The radiation characteristics of high-pressure sodium lamps were examined by changing the bore and input power of an arc tube:
(a) Increase of the bore results in a better color rendition. This is the same effect as is observed with an increased sodium vapour pressure.
(b) In case the input power is kept constant, the lamp efficacy drops with an increase of the bore. However, in case the wall loading is maintained constant, the efficacy scarcely depends on the bore, since it rises with an increase of the input power.
The individual factor determining the lamp efficacy was studied through the theoretical analysis of the phenomena in an arc tube. Relationship between each factor and the three discharge parameters, viz., the bore, input power and vapour pressure, has been clarified as follows:
(a) The radiant power P
r (W·cm
-1) is determined only by the input power P
in (W·cm
-1) through the equation P
r=0.78 (P
in-6.7) in a translucent alumina ceramic tube; where the above 0.78 and 6.7 correspond respectively to total transmittance of a light path and thermal conduction loss per unit arc length Pc (W·cm
-1).
(b) The visible component of the radiant power and the luminous efficacy of the radiation depend on the three discharge parameters; they drop with an increase the bore and the vapour pressure, and rise with increase of the input power.
抄録全体を表示