抄録
Inductively coupled electrode-less discharge lamps have been developed as new light sources. To operate these lamps, matching networks are used for stabilizing the plasma. However, the design theory of the matching networks for these lamps has not been clearly known. The difficulty comes from the non-linearity of the plasma impedance. In this paper, the matching networks for the inductively coupled electrode-less discharge lamps are theoretically analyzed by means of an equivalent circuit model consisting of the two inductors connected in parallel and in series to the plasma resistance. First, the author took measurement of the input impedance of the electrode-less fluorescent lamp circuit, and confirmed the validity of the equivalent circuit model. Using this model, he analyzed the matching network, and found that an impedance-inverter circuit consists of the matching network and the coil is most preferable for starting and stabilizing the plasma. In this circuit, the plasma current lp is limited by the formula, /lp/<ne/B/, where n is the constant defined by the coil structure, e is electromotive force of the power source, and B is the parameter determined by the circuit. The author also calculated the circuit parameters in the case of a 5-ladder circuit.
