帯電金属球の接近時に発生する静電気放電に伴う過渡電界の測定

Abstract

メカトロニクス機器等の動作に影響を及ぼす可能性のある電磁波ノイズ源の一つである静電気放電について，帯電物体が接地体に接近しながら静電気放電が発生する場合の火花長，放電電流，過渡電界を測定した．接近速度が速くなると火花長が短くなる傾向を確認した．また火花長が短くなると，放電電流ピーク値は大きく，立ち上がり時間は短くなる傾向を確認した．静電気放電に伴って発生する過渡電界を測定し，火花長が短くなると電界の時間変化は急峻となり，振幅スペクトルは強くなる傾向となった．今回の実験での放電発生源から138mm離れた箇所における電界時間微分の最大値は，放電電流ピーク値，放電電流の時間微分の最大値及び放電電流の時間二階微分の最大値と相関性が認められ，準静電界が優位と考えられた．

Electrostatic discharge (ESD) is one of the electromagnetic wave noise sources which affect the function of mechatronics equipment. Spark lengths, discharge currents and electric fields at the occurrence of ESD were measured when a charged object approached a grounded object. It was confirmed that the spark lengths tended to shorten when approach speeds of the charged object increased. It was also confirmed that peak discharge currents tended to increase and rise times of the discharge current tended to shorten when the spark lengths shortened. Time change rates of electric field tended to become faster and amplitude spectra of the electric field tended to increase when the spark lengths shortened. Maximum values of time change rate of the electric field at 138 mm away from the point where ESD occured correlated with the peak discharge current, maximum values of the time change rate of the discharge current, and maximum second order differential values of the discharge current; quasi electric field was dominant among components of the electric field measured in this experiment.