Electric lamps high-pressure sodium

Niobium is used as a substrate for platinum in impressed-current cathodic protection anodes because of its high anodic breakdown potential (100 V in seawater), good mechanical properties, good electrical conductivity, and the formation of an adherent passive oxide film when it is anodized. Other uses for niobium metal are in vacuum tubes, high pressure sodium vapor lamps, and in the manufacture of catalysts. 

Electrical Niobium is finding growing use in components for high-pressure sodium lamps. 

In this review of the high pressure sodium lamp, emphasis is placed on evidence concerning the interaction of resonantly excited sodium atoms with sodium, mercury or xenon atoms, which modifies the spectral radiance of lamps to improve the color or efficacy. The influence of mercury and xenon buffer gases on tne thermal and electrical conductivities and hence on lamp efficacy are also indicated. 

Lemington H.26X., made by the General Electric Co., is a very hard borosilicate glass of high softening temperature. Tte Mg point is 780°C. It is used in high pressure mercury vapour lamps. The linear expansion coefficient is 4-6 x 10 from 20 to 580°C. Sodium and potassiiun are absent and alumina is present in quantity in this glass. 

The Na D emission can be efficiently generated by an electrical discharge through sodium vapor and so such lamps are used for high-power illumination. But some people find the intense yellow color uncomfortable. The solution use a high-pressure lamp so as to shift the emission toward the red, as we discuss below. 

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