Experimental approach to high-pressure sodium lamp design

Abstract

The paper describes a concise experimental procedure for the rapid design of any new rating of lamp, with particular emphasis on low power lamps. Information, in some cases obtained from 400 W lamps, has been used to reduce the number of free variables associated with the design of a lamp from 11 to three. Experiments in which the amalgam temperature is altered in an indium bath are carried out to optimize the lamp and ballast simultaneously. Nine such experiments give six possible designs for any new rating of lamp, and fix the ballast impedance needed for correct operation. From these six designs, one lamp may be chosen to satisfy best the main criteria of good colour, long life, high efficacy, ease of manufacture and commercial considerations.