Measuring the instability of AC arc discharges

A digital approach using a microprocessor has been developed to give accurate values for AC arc discharge instabilities. This case study is based on theoretically interpreting the instability of arcs in terms of an instability factor related to the deviation of instantaneous values of arc voltages from a predetermined average value. A simple AC atmospheric pressure low-power arc discharge simulation circuit is used and the microprocessor-based measurements applied were found to give accurate indications of instability factors at different arc gaps. This article describes the hardware and software aspects of the system, accounts for the results and provides final critical remarks.