Mercury vapour lamps doped with iodides - having an upper cold zone to improve efficiency and give a stable arc

摘要

A process is described for stabilising the plasma and preventing the decantation of elements and cpds. introduced into doped high pressure Hg lamps operating in a vertical position. At the top of the lamp a cold zone is created w.r.t. the remainder of the lower wall of the lamp in contact with the plasma by increasing the distance between the upper electrode and the top of the lamp when the lower electrode is sealed normally in the lower end of the lamp. The efficiency, i.e. the ratio of emitted power to electric power dissipated in the discharge, is improved. The arc is stable. The spectral compsn. of the emission is no longer inhomogeneous.