Various highly loaded arcs

The series presented here shows the structure of arcs burning in various atmospheres, resulting in different color patterns. All these lamps are based on the Philips MSR 200 W burner, characterized by a 5-mm electrode gap length and filled with a mercury dose resulting in a 30-bar buffer pressure during operation. Except for one, these lamps are all filled with a single metal halide additive of the type usually used in metal halide lamps intended for sport, stage, and studio lighting applications. From left to right we have:

Top - no additive, mercury iodide (HgI2), mercury bromide (HgBr2), cesium bromide (CsBr), cerium bromide (CeBr3)

Bottom - cerium iodide (CeI3), dysprosium bromide (DyBr3), dysprosium iodide (DyI3), thulium bromide (TmBr3), manganese iodide (MnI2)