AC ignition of HID lamps –statistical and formative lag times

Noble gas discharges are typically used in lighting applications, under a very large range of conditions. A lot of modelling and experimental work has already been done in order to describe the starting behaviour of lamps. Focusing on high-pressure systems, high voltages needed for the ignition of lamps pose a problem. The purpose of this work is to examine the mechanisms of AC lamp ignition, which was already proven to be efficient in lowering HID lamp ignition voltage. More specifically, we use electrical measurements and observe the discharge by means of iCCD imaging to determine the lag times associated with AC lamp ignition. We use sine voltage with frequencies ranging from 60 kHz to 1 MHz, with various rise rates of the voltage amplitudes. Lamps we use are standard 70 W Philips burners, filled with 0.3 or 0.7 bar Argon or Xenon. We find that the statistical lag times in the system can be as long as 0.15 s and that they are at least two orders of magnitude longer than formative lag times.