关键词：光机电；传感器；激光波；二维电子
摘 要：Applying external magnetic fields to arc discharges in gas circuit breakers is very helpful for facilitating arc extinguishing process. However, there has never been a report on decreases in arc electron densities under external magnetic fields. Here, 2-dimensional electron density distribution over an arc channel under an external magnetic field were obtained by only a single measurement using a Shack-Hartmann type laser wavefront sensor. The electron densities around a gap centre of about 10~(22)m~(-3) were lower than those without external magnetic fields when an instantaneous current decreased to 20A.