電流零点前の真空アークから拡散する荷電粒子電流の測定

概要

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Particles diffused from vacuum arc can be used for thin film formation. Diffusion of particles from vacuum arc influences current breaking properties of a vacuum interrupter. For these application it is essential to clarify the behavior of particles diffused from vacuum arc at around current zero point. In this paper dependence of diffused charged particles current on the crest value of arc current before current interruption point was shown with Faraday cup in case of oxygen-free copper electrodes and CuCr (Cu:Cr=50:50) electrodes. Experimental results were as follows. Ions and electrons diffused from vacuum arc entered into the Faraday cup with pulsive and intermittent states, when vacuum arc of DC 100 A∼150 A was generated in case of oxygen-free copper electrodes. This phenomenon corresponds to the behavior of cathode spots. Electron current value was about 100 times as large as ion current value. The pulse width is about 1∼10μs. When the crest value of arc current were 2,000 A∼10,000 A in case of oxygen-free copper electrodes and CuCr (Cu:Cr=50:50) electrodes, the amount of charged particle current for CuCr before the current interruption point was larger than those for Cu. The ratios of the ion current to the electron current diffused from vacuum arc were calculated by the waveforms of electron and ion currents. The current ratios of 0∼0.02 were taken when the crest value of arc current 2,000 A∼10,000 A.
2010-09-01