ELECTRICAL AND LIGHT CHARACTERISTICS OF RF-INDUCTIVE FLUORESCENT LAMPS

The authors have measured the external electrical characteristics (RF voltage, current, and phase angle) and the relative light output of in ductively coupled fluorescent lamps driven at 13.56 MHz in a range of RF power levels between 9 and 37 W. The experiments have been carried out using glass envelopes having a spherical external shape with a re- entrant cylindrical cavity in the center. Measurements were taken of r eentrant cavities of different diameters and of exciter coils having a different number of turns. RF-lamp power, power transfer efficiency, relative LPW, and effective RF field in the plasma have been inferred from measured electrical and light output characteristics. The conditi on of maximum RF power transfer efficiency to the plasma and the condi tion for maximum RF-lamp LPW were found for different lamps. The resul ts of these measurements can be used in optimizing RF-driven inductive ly coupled fluorescent lamps and RF power converters needed to drive t hese lamps.