Studying the Performance Characteristics of Asymmetrical Electrodeless Induction Lamps

Abstract

The electrical and photometrical characteristics of an asymmetrical electrodeless induction (transformer-type) lamp the high-frequency inductor (RF coupler) of which, consisting of a circular ferromagnetic core and afour-turn induction coil, is placed at one end of a closed-loop discharge tube,are studied. The discharge, having the shape of a closed plasma filament with the length, was ignited in a tube 60 mm in diameter at a frequency of 135 kHz and power in a mixture of mercury vapor (0.0075 Torr) and krypton (0.3 and 0.5Torr). It is found that the power loss in the inductor core decreaseswith increasing the plasma power and the core cross section. The inductor efficiency increased,asymptotically tending to unity, as the lamp power and core cross section were increased. As the plasma power Ppl increased, itsluminous efficacy ηpl decreased from 111 lm/W to 101 lm/W at a rateincreasing with a growth of krypton pressure. The lamp efficacy as a function of lamp power was found to have a maximum,which shifts toward lower values of lamp power with increasing the core cross section and krypton pressure.