Studies concerned with improvement of the low pressure sodium discharge lamp

Abstract

In the low pressure sodium-rare gas discharge lamp the generation of light is strongly dependent on the realization of an optimum sodium vapour pressure and optimum plasma conditions within the complete halfcycle of a.c. operation. Various diagnostic techniques will be discussed which give information about the plasma conditions and thus the light generation in the discharge. The influence of the current waveform and magnitude will also be considered. These studies indicate the necessary conditions which must be fulfilled if improvements in lamp performance are to be realized. Finally the application of these results to the improvement of the low pressure sodium discharge lamp and its associated ballast will be described.

Low-pressure sodium discharge lamps

“…Fig. 43 Method of determining the local sodium vapour pressure by measuring local light ouput within one half cycle and comparing the result with a set of characteristics obtained from a similar discharge placed in a heat-pipe thermostat [53] mine the local sodium vapour density in a normally burning low-pressure sodium lamp. To do this, the local light output of such a lamp during one half cycle is measured, and this result is compared with a set of characteristics obtained from a similar discharge placed in a heat-pipe thermostat.…”

“…34 Measured V/l curve for sodium/rare-gas discharge showing its multivalued character [50] -t(ms) Fig. 35 Measured electric field E, electron temperature T e and axial electron density N e in sodium-neon discharge [53] 900 mA, 50 Hz, tube diameter 19 mm, neon pressure 730 Pa, tube-wall temperature 530 K and electron density have also been carried out on a discharge operating on a 50Hz supply [52,53]. Fig.…”

“…Measured lamp voltage and current within one mains cycle[53] a With auto-leakage transformer ballast (sinusoidal current) b With new hybrid ballast (modified current waveform)…”