Topical phenomena observed in a short-gap atmospheric discharge using rotor and post electrodes

In order to eliminate electromagnetic interference due to a short-gap discharge, the dependency of light emission, discharge structure, and current waveform on the rotation speed of the rotor, gap length, electrode configuration, and polarity is analyzed. Preliminary measurement of electromagnetic radiation (EMR) levels and their spectra were carried out, and the relationships between the EMR level, the discharge structure, and the pulsative discharge current were determined using a pair of rotor (anode) and post (cathode) electrodes. It is shown that the cathode spot jumps on the post surface along the direction of rotation of the rotor, resulting in current steps. A combination of needle rotor and needle post gave the smallest EMR level. When the rotation speed of the rotor exceeded 1500 r/min, or the value of resistance was around 500 k ohms, a high-frequency noise component arose in the current wave form, but the EMR level due to this component was slight.