ABSTRACT
Absence of electrodes eliminates the 5 to 10 % power loss related to cathode heating and allows for a lower fill gas pressure. Optimization of fill gas pressure gives a 20 % gain in discharge efficacy compared to conventional FL. It makes a discharge efficacy of 120 LPW feasable. Electrodeless lamps can be driven at much higher discharge currents then conventional FL. That opens the way for an increase in light intensity of compact lamps with integrated electronics and makes possible high light output FL lamps that are driven at power up to 1000 W. EMI regulations could be met with proper shielding and filtering. Particular technical solutions for EMI reduction are usually feasible although they require ingenuity from lamp designers. Thermal management is the major concern of the lamp designers. Electrodeless lamps have the same temperature restrictions as the conventional FL. Only 20 - 30 % of the lamp power is converted to visible light, the rest 70 — 80 % goes into heat. Electronic ballast dissipates around 10% of the delivered power; so about 85 % of the system power goes in to heat. That puts restrictions on the lamp size and limits its lifetime. • The temperature of the induction coil of 'Ho(lister' lamp (the lamp with the inductor placed
into a re-entrant cavity) reaches 300 °C. At this temperature estimated life of the lamp is only few thousands hours. To insure long life (60.000 hours) the temperature in the re-entrant cavity should not exceed 170 °C.
