Abstract
The characteristics of inductively coupled electrodeless discharge lamps using a ferrite core are investigated. The discharge tube has a hollow cylinder shape, and a ferrite core with an excitation coil is inserted into the hollow. A voltage is applied across the coil, and light emission is measured at 100-200kHz. The voltage per turn of the coil is constant at about 7V. The luminous efficacy defined by the input power increases with the number of turns and is independent of operating frequency.
The characteristics of the inductively coupled electrodeless discharge lamps are analyzed using the equivalent circuit. The luminous efficacy defined by the discharge wattage is independent of the number of turns. The core loss, which is mostly due to eddy current loss, is nearly constant when discharge takes place due to the constant discharge voltage characteristics, whereas the joule loss in the winding coil decreases with an increasing number of turns. Thus, the efficacy defined by the input power increases with the number of turns of the winding coil.
