Convection in Vertical Mercury and Metal Halide Arc Lamps

The effects of convection in vertical mercury, mercury plus iodine, and metal halide arc lamps have been studied by experimental and theoretical methods. Primarily axial convection velocities were found which increase in magnitude with decrease in power loading, with increase in pressure, and with arc constriction. Convection velocities, in turn, cause arc constriction near the lower electrode and play a role in additive segregation. No evidence was found for multicellular convection.