Toshinori Tsuji

Basic study on acoustic noise of polluted insulator and waveform analysis method

A partial discharge appears when the surface of a transmission line insulator is polluted by an adhesion of a sea salt. A corona noise is made due to the occurrence of the partial discharge on the insulator. The purpose of this research is to develop a monitoring system of the corona noise. To develop the monitoring system, we must investigate the relationship between the corona noise level and the polluted condition of the insulator and establish the measurement technique of the corona noise. This paper describes mainly about the characteristics of the corona noise waveform and the detection of the corona noise from the measured sound in the outside. As a result, we found that the frequency band of the corona noise generated by the partial discharge was 1 kHz - 6 kHz and the corona noise could be extracted in the band of 1 kHz - 2 kHz from the analysis using FFT and wavelet transfer. The occurrence of the partial discharge took an influence in the atmospheric humidity from the analysis of the measured corona noise near the transmission tower.

Basic study on discharge induction by laser‐produced plasmas in atmospheric air

To clarify the characteristics of the discharge induction against the delay time of impulse application with a long gap/1/, the electron and neutral particle density in the plasma were measured. The electron density was about 1023 m−3 at 10 μs after firing the laser and then gradually decreases in several tens of microseconds. The rarefied air region of lower neutral particle density takes a spherical shell profile in later stages after firing the laser. From the experiments of the laser‐induced discharge, it seems that the discharge induction was greatly influenced by the electron attachment to oxygen molecules and rarefied region of the neutral particle density.