Development of an Ion Measuring System for AC Corona Discharge

Abstract

A simple and useful ion measuring system for AC corona discharge is developed to understand the fundamental mechanism of the charge neutralization process. The ion measuring system consists of ion trapping plate, capacitors, and a buffer circuit op-amp. The voltage of ion trapping plate is divided by the capacitors and the voltage is measured by the op-amp buffer. The frequency response of ion measuring system is evaluated using a plate electrode faced to the ion trapping plate separated by a gap. The ratio and phase shift between voltages on the plate electrode and ion trapping plate has a constant value with the frequency lower than 10 kHz. The ion generated by corona discharge is measured using a needle-to-ring electrode. The voltage on the ion trapping plate induced by the high voltage applied to the needle electrode is almost rejected by voltage on a metal rod placed near the high voltage cable. The increase of voltage on the ion trapping plate caused by ion flows into the plate is observed. The charge flows into the plate and the ring electrode for a half cycle are estimated to be approximately 0.32×10^-9 C and 1.1×10^-9 C, respectively.