Effect of sodium/mercury ratio and amalgam temperature on the efficacy of 400 W high-pressure sodium lamps

Abstract

400 W high-pressure sodium arc tubes containing different quantities of mercury in the sodium/mercury amalgam were placed with one end submerged in a bath of molten indium which controlled the temperature of the amalgam. For a series of different amalgam temperatures the following parameters were measured on 240 V supply: voltage, current, power input, self-reversal width and luminous flux. Information taken from these graphs and replotted as a function of the amalgam composition provided the amalgam temperature and amalgam composition for maximum efficacy at 400 W. A broad maximum was observed with a peak of 116:t 1 tm W- 1 at an amalgam temperature of -640°C with a mole fraction of sodium of 0. 7. Now these optimum conditions have been established, higher efficacies still have been obtained using superior arc tube materials.

Get full access to this article

View all access options for this article.

References

I Schmidt, K. , Proc. 6th lnt. Conf. Ion. Phen. in Gases (Paris ), 3, 323 (1963).

Schmidt, K. , Proc. 7th Int. Coni. Ion. Phen. in Gases ( Beograd), 1, 654 (1965).

General Electric Co. (USA), Improvements in high-pressure saturated vapour sodium lamp containing mercury, British Patent 1 143 452 (1969).

Ozak4 N. , J. Appl. Phys., 42, 3171 (1971).

Mizuno, H. , et al., New high-pressure sodium lamp with higher colour rendition , CIE (Barcelona), p. 71.14 (1971 ).

Kubaschewski, O. ,, and Evans, E. , Metallurgical thermochemistry , Pergamon (1955).

Nesmeyanov, A.N. , Vapour pressures of the chemical elements , Elsevier (1963).