2011 Volume 95 Issue 11 Pages 722-725
The electric characteristics of a magnetic-coupling-type electrodeless discharge lamp are investigated. The discharge tube of the lamp is a hollow cylinder, and a magnetic path made of a ferrite core passes through the tube. A high-frequency power voltage is applied across an excitation coil wound around the core through a capacitor. The operating frequency is adjusted to the resonance frequency of the circuit. The light emission from the lamp and magnetic loss are measured as a function of the number of excitation coil turns. The resonance frequency and light output from the lamp decrease with increase of the number of coil turns, while the coil input power shows nearly constant characteristics. The light output decreases with the number of coil turns due to increment of magnetic loss. The eddy current loss in the magnetic material is independent of the operating frequency, but the hysteresis loss that comprise a large part of the magnetic loss around 150 kHz increases with decrease of the operation frequency. These results show that higher frequency is preferable for operating an inductively coupled electrodeless lamp with a magnetic core.