FLUORESCENT LAMPS AND LOW-PRESSURE SODIUM LAMPS

The fluorescent and the low pressure sodium lamps are based on the same type of discharge, namely the low pressure metal/rare-gage discharge. Recent advances and possible future developments for both types are considered. For the fluorescent lamp, recent advances include a better understanding of the discharge processes, the introduction of narrow emission band phosphors, the use of more efficient narrower diameter discharges and improvements in the control of the mercury vapor pressure. Future developments include the more general use of electric control gear, electrodeless discharge lamps, and more compact lamps realized, e. g. by using a recombination structure in the discharge vessel. For the low pressure sodium lamp recent advances include a better understanding of the discharge processes, improvements in the thermal insulation of the discharge tube, leading to better arc voltage control, and a modified current waveform leading to an improved combination of lamp and control gear. Future developments are likely to be similar to those for the fluorescent lamp, e. g. a further introduction of electronic control gear, and also further miniaturization.