachment in reducing the ESD fields by charged metals. Less