Clarification of Generation Mechanism on Electromagnetic Radiation from Short-Gap Rotating Electrode

The correlation between discharge structure, current waveform, electrode configuration, and level and frequency distribution of the EMR are discussed by using a pair of rotor(anode) and post(cathode) electrodes with an intent of simulation of a distributor in an automotive ignition system. There are three portions for each revolution of the rotor where the electromagnetic radiation originates; i.e., breakdown, self-suatained, and turnoff portions of the discharge. The EMR due to the breakdown is the strongest in the three. A combination of needle rotor and needle post gives the smallest EMR in various combinations; this is due to the concentration of the electric lines of force at the tip of the rotor.