Single ended arc discharge vessel with a divider wall

摘要

A single-ended arc discharge vessel (10) for a metal halide lamp includes a U-shaped arc discharge chamber (12) that has two juxtaposed subchambers with a divider wall (28) therebetween and a passageway (30) around the divider wall (28) that connects the two subchambers to each other. The vessel (10) has two parallel electrodes (14) in a same end (16) of the vessel (10) that is opposite the passageway (30). Each of the electrodes (14) extends into a respective one of the two subchambers a distance less than a height of the divider wall (28) so that the arc discharge (24) between the electrodes (14) is U-shaped. This arrangement moves the vessel cold spot away from the electrodes (14) to permit higher operating temperatures and increases arc gap length for a given vessel size to permit a higher lamp voltage.