GEC 60W SLI/H 1

The linear low-pressure sodium lamp is iconic for many reasons, its elaborately designed burner, its double-ended structure, and the fact that its production ceased a long time ago makes it a venerated relic of ancient lighting engineering, an evidence of the level of craftsmanship and detail to attention that once went into the design and production of discharge-based light sources. It is thus always a privilege to see such lamp coming to life, a once usual sight before the technology faded into extinction. The present photo series is thus dedicated to that lamp's legacy by showing different stages of the run-up phase of a GEC 60W SLI/H, first presenting the light color pattern of a cold lamp. It's crescent-shaped burner was designed to increase the discharge surface-to-volume ratio in order to increase the electrons mean energy and minimize optical self-absorption in the sodium plasma, keys to maximize the lamp's performances. In the present case there is no sodium in the vapor phase, so the discharge burns exclusively in the lamp's unique neon-argon-xenon buffer fill, resulting in a bluish light color due mainly to xenon. The plasma conditions at the electrodes are different enough that neon is preferentially excited there, resulting in the characteristic emission of red light.